Questo studio ha ricevuto il sostegno della ricerca Initiation Grant (RIG) del Vice Presidente per la Ricerca e lo Sviluppo Economico presso l&#39;Università del North Texas (UNT). Gli autori ringraziano anche KCIS Co. Ltd per sostenere in parte questo studio. Il sostegno da PACCAR Technology Institute at UNT per il successo di questa pubblicazione è molto apprezzato.

1. Progettazione di Experiment <ol><li> Disegnare un modello sacrificale (a struttura reticolare ottetto con un sistema di canale di colata) utilizzando il software progettazione assistita da computer (CAD) come mostrato in Figura 1 e salvare il modello CAD come formato STL. Nota: Il modello sacrificale è un modello integrato della struttura reticolare ottetto con un sistema materozza che verrà poi fusa per colata. Poiché il modello sacrificale comprende sia la struttura reticolare ottetto e il sistema materozza, non esattamente rappresenta l&#39;ottetto traliccio stesso. Viene fornito un file STL del modello sacrificale. Registrare il volume del modello sacrificale fornito dal software CAD, che sarà utilizzato per calcolare la massa metalli &#39;. </li><li> Aprire il disegno CAD del modello sacrificale sul software di stampa 3D collegato a una stampante 3D per la stampa del modello. </li><li> Assicurarsi che la stampante 3D ha abbastanza UV curabile / castable plastica acrilica e un materiale di supporto costituito da una ceranelle cartucce per stampanti. </li></ol> 2. Realizzazione di modello sacrificale <ol><li> Fabbricazione il modello sacrificale costituito dalla struttura reticolare ottetto e il sistema di canale di colata utilizzando una stampante 3D (Figura 2A - C). Nota: I processi in 2.1.3 - 2.1.7 non sono necessarie se si utilizza una stampante 3D che non genera materiali di supporto. <ol><li> Invia un file STL del modello sacrificale alla stampante 3D per stampare un motivo sacrificale (Figura 2A). </li><li> Sciogliere un materiale di supporto del pattern sacrificale in un forno a sopra la temperatura di fusione del materiale di supporto (60 - 70 ° C) per 2 ore (Figura 2B). Nota: La temperatura di rimuovere il materiale di supporto non deve essere troppo elevata. Altrimenti, può causare danni al modello sacrificale. Il modello sacrificale inizia sempre danneggiato a circa 80 ° C in questo studio. Nota: La temperatura di fusione del suppormateriali t varia con le stampanti 3D in cui possono essere utilizzati diversi materiali di supporto. </li><li> Compilare un pulitore ad ultrasuoni digitale con olio per bambini fino a 2,5 L, il volume massimo che il più pulito può contenere (Figura 2C). Nota: E &#39;stato raccomandato dal fornitore della stampante 3D da utilizzare l&#39;olio di bambino per sciogliere i residui del materiale di supporto simile alla cera. </li><li> Mettere il modello sacrificale nella pulitore ad ultrasuoni digitale e accendere l&#39;alimentazione del detergente (Figura 2C). Assicurarsi che il modello sacrificale è completamente immerso nell&#39;olio. </li><li> Rimuovere il residuo del materiale di supporto immergendo il modello sacrificale nell&#39;olio a 65 C per 40 min (Figura 2C). </li><li> Estrarre il modello sacrificale dal pulitore se il materiale di supporto viene completamente rimosso. </li><li> Avere il sacrificale modello asciugare con un ventilatore a temperatura ambiente (~ 20 C) (Figura 2C). Nota: Ci vogliono circa 2 orefinché l&#39;olio sulla superficie del modello sacrificale è completamente essiccata. Si consideri il modello sacrificale per essere completamente secchi se la superficie non è appiccicoso. </li></ol></li></ol> 3. Realizzazione di Mold <ol><li> gruppo di modello <ol><li> Fissare una guarnizione in gomma al modello sacrificale (il traliccio ottetto con il sistema materozza) e disporli sul fondo di un pallone a cilindro con una altezza di 6,35 cm e un diametro di 6,35 cm (Figura 2D). Nota: Preparare due palloni per la fusione di ogni metallo; Al e Cu leghe. </li><li> Doppio controllo la guarnizione di gomma con il modello sacrificale è completamente collegato al fondo del pallone. </li><li> Avvolgere il pallone con un nastro adesivo in modo che la miscela di investimento in polvere-acqua, la cui procedura sarà descritta nella sezione successiva, non può fuoriuscire dal pallone. </li></ol></li><li> Preparazione di stampo Investment <ol><li> Preparare polvere refrattaria (CaSO 4 </sub&gt;, ρ = 1019 kg / m 3) di 89 g, che è 87.16 ml. Usare una scala per pesare la polvere d&#39;investimento. Nota: Le proprietà fisiche della polvere refrattaria sono riportati in Tabella 1. </li><li> Versare la polvere di investimento in una ciotola (1 L). </li><li> Versare l&#39;acqua (114 ml) nella ciotola di miscelazione. Utilizzare un contenitore per misurare il volume di acqua. </li><li> Mescolare la polvere refrattaria con acqua nella tazza per 3 min. Mescolare bene fino a quando non ci sono grumi nella miscela degli investimenti in polvere in acqua. In caso contrario, potrebbe causare una scarsa qualità della superficie di muffe investimento. Seguire la flusso di lavoro, come mostrato in figura 3. </li><li> Al fine di rimuovere le bolle d&#39;aria nella miscela, posizionare la ciotola in una camera a vuoto per 90 secondi fino a quando le bolle d&#39;aria non può essere visto nella miscela con gli occhi nudi (Figura 3). </li><li> Versare il composto in un pallone incorporare il modello sacrificale e la guarnizione in gomma (Figura 2E). </li><li> Posizionare i flask nella camera a vuoto ancora per 90 secondi per rimuovere il residuo di bolle d&#39;aria all&#39;interno della miscela (Figura 3). </li><li> Essiccare la miscela all&#39;interno del pallone fino viene indurito a RT (Figura 3). Nota: Solitamente, richiede circa 10 - 15 min per la miscela di essere indurito a temperatura ambiente. </li><li> Rimuovere la beuta e la guarnizione di gomma nella parte inferiore della miscela nel pallone una volta che la miscela è indurito (Figura 3). Questo prodotto può essere chiamato uno stampo in gesso. </li></ol></li><li> Esaurito <ol><li> Impostare un tempo burn-in forno seguendo il riscaldamento e raffreddamento calendario (Figura 4) riscaldamento da 23 a 150 ° C in 2,1 C / min; 150-370 C a 3,7 C / min; 370-480 C a 1,85 C / min; 480-730 C a 4.17 C / min; 730 C per 1 ora; raffreddamento 730-480 C a -4,17 C / min. Nota: Il tempo per burn-out vari con dimensioni di un pallone. In questo studio, impostare il tempo di burn-out di 6 ore. </li><li> Collocare lo stampo in gesso in un forno (Figura 2F). </li><li> Accendere il forno e aumentare la temperatura nel forno per rimuovere il modello sacrificale all&#39;interno dello stampo in gesso. Seguire la condizione di temperatura in figura 4. Nota: Poiché la plastica acrilica induribile / calcinabile UV, i materiali del modello sacrificale, è una plastica termoindurente