碳纤维表面处理对C_f/SiO_2复合材料力学性能的影响

Effect of Surface Treatment of Carbon Fiber on the Mechanical Properties of C_f/SiO_2 Composite

对T-300碳纤维进行表面改性处理,并采用浆料浸渍-热压法制备了单向碳纤维补强石英基复合材料(C_f/SiO_2)。对改性前后碳纤维的表面形貌、官能团的变化以及复合材料的力学性能和断面形貌进行了研究。结果表明,T-300碳纤维经过硝酸氧化处理后,去除了表面的有机胶料层,含氮、氧的官能团数量增加,有利于改善成型时纤维和浆料之间的润湿性能。复合材料的抗弯强度由处理前的433 MPa提高到了655 MPa,断裂韧性也从9.1 MPa·m^(1/2)提高到12.9MPa·m^(1/2)。在热压烧结的过程中,碳纤维表面有机胶料发生热解形成的气态物质难以排出,在纤维/基体界面上形成了孔洞,影响了界面结合状态,不利于载荷的传递。因此,对碳纤维进行表面改性有效地提高了复合材料的力学性能。

Unidirectional T-300 carbon fiber reinforced fused.silica （Cf/SiO2） was prepared by slurry infiltrating and hot-pressing after the carbon fiber was treated by nitric acid oxidation. The surface morphologies and functional groups on the surface of carbon fiber before and after treatment were studied, and the mechanical properties of Cf/SiO2 composite were tested. The clean organic layer on the fiber surface consisted of the functional groups of oxygen and nitrogen whose amount was increased by oxidation in nitric acid. The flexural strength and fracture toughness of composites increased from 433 MPa, 9.1 MPa·m^1/2 to 655 MPa, 12.9 MPa·m^1/2, respectively. This attributed to the suppressed formation of pores at the fiber/matrix interface by the treatment.