A STUDY OF FIBER COATING IN AL2O3 FIBER-REINFORCED NIALFE MATRIX COMPOSITES

The effectiveness of using oxide coating to modify the interface in th e Al2O3 fiber-reinforced NiAlFe matrix composites was studied. ZrO2, Y 2O3-stabilized ZrO2, and yttrium aluminum garnet (i.e. Y3Al5O12) coati ngs were applied onto the Al2O3 fibers by the sol-gel process, and the composites with Various coated fibers were consolidated by using a ta pe-casting/hot isostatic pressing technique. The interface morphology and integrity of the coating layer, as well as the chemical compatibil ity and thermal stability with the matrix were characterized by scanni ng electron microscopy, energy dispersive spectroscopy, and scanning A uger electron spectroscopy. Transverse tensile and flexural strengths of the uncoated and coated composites were determined at 980 degrees C and room temperature, respectively, to evaluate the effect of coating on their mechanical properties and failure behavior. Critical issues on tailoring a functional interface using fiber coatings to control in terdiffusion between the fiber and matrix, and improving the mechanica l behavior of the Al2O3/NiAlFe composite were discussed.