HOOP TENSILE STRENGTH AND FRACTURE BEHAVIOR OF CONTINUOUS FIBER CERAMIC COMPOSITE (CFCC) TUBES FROM AMBIENT TO ELEVATED TEMPERATURES

摘要

presently, continuous-fiber ceramic composites (CFCCs) are considered leading candidate materials for many high-temperature applications, such as high-pressure heat exchangers, radiant burner tubes, and engine combustors. To adequately evaluate these materials in their cylindrical configurations, a hoop tension test is needed. A hydrostatic pressurized test was developed to obtain the hoop tensile strength from ambient to elevated temperatures (>1500 degrees C). The method allows only hydrostatic pressure to develop inside the cylinder to cause failure from a hoop tensile stress. This test method evolved from testing monolithic ceramics to continuous-fiber ceramic matrix composite (CMC) tubes. The results of early hydrostatic rests are briefly reviewed. A highlight of one test identified fiber tow pull-out at 1000 degrees C where the tube indicated localized aneurysm-type deformation. Another CFCC material system, evaluated at room temperature, exhibited fiber pull-out on the order of 5 to 7 mm. The circumferential elastic modulus was also obtained. [References: 8]