Friction And Wear Properties Of MoS₂/Fluoride Self-lubricating Coatings By Laser Cladding

Solid self- lubricating technology has great significance to solve some friction and wear problems in aerospace, metallurgy, chemical industry, thermonuclear industrial equipment and other key parts of it. However, single solid lubricant can’t work under a wide range of temperature with low friction and wear. Therefore, we can make composite solid lubricant coatings to meet the requirements of enviro nment on the properties of friction materials.With reasonable collocating a variety of solid lubricant, it can solve lubrication failure problem caused by the temperature rising, and it is one of the developing direction of lubrication technology in recent years.In this paper, by adopting the laser cladding technology, we preparare the Ni base MoS₂ / LaF₃·CeF₃ self- lubricating coating and Co based MoS₂ / CaF₂ self- lubricