Vipul Sharma

Date of Award

9-2008

Document Type

Thesis

Degree Name

Master of Science in Aeronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Richard D. Branam, PhD

Abstract

The fatigue behavior of two woven SiC-SiNC ceramic matrix composites (CMCs) was investigated at 1300 °C in laboratory air and in steam. The first composite (C1) consists of a PIP SiNC matrix reinforced with Sylramic (Syl) fibers woven in a five-harness satin weave fabric and coated with a proprietary dual-layer interface. The second composite (C2) consists of a modified PIP SiNC matrix reinforced with Sylramic-iBN (Syl-iBN) fibers woven in a five-harness satin weave fabric and coated with a proprietary dual-layer interface. The tensile stress-strain behavior was investigated and the tensile properties measured at 1300°C. Tension-tension fatigue behavior was studied for fatigue stresses ranging from 100 to 180 MPa at 1300 °C in air and in steam. The presence of steam caused noticeable degradation in fatigue performance of both composites at 1300°C. The fatigue limit of the composite C1 (based on a run-out condition of 2 x 105 cycles) was 100 MPa (53% UTS at 1300°C) in both air and steam. The fatigue limit of the composite C2 was 160 MPa (66% UTS) in air and 140 MPa (58% UTS) in steam. The retained strength and modulus of all specimens that achieved run-out were characterized. Specimens of both composites tested in air retained 100% of their tensile strength, while the specimens of both composites tested in steam retained only about 90% of their tensile strength.

AFIT Designator

AFIT-GAE-ENY-08-S02

DTIC Accession Number

ADA487597

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