Influence On Part Of The Performances Of Resin-based Friction Materials By Carbon Fiber Content And Form

As a new material, carbon fibers have a wide range of applications in many fields. Theresearch of carbon fiber in China since the1960s, and from1980s the field of high-strengthcarbon fiber was involved. Gone through the course of many years of research on its own inChina, although progress is slow but also achieved some results. For example Jilin City of JilinProvince, due to the development of the carbon fiber industry is hailed named “Carbon Valley”.Carbon fibers have excellent performance on various fronts. High-strength, low-density,high hardness, acid and alkali resistance, good dimensional stability and good electricalconductivity. It has been applied in the aerospace and military fields. There are instances ofcarbon fiber application in civilian area, such as sports equipment, transport, bridge constructionand other fields.The friction material was prepared by making the polyacrylonitrile-based carbon fiber as areinforcing member, ordinary phenol resin as a binder, kaolin, alumina, barium sulfate as filler.Main research is the effect of content and morphology of carbon fibers on the coefficient offriction and the wear rate of friction materials. And studied the water absorption of the frictionmaterial, density, hardness and impact strength properties. Further, by optical microscopy,scanning electron microscopy and other equipment, the friction-wear mechanism of was studied.Understudied the impact of the addition of carbon fiber on friction and wear mechanisms of thefriction material.In this experiment, we used experiment-micro-ball mill to mix kaolin, alumina, bariumsulfate, phenolic resin with the quality of a geometric proportion uniformly mixed, and then addthe carbon fibers that pretreated. The preparation process is ordinary hot-pressing process,repression parameters is40MPa and140°C, and holding pressure to the mold temperaturedropped to70°C. The pretreatment using a liquid of the surface of the carbon fiber oxidationmethod, to increase the roughness of the surface of the carbon fiber and improve the bonding strength of the carbon fibers and resin matrix.The friction coefficient, wear rate, hardness, impact strength, water absorption and densityare several important properties of the friction material. Disc friction machine was used in thisexperiment on testing the friction coefficient and wear rate of the friction material. Found that,the high hardness as well as self-lubricating properties of the carbon fibers will improve thestability of friction coefficient and affect the friction coefficient of the friction material.Simultaneously adding of the carbon fiber can also play a role to reduce the wear rate of thefriction material. In addition, the carbon fiber in friction material can play the role of fibertoughening increasing the impact strength of the friction material. And carbon fiber is added toimprove the hardness of the friction material. Adding carbon fibers increased the internalporosity in friction material, lowered the density of the friction material and increased the waterabsorption of the friction material.Carbon fiber used in this experiment is divided into two forms. One is carbon fiber powdermade by ball mill and the other one is continuous long fiber with maintaining the factory state. Itwas found that when the carbon fibers added in the form of long fibers, the role of promoting theslip film forming is not great. When the carbon fibers added in the form of carbon fiber powderthe high hardness of the carbon fibers can promote the generation of the slip film to reduce thewear rate of the friction material. When carbon fiber is added in the form of long fibers, itshowed a high degree of influence of the high hardness on friction material, and added in theform of carbon fiber powder, the influence degree of the self-lubricating properties of carbonfibers on the friction material is great. In the friction and wear mechanisms, the high hardness ofthe carbon fibers and high abrasion resistance can promote the generation of slip film is in thefriction process, reduce the wear rate of the friction material. The presence of carbon fiberschanged the surface crack distribution in the friction process, makes cracks concentrated in thevicinity of the carbon fiber. The carbon fibers can also serve to reduce the delamination.