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Abstract

A commercially available HP-Si(3)N(4) has been exposed for 200 hours in a 0.4 % H(2)S + 0.75 % H(2)O + H(2) bal. environment at 1200 and 1300 C. Subsequently, long-term constant stress tests have been performed at the exposure temperature in the uniaxial tensile mode. Strength, toughness and subcritical crack growth tests results obtained in the flexural loading mode presented elsewhere highlight the effect of a reduction in the amount in the intergranular glassy phase. However, the interpretation of flexural test results at high temperature is hampered by time-dependent changes in the stress distribution and a shift of the neutral axis, making it very difficult to derive the constitutive equations without making arbitrary assumptions. This paper deals with the comparison of the long-term uniaxial tensile mechanical behaviour of the material in both as-received and exposed conditions. In order not to mask the intrinsic behaviour of the exposed material, all tests are performed in vacuum.

Additional information

Authors: SARAIVA MARTINS C, CEMUL, Instituto Superior Técnico, Lisboa (PT);GUERRA ROSA L, CEMUL, Instituto Superior Técnico, Lisboa (PT);STEEN M, JRC Petten (NL);BRESSERS J, JRC Petten (NL)
Bibliographic Reference: Paper presented: Silicon Nitride '93, Stuttgart (DE), October 4-6, 1993
Availability: Available from (1) as Paper EN 37898 ORA
Record Number: 199311362 / Last updated on: 1994-11-28
Category: PUBLICATION
Original language: en
Available languages: en