Lenk, R.R.Lenk2022-03-082022-03-082003https://publica.fraunhofer.de/handle/publica/305787Producing 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. USE - Used e.g. for production of drill bits, screws, etc. useful in machine, vehicle and appliance construction, and in surgery. ADVANTAGE - The process allows simple and inexpensive production of components which have a helical external contour and which have high wear resistance, are less brittle, have chemical resistance and can be sterilised.de608666620patent1997-19703175