Mechanical Properties of Gas Pressure Sintered Silicon Nitride
The densification behavior of Si3N4-powders during gas pressure sintering with additions of Y2O3 and Al2O3 was studied by dilatometer measurements. High densities of 99.5% of the theoretical value were achieved by 2-step gas pressure sintering while the density of pressureless sintered material was 1–2 % less. The reliability of the sintered ceramic material was improved by applying gas pressure after the main densification step. The Weibull modulus of pressureless sintered materials of m=8–11 increased to m=20–25 by applying gas pressure sintering. The average bending strength (4-point) was 800–900 MPa for pressureless as well as gas pressure sintered materials.
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