acrilico-polimero, non scorre, ma è dissociato ad una fase gassosa nel forno. </li></ol></li><li> Fusione centrifuga (Figura 2G) <ol><li> Verificare che il braccio della macchina di colata centrifuga ruota con una velocità angolare di 425 rpm con un contagiri dopo l&#39;accensione di una macchina di colata centrifuga. </li><li> Preparare due crogioli in ceramica che può contenere un 150 g in lega a sciogliersi. Utilizzare crogioli separati per Al e Cu leghe per impedire loro di essere contaminati da each altro. </li><li> Accendere l&#39;alimentazione della macchina di colata centrifuga. </li><li> Utilizzando un cutter in metallo, tritare le leghe in pezzi con 10 - 20 mm di lunghezza. Preparateli sufficiente per riempire completamente la cavità dello stampo cui volume dovrebbe essere lo stesso come il modello sacrificale. Nota: La massa di metalli necessari per compilare lo stesso volume della cavità di stampo varia considerando densità variabile per ogni metallo. </li><li> Indossare i panni ritardanti di fiamma e guanti e occhiali. Preparare un secchio d&#39;acqua (30 L) a temperatura ambiente. </li><li> Prendere lo stampo in gesso temporaneamente fuori dal forno al punto 3.3, installarlo nella culla pallone e bilanciare il braccio della macchina di colata centrifuga (Figura 5). </li><li> Mettere lo stampo in gesso di nuovo al forno e pre-calore fino a 482 ° C prima del getto. </li><li> Collocare il crogiolo nel supporto crogiolo (Figura 5). </li><li> Mettere la lega tritato nel crogiolo. </li><li> Aprire la valvola di ossigenoserbatoio collegato con un cannello ossigeno-acetilene e mantenere un livello di pressione nel serbatoio di 96,5 kPa (14 psi). </li><li> Accendere il cannello ossigeno-acetilene con un accendino e controllare l&#39;intensità della fiamma regolando la miscela di gas. Nota: Si deve fare attenzione quando si utilizza la torcia di ossigeno-acetilene. La temperatura massima della torcia è di circa 1200 ° C. </li><li> Melt lega tritato (lega di Al o lega Cu) con la torcia nel crogiolo fino la lega diventa completamente liquido. </li><li> Mescolare la lega nel crogiolo con una canna in carbonio fino a quando la lega tritato è completamente sciolto. </li><li> Collocare lo stampo in gesso in culla fiaschetta accanto al crogiolo contenente lega fusa (Figura 5). </li><li> Chiudere il coperchio della macchina di colata centrifuga, lasciare che la rotazione del braccio centrifugo ed attendere almeno per 3 min. Nota: la macchina di colata centrifuga entra in funzione non appena il coperchio della macchina di colata è chiuso. Il braccio centrifugaruota ad una velocità di 425 rpm che corrisponde alla velocità di ingresso nella cavità dello stampo del modello sacrificale, v r = 8.03 m / sec 28, 29 in figura 5 in cui l&#39;ingresso-velocità viene calcolata utilizzando le dinamiche delle particelle macroscopiche da un angolare velocità della colata centrifuga braccio 28, 29. </li><li> Spegnere della macchina di colata centrifuga dopo 3 min rotazione del braccio. </li><li> Aprire il coperchio della macchina di colata. </li><li> Prendere lo stampo in gesso dalla culla pallone usando pinze. </li><li> Mantenere lo stampo a temperatura ambiente per 15 - 20 minuti finché il colore della lega fusa si rivolge a quello originale nella fase solida. </li><li> Utilizzando pinze, placare lo stampo in gesso in acqua collocato in un secchio (30 L) a temperatura ambiente per circa 5 minuti. Assicurarsi che la temperatura dello stampo in gesso è vicino a RT dopo tempra. </li><li> Per ottenere il reticolo di metallo all&#39;interno dello stampo, sciogliere ilstampo in acqua. Lo stampo di gesso si scioglie facilmente in acqua. </li></ol></li></ol> 4. Post-elaborazione per Final Prodotti di Octet Truss Metalli <ol><li> Accendere la potenza di una sabbiatrice. </li><li> Posizionare i metalli ottetto travatura sulla piattaforma all&#39;interno del sandblaster e chiudere lo sportello della macchina. </li><li> Indossare guanti e afferrare la pistola sabbiatrice. </li><li> Afferra la parte sprue del prodotto metallo e spegnere l&#39;intonaco residua dal reticolo di metallo con la sabbiatrice per 2 ore. Nota: L&#39;intensità della sabbiatrice viene automaticamente fissata approssimativamente a 550 kPa. Una volta che la sabbiatrice viene azionato, poi l&#39;aria esce automaticamente dalla pistola. </li><li> Mantenere la sabbiatrice in esecuzione fino a quando il residuo di gesso di investimento all&#39;interno del metallo ottetto capriata viene completamente rimosso durante il controllo ad occhio nudo. Nota: Non c&#39;è un criterio microscopica sulla rimozione dei residui di gesso. Questo va oltre lo scopo di questo studio. Tegli rimozione del residuo intonaco è facilmente determinata ad occhio nudo. Poiché il traliccio ottetto è una struttura a celle aperte, è possibile vedere attraverso e controllare se o meno il residuo gesso viene completamente rimosso. Nota: Si deve fare attenzione per la sabbiatrice a non danneggiare il metallo ottetto traliccio con uno spessore di parete sottile (0,5 mm) ad alta pressione (550 kPa). </li><li> Se il residuo intonaco investimento all&#39;interno del metallo ottetto traliccio non è completamente rimosso con la sabbiatrice, utilizzare metodi di post-elaborazione aggiuntive, ad esempio, una pulizia a ultrasuoni o di lasciare il prodotto in acqua per un giorno. </li><li> Nel caso di utilizzo di un pulitore ad ultrasuoni, riempire 0,7 L di acqua nella lavatrice ad ultrasuoni e posizionare il metallo ottetto capriata con residui di intonaco nel pulitore ad ultrasuoni. <ol><li> Accendere il potere del pulitore ad ultrasuoni. </li><li> Impostare una condizione di funzionamento, ad esempio, 3 ore a 70 ° C. </li><li> Prendere il metallo ottetto capriata fuori del pulitore ad ultrasuoni una volta esimooperazione e finisce. </li><li> Essiccare il metallo ottetto traliccio a RT finché l&#39;acqua sulla superficie metallica è completamente rimosso. </li></ol></li><li> Come un metodo di post-elaborazione alternativa, lasciare il metallo ottetto capriata in acqua. Ciò causa il residuo intonaco da sciogliere in acqua. <ol><li> Posizionare il metallo ottetto traliccio con il residuo di gesso in acqua e lasciare per un giorno in modo che la forza di legame tra intonaco investimento e la superficie metallica diventa indebolire in acqua. </li><li> Prendere il metallo ottetto capriata fuori dall&#39;acqua. </li><li> Essiccare il metallo ottetto traliccio a RT finché l&#39;acqua sulla superficie metallica è completamente rimosso. </li></ol></li><li> Utilizzando una sega o altri strumenti adatti, tagliare il metallo riempito la cavità della parte di sistema materozza dal prodotto metallico ed ottenere la finale metallo ottetto traliccio con dimensioni 25 mm x 25 mm x 25 mm, come mostrato nella Figura 1B. </li></ol>

