Tribological behavior of Ni-Cr-based composite at high temperatures
(Changzhou Institute of Light Industry Technology, Changzhou 213164, China)
Abstract: The wear behavior of Ni-Cr-based alloys was investigated at ambient and elevated temperatures. The wear samples were prepared by metallurgical hot pressing. Wear tests were carried out on a general purpose wear testing machine having a heating unit and pin-disc sample configuration. The counterface material was prepared from Al2O3 ceramics. The tests were carried out at room temperature (RT), 200 ℃ and 600 ℃. The effects of temperatures on the tribological properties were determined by using optical microscopy, and X-ray diffractometry. The results show that at room temperature the worn surfaces of the alloys are characterized by mild scuffing and micro cracks, the action of nano-crystal structural wear debris on the worn surfaces is responsible for the reduction of friction. At 200 ℃, the friction coefficient is the highest. The worn surfaces of the alloys are adhesive and oxidative. At 600 ℃, the friction coefficient is reduced due to the effect of the oxides, tungstates and sulfides residue on the worn surface.
Key words: Ni-based alloys; powder metallurgy; wear mechanism; tribological behavior; dry friction