PROCESSING METHOD FOR INTERPENETRATING NETWORK METAL-CERAMIC COMPOSITES WITH A NON-LINEAR COMPOSITIONAL GRADIENT

摘要

A new method for processing large flat compositionally graded metal-ceramic parts with connected interpenetrating metal and ceramic network is described. Based on powder metallurgical methods, a metal foam is obtained by slip casting of metal powder slurries on a polyurethane foam, and used as preform to achieve a metallic interpenetration within the composite. The porous metallic preform is infiltrated with a ceramic slip and co-sintered. The composites contain Ni-Cr-alloy, or the P/M superalloy Saratherm 2 and Nimonic 90 as metallic part and pure 8Y-Zr02 or zirconia mixed with ZrSiO{sub}4, as ceramic part. Sintering behaviour, microstructure development and phase composition were characterised by dilatometer measurements, X-ray diffraction, light and scanning electron microscopy and energy dispersive X-ray analysis, for different variants of the process. Composites of nominal same composition sintered without the metal foam preform show no metallic interpenetration.