Effect of Oxidation Embrittlement on the Impact Behavior of Nicalon ReinforcedGas II Ceramic Matrix Composites

摘要

The impact behavior of Nicalon reinforced CAS II composites is described. Impacttests of samples loaded to 1.0 microcracking yield and heated to 600 deg C for 10 hours were compared to tests of as received samples to determine the degree of degradation caused by the treatment. In addition, samples which were loaded to 1.0 micro-cracking yield but not heated and samples which were heated to 600 deg C for 10 hours were compared to isolate the effects of pre-cracking and heating. It was demonstrated that oxidation embrittlement has a negative effect on the maximum stress and dynamic fracture toughness of CAS II composites when fractured in impact. It was further demonstrated that specimens reinforced with mica-coated Nicalon fibers are more susceptible to oxidation embrittlement than specimens reinforced with standard Nicalon fibers. Ceramic matrix composites, Calcium aluminosilicate(CAS) matrix, Nicalon(Mica and Uncoated) fibers, Instrumented impact behavior, Flexure strength, Oxidation embrittlement, Microyield(MCY) stress.