Tribological property and wear mechanism of undercooled Ni-Pb monotectic alloys
(1. State Key Lab of Solidification Processing, Northwestern Polytechnical University,
Xi'an 710072, China;
2. State Key Lab of Solid Lubrication, Lanzhou Institute of Chemical Physics,
Chinese Academy of Sciences, Lanzhou 730000, China)
Xi'an 710072, China;
2. State Key Lab of Solid Lubrication, Lanzhou Institute of Chemical Physics,
Chinese Academy of Sciences, Lanzhou 730000, China)
Abstract: The tribological properties of Ni-31.44%Pb monotectic alloys were measured by using a SRV reciprocating tribo-tester. The effects of load, sliding speed and melt undercooling on wear rate of the sample were investigated. The worn surface of Ni-31.44%Pb was examined using scanning electron microscope (SEM) and X-ray photoelectron spectroscope (XPS). The results show that the wear properties of the samples undercooled by 80K and 310K are obviously superior, which is attributed to more efficient transfer of Pb from the bulk material to the worn surface. The lubricating film is identified as a mixture of Ni2O3 and PbO by XPS analysis. At the same load and sliding speed, the predominant wear mechanisms can be identified as oxidative wear for the lower and larger undercooling, and plastic deformation and fracture for the medium undercooling.
Key words: Ni-Pb monotectic alloy; high undercooling; wear rate; wear mechanism