Method of making a homogeneous silicon nitride sintered body having a high density.

摘要

The invention relates to a process for the pressure sintering of silicon nitride, in which silicon nitride powder is mixed with sintering additives, shaped into components and then sintered to high density by a two-stage sintering programme, the increase of the nitrogen pressure at a density of > 95 % of the theoretically achievable maximum density (Dth) being carried out to a maximum pressure in the range from 1.7 to 100 MPa. In the process of the invention, the nitrogen pressure at the time at which the density reaches 85 % of Dth should be set in the range from 0.1 to 0.3 of the maximum pressure and at the time at which the density reaches 93 % of Dth should be set in the range from 0.2 to 0.4 of the maximum pressure. The actual density of the components within the pressure sintering furnace is carried out by calculation of the shrinkage value in % of Dth in accordance with the following formula: with [ DELTA l/L0]x = linear shrinkage to reach x of the theoretical density, Dg = starting density of the sinter specimens Dth = theoretically achievable maximum density x = % of the theoretically achievable maximum density to be actually achieved.