The Research Of Preparation And Tribological Characteristics Of Iron-based High Temperature Self-lubricating Composites

Taking graphite and authigenic oxide as lubricating phase, adding molybdenum, nickel and copper into the composites,the iron-based self-lubricating composites at high temperature which could be used continuously between room temperature and450℃were prepared by powder metallurgy technology.. The microstructure was observed and analyzed by the optical microscope and X-ray diffraction (XRD) Diffractionmeter instrument. Tribological property in different conditions was measured with high temperature tribometer, which was a pin-on-disc configuration. The density, hardness and compressive strength were also measured by different measuring instruments. Wear mechanism was analyzed by scanning electron microscope (SEM), Energy Disperse Spectroscopy (EDS) and XRD. Experimental results showed that different iron-based self-lubricating material owned similar wear mechanism. Strengthening phase which was composed of metal carbide and small amounts of metal solid solution on the wear surface decided the wearability of the organization. Graphite and metallic oxide produced in the process of friction were the main reason why it had good elevated temperature antifriction performance and wearable ability.Adding nickel and copper into self-lubricating composites could aggravate the degree of alloying effectively and reinforce mechanical properties,it was attributed to the strengthening phase, which was caused by solid solution content and a large amount of metal carbide, reinforced matrix strength. The tribological properties of materials improved with adding of nickel and copper. In the condition of high temperature, the decreasing trend of friction coefficient was obvious. Especially when the content of copper was15wt%, average friction coefficient of Fe-Mo-Ni-Cu-graphite at500℃was only0.28. The wear rate level was10-8cm3/N·m, it represented superior properties of anti-friction and wear resistance at high temperature.When the content of graphite was1wt%, the microstructure of the composites was mostly ferrite. Friction coefficient changed slightly with different wear speed, when wear speed was in the range from0.2m/s to0.8m/s,the average friction coefficient was0.45. and the wear rate increased with the increasing of revolving speed. When the content of graphite was more than1wt%, the microstructure of the composites was mostly pearlite, friction coefficient increased with the increasing of wear speed, then the wear rate decreased with the increasing of wear speed. The pearlite and metal carbide formed in the composites, as well as Fe2O3, Fe3O4formed on the worn surface of composites were the main reasons why graphite material had good elevated wear-resisting ability.