Influence of Steel Fiber on Mechanic and Tribological Properties of Cu-Based Cermet Friction Material

Cu-based friction materials reinforced with steel fibers of different ratios of, length-to-diameter ratios were prepared making use of powder metallurgy. The surfaces and cross-sections of the resulting friction materials were observed on a scanning electron microscope. The mechanic properties of the friction materials were measured, while their friction and wear behaviors sliding against cast iron counterparts were evaluated on an MM-1000 friction and wear tester. It was found that the reinforcement with the steel fibers led to an increase in the hardness and bend strength of the friction materials, and the friction and wear behaviors of the steel fiber reinforced Cu-based friction materials were highly dependent on the mass fraction and length-to-diameter ratio of the steel fibers. Namely, the friction material reinforced with the steel fiber of a larger length-to-diameter ratio and mass fraction had a larger and more stable friction coefficient with varying specific braking pressure, i.e., the friction coefficients in this case were less sensitive to the specific braking pressure. In terms of the optimized comprehensive tribological behaviors, the cermets reinforced with the SF-1 steel fiber of a larger length-to-diameter ratio were superior to those reinforced with the other two kinds of steel fibers, and the corresponding cast iron counterpart had a smaller wear as well.