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.&lt;br/&gt; 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&quot;, 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&amp;nbsp;</td><td>Honeywell Inc.&amp;nbsp;</td><td>HT-800</td><td>120 V A.C., 60 Hz., 0.85 A. TP</td></tr><tr><td>Paraffin wax for wax sheet - Modeler&#039;s Pink Wax Sheet, 3&quot; by 6&quot;, 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&amp;rsquo;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&#039;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&quot; x 3/16&quot; 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. (150 ml) 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&quot; 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&quot; 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, 450 g</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&amp;reg; Colored Duct Tape, 1 7/8&quot; x 20 Yd., Blue</td><td>OfficeMax&amp;nbsp;</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 1/2 hp, 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&quot; x 7&quot; 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&lt;br/&gt; 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 &amp;deg;F (427 &amp;deg;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&quot; 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&quot;-diameter, 11-1/2&quot;-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.&amp;nbsp;</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&#039;s Baby Oil Shea &amp;amp; Cocoa Butter&amp;nbsp;</td><td>Wal-Mart</td><td>260074132</td><td>This baby&amp;nbsp; 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&quot; 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&quot;). 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

Fabricating Metamaterials Using the Fiber Drawing Method

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe their electromagnetic properties to the structure of their constituents, instead of the atoms that compose them. For example, sub-wavelength metal wires can be arranged to possess an effective electric permittivity that is either positive or negative at a given frequency, in contrast to the metals themselves 2. This unprecedented control over the behaviour of light can potentially lead to a number of novel devices, such as invisibility cloaks 3, negative refractive index materials 4, and lenses that resolve objects below the diffraction limit 5. However, metamaterials operating at optical, mid-infrared and terahertz frequencies are conventionally made using nano- and micro-fabrication techniques that are expensive and produce samples that are at most a few centimetres in size 6-7. Here we present a fabrication method to produce hundreds of meters of metal wire metamaterials in fiber form, which exhibit a terahertz plasmonic response 8. We combine the stack-and-draw technique used to produce microstructured polymer optical fiber 9 with the Taylor-wire process 10, using indium wires inside polymethylmethacrylate (PMMA) tubes. PMMA is chosen because it is an easy to handle, drawable dielectric with suitable optical properties in the terahertz region; indium because it has a melting temperature of 156.6 &deg;C which is appropriate for codrawing with PMMA. We include an indium wire of 1 mm diameter and 99.99% purity in a PMMA tube with 1 mm inner diameter (ID) and 12 mm outside diameter (OD) which is sealed at one end. The tube is evacuated and drawn down to an outer diameter of 1.2 mm. The resulting fiber is then cut into smaller pieces, and stacked into a larger PMMA tube. This stack is sealed at one end and fed into a furnace while being rapidly drawn, reducing the diameter of the structure by a factor of 10, and increasing the length by a factor of 100. Such fibers possess features on the micro- and nano- scale, are inherently flexible, mass-producible, and can be woven to exhibit electromagnetic properties that are not found in nature. They represent a promising platform for a number of novel devices from terahertz to optical frequencies, such as invisible fibers, woven negative refractive index cloths, and super-resolving lenses.

Metamaterials at terahertz frequencies offer unique opportunities, but are challenging to fabricate in bulk. We adapt the fabrication procedure for microstructured polymer optical fibers to inexpensively fabricate metamaterials potentially on an industrial scale. We produce polymethylmethacrylate fibers containing ~10 &mu;m diameter indium wires separated by ~100 &mu;m, which exhibit a terahertz plasmonic response.

Metamateriali Realizzazione tramite il metodo di disegno fibra

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe ...

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A Method to Fabricate Disconnected Silver Nanostructures in 3D

The standard nanofabrication toolkit includes techniques primarily aimed at creating 2D patterns in dielectric media. Creating metal patterns on a submicron scale requires a combination of nanofabrication tools and several material processing steps. For example, steps to create planar metal structures using ultraviolet photolithography and electron-beam lithography can include sample exposure, sample development, metal deposition, and metal liftoff. To create 3D metal structures, the sequence is repeated multiple times. The complexity and difficulty of stacking and aligning multiple layers limits practical implementations of 3D metal structuring using standard nanofabrication tools. Femtosecond-laser direct-writing has emerged as a pre-eminent technique for 3D nanofabrication.1,2 Femtosecond lasers are frequently used to create 3D patterns in polymers and glasses.3-7 However, 3D metal direct-writing remains a challenge. Here, we describe a method to fabricate silver nanostructures embedded inside a polymer matrix using a femtosecond laser centered at 800 nm. The method enables the fabrication of patterns not feasible using other techniques, such as 3D arrays of disconnected silver voxels.8 Disconnected 3D metal patterns are useful for metamaterials where unit cells are not in contact with each other,9 such as coupled metal dot10,11or coupled metal rod12,13 resonators. Potential applications include negative index metamaterials, invisibility cloaks, and perfect lenses.
In femtosecond-laser direct-writing, the laser wavelength is chosen such that photons are not linearly absorbed in the target medium. When the laser pulse duration is compressed to the femtosecond time scale and the radiation is tightly focused inside the target, the extremely high intensity induces nonlinear absorption. Multiple photons are absorbed simultaneously to cause electronic transitions that lead to material modification within the focused region. Using this approach, one can form structures in the bulk of a material rather than on its surface.
Most work on 3D direct metal writing has focused on creating self-supported metal structures.14-16 The method described here yields sub-micrometer silver structures that do not need to be self-supported because they are embedded inside a matrix. A doped polymer matrix is prepared using a mixture of silver nitrate (AgNO3), polyvinylpyrrolidone (PVP) and water (H2O). Samples are then patterned by irradiation with an 11-MHz femtosecond laser producing 50-fs pulses. During irradiation, photoreduction of silver ions is induced through nonlinear absorption, creating an aggregate of silver nanoparticles in the focal region. Using this approach we create silver patterns embedded in a doped PVP matrix. Adding 3D translation of the sample extends the patterning to three dimensions.

Femtosecond-laser direct-writing is frequently used to create three-dimensional (3D) patterns in polymers and glasses. However, patterning metals in 3D remains a challenge. We describe a method for fabricating silver nanostructures embedded inside a polymer matrix using a femtosecond laser centered at 800 nm.

Un metodo per fabbricare nanostrutture d&#39;argento disconnesse in 3D

The standard nanofabrication toolkit includes  techniques primarily aimed at creating 2D patterns in dielectric media. Creating  metal patterns on a ...

Process of Making Three-dimensional Microstructures using Vaporization of a Sacrificial Component

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material fabrication techniques are able to mimic the complexity of these structures while maintaining scalability. The Vaporization of a Sacrificial Component (VaSC) process is able to do so. This process uses sacrificial fibers as a template to form hollow, cylindrical microchannels embedded within a matrix. Tin (II) oxalate (SnOx) is embedded within poly(lactic) acid (PLA) fibers which facilitates the use of this process. The SnOx catalyzes the depolymerization of the PLA fibers at lower temperatures. The lactic acid monomers are gaseous at these temperatures and can be removed from the embedded matrix at temperatures that do not damage the matrix. Here we show a method for aligning these fibers using micromachined plates and a tensioning device to create complex patterns of three-dimensionally arrayed microchannels. The process allows the exploration of virtually any arrangement of fiber topologies and structures.

The Vaporization of a Sacrificial Component (VaSC) process is used to fabricate microvascular structures. This procedure uses sacrificial poly(lactic) acid fibers to form hollow microchannels with precise 3D geometric positioning provided by laser micromachined guide plates.

Processo di creazione di microstrutture tridimensionali mediante vaporizzazione di un componente sacrificale

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material ...

Fabrication of Spatially Confined Complex Oxides

Complex materials such as high Tc superconductors, multiferroics, and colossal magnetoresistors have electronic and magnetic properties that arise from the inherent strong electron correlations that reside within them. These materials can also possess electronic phase separation in which regions of vastly different resistive and magnetic behavior can coexist within a single crystal alloy material. By reducing the scale of these materials to length scales at and below the inherent size of the electronic domains, novel behaviors can be exposed. Because of this and the fact that spin-charge-lattice-orbital order parameters each involve correlation lengths, spatially reducing these materials for transport measurements is a critical step in understanding the fundamental physics that drives complex behaviors. These materials also offer great potential to become the next generation of electronic devices 1-3. Thus, the fabrication of low dimensional nano- or micro-structures is extremely important to achieve new functionality. This involves multiple controllable processes from high quality thin film growth to accurate electronic property characterization. Here, we present fabrication protocols of high quality microstructures for complex oxide manganite devices. Detailed descriptions and required equipment of thin film growth, photo-lithography, and wire-bonding are presented.

We describe the use of pulsed laser deposition (PLD), photolithography and wire-bonding techniques to create micrometer scale complex oxides devices. The PLD is utilized to grow epitaxial thin films. Photolithography and wire-bonding techniques are introduced to create practical devices for measurement purposes.

Fabbricazione di ossidi complessi spazialmente confinati

Complex materials such as high Tc superconductors, multiferroics, and colossal magnetoresistors have electronic and magnetic properties that arise from ...

Fabrication of Uniform Nanoscale Cavities via Silicon Direct Wafer Bonding

Measurements of the heat capacity and superfluid fraction of confined 4He have been performed near the lambda transition using lithographically patterned and bonded silicon wafers. Unlike confinements in porous materials often used for these types of experiments3, bonded wafers provide predesigned uniform spaces for confinement. The geometry of each cell is well known, which removes a large source of ambiguity in the interpretation of data.
Exceptionally flat, 5 cm diameter, 375 &#181;m thick Si wafers with about 1 &#181;m variation over the entire wafer can be obtained commercially (from Semiconductor Processing Company, for example). Thermal oxide is grown on the wafers to define the confinement dimension in the z-direction. A pattern is then etched in the oxide using lithographic techniques so as to create a desired enclosure upon bonding. A hole is drilled in one of the wafers (the top) to allow for the introduction of the liquid to be measured. The wafers are cleaned2 in RCA solutions and then put in a microclean chamber where they are rinsed with deionized water4. The wafers are bonded at RT and then annealed at ~1,100 &#176;C. This forms a strong and permanent bond. This process can be used to make uniform enclosures for measuring thermal and hydrodynamic properties of confined liquids from the nanometer to the micrometer scale.

A method for permanently bonding two silicon wafers so as to realize a uniform enclosure is described. This includes wafer preparation, cleaning, RT bonding, and annealing processes. The resulting bonded wafers (cells) have uniformity of enclosure ~1%1,2. The resulting geometry allows for measurements of confined liquids and gasses.

Fabbricazione di cavità uniformi su nanoscala tramite silicon direct wafer bonding

Measurements of the heat capacity and superfluid fraction of confined 4He have been performed near the lambda transition using lithographically patterned ...

Preparation of Liquid-exfoliated Transition Metal Dichalcogenide Nanosheets with Controlled Size and Thickness: A State of the Art Protocol

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. Layered crystals of molybdenum disulphide (MoS2) and tungsten disulphide (WS2) are exfoliated in aqueous surfactant solution by sonication. This yields highly polydisperse mixtures containing nanosheets with broad size and thickness distributions. However, for most purposes, specific sizes (in terms of both lateral dimension and thickness) are required. For example, large and thin nanosheets are desired for (opto) electronic applications, while laterally small nanosheets are interesting for catalytic applications. Therefore, post-exfoliation size selection is an important step that we address here. We provide a detailed protocol on the efficient size selection in large quantities by liquid cascade centrifugation and the size and thickness quantification by statistical microscopic analysis (atomic force microscopy and transmission electron microscopy). The comparison of MoS2 and WS2 shows that both materials are size-selected in a similar way by the same procedure. Importantly, the dispersions of size-selected nanosheets show systematic changes in their optical extinction spectra with size due to edge and confinement effects. We show how these optical changes are related quantitatively to the nanosheets dimensions and describe how mean nanosheets length and layer number can be extracted reliably from the extinction spectra. The exfoliation and size selection protocol can be applied to a broad range of layered crystals as we have previously demonstrated for graphene, gallium sulphide (GaS) and black phosphorus.

A protocol for the liquid exfoliation of layered materials to nanosheets, their size selection and size measurement by microscopic and spectroscopic techniques is presented.

Preparazione di Liquid-espansa di metalli di transizione Dichalcogenide nanosheets regolabile dimensioni e spessore: uno stato del protocollo d&#39;arte

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. ...

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 ...

Processing of Bulk Nanocrystalline Metals at the US Army Research Laboratory

Given their potential for significant property improvements relative to their large grained counterparts, much work has been devoted to the continued development of nanocrystalline metals. Despite these efforts, the transition of these materials from the lab bench to actual applications has been blocked by the inability to produce large scale parts that retain the desired nanocrystalline microstructures. Following the development of a method proven to stabilize the nanosized grain structure to temperatures approaching that of the melting point for the given metal, the US Army Research Laboratory (ARL) has progressed to the next stage in the development of these materials - namely the production of large scale parts suitable for testing and evaluation in a range of relevant test environments. This report provides a broad overview of the ongoing efforts in the processing, characterization, and consolidation of these materials at ARL. In particular, focus is placed on the methodology used for producing the nanocrystalline metal powders, in both small and large-scale amounts, that are at the center of ongoing research efforts.

This paper provides a brief overview of the ongoing efforts at the Army Research Laboratory on the processing of bulk nanocrystalline metals with an emphasis on the methodologies used for the production of the novel metal powders.

Lavorazione dei metalli nanocristallini Bulk presso la US Army Research Laboratory

Given their potential for significant property improvements relative to their large grained counterparts, much work has been devoted to the continued ...

Fused Filament Fabrication (FFF) of Metal-Ceramic Components

Technical ceramics are widely used for industrial and research applications, as well as for consumer goods. Today, the demand for complex geometries with diverse customization options and favorable production methods is increasing continuously. With fused filament fabrication (FFF), it is possible to produce large and complex components quickly with high material efficiency. In FFF, a continuous thermoplastic filament is melted in a heated nozzle and deposited below. The computer-controlled print head is moved in order to build up the desired shape layer by layer. Investigations regarding printing of metals or ceramics are increasing more and more in research and industry. This study focuses on additive manufacturing (AM) with a multi-material approach to combine a metal (stainless steel) with a technical ceramic (zirconia: ZrO2). Combining these materials offers a broad variety of applications due to their different electrical and mechanical properties. The paper shows the main issues in preparation of the material and feedstock, device development, and printing of these composites.

Fused Filament Fabrication FFF of Metal-Ceramic Components

This study shows multi-material additive manufacturing (AM) using fused filament fabrication (FFF) of stainless steel and zirconia.

Filamento fuso fabbricazione (FFF) dei componenti in metallo-ceramica

Technical ceramics are widely used for industrial and research applications, as well as for consumer goods. Today, the demand for complex geometries with ...

Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared on transparent membranes which are very fragile and difficult to manipulate. We present processes for the fabrication of samples with magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for Lorentz transmission electron microscopy and magnetic transmission x-ray microscopy studies. The samples are prepared on silicon nitride membranes and the fabrication consists of a spin coating, UV and electron-beam lithography, the chemical development of the resist, and the evaporation of the magnetic material followed by a lift-off process forming the final magnetic structures. The samples for the Lorentz transmission electron microscopy consist of magnetic nanodiscs prepared in a single lithography step. The samples for the magnetic x-ray transmission microscopy are used for time-resolved magnetization dynamic experiments, and magnetic nanodiscs are placed on a waveguide which is used for the generation of repeatable magnetic field pulses by passing an electric current through the waveguide. The waveguide is created in an extra lithography step.

A protocol for the fabrication of magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for transmission electron microscopy (TEM) and magnetic transmission x-ray microscopy (MTXM) studies is presented.

Fabbricazione di nanostrutture magnetiche sulle membrane di nitruro di silicio per studi di vortice magnetico utilizzando tecniche di microscopia di trasmissione

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared ...

Fabbricazione indiretta di Lattice metalli con sezioni sottili Utilizzando Fusione centrifuga

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