Hot Corrosion of Nicalon Fiber Reinforced Glass-Ceramic Matrix Composites: Microstructural Effects.
Abstract
Continuous Nicalon fiber-reinforced calcium aluminosilicate (SiC/CAS) and lithium aluminosilicate (SiC/LAS) are two glass-ceramic composites that show promise for turbine engine applications. A study was undertaken to determine the hot corrosion resistance of these two composites. The composites were coated with 3.Omg/sq.cm. of sodium sulfate and atmospherically exposed at 900 C from 1 to 100 hours. Reactions appeared to initially occur at the exposed fibers in both systems. In the CAS system, the dissolution of the matrix occurred with the formation of CaSiO3 and NaAlSiO4. The LAS system studied (URC2OO) was doped with B2O3. Apparently the boron oxide glass reacted at 900 C and formed a protective layer around the Nicalon fiber. After exposure, two additional phases (SiO2 and an amorphous phase) in the LAS system were detected a thin surface layer of molten so appeared to have little effect on the LAS system since exposure at the same temperature without sodium sulfate produced similar microstructures and diffraction patterns. However, when the same specimen was subjected to a hot corrosion crucible test, where the specimen is completely immersed in molten salt, it was severely attacked within one hour of exposure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1992
- Accession Number
- ADA325790
Entities
People
- R. R. Sands
- R. W. Kowallk
- S. W. Wang
Organizations
- Naval Air Warfare Center Aircraft Divison