Environmental Resistance of Ceramic Matrix Composite Materials for Gas Turbine Applications

Continuous fibre-reinforced CMCs are currently the most promising candidate material class for a number of commercial applications in power engineering. A test campaign was performed to assess and rank the performance of four commercially available ceramic fibre-reinforced CMCs for possible use in advanced gas turbines for power generation. The test campaign focused on critical environmental tests, which were tailored to closely simulate predicted service conditions of a first stage vane. Composites used were SiC fibre/SiC, coated SiC fibre/SiC, SiC fibre/Al2O3, and SiC fibre/NB-SiC. High pressure/high temperature corrosion tests at 1350 C and 4 bar total pressure, long-term static oxidation tests at 1350 C under air at atmospheric pressure, and thermal shock (rapidly cooled from 400 C) and thermal cycling (500 cycles of cooling rapidly from 400 C) tests were carried out. Two of the four materials, coated SiC/SiC and SiC/NB-SiC, show excellent environmental resistance and appear to be highly promising, but still fall short of service requirements at the current state of development. The need to accurately simulate environmental conditions in testing is shown. 6 refs.