Ceramic or powder metallurgical component with helical external contour

摘要

Producing ceramic or powder metallurgical components with a helical external contour involves: (a) forming a thermoplastic slip of 0.05-4.0 Pa.sec. viscosity from ceramic or powder metallurgical materials and one or more thermoplastic binders; (b) introducing the slip at 40-180 deg C into a mould which has an inner contour corresponding to the helical contour to be produced and which is evacuated to 5 Pa to 0.09 MPa before, during and/or after slip introduction; and (c) heat treating the resulting green body. Preferably a self-sharpening composition of dense silicon nitride containing 1-20 wt.% of one or more of MgO, CaO, Y2O3 or rare earths, 0-0.8 wt.% Al2O3 and 0-30 wt.% TiC and/or TiN is used as the ceramic material, and hard metal is used as the powder metallurgical material.