Preparation And Property Research Of C_f/SiC Brake Materials Of High-Speed Train

C_f/SiC has the broad application prospect when it as a new kind of braking material. On this article, in order to shorten preparation cycle and reduced production costs, carbon fiber and resin binder could be adopted instead of continuous fiber felt. C_f/SiC brake materials were prepared by the way of molding compression-pressureless sintering. The effect of sintering aids content, sintering temperature, fibers distributing, fibers length and fibers volume on mechanical properties were investigated by measuring the bending, compressive and friction and wear. The bending fracture mechanism, compression damage mechanism and friction and wear mechanism were analyzed. The results show that:(1) The sintering aids content can influence bending strength of C_f/SiC brake materials. With the increase of sintering aids content, the density and bending strength of C_f/SiC brake materials first rise and then fall. When the sintering aids content is 10%, the bending strength is the highest.(2) With the increase of sintering temperature, the bending strength of C_f/SiC brake materials first rise and then fall. When sintering temperature is too high, which induced crystal grain grown up and the crack is easy to produce. Finally make the bending strength of composites reduced. When sintering under 1850℃, the bending strength reached maximum.(3) The distributing of fibers in matrix can influence the combine of fiber and matrix in short fiber reinforced composites. Dispersing fiber distributing have compact fill between single fibers, more interface between fiber and matrix. The bending strength, compressive strength and wear resistance were improved by the fibers full play the role of strengthening and toughening.(4) Carbon fiber length has important impact on mechanical properties of composites. With the increase of carbon fiber length, the bending strength and compressive strength first rise and fall, the wear loss is also too. The composites have the best properties when the carbon fiber length is 5mm.(5) When the carbon fiber content is 5%, 10% and 15%, wit the carbon fiber content increasing, the bending strength, compressive strength and wear resistance first rise and then fall. The result shows that when fiber content is 10%, bending strength, vertical compressive and parallel compressive separately were 18.81MPa, 39.04MPa, 35.24MPa. Wear resistance is also best.(6) In the C_f/SiC brake materials, the carbon fiber debonding and fiber pull were the main toughening mechanism when the bending fracture; vertical compressive specimens were destroyed by shear failure mode, the parallel compressive specimen were destroyed by split between fiber layer and matrix; in the process of friction and wear, abrasive wear and adhesive wear were the main wear mechanism.