Process for producing sintered parts from fine metal or ceramic powders

摘要

To produce the sintered parts, powders having a particle size of up to 500 mu m and a particle size distribution close to the "Fuller distribution" are used. The multicomponent binder added contains at least one component which forms a liquid phase below the melting/softening point of the other component(s), while these solidify to form a sponge-like skeleton having pores going right through. The amount of the liquid phase is selected in such a way that, after it is removed by chemical means, there remains in the shaped part a free pore volume matching the sintering process. The remaining components are then thermally decomposed under optionally pulsating, superatmospheric pressure above their decomposition temperature and above the temperature at which the powder particles just begin to grow together, in a gas atmosphere whose carbon or oxygen activity corresponds to the respective carbon or oxygen activity of the shaped part. Decomposition gases remaining therein are removed by vacuum treatment, before the shaped part is sintered to closed porosity in vacuo at temperatures below the material flow point and is finally densified isostatically under inert gas.