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	<li>Gibson, L. J., Ashby, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Cellular Solids-Structure and properties. , (1997).</li><li>Schaedler, T. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultralight+Metallic+Microlattices.">Ultralight Metallic Microlattices.</a> J. Science. 334 (6058), 962-965 (2011).</li><li>Zheng, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrastiff+Mechanical+Metamaterials.">Ultrastiff Mechanical Metamaterials.</a> J. Science. 334 (6190), 1373-1377 (2014).</li><li>Ju, J., Summers, J. D., Ziegert, J., Fadel, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+of+Honeycombs+for+Modulus+and+Yield+Strain+in+Shear.">Design of Honeycombs for Modulus and Yield Strain in Shear.</a> J. Eng. Mater. &amp; Technol. 134 (1), 11-22 (2012).</li><li>Lee, J., Kim, K., Ju, J., Kim, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Compliant+Cellular+Materials+with+Elliptical+Holes:+Materials+Design+with+Mechanisms.">Compliant Cellular Materials with Elliptical Holes: Materials Design with Mechanisms.</a> Transactions of the ASME: Eng. Maters. &amp; Technol. 131 (1), 1-14 (2015).</li><li>Tan, H., Qu, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chap+6:+Impact+of+Cellular+Materials.">Chap 6: Impact of Cellular Materials.</a> Cellular and Porous Materials in Structures and Processes. , (2010).</li><li>Phani, A. S., Woodhouse, J., Fleck, N. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wave+Propagation+in+Two-Dimensional+Periodic+Lattices.">Wave Propagation in Two-Dimensional Periodic Lattices.</a> Acoust. Soc. A. 119 (4), 1995-2005 (2006).</li><li>Kumar, R. S., McDowell, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+Preliminary+Design+of+Rectangular+Linear+Cellular+Alloys+for+Maximum+Heat+Transfer.">Rapid Preliminary Design of Rectangular Linear Cellular Alloys for Maximum Heat Transfer.</a> AIAA. 42 (8), 1652-1661 (2004).</li><li>Banhart, J., Weaire, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+Road+Again:+Metal+Foams+Find+Favor.">On the Road Again: Metal Foams Find Favor.</a> Physics Today. 55 (7), 37-42 (2002).</li><li>Wadley, H. N. G., Fleck, N. A., Evans, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+and+Structural+Performance+of+Periodic+Cellular+Metal+Sandwich+Structures.">Fabrication and Structural Performance of Periodic Cellular Metal Sandwich Structures.</a> Comp. Sci. and Technol. 63, 2331-2343 (2003).</li><li>Mori, L. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deformation+and+Fracture+Modes+of+Sandwich+Structures+Subjected+to+Underwater+Impulsive+Loads.">Deformation and Fracture Modes of Sandwich Structures Subjected to Underwater Impulsive Loads.</a> Mech. of Mater. &amp; Struct. 2 (10), 1981-2006 (2007).</li><li>Queheillalt, D. T., Murty, Y., Wadley, H. N. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+Properties+of+an+Extruded+Pyramidal+Lattice+Truss+Sandwich+Structure.">Mechanical Properties of an Extruded Pyramidal Lattice Truss Sandwich Structure.</a> Scripta Materialia. 58 (1), 76-79 (2008).</li><li>Queheillalt, D. T., Desphande, V. S., Wadley, H. N. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Truss+Waviness+Effects+in+Cellular+Lattice+Structures.">Truss Waviness Effects in Cellular Lattice Structures.</a> Mech. of Mater. &amp; Struct. 2 (9), 1657-1675 (2007).</li><li>Mullen, L., Stamp, R. C., Brooks, W. K., Jones, E., Sutcliffe, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+Laser+Melting:+A+Regular+Unit+Cell+Approach+for+the+Manufacture+of+Porous,+Titanium,+Bone+In-Growth+Constructs,+Suitable+for+Orthopedic+Applications.">Selective Laser Melting: A Regular Unit Cell Approach for the Manufacture of Porous, Titanium, Bone In-Growth Constructs, Suitable for Orthopedic Applications.</a> Biomed. Mater. Res. Part B: Appl. Biomaterials. 89, 325-334 (2009).</li><li>Murr, L. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Next-Generation+Biomedical+Implants+using+Additive+Manufacturing+of+Complex,+Cellular+and+Functional+Mesh+Arrays.">Next-Generation Biomedical Implants using Additive Manufacturing of Complex, Cellular and Functional Mesh Arrays.</a> Phil. Trans. R. Soc. A. 368, 1999-2032 (2011).</li><li>Murali, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+Selective+Laser+Sintering+of+Iron-Graphite+Powder+Mixture.">Direct Selective Laser Sintering of Iron-Graphite Powder Mixture.</a> Mater. Proc. Technol. 136, 179-185 (2003).</li><li>Lott, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+of+an+Optical+System+for+the+In-Situ+Process+Monitoring+of+Selective+Laser+Melting+(SLM).">Design of an Optical System for the In-Situ Process Monitoring of Selective Laser Melting (SLM).</a> Ph. P. 12, 683-690 (2011).</li><li>Song, B., Dong, S., Liu, Q., Liao, H., Coddet, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vacuum+Heat+Treatment+of+Iron+Parts+Produced+by+Selective+Laser+Melting:+Microstructure,+Residual+Stress,+and+Tensile+Behavior.">Vacuum Heat Treatment of Iron Parts Produced by Selective Laser Melting: Microstructure, Residual Stress, and Tensile Behavior.</a> Mater. Design. 54, 727-733 (2014).</li><li>Yadroitsev, I., Smurov, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+Morphology+in+Selective+Laser+Melting+of+Metal+Powders.">Surface Morphology in Selective Laser Melting of Metal Powders.</a> Ph. P. 12, 264-270 (2011).</li><li>Antonysamy, A. A., Meyer, J., Prangnell, P. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Build+Geometry+on+the+&#946;-grain+Structure+and+Texture+in+Additive+Manufacture+of+Ti-6Al-4V+by+Selective+Election+Beam+Melting.">Effect of Build Geometry on the &#946;-grain Structure and Texture in Additive Manufacture of Ti-6Al-4V by Selective Election Beam Melting.</a> J. of Mat. Charact. 84, 153-168 (2013).</li><li>Ladani, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Local+and+Global+Mechanical+Behavior+and+Microstructure+of+Ti6Al4V+Parts+Built+Using+Electron+Beam+Melting+Technology.">Local and Global Mechanical Behavior and Microstructure of Ti6Al4V Parts Built Using Electron Beam Melting Technology.</a> J. of Metalllur. &amp; Mater. Trans. 46, (2015).</li><li>Chiras, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Structural+Performance+of+Near-Optimized+Truss+Core+Panels.">The Structural Performance of Near-Optimized Truss Core Panels.</a> Solids Struct. 39, 4093-4115 (2002).</li><li>Meisel, N. A., Williams, C. B., Druschitz, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lightweight+Metal+Celluar+Structures+via+in+Direct+3D+Printing+and+Casting.">Lightweight Metal Celluar Structures via in Direct 3D Printing and Casting.</a> Proceedings of the 24th Solid Freeform Fabrication Symposium. , (2013).</li><li>Mun, J., Ju, J., Yun, B. -. G., Chang, B. -. M., Kim, D. -. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Numerical+Study+of+Molten+Aluminum+for+Investment+Casting+of+3D+Cellular+Metals.">A Numerical Study of Molten Aluminum for Investment Casting of 3D Cellular Metals.</a> Proceedings of the ASME International Mechanical Engineering Congress and Exposition. , (2013).</li><li>Mun, J., Yun, B. -. G., Ju, J., Chang, B. -. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Indirect+Additive+Manufacturing+Based+Casting+of+a+Periodic+3D+Cellular+Metal+-+Flow+Simulation+of+Molten+Aluminum+Alloy.">Indirect Additive Manufacturing Based Casting of a Periodic 3D Cellular Metal - Flow Simulation of Molten Aluminum Alloy.</a> Manufact. Process. 17, 28-40 (2015).</li><li>Challapalli, A., Ju, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuum+Model+for+Effective+Properties+of+Orthotropic+Octet-Truss+Lattice+Materials.">Continuum Model for Effective Properties of Orthotropic Octet-Truss Lattice Materials.</a> Proceedings of the ASME International Mechanical Engineering Congress and Exposition. , (2014).</li><li>Taylor, H. F., Flemings, M. C., Wulff, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Foundry Engineering. , (1959).</li><li>Mun, J., Ju, J., Thurman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Indirect+Additive+Manufacturing+Based+Casting+(I+AM+Casting)+of+a+Lattice+Structure.">Indirect Additive Manufacturing Based Casting (I AM Casting) of a Lattice Structure.</a> Proceedings of the ASME International Mechanical Engineering Congress and Exposition. , (2014).</li><li>Mun, J., Ju, J., Thurman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Indirect+Additive+Manufacturing+of+a+Copper+Alloy+Cubic+Lattice+Structure.">Indirect Additive Manufacturing of a Copper Alloy Cubic Lattice Structure.</a> Proceedings of the 25th Annual International Solid Freeform Fabrication Symposium. , (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Volume+2+Properties+and+Selection:+Nonferrous+Alloys+and+Pure+Metals.">Volume 2 Properties and Selection: Nonferrous Alloys and Pure Metals.</a> Metals Handbook Ninth Edition. , (1979).</li><li>Romano, J., Ladani, L., Razmi, J., Sadowski, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temperature+Distribution+and+Melt+Geometry+in+Laser+and+Electron-beam+Melting+Processes+-+A+Comparison+Among+Common+Materials.">Temperature Distribution and Melt Geometry in Laser and Electron-beam Melting Processes - A Comparison Among Common Materials.</a> J. of Additive Manuf. 8, 1-11 (2015).</li></ol>

