Effect of Ni Content on Iron-based Friction Material Prepared by In-situ Synthesized from Vanadium-bearing Titanomagnetite Concentrates

A method for preparing iron-based friction material directly from the vanadium-bearing titanomagnetite concentrates by means of in-situ carbothermic reaction and sintering was presented. Effect of Ni content (1%-4%, mass fraction, the same below)on microstructure, mechanical properties and wear performance of iron-based friction material was investigated. The results show that the sintered sample consists of iron matrix, graphite lubricating phases and hard particles (mainly TiC). The matrix is predominantly composed of laminated pearlite with higher strength and hardness than those of ferrite. Compared with the sintered sample without Ni, the microstructure and properties of iron-based friction material are improved in varying degrees with different Ni contents. Low Ni content (1%-2%) promotes sintering process, which exhibits the decreasing amount of pores and uniform distribution of lubricating graphite phases and hard particles. Besides, the hardness and wear performance are improved significantly with the increase of Ni content. However, when Ni content exceeds 2%, not only the amount of pores increases, but also graphite phases and hard particles segregate in the microstructure, which result in decreasing hardness and poor wear performance of the material. To sum up, the microstructure and properties are the best when the Ni content is 2%.