Accession Number:

ADA558297

Title:

Creep of Hi-Nicalon S Ceramic Fiber Tows at Elevated Temperature in Air and in Steam

Descriptive Note:

Master's thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT

Personal Author(s):

Report Date:

2012-03-22

Pagination or Media Count:

121.0

Abstract:

Structural aerospace components require materials to have superior long-term mechanical properties that can withstand severe environmental conditions, such as high temperatures, high pressures and moisture, whilst enduring the loads they are designed for. Ceramic-matrix composites CMCs are capable of maintaining excellent strength and creep resistance at high temperatures, which make them attractive candidate materials for aerospace applications, particularly in propulsion. Silicon Carbide SiC ceramic fibers have been used as constituent materials in CMCs, although oxidation of the SiC to SiO2 has been a known degredation mechanism. Recently developed near stoichiometric SiC fibers have shown significant improvements in thermochemical stability however performance of the new fibers at elevated temperatures in steam environments has not been studied thoroughly. The objective of this thesis is to investigate creep of near stoichiometric SiC fiber tows at elevated temperatures in air and in steam environments. The creep response of Hi-Nicalon trademark-S SiC fiber tows was investigated at 800 deg C and 1100 deg C in laboratory air and in steam environments. The creep stresses ranged from 76 MPa to 1560 MPa. Creep run-out was defined as 100 h at creep stress. The presence of steam significantly degraded the creep performance of the fiber tows both at 800 deg C and at 1100 deg C. The creep lifetimes of the Hi-Nicalon trademark-S SiC fiber tows were reduced by approximately an order of magnitude due to steam.

Subject Categories:

  • Ceramics, Refractories and Glass

Distribution Statement:

APPROVED FOR PUBLIC RELEASE