Accession Number:

ADA517389

Title:

Fatigue Behavior of an Advanced SiC/SiC Composite with an Oxidation Inhibited Matrix at 1200 deg C in Air and in Steam

Descriptive Note:

Master's thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS

Personal Author(s):

Report Date:

2010-03-01

Pagination or Media Count:

201.0

Abstract:

The fatigue behavior of an advanced Silicon CarbideSilcon SiCSiC ceramic matrix composite CMC with oxidation inhibited matrix was investigated at 1200 deg C in laboratory air and in steam environments. The composite consisted of an oxidation inhibited SiC matrix reinforced with Hi-Nicalon fibers coated with pyrolytic carbon PyC with a boron carbide overlay woven into eight-harness-satin 8HS weave plies. Tensile stress-strain behavior and tensile properties were evaluated at 1200C. Tension-tension fatigue tests were conducted in both laboratory air and in steam at 1200 deg C at frequencies of 0.1 Hz, 1.0 Hz, and 10 Hz. The tension-tension fatigue tests had a ratio of minimum stress to maximum stress of R 0.05, with maximum stresses ranging from 100 to 140 MPa in air and in steam. Fatigue run-out was defined as 105 cycles for the 0.1 Hz tests and as 2 x 105 cycles for the 1.0 Hz and 10 Hz tests. Strain accumulation with cycles and modulus evolution with cycles were analyzed for each fatigue test. The presence of steam degraded the fatigue resistance of the material at 0.1 Hz and 10 Hz. At 1.0 Hz, the presence of steam appeared to have little influence on the fatigue resistance for the fatigue stress levels 140 MPa. The presence of steam degraded the fatigue performance of the CMC at 1.0 Hz for the fatigue stress level of 140 MPa. Fatigue limit was 100 MPa 32.6 UTS in air and steam at 1.0 Hz and in steam at 0.1 Hz. Fatigue limit was 140 MPa 45.6 in air at 10 Hz. Specimens that achieved run-out were subjected to tensile tests to failure to characterize the retained tensile properties. Specimens tested in air retained 42-61 of their tensile strength and specimen tested in steam retained 59-75 of their tensile strength. The modulus loss in air and in steam was limited to 56.

Subject Categories:

  • Laminates and Composite Materials
  • Test Facilities, Equipment and Methods
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE