Investigation of Ceramics for High-Temperature Turbine Vanes
Abstract
The objective of the work has been to investigate those parameters which limit the mechanical properties of SiC at high temperatures. The main approach used in this work has been to optimize processes and compositions for the base structural ceramic, SiC, such that appropriate microstructures could be obtained by hot-pressing at low pressures. These materials are then subjected to high-temperature mechanical tests. The results show that carbon reduction of amorphous silica containing 0.5 percent boron at 1650 degree to 1800 degree temperatures in argon will yield submicron beta-SiC powders well sinterable under nominal hot pressing conditions. Three different microstructures are obtained, depending on whether the powders are oxidized in air at 700 degree C, oxidized and leached with HF, or blended with hyperstoichiometric carbon additions. Of the three, the latter obtained with excess carbon additions is shown to be the preferred structure. In addition, measurements of the the three point bending strength up to 1600 degree C, creep rate, delayed failure, and oxidation rate at 1600 degree C show improvements are obtained by these small carbon additions. At this temperature, strengths in excess of 60 Kpsi have been developed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1972
- Accession Number
- AD0757796
Entities
People
- Svante Prochazka
Organizations
- General Electric