Fabrication And Wear Properties Of In Situ Iron Matrix Composites

The reaction mechanism of Al-Fe2O3-Fe and Ti-C-Fe system to fabricate i n situ TiC/Fe and Al2O3/Fe composites was analyzed by DSC curves with ther modynamic and dynamic mechanism. The in situ TiC/Fe and Al2O3/Fe composi tes were successfully fabricated in vacuum furnace, the microstructure and com position of which was analysised and researched by means of OM, XRD, SEM, EDS techniques et al. The wear behaviors of the two composites were tested by the pin-disc friction-wear tester. According to the SEM morphologies and E DS images of wear surface and the OM images of wear subsurface, the influe nce of the sliding load, velocity and the reinforcement volume fraction on the friction and wear properties of the composites was analyzed at ambient temper ature. At last, the wear mechanisms of the composites were investigated, too.According to the reaction mechanism, the reaction of Al-Fe2O3-Fe systemis divided into 3 temperature ranges:①1000℃4Al(1)+12Fe2O3(s)=Al2O3(s)+5Fe O(s)+6Fe3O4(s)+FeAl2O4(s),②1100℃4FeO(s)+3Fe3O4 (s)+12Al(1)=4Al2O3(s) +12Fe(s)+FeAl2O4(s),③1200℃3FeAl2O4(s)+2Al(1)=4Al2O3+3Fe, and the reinf orcement volume fraction is a great impact on the reaction of the system. The reaction of Ti-C-Fe system is the formation of non-stoichiometric TiCx (x<1) because of the combination of Ti and C in the strong exothermic reaction at 1161℃. And the pearlite formed in the Fe matrix because the remaining C an d Fe occurred eutectoid and eutectic reaction in the cooling process. And the a dditives are good to the uniformity of reinforcements.The friction and wear properties tests reveal that the wear properties of th e two composites are greatly improved over the iron matrix. The study found t hat, the wear loss mass of the TiC/Fe composite increased as the load, at the same time, the friction coefficient decreased and the wear debris of the worn s urface of the composite increased with the reunion and oxidation. Under the sa me conditions, the wear debris of the worn surface of the composite decreased with the reunion with the reinforcement volume fraction increasing, and the w ear properties of the composite became better. The wear loss mass of the 10% TiC/Fe composite decreased first and then increased while the 30%TiC/Fe and 50%TiC/Fe composite changed in the opposite with the velocity. Changes in fri ction coefficient was relatively stable. By observing sub-surface layer of the we ar specimen of the TiC/Fe composite, sub-surface layer deformation was not ob vious, but the hardness increased.