EXTRUSION FORMING OF SI3N4

The extrusion forming of silicon nitride produced by imide decompositi on was studied to fabricate Si3N4 ceramic parts. Green bodies were pre pared from a slurry containing 60% solids (92% Si3N4, 4% Al2O3 and 4% Y2O3), 40% distilled water and 0.12% deflocculant (polyacrylic ammoniu m) with binder (curdlan). The green bodies were dried after formed by vacuum extrusion, and sintered in the range of 1650 to 1800 degrees C under N-2 gas at 0.9 MPa, The most dense body (3.22 x 10(3) kg.m(-3)) was obtained by sintering at 1800 degrees C for 4h. These results indi cate that dense silicon nitride parts can be produced by an extrusion method.