Preparation and properties of Y₂Si₂O₇ whisker-toughened MoSi₂ coatings

Y₂Si₂O₇ whisker-toughened MoSi₂ oxidation resistant coatings were deposited on SiC-C/C composites surface by a hydrothermal electrophoretic deposition process. The phase compositions and microstructures of coatings were analyzed by X-ray diffraction (XRD) and scanning electron microscopy(SEM). The influences of Y₂Si₂O₇ whisker on the microstructure and oxidation resistance of coatings were particularly investigated. The results show that Y₂Si₂O₇ whisker has a strong influence on the microstructure and oxidation resistant performance of the coated composites. Compared with MoSi₂/ SiC coating, Y₂Si₂O₇-MoSi₂/SiC coating exhibits dense, uniform and homogeneous morphologies without any microcracks. Y₂Si₂O₇ whisker can effectively prevent coatings from cracking as a result of improving oxidation resistant performance of the coated composites. The as-prepared multi-layer coating can protect C/C composites from oxidation for 100 h at 1773 K with a mass loss of 0.73 %. The corresponding mass loss rate is 1.48×10^-5 g·cm^-2·h^-1.