Solutions of YPO₄ were used to precipitate YPO₄ on pre-oxidized Hi-Nicalon-S SiC fibers. Tows of the coated fibers were then infiltrated with a preceramic polymer loaded with SiC particles to form mini-composites. During pyrolysis of the matrix, SiO₂ and YPO₄ on the fibers reacted and formed a Y₂Si₂O₇ fiber matrix interphase. Mini-composites were exposed to steam at 1000 °C for 10, 50, and 100 h, tensile tested, and the effect of oxidation in steam on the functionality of the Y₂Si₂O₇ fiber coating was investigated. The minicomposites oxidized at 1000 °C for 10 h retained 100 % of their unoxidized strength, and those oxidized for 50 and 100 h retained 92 % and 90 % of unoxidized strength, respectively. Strength retention and fiber pullout in both unoxidized and oxidized minicomposites suggests that the Y₂Si₂O₇ interphase was effective in maintaining a weak fiber-matrix interface.

使用YPO ₄溶液在预氧化的Hi-Nicalon-S SiC纤维上沉淀YPO ₄。然后，用负载有SiC颗粒的陶瓷前聚合物渗透涂层纤维束，以形成微复合材料。在基体热解期间，纤维上的SiO ₂和YPO ₄反应并形成Y ₂ Si ₂ O ₇纤维基体中间相。将微型复合材料暴露于1000°C的蒸汽中10、50和100 h，进行拉伸测试，以及蒸汽中氧化对Y ₂ Si ₂ O ₇官能度的影响研究了纤维涂层。在1000°C氧化10 h的微复合材料保留其未氧化强度的100％，在50和100 h氧化的微复合材料分别保留92％和90％的未氧化强度。在未氧化和已氧化的微复合材料中，强度保持率和纤维拉出性均表明，Y ₂ Si ₂ O ₇界面有效地维持了弱的纤维-基质界面。