Study on stress relaxation behavior of silicon carbide by BSR method

Abstract

Bend stress relaxation (BSR) experiment at temperatures of 600–1400°C for 1–100h was performed on the two types of highly crystallized monolithic silicon carbide (SiC) produced by chemically vapor deposition (CVD) and liquid phase sintering (LPS) methods. Both materials exhibited similar time-dependent trend of stress relaxation. The BSR ratio dropped rapidly during the first hour of the tests and then decreased gradually in the higher temperature tests. The CVD-SiC and the LPS-SiC showed good thermal creep resistance at the expected operating temperature (about 600–1000°C) of fusion blanket using SiC fiber-reinforced SiC matrix (SiC/SiC) composite. On the other hand, the BSR ratio of those two materials, especially of the LPS-SiC, dropped steeply at the temperatures of 1200–1400°C. The activation energy of the stress relaxation calculated by a cross-cut method increased with the temperature.