The authors have nothing to disclose.

Per colata di metallo convenzionale, è importante mantenere il flusso del metallo fuso FLUIDITÀ in &#39;laminare&#39; nella cavità dello stampo e piuttosto evitare un flusso irregolare e agitata generalmente osservata in flusso turbolento 27. Pertanto, è importante progettare correttamente l&#39;ingresso del sistema materozza associato alla velocità di rotazione di un braccio di centrifugazione per mantenere il flusso di metallo fuso all&#39;interno della cavità dello stampo lattice &#39;laminare&#39;. ...

Metalli cellulari sono i metalli costituiti da una rete interconnessa di puntoni solidi o piastre e hanno complessi micro-architetture con vuoti 1. Gli esempi includono sia i) schiume stocastici strutturati in modo casuale e ii) periodicamente ordinato bidimensionali () favi 2D e tridimensionali (3D strutture reticolari) reticolari. Hanno ricevuto attenzione a causa della loro elevata rigidità specifica e resistenza 1-3 e alta resilienza specifica 4-5, eccellente assorbimento di energia all&#39;impatto di caricamento 6, isolamento acustico 7, possibile progettazione di dissipatori di calore e scambiatori di calore 8. In particolare, strutture a traliccio periodicamente ordinate hanno il potenziale per ingegnerizzare le proprietà superiori con una capacità di controllare la geometria della rete porosa interna. A causa della loro complessa geometria interna rete porosa, è difficile fabbricare metalli cellulari usando l&#39;machinin sottrattiva convenzionaleg. Come tale, i ricercatori hanno iniziato a cercare metodi alternativi per fabbricare metalli cellulari: la formazione di gas nel metallo liquido o mescolando polvere di metallo con agenti espandenti sono stati esplorati per la produzione di forme di metallo stocastici 9. A causa della mancanza di controllo sulla topologia cellulare, è difficile adattare le proprietà meccaniche. In alternativa, i metodi di produzione di metalli cellulari periodicamente ordinate sono stati esplorati: stampaggio lamiere sottili di metallo in una forma ondulata seguita da unirsi a loro per creare strutture periodiche 10, incollaggio a taglio lamiere 11, estrusione 12, la tessitura e ardente filamenti metallici per fabbricare tessuti 13. Anche se questi metodi di fabbricazione offrono modelli ripetibili, i modelli sono ancora limitate nella direzione planare. Nel tentativo di generare modello ripetizione 3D, i ricercatori hanno iniziato a utilizzare la produzione additiva (AM), ad esempio, laser selettiva Melting (SLM) 14, Electron Beam Melting (EBM) <sup&gt; 15, e Direct-Metal sinterizzazione laser (LMD) 16. Nonostante la loro capacità di fabbricare 3D ordinato geometrie reticolari complesse, esistono ancora alcune limitazioni: difficoltà utilizzo di metalli ad elevata conducibilità termica ed elevata riflettività ottica 17, ad alta tensione residua termico 18, scarsa finitura superficiale con il fenomeno &#39;balling&#39; durante laser o electron fusione 19, proprietà anisotrope 20-21 di parti causati da un effetto combinato della fabbricazione stratificato, formazione anisotropo di grani, granulometria, potenza e velocità di scansione del laser o fascio di elettroni 15, un elevato consumo di energia, ecc. Combinando AM basato polimero con colata di metallo può fornire un metodo alternativo per la fabbricazione di metalli reticolari. Si può chiamare questa &quot;AM indiretto&quot;. Indiretta AM può fornire una soluzione per superare i problemi tecnici di AM diretta dei metalli di cui sopra. Diversi tentativi sono stati made per la fabbricazione di metalli reticolo usando indiretta AM dell&#39;incontro fra la stampa 3D di polimeri con colata a gravità basato 22-25, ad esempio, una fusione a cera persa in combinazione con Fused Deposition Modeling (FDM) per fabbricare una lega reticolo 22-25 o colata in sabbia combinata con una polvere di sabbia basato AM 23. Il casting a gravità sembra rimanere una sfida tecnica per superare - misrun e porosità causata da improvvisa solidificazione di metalli fusi quando si incontrano strutture di rete con spigoli vivi di stampi strutturali reticolari 25-26. Relativamente grande superficie di stampi strutturali reticolari appare anche contribuire al repentino raffreddamento, con conseguente solidificazione prematura 25-26. In questo studio, proponiamo un AM indiretta alternativa che può superare la misrun durante la fabbricazione di metalli reticolo - colata centrifuga ad una cavità di stampo grata fatta da un reticolo reticolo polimerico sacrificale 3D stampata. Usiamo un digitaleLight Processing (DLP) metodo di stampa 3D basato per costruire un modello sacrificale strutturale reticolare seguito da colata centrifuga di Al e Cu leghe. L&#39;obiettivo di questo studio è fornire un protocollo dettagliato sulla fabbricazione di metalli reticolari 3D di forma complessa e spessore di parete sottile. Il contributo principale di questo processo è quello di fornire la possibilità di estendere la selezione dei materiali basso costo di fabbricazione per la produzione di metalli reticolari.

