Preparation Of TiC Coating On Carbon Fiber And Its Effect On Aluminum Matrix Composites

Carbon fiber is composed of carbon element,with high temperature resistance,high specific strength and high specific modulus and other characteristics of a fiber.Carbon fiber reinforced aluminum matrix composites(Cf/Al),which are used as reinforcement material and aluminum alloy,have excellent properties such as high specific modulus,high specific strength and low density.Therefore,it has become the research object of structural materials scholars and is widely used in the fields of transportation,aerospace and so on.With the research of Cf/Al composites,it is found that there are two problems in the process of preparing Cf/Al composites:poor wettability between carbon fiber and aluminum matrix,and the Al4C3 brittle phase is easily formed by harmful interfacial reaction between them at high temperature.These two problems will lead to the decline of Cf/Al composite properties and restrict the development of Cf/Al composites.In this paper,the molten salt method was used to prepare TiC coating on the surface of carbon fiber.By optimizing fiber pretreatment,ball milling parameters,the placement mode of molten salt mixture and fiber,as well as cleaning mode and other processes,comparative tests were carried out and the influence rules of molten salt type,reaction temperature and holding time on the TiC coating were analyzed.Short Cf/Al composites with no TiC coating,0.6?m TiC coating and 1.2?m TiC coating were prepared by vacuum melting method,and the effects of TiC coating on the microstructure and mechanical properties of Cf/Al composites were analyzed.The TiC coating prepared by molten salt method showed that the reaction rate of NaCl under molten salt was slower than that of KCl under the same reaction temperature and holding time,and the TiC coating on the fiber surface was relatively uniform.With the increase of reaction temperature and the prolonging of holding time,the thickness of TiC coating increases gradually,and a mathematical model is established.The results of preparation of short Cf/Al composites show that the carbon fibers in Cf/Al composites are uniformly distributed in the aluminum matrix,showing circular,elliptical and linear shapes.The TiC coating makes the interfacial bonding between the carbon fibers and the aluminum alloy matrix achieve a good performance.With the increase of the thickness of TiC coating,the hardness of the composite increases,and the tensile strength increases first and then decreases.When the thickness of TiC coating is 0.6?m,the tensile strength reaches the maximum value of 183MPa,which increases by 37.6%compared with the matrix for Cf/Al.The results show that when the interfacial bonding of the composites is good and moderate,the carbon fibers break first and then pull out,which can bear a large load in the whole fracture process and improve the mechanical properties of the composites.These results indicate that the interfacial bonding between carbon fiber and aluminum matrix can be effectively improved by preparing appropriate coating on the surface of carbon fiber by molten salt method,and the overall properties of the composites can also be improved.