Study On Preparation And Properties Of SiO₂Layer Covered On The Surface Of SiC Fiber

SiC fiber prepared by CVD method has been an ideal material in the enhancement of Ti matrix and has been used due to its good properties, such as antioxidant, high intensity, resistant to corrosion and high temperature. However, in the preparation of SiC/Ti matrix composites, interface reaction between SiC fiber and titanium matrix can be occurred in the hot pressing, which decrease the mechanic performances and limite its development and applications. Therefore, fabricating protection layer covered on the surface of SiC fiber of climinish the interface reaction is of great significance.In this paper, Sol-Gel method was used to fabricate SiO2layer on the surface of SiC fiber through controlling the Sol component, dipping speed, heating and sintering processes. A Magnetron Sputtering was also applied to prepare SiC/Ti22A126Nb composite materials with the SiC fiber whith surface protected by SiO2layer with a layer and four SiO2coating. Some means, such as TG-DSC, SEM and EDS, were used to character the structure, morphology, High temperature resistant performance and mechanical properties of SiO2coating.The results showed that the crack-free SiO2layer was fabricated on the SiC fiber at optimum conditions. After vaccum sintering at800℃, the SiO2coating was still exisiting and crack-free. The mechanical properties of SiC (SiO2) fiber decreased a little.The results also showed that. When Ti22A126Nb matrix was sputtered on the SiC fiber with one layer and four layers SiO2coating surface, SiO2coating existed between SiC fiber and aluminum, matic the thickness of which were155nm and444nm, and reaction layer thickness were0.5μm and0.3μm, respectively. The chemical composition of interface reaction was TiSi and TiSi2. Therefore, SiO2layer can effectively diminish the interface reaction between SiC fiber and Ti matrix, and the protection was melt efficiently when SiO2layer with thicker thickness.