双涂层和梯度涂层改善SiC_f/Al界面性能的微观机制

MICROMECHANISM OF IMPROVING THE INTERFACE PROPERTIES OF SiC_f/Al COMPOSITE BY FIBER MODIFICATION WITH DOUBLE AND GRADIENT COATING

研究了双涂层（ＲＤ）和梯度涂层（ＲＧ）处理改善ＳｉＣｆ／Ａｌ界面和复合材料性能的微观机制．发现ＲＤ试样中纤维外涂层氮化硼（ＢＮ）阻档了Ａｌ向界面内层Ｃ的扩散，从而阻止Ａｌ、Ｃ脆性相的生成，同样ＲＧ试样中Ｃ、Ｓｉ梯度分布阻碍Ａｌ、Ｃ脆性相的形成，故这二种涂层处理均较单Ｃ涂层较好地改善了界面和复合材料性能。

The micromechanism of improving the interface properties of SiCf/Al composite using fiber surface modification with double coating (RD) and gradient coating (RG) has been studied by cold field emission scanning electromicroscope and acoustic emission method. It is found that BN coating outside of fiber prevents Al from diffusion toward inner C in interface. As a result, the brittle phase of Al, C compound could not be formed in interface. Similarly, RG coating prevents the brittle phase of Al, C compound from producing in interface. Therefore, the properties of interface and SiCf/Al composite could be improved with above fiber surface modification. Whereas the protection of BN coating is destroyed by over high temperature and pressure which makes violent diffusion of Al across BN obstruction. As a result, protection of interface with double coating degenerates. Moreover, the property of interface with rich C was poor due to forming the brittle compound of Al, C.