Preparation and high temperature properties of new self-lubricating die materials

A new high-temperature self-lubricating die materials was prepared by powder metallurgy using Fe-Ni alloy as the base materials, Cr₂O₃ as the hard phase, and CaF₂ as the solid lubricant. The effects of sintering process on the mechanical properties of Fe-Ni-based self-lubricating materials were investigated by X-ray diffractometer, scanning electron microscope, and microhardness tester, the influences of Cr₂O₃ and CaF₂ on the sintering properties of the self-lubricating materials were studied, and the optimum sintering process was obtained. The results show that, the self-lubricating materials sintered at 1320℃ for 2 h exhibit the excellent mechanical properties. When the content of Cr₂O₃ by mass increases from 0 to 30%, the relative density of the sample decreases by 4.0%, and the hardness increases from HV 227.3 to HV 342.8. When the content of CaF₂ by mass increases from 0 to 10%, the relative density and hardness of the sample gradually decrease. With the increase of CaF₂ content by mass in the friction and wear test at 600℃, the friction coefficient and wear rate decrease first and then increase. The self-lubricating die materials show the best combination performances as the Cr₂O₃ content of 20% and the CaF₂ content of 8% by mass.