<table>
	<tbody>
		<tr>
			<td>Motorized centrifugal casting machine</td>
			<td>Rey Motorized Centrifugal Casting Machine, Rey Industries Inc.</td>
			<td></td>
			<td>Made in U.S.A. by Rey industries, Inc. Dallas, TX 75220</td>
		</tr>
		<tr>
			<td>Gypsum powder</td>
			<td>Satin Cast 20, FindingKing Kerr</td>
			<td>7960</td>
			<td>Gypsum powder is used to make the investment mixture</td>
		</tr>
		<tr>
			<td>Ployjet 3D printer</td>
			<td>Projet HD3500 Plus, 3D Systems</td>
			<td></td>
			<td>This polymer based 3D printer to print out sacrificial pattern for casting.</td>
		</tr>
		<tr>
			<td>Cartridge materials - UV curable and castable acrylic plastic</td>
			<td>VisiJet Procast, 3D Systems</td>
			<td></td>
			<td>This is castable material that is going to be burn out before casting</td>
		</tr>
		<tr>
			<td>Cartridge materials- support material</td>
			<td>VijiJet S300, 3D Systems</td>
			<td></td>
			<td>This is support material that is going to be removed before pattern assemble</td>
		</tr>
		<tr>
			<td>Ancient Bronze Casting Grain</td>
			<td>Rio Grande</td>
			<td>706051</td>
			<td>This true bronze grain contains no zinc. Highly fluid, it melts quickly, casts cleanly and provides a good balance between strength and durability. The warm, deep-bronze color has rich red undertones, and the alloy takes a good patina. 
			Composition is 90% copper with an amount of tin; fits into the CDA#90700 category. This grain is sold in 1-lb. packages.</td>
		</tr>
		<tr>
			<td>Aluminum Round Wire, 1/8&#34;, 1-Lb. Spool, Dead Soft</td>
			<td>Rio Grande</td>
			<td>134700</td>
			<td>Lightweight and strong, aluminum wire is an economical and versatile choice. Not as bright-white as silver, aluminum offers a warmer tone much like that of platinum. Solder ONLY with low-temp solders such as Stay-Brite; suitable for both pulse-arc and laser welding. This quality aluminum wire is packaged on 1-lb. spools.</td>
		</tr>
		<tr>
			<td>Computer aided design software (Pro-e)</td>
			<td></td>
			<td></td>
			<td>This software can be replaced with the others such as Auto CAD, Catia, and so on.</td>
		</tr>
		<tr>
			<td>ProJet Finisher 1-A</td>
			<td>3D Systems</td>
			<td></td>
			<td>This machine is used to melt the support material.</td>
		</tr>
		<tr>
			<td>160 Watt 2.5 Liters Digital Ultrasonic Cleaner with Timer Heater Rings Tools</td>
			<td>Chicago, Electric, Power Tools</td>
			<td></td>
			<td>85 oz. capacity, Five cleaning cycles: 90, 180, 280, 380 and 480 seconds, Clean with or without heat, Easy-to-read LED digital timer, Clear-view window</td>
		</tr>
		<tr>
			<td>Fan&#160;</td>
			<td>Honeywell Inc.&#160;</td>
			<td>HT-800</td>
			<td>120V A.C., 60Hz., 0.85A. TP</td>
		</tr>
		<tr>
			<td>Paraffin wax for wax sheet - Modeler&#39;s Pink Wax Sheet, 3&#34; by 6&#34;, 24-Ga.</td>
			<td>Rio Grande</td>
			<td>700075</td>
			<td>Sheet wax is flexible and can be cut or formed into any shape. It&#8217;s ideal for designing since you can draw or trace directly onto the sheet; choose green or pink depending on which will best show your designs. High manufacturing standards ensure exceptional consistency and significant price savings. Value is enhanced by larger package quantities at the same price as the smaller packages available elsewhere. Each 8-oz. package contains approximately 30 sheets.</td>
		</tr>
		<tr>
			<td>Paraffin wax for wax stick - Modeler&#39;s Medium Red Sprue Wax, 8-Ga</td>
			<td>Rio Grande</td>
			<td>700741</td>
			<td>A pliable, softer sprue wax than the firm blue. Good for forming gates and sprues and burns out cleanly with no residue.</td>
		</tr>
		<tr>
			<td>Alcohol Lamp</td>
			<td>Rio Grande</td>
			<td>700008</td>
			<td>Use this lamp to heat wax-working tools or as a flame polisher. The heavy glass reservoir has faceted sides to allow it to be tipped for angling the flame. A screw adjustment for the 7&#34; x 3/16&#34; wick controls the height of the flame. A safety cap snuffs the flame and prevents fuel evaporation. For the best flame, use methyl alcohol fuel. Replacement wicks available. Reservoir holds 5 oz. (150ml) of fuel.</td>
		</tr>
		<tr>
			<td>Wax carving tool set - Soft Grip Wax Carvers, Set of 10</td>
			<td>Rio Grande</td>
			<td>700329</td>
			<td>This boxed set offers the best in cutting and shaping technology. Each of these ten high-quality steel wax-carving tools features a 5/16&#34; PVC covered handle that ensures a sure, comfortable grip through hours of work and all have sharp edges for shaping and fine detailing. Sharpen or custom-shape each tool to fit your needs. These tools provide exceptional tool strength and deliver excellent results. This set comes in a hinged, foam-lined wood box.</td>
		</tr>
		<tr>
			<td>Rubber Mixing Bowl, 1-1/2 Qt.</td>
			<td>Rio Grande</td>
			<td>702131</td>
			<td>This highly-flexible vulcanized rubber bowl is easy to grip, will not be marred by a spatula and cleans with ease.</td>
		</tr>
		<tr>
			<td>Pyrex Beaker, 1,000ml</td>
			<td>Rio Grande</td>
			<td>335040</td>
			<td>Ideal for holding and heating bath plating solutions, this genuine Pyrex glass beaker is sturdy and durable.</td>
		</tr>
		<tr>
			<td>Rio Premium Stainless Steel Flask, 2-1/2&#34; dia.</td>
			<td>Rio Grande</td>
			<td>70201514</td>
			<td>This solid, #304-quality stainless steel flask is corrosion-resistant, durable for a long service life and performs under extreme temperature without distortion.</td>
		</tr>
		<tr>
			<td>CAST/T Ceramic Casting Crucible, 450g</td>
			<td>Rio Grande</td>
			<td>705047</td>
			<td>Made exclusively for the CAST/T centrifugal casting machine, this crucible is designed with an angled base that slides into the hinged bracket on top of the casting machine. This brings the crucible into perfect alignment with the center of the flask ring to ensure an error-free pour.</td>
		</tr>
		<tr>
			<td>MyWeigh iBalance 300 Digital Scale</td>
			<td>Rio Grande</td>
			<td>116850</td>
			<td>This scale is used to measure the weight of the sacrificial and sprue system for metal which is going to be used for centrifugal casting.</td>
		</tr>
		<tr>
			<td>Rubber bottom - CAST/T Flask Ring Base</td>
			<td>Rio Grande</td>
			<td>705025</td>
			<td>Specially made for the CAST/T centrifugal casting machine, this rubber base accommodates all Table King flask ring styles, creating a secure, airtight seal throughout the investment process. The center post fits either of the wax disc styles for complete versatility.</td>
		</tr>
		<tr>
			<td>Scotch&#174; Colored Duct Tape, 1 7/8&#34; x 20 Yd., Blue</td>
			<td>OfficeMax&#160;</td>
			<td>22353766</td>
			<td>This scotch tape is used to make sure that the gypsum-water mixture fully covers the assembled sacrificial pattern inside the flask by allowing for extra material above the flask height</td>
		</tr>
		<tr>
			<td>Vacuum casting machine - V.I.C. 12 Tabletop Solid- and Perforated-Flask Casting Machine with The Rio Assistant, 110-Volt</td>
			<td>Rio Grande</td>
			<td>70511814</td>
			<td>The V.I.C. 12 casting machine offers all the latest technical innovations for efficient, productive vacuum investing and casting. Designed to meet the demands of medium-sized casting operations, this machine includes a powerful 1/2hp, 5cfm vacuum pump for effective vacuuming and outstanding casting results. The V.I.C. 12 casts small or large flasks. Includes an adapter table that accepts standard solid flasks up to 5&#34; x 7&#34; high and is mounted on rubber feet for stability.</td>
		</tr>
		<tr>
			<td>Furnace for burn out sacrificial pattern -Rio Model 1000 Enameling Kiln with Nine Program Controller</td>
			<td>Rio Grande</td>
			<td>703121</td>
			<td>The Rio enameling kiln features three pre-set firing temperatures for enamels and six that you can define. Use the exclusive Rio controller to set and maintain firing temperatures. Perfect for all types of enameling, including tall pieces. Includes ample space for firing and an easy-latch door that will not jar your enamels when opening and closing. Also suitable for metal clay, glass and ceramics. Galvanized steel case with high-temperature insulating firebrick keeps them cool. Element protected in recessed groove. Includes user instructions.</td>
		</tr>
		<tr>
			<td>Smith Complete Little Torch Acetylene and Oxygen System</td>
			<td>Rio Grande</td>
			<td>500030</td>
			<td>Get everything you need to equip your shop for soldering and brazing. Use Little Torch systems for gold 
			or silver soldering, brazing and casting applications. Complete every soldering and melting job with confidence and ease! This system accepts all Little Torch accessory tips for melting, brazing and large soldering jobs and is a staple for every jeweler.</td>
		</tr>
		<tr>
			<td>Heat-Resistant Safety Apron</td>
			<td>Rio Grande</td>
			<td>750160</td>
			<td>The specially designed apron has an 800&#176;F (427&#176;C) temperature resistance. Its reflective finish repels hot metal splashes and helps insulate the wearer from heat.</td>
		</tr>
		<tr>
			<td>Radnor Heat-Resistant Gloves</td>
			<td>Rio Grande</td>
			<td>350050</td>
			<td>These flexible, heat-resistant gloves are ideal for enameling projects, allowing you to grip even small tongs securely. Blue, shoulder-split leather gloves are made of tough cowhide and lined with cotton and foam, and have reinforced thumb wings.</td>
		</tr>
		<tr>
			<td>Platinum Soldering Glasses, #7</td>
			<td>Rio Grande</td>
			<td>113914</td>
			<td>Protect yourself and your employees when soldering platinum. Comfortable glasses feature adjustable earpieces and 52mm IR green polycarbonate #7 lenses. The #7 lens is approved by The Platinum Guild.</td>
		</tr>
		<tr>
			<td>Economy Light-Duty Flask Tongs</td>
			<td>Rio Grande</td>
			<td>704026</td>
			<td>Constructed of bent steel, these tongs are designed to handle flasks 3-1/2&#34; or less in diameter. The small-angle notches grip smaller flask sizes and the larger, rounded contour area securely holds larger flasks.</td>
		</tr>
		<tr>
			<td>Separating Screen Bucket</td>
			<td>Rio Grande</td>
			<td>201360</td>
			<td>15&#34;-diameter, 11-1/2&#34;-deep</td>
		</tr>
		<tr>
			<td>Sand blaster - Econoline - 101701CB-A - Free-Standing Cabinets Workspace Width (Inch): 60 Workspace Depth (Inch): 48</td>
			<td>MSC industrial supply Co.&#160;</td>
			<td>223818</td>
			<td>Ree-Standing Cabinets; Workspace Width (Inch): 60; Workspace Depth (Inch): 48; Workspace Height (Inch): 40; Air Requirement: 12 CFM @ 80 psi; Overall Cabinet Width (Inch): 65; Maximum Cabinet Depth (Inch): 86</td>
		</tr>
		<tr>
			<td>Johnson&#39;s Baby Oil Shea &#38; Cocoa Butter&#160;</td>
			<td>Wal-Mart</td>
			<td>260074132</td>
			<td>This baby&#160; oil is used for removing the residue of the support material for the castable sacrificial pattern using Digital Ultrasonic Cleaner.</td>
		</tr>
		<tr>
			<td>German 4&#34; Saw Frame and Saw Blade Kit</td>
			<td>Rio Grande</td>
			<td>110112</td>
			<td>Quality, German-made frames are our most popular saw frames, and this frame includes a sampler pack of Rio German saw blades! The adjustable saw frame allows you to achieve the blade tension you want. Throat depth is 102mm (4&#34;). Saw blades have rounded backs that make cutting curves and corners easy and are made from hardened, tempered steel.</td>
		</tr>
	</tbody>
</table>

