目的 通过选择合适的复合材料拉伸方向和涂层制备工艺，在SiCf/SiC复材上获得高结合强度的Si/Yb2Si2O7双层涂层。方法 采用真空等离子喷涂技术在2.5D编织的SiCf/SiC复合材料表面制备Si涂层、Si/Yb2Si2O7双层涂层。采用金相、XRD、SEM和EDS对试样进行表征，采用拉伸试验测试涂层的结合强度，观察涂层拉伸后的断裂面形貌，分析涂层结合强度的影响因素。结果 采用胶粘拉拔法，2.5D编织的SiCf/SiC复合材料拉伸后的强度值为(32.41±3.52) MPa，Si涂层和Yb2Si2O7涂层的孔隙率分别为2.3%和5.2%，Si涂层与SiCf/SiC复合材料的结合强度为(30.48±4.43) MPa，Si/Yb2Si2O7双层涂层与SiCf/SiC复合材料的结合强度为(26.23±3.13) MPa。Si涂层在拉伸过程中，部分Si层、SiCf/SiC复合材料表面纬向SiC纤维、SiC基体和粘接胶都发生了断裂。Si/Yb2Si2O7双层涂层在拉伸过程中，大量Si层、复合材料表面纬向SiC纤维和SiC基体以及少量Yb2Si2O7层被拉开。结论 Si/Yb2Si2O7双层涂层与SiCf/SiC复合材料结合强度较高的主要原因是SiCf/SiC复合材料沿拉伸方向强度较高，Si涂层与复合材料结合强度高。真空等离子喷涂技术有利于减少涂层微观缺陷。Yb2Si2O7的热膨胀系数与Si、SiCf/SiC相近。Si涂层与Yb2Si2O7涂层化学相容性好。

By the means of choosing suitable stretched direction of SiC fiber-reinforced SiC ceramic matrix composites (SiCf/SiC composites) and preparation technology of coatings, this work aims to obtain Si/Yb2Si2O7 duplex coatings of high bonding strength on SiCf/SiC composites. Si coating and Si/Yb2Si2O7 duplex coatings were prepared by vacuum plasma spraying (VPS) on 2.5D woven SiCf/SiC composites. The specimens were investigated by metallographic, XRD, SEM and EDS, and the bonding strength was tested by tensile test. The fracture morphology after the tensile test was observed and possible influence factors of the bonding strength were analyzed. The results show that:by using adhesion-drawing method, the tensile strength of 2.5D woven SiCf/SiC composites is (32.41±3.52) MPa. Porosities of Si coating and Yb2Si2O7 coating are 2.3% and 5.2%. The bonding strength of Si coating on SiCf/SiC is (30.48±4.43) MPa, while that of Si/Yb2Si2O7 duplex coatings (26.23±3.13) MPa. When the Si coating is stretching, parts of Si coating, weft yarn of SiC fibers and SiC ceramic matrix on the surface of SiCf/SiC composites and adhesive film are broken. When the Si/Yb2Si2O7 duplex coating is stretching, a great deal of Si coating, weft yarn of SiC fibers and SiC ceramic matrix on the surface of SiCf/SiC composites and a little of Yb2Si2O7 coating are broken. The main reasons for the high bonding strength of Si/Yb2Si2O7 duplex coatings on SiCf/SiC composites are as follows:the strength of SiCf/SiC along stretched direction is high, and the bonding strength of Si coating and SiCf/SiC is high; the vacuum plasma spraying is beneficial to decrease the defects of coatings; thermal expansion coefficient of Yb2Si2O7 is approximately with that of Si and SiCf/SiC; chemical compatibility between Si coating and Yb2Si2O7 coating is excellent.