用CVI方法制备SiC_f/SiC复合材料的弯曲断裂强度

对Ｓａｔｉｎｅ、Ｐｌａｉｎ 两种编织方式和不同涂层的Ｈｉ－Ｎｉｃａｌｏｎ 纤维，采用气相浸渍（ＣＶＩ）工艺技术制备出纤维强化型ＳｉＣｆ／ＳｉＣ复合材料，获得其室温至１７７３Ｋ温度范围内３ 点弯曲实验断裂强度曲线。分析Ｓａｔｉｎｅ、Ｐｌａｉｎ 两种二维纺织方法以及纤维涂层（碳、ＢＮ）对ＳｉＣｆ／ＳｉＣ复合材料弯曲断裂强度的影响。结果表明，Ｓａｔｉｎｅ样品的平均断裂强度高于Ｐｌａｉｎ 样品。而纤维涂层虽然使ＳｉＣｆ／ＳｉＣ复合材料的断裂强度有不同程度的下降，但其宏观塑性（挠度）得到明显提高，而且ＢＮ 涂层还使其高温强度增加。热处理工艺对样品弯曲断裂强度影响的实验表明，随着热处理温度升高，材料强度下降，宏观塑性提高。

THE BENDING PROPERTIES OF SiC_f/SiC COMPOSITES PREPARED BY CVI

Hi Nicalon SiC fiber reinforced SiC f/SiC composites using Satine and Plain woven fiber clothes respectively have been prepared by the Chemical Vapor Infiltration (CVI) method.The Three point Bending Test (BT) of these composites has been carried out within the temperature range from room temperature (RT) to 1773 K.The average fracture strength of Satine woven samples is higher than that of Plain woven samples.The effects of carbon coating and BN coating on the Hi Nicalon fiber on the fracture strength (FS) of the composites have also been tested.The carbon coating obviously improves the pseudo ductility of the composites but with reduced FS,while the BN coating improves its pseudo ductility with enhanced FS at high temperature.The BT results of the samples after heat treatment show that the heat treatment degrades the mechanical property of the composites.The higher the temperature of the heat treatment,the more the degradation of the fracture strength.