indirect fabrication of lattice metals with thin sections using centrifugal casting

Uno dei metodi tipici per la fabbricazione di metalli reticolo 3D è il processo di fabbricazione di metallo diretta additivo (AM) come Selective Laser Melting (SLM) e fusione Electron Beam (EBM). Nonostante la sua capacità di elaborazione potenziale, il metodo AM diretta ha diversi svantaggi quali costo elevato, scarsa finitura superficiale dei prodotti finali, limitazione nella scelta dei materiali, elevati stress termici, e proprietà anisotrope di parti. Noi proponiamo un metodo conveniente per la produzione di metalli reticolo 3D. L&#39;obiettivo di questo studio è fornire un protocollo dettagliato sulla fabbricazione di metalli reticolari 3D di forma complessa e spessore di parete sottile, ad esempio, capriata ottetto fatti di Al e Cu leghe aventi lunghezza cella unitaria di 5 mm e spessore della parete cellulare di 0,5 mm. Una procedura sperimentale complessiva è divisa in otto sezioni: (a) stampa 3D dei modelli sacrificali (b) scioglie su materiali di supporto (c) rimozione di residui di materiale di supporto (d) assembl reticoloy (e) gli investimenti (f), burn-out dei modelli sacrificali (g) colata centrifuga (h) post-trasformazione dei prodotti finali. La tecnica AM indiretta suggerito fornisce il potenziale per la produzione di metalli reticolo ultra-leggero,. Ad esempio, strutture a traliccio con leghe di Al. Risulta che i parametri di processo devono essere adeguatamente controllati seconda dei materiali e della geometria reticolare, osservando i prodotti finali di metalli ottetto travatura dalla tecnica AM indiretta.

Utilizzando la fabbricazione additiva indiretta descritta nella sezione del protocollo, Al e Cu leghe sono stati usati per metalli fabbricazione ottetto reticolari, come mostrato in Figura 1 La tecnica di fusione intera è riassunto in Figura 2 La procedura consiste di otto sezioni:.. (A) sacrificale modello di stampa (b) di fusione di materiale di supporto (c) rimozione di residui di materiale di supporto (d) gruppo di modello (e) investimenti (f) burn-...

Watch this Scientific Journal Video about Indirect Fabrication of Lattice Metals with Thin Sections Using Centrifugal Casting at JoVE.com

Indirect Fabrication of Lattice Metals with Thin Sections Using Centrifugal Casting

Un metodo indiretto fabbricazione additivo combinando una stampa 3D di polimeri con una colata centrifuga è delineato per fabbricazione metalli reticolari 3D ottetto (Al e Cu leghe) di lunghezza cella unitaria di 5 mm con uno spessore di 0,5 mm.

Fabbricazione indiretta di Lattice metalli con sezioni sottili Utilizzando Fusione centrifuga

One of the typical methods to manufacture 3D lattice metals is the direct-metal additive manufacturing (AM) process such as Selective Laser Melting (SLM) ...

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12.4K Views.  University of North Texas.  Un metodo indiretto fabbricazione additivo combinando una stampa 3D di polimeri con una colata centrifuga è delineato per fabbricazione metalli reticolari 3D ottetto (Al e Cu leghe) di lunghezza cella unitaria di 5 mm con uno spessore di 0,5 mm. 

