A study of fiber coating in Al2O3 fiber-reinforced NiAlFe matrix composites

The effectiveness of using oxide coating to modify the interface in the Al2O3 fiber-reinforced NiAlFe matrix composites was studied. ZrO2, Y2O3-stabilized ZrO2, and yttrium aluminum garnet (i.e. Y3Al5O12) coatings were applied onto the Al2O3 fibers by the sol-gel process, and the composites with various coated fibers were consolidated by using a tape-casting/hot isostatic pressing technique. The interface morphology and integrity of the coating layer, as well as the chemical compatibility and thermal stability with the matrix were characterized by scanning electron microscopy, energy dispersive spectroscopy, and scanning Auger electron spectroscopy. Transverse tensile and flexural strengths of the uncoated and coated composites were determined at 980 °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 interdiffusion between the fiber and matrix, and improving the mechanical behavior of the Al2O3/NiAlFe composite were discussed.