Influence of phosphorus on iron-based friction material prepared directly from vanadium-bearing titanomagnetite concentrates

In situ selective carbothermic reactions and vacuum sintering were used to prepare iron-based friction material directly from vanadium-bearing titanomagnetite concentrates. Effects of phosphorus addition (0.05–0.20 wt.%) on the microstructure and properties of iron-based friction material were investigated. The results show that the addition of phosphorus improves the microstructure and properties of the material significantly. When phosphorus addition increases to 0.15 wt.%, the sintering densification is promoted and the number of lamellar pearlites increases. Therefore, the relative density, hardness and tribological properties of the material are greatly enhanced. Particularly, the friction coefficient decreases from 0.58 to 0.43, and the wear rate reduces from 1.829 × 10^–7 to 0.694 × 10^–7 cm³ J⁻¹. The dominant wear mechanism of the material changes from severe abrasive wear to mild oxidation wear accordingly. However, when phosphorus addition exceeds 0.15 wt.%, the matrix continuity and tribological properties of the material are deteriorated. Comprehensively, the optimal addition of phosphorus in the iron-based friction material is 0.15 wt.%.