Video: Indirect Fabrication of Lattice Metals with Thin Sections Using Centrifugal Casting

Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To compensate for lower light absorption such physically thin devices have to incorporate light-trapping which increases their optical thickness. Light scattering by textured surfaces is a common technique but it cannot be universally applied to all solar cell technologies. Some cells, for example those made of evaporated silicon, are planar as produced and they require an alternative light-trapping means suitable for planar devices. Metal nanoparticles formed on planar silicon cell surface and capable of light scattering due to surface plasmon resonance is an effective approach.
The paper presents a fabrication procedure of evaporated polycrystalline silicon solar cells with plasmonic light-trapping and demonstrates how the cell quantum efficiency improves due to presence of metal nanoparticles.
To fabricate the cells a film consisting of alternative boron and phosphorous doped silicon layers is deposited on glass substrate by electron beam evaporation. An Initially amorphous film is crystallised and electronic defects are mitigated by annealing and hydrogen passivation. Metal grid contacts are applied to the layers of opposite polarity to extract electricity generated by the cell. Typically, such a ~2 &mu;m thick cell has a short-circuit current density (Jsc) of 14-16 mA/cm2, which can be increased up to 17-18 mA/cm2 (~25% higher) after application of a simple diffuse back reflector made of a white paint.
To implement plasmonic light-trapping a silver nanoparticle array is formed on the metallised cell silicon surface. A precursor silver film is deposited on the cell by thermal evaporation and annealed at 23&deg;C to form silver nanoparticles. Nanoparticle size and coverage, which affect plasmonic light-scattering, can be tuned for enhanced cell performance by varying the precursor film thickness and its annealing conditions. An optimised nanoparticle array alone results in cell Jsc enhancement of about 28%, similar to the effect of the diffuse reflector. The photocurrent can be further increased by coating the nanoparticles by a low refractive index dielectric, like MgF2, and applying the diffused reflector. The complete plasmonic cell structure comprises the polycrystalline silicon film, a silver nanoparticle array, a layer of MgF2, and a diffuse reflector. The Jsc for such cell is 21-23 mA/cm2, up to 45% higher than Jsc of the original cell without light-trapping or ~25% higher than Jsc for the cell with the diffuse reflector only.
Introduction
Light-trapping in silicon solar cells is commonly achieved via light scattering at textured interfaces. Scattered light travels through a cell at oblique angles for a longer distance and when such angles exceed the critical angle at the cell interfaces the light is permanently trapped in the cell by total internal reflection (Animation 1: Light-trapping). Although this scheme works well for most solar cells, there are developing technologies where ultra-thin Si layers are produced planar (e.g. layer-transfer technologies and epitaxial c-Si layers) 1 and or when such layers are not compatible with textures substrates (e.g. evaporated silicon) 2. For such originally planar Si layer alternative light trapping approaches, such as diffuse white paint reflector 3, silicon plasma texturing 4 or high refractive index nanoparticle reflector 5 have been suggested.
Metal nanoparticles can effectively scatter incident light into a higher refractive index material, like silicon, due to the surface plasmon resonance effect 6. They also can be easily formed on the planar silicon cell surface thus offering a light-trapping approach alternative to texturing. For a nanoparticle located at the air-silicon interface the scattered light fraction coupled into silicon exceeds 95% and a large faction of that light is scattered at angles above critical providing nearly ideal light-trapping condition (Animation 2: Plasmons on NP). The resonance can be tuned to the wavelength region, which is most important for a particular cell material and design, by varying the nanoparticle average size, surface coverage and local dielectric environment 6,7. Theoretical design principles of plasmonic nanoparticle solar cells have been suggested 8. In practice, Ag nanoparticle array is an ideal light-trapping partner for poly-Si thin-film solar cells because most of these design principle are naturally met. The simplest way of forming nanoparticles by thermal annealing of a thin precursor Ag film results in a random array with a relatively wide size and shape distribution, which is particularly suitable for light-trapping because such an array has a wide resonance peak, covering the wavelength range of 700-900 nm, important for poly-Si solar cell performance. The nanoparticle array can only be located on the rear poly-Si cell surface thus avoiding destructive interference between incident and scattered light which occurs for front-located nanoparticles 9. Moreover, poly-Si thin-film cells do not requires a passivating layer and the flat base-shaped nanoparticles (that naturally result from thermal annealing of a metal film) can be directly placed on silicon further increases plasmonic scattering efficiency due to surface plasmon-polariton resonance 10.
The cell with the plasmonic nanoparticle array as described above can have a photocurrent about 28% higher than the original cell. However, the array still transmits a significant amount of light which escapes through the rear of the cell and does not contribute into the current. This loss can be mitigated by adding a rear reflector to allow catching transmitted light and re-directing it back to the cell. Providing sufficient distance between the reflector and the nanoparticles (a few hundred nanometers) the reflected light will then experience one more plasmonic scattering event while passing through the nanoparticle array on re-entering the cell and the reflector itself can be made diffuse - both effects further facilitating light scattering and hence light-trapping. Importantly, the Ag nanoparticles have to be encapsulated with an inert and low refractive index dielectric, like MgF2 or SiO2, from the rear reflector to avoid mechanical and chemical damage 7. Low refractive index for this cladding layer is required to maintain a high coupling fraction into silicon and larger scattering angles, which are ensured by the high optical contrast between the media on both sides of the nanoparticle, silicon and dielectric 6. The photocurrent of the plasmonic cell with the diffuse rear reflector can be up to 45% higher than the current of the original cell or up to 25% higher than the current of an equivalent cell with the diffuse reflector only.

Polycrystalline silicon thin-film solar cells on glass are fabricated by deposition of boron and phosphorous doped silicon layers followed by crystallisation, defect passivation and metallisation. Plasmonic light-trapping is introduced by forming Ag nanoparticles on the silicon cell surface capped with a diffused reflector resulting in ~45% photocurrent enhancement.

Celle in silicio policristallino solari a film sottile con plasmoniche-enhanced Light-trapping

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To ...

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Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

Rilevamento e recupero di palladio, oro e metalli di cobalto dalla miniera urbana Utilizzando novelli Sensori / Adsorbenti designate con nanoscala Wagon a forma di ruote pori

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Speciation and Bioavailability Measurements of Environmental Plutonium Using Diffusion in Thin Films

The biological uptake of plutonium (Pu) in aquatic ecosystems is of particular concern since it is an alpha-particle emitter with long half-life which can potentially contribute to the exposure of biota and humans. The diffusive gradients in thin films technique is introduced here for in-situ measurements of Pu bioavailability and speciation. A diffusion cell constructed for laboratory experiments with Pu and the newly developed protocol make it possible to simulate the environmental behavior of Pu in model solutions of various chemical compositions. Adjustment of the oxidation states to Pu(IV) and Pu(V) described in this protocol is essential in order to investigate the complex redox chemistry of plutonium in the environment. The calibration of this technique and the results obtained in the laboratory experiments enable to develop a specific DGT device for in-situ Pu measurements in freshwaters. Accelerator-based mass-spectrometry measurements of Pu accumulated by DGTs in a karst spring allowed determining the bioavailability of Pu in a mineral freshwater environment. Application of this protocol for Pu measurements using DGT devices has a large potential to improve our understanding of the speciation and the biological transfer of Pu in aquatic ecosystems.

The technique of diffusive gradients in thin films (DGT) is proposed for speciation studies of plutonium. This protocol describes diffusion experiments probing the behavior of Pu(IV) and Pu(V) in presence of organic matter. DGTs deployed in a karstic spring allow assessment of the bioavailability of Pu.

