Publications

Robocasting and cofiring of functionally graded Si3N4-W materials

He, Guoping; Hirschfeld, Deidre A.; Cesarano, Joseph C.; Stuecker, John N.

Functionally graded materials consisting of two different materials with graded interlayers may be used in selected advanced engine applications. For example, Si3N4 ceramic components may be joined to metallic alloys using a W buffer layer. This study describes the design and fabrication of an intermediate layer with graded composition using robocasting, a novel solid free form fabrication technique. The robocast graded Si3N4-W samples were cofired at 1720°C for 1 h in an N2 atmosphere. Sintered density, shrinkage and other properties were measured. The interfacial microstructure and the atomic element distributions in the cross-sections were evaluated by scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). A densified graded structure without pores was obtained.