Interfacial Studies of Coated Fiber Reinforced Glass-Ceramic Matrix Composites.
Abstract
The objective of this program is to develop an understanding of the relationships between the fiber, fiber coating or coatings, and the glass-ceramic matrix, that will lead to a composite system exhibiting high strength, high toughness, and good thermal and environmental stability to temperatures of 1200 deg C. To meet this objective, the chemistry and microstructure of the fiber/coating(s)/matrix interfacial region and how these influence the interfacial bonding, strength, and toughness of the particular composite system was investigated. During the course of this program, emphasis was placed on the determination of the high temperature mechanical properties of the BMAS matrix/SiC over BN coated Nicalon fiber composite system, and how these properties relate to changes that may occur in the matrix, fiber coatings, or Nicalon fiber chemistry and microstructure. Specifically, short time flexural, short time tensile, tensile creep, and tensile fatigue testing was conducted in air to temperatures of 12OO deg C, all on the same composite sample. Flexural creep was also performed on similar composite samples and compared to the tensile creep results. In addition, Si3N4 over SN and BN by itself were evaluated as fiber coatings in the BMAS matrix/Nicalon fiber composite system. The effect of long-time heat-treatments in oxidizing and non- oxidizing environments were conducted on composites with different interface chemistries. With the collaboration of Brown University, SEM and TEM analyses of the composites after being subjected to the various stress and temperature conditions were conducted. From these studies, damage modes and microstructural and chemical changes that occurred as a result of these tests were determined. Results of these studies are presented.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1994
- Accession Number
- ADA290780
Entities
People
- Ellen Sun
- John K Brennan
- Steven Nutt
Organizations
- United Technologies Corporation