Speciazione e di biodisponibilità Misure di plutonio ambientale Uso Diffusione in film sottili

The biological uptake of plutonium (Pu) in aquatic ecosystems is of particular concern since it is an alpha-particle emitter with long half-life which can ...

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-&#954; dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.

A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.

Fabbricazione di bassa temperatura Nanotubi di carbonio interconnessioni verticali Compatibile con la tecnologia Semiconductor

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive ...

A Fabrication Method for Highly Stretchable Conductors with Silver Nanowires

Stretchable electronics are identified as a key technology for electronic applications in the next generation. One of the challenges in fabrication of stretchable electronic devices is the preparation of stretchable conductors with great mechanical stability. In this study, we developed a simple fabrication method to chemically solder the contact points between silver nanowire (AgNW) networks. AgNW nanomesh was first deposited on a glass slide via spray coating method. A reactive ink composed of silver nanoparticle (AgNPs) precursors was applied over the spray coated AgNW thin films. After heating for 40 min, AgNPs were preferentially generated over the nanowire junctions to solder the AgNW nanomesh, and reinforced the conducting network. The chemically modified AgNW thin film was then transferred to polyurethane (PU) substrates by casting method. The soldered AgNW thin films on PU exhibited no obvious change in electrical conductivity under stretching or rolling process with elongation strains up to 120%.

A simple synthesis method is used to chemically solder silver nanowire thin film to fabricate highly stretchable and conductive metal conductors.

Un metodo di fabbricazione di conduttori è molto estensibile con argento Nanofili

Stretchable electronics are identified as a key technology for electronic applications in the next generation. One of the challenges in fabrication of ...

Capillary-based Centrifugal Microfluidic Device for Size-controllable Formation of Monodisperse Microdroplets

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal microfluidic device. W/O microdroplets have recently been used in powerful methods that enable miniaturized chemical experiments. Therefore, developing a versatile method to yield monodisperse W/O microdroplets is needed. We have developed a method for generating monodisperse W/O microdroplets based on a capillary-based centrifugal axisymmetric co-flowing microfluidic device. We succeeded in controlling the size of microdroplets by adjusting the capillary orifice. Our method requires equipment that is easier-to-use than with other microfluidic techniques, requires only a small volume (0.1-1 &#181;l) of sample solution for encapsulation, and enables the production of hundreds of thousands number of W/O microdroplets per second. We expect this method will assist biological studies that require precious biological samples by conserving the volume of the samples for rapid quantitative analysis biochemical and biological studies.

Here, we demonstrate a simple production method for size-controllable, monodisperse, water-in-oil (W/O) microdroplets using a capillary-based centrifugal microfluidic device. This method requires only a small sample volume and enables high-yield production. We expect this method will be useful for rapid biochemical and cellular analyses.

Centrifuga dispositivo a microfluidi capillare a base per la Formazione Size-controllabile di Monodisperse microgocce

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal ...

Fabrication of White Light-emitting Electrochemical Cells with Stable Emission from Exciplexes

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active layer which consists of blue-fluorescent poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFD) and &#960;-conjugated triphenylamine molecules. This white light emission originates from exciplexes formed between PFD and amines in electronically excited states. A device containing PFD, 4,4&#39;,4&#39;&#39;-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA), Poly(ethylene oxide) and K2CF3SO3 showed white light emission with Commission internationale de l&#39;&#233;clairage (CIE) coordinates of (0.33, 0.43) and a Color Rendering Index (CRI) of Ra = 73 at an applied voltage of 3.5 V. Constant voltage measurements showed that the CIE coordinates of (0.27, 0.37), Ra of 67, and the emission color observed immediately after application of a voltage of 5 V were nearly unchanged and stable after 300 sec.

The authors present a method for fabricating stable white-light-emitting electrochemical cells utilizing emission from exciplexes formed between a blue-emitting fluorene polymer and aromatic amines.

Fabbricazione di White Light-emitting cellule elettrochimiche con emissione stabile da ecciplessi

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active ...

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for Cu(In,Ga)Se2 Solar Cells

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction of degradation mechanisms and prevention of module field failure can consequently decrease investment risks as well as increase the electricity yield. An improved knowledge level can for these reasons significantly decrease the total costs of PV electricity. 
In order to better understand and minimize the degradation of PV modules, the occurring degradation mechanisms and conditions should be identified. This should preferably happen under combined stresses, since modules in the field are also simultaneously exposed to multiple stress factors. Therefore, two 'Combined Stress test with in situ measurement' setups have been designed and constructed. These setups allow the simultaneous use of humidity, temperature, illumination, and electrical biases as independently controlled stress factors on solar cells and minimodules. The setups also allow real-time monitoring of the electrical properties of these samples. This protocol presents these setups and describes the experimental possibilities. Moreover, results obtained with these setups are also presented: various examples about the influence of both deposition and degradation conditions on the stability of thin film Cu(In,Ga)Se2 (CIGS) as well as Cu2ZnSnSe4 (CZTS) solar cells are described. Results on the temperature dependency of CIGS solar cells are also presented.

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for CuIn,GaSe2 Solar Cells

Two &#39;Combined Stress test with in situ measurement&#39; setups, which allow real-time monitoring of accelerated degradation of solar cells and modules, were designed and constructed. These setups allow the simultaneous use of humidity, temperature, electrical biases, and illumination as independently controlled stress factors. The setups and various experiments executed are presented.

In Situ Monitoraggio del degrado prestazioni accelerate di celle e moduli solari: un caso di studio per le celle solari di Cu (In, Ga) Se2

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction ...

Fabrication of Periodic Gold Nanocup Arrays Using Colloidal Lithography

Within recent years, the field of plasmonics has exploded as researchers have demonstrated exciting applications related to chemical and optical sensing in combination with new nanofabrication techniques. A plasmon is a quantum of charge density oscillation that lends nanoscale metals such as gold and silver unique optical properties. In particular, gold and silver nanoparticles exhibit localized surface plasmon resonances-collective charge density oscillations on the surface of the nanoparticle-in the visible spectrum. Here, we focus on the fabrication of periodic arrays of anisotropic plasmonic nanostructures. These half-shell (or nanocup) structures can exhibit additional unique light-bending and polarization-dependent optical properties that simple isotropic nanostructures cannot. Researchers are interested in the fabrication of periodic arrays of nanocups for a wide variety of applications such as low-cost optical devices, surface-enhanced Raman scattering, and tamper indication. We present a scalable technique based on colloidal lithography in which it is possible to easily fabricate large periodic arrays of nanocups using spin-coating and self-assembled commercially available polymeric nanospheres. Electron microscopy and optical spectroscopy from the visible to near-infrared (near-IR) was performed to confirm successful nanocup fabrication. We conclude with a demonstration of the transfer of nanocups to a flexible, conformal adhesive film.

We demonstrate the fabrication of periodic gold nanocup arrays using colloidal lithographic techniques and discuss the importance of nanoplasmonic films.

Fabbricazione di matrici Nanocup oro periodica mediante Litografia colloidale

Within recent years, the field of plasmonics has exploded as researchers have demonstrated exciting applications related to chemical and optical sensing ...

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.&#160; Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

We present a detailed method for fabricating ultra-thin color films with improved characteristics for optical coatings. The oblique angle deposition technique using an electron beam evaporator allows improved color tunability and purity. Fabricated films of Ge and Au on Si substrates were analyzed by reflectance measurements and color information conversion.

Fabbricazione di film ultra-sottile di colore con altamente assorbente Media mediante deposizione di angolo obliquo

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present ...