화학공학소재연구정보센터
Materials Science Forum, Vol.426-4, 4295-4300, 2003
Extrusion and thermo-chemical processing of layered linear cellular alloys
Linear Cellular Materials (LCM) technology developed by the Lightweight Structures Group at Georgia Tech has obvious potential for multifunctional service as combined heat exchange and structural elements. These thin-walled metallic honeycombs, with highly functional cell geometries and complex cross sections, are extruded from mixtures of transition metal oxides, directly reduced to alloys in H-2 and sintered to densify the cell walls. Demonstrated alloys include steels, nickel based alloys, and copper alloys. Strength and specific energy absorption of a maraging steel honeycomb at 2.1 gm/cc were 600 MPa and 100 Joules/gm, respectively. Recently, techniques have been developed which allow extrusion of multiple compositions in layers in honeycomb structures. To join these layered composition structures and sinter to full cell wall density requires matching total shrinkages and expansion coefficients. Shrinkages can be manipulated by adjusting the particle packing fraction, solids content, and binder quantity in the paste. Models of paste rheology based on the Dougherty-Kreiger equation accelerate matching paste properties for different compositions. Examples of metal/metal and ceramic/metal layered structures will be presented along with shrinkage and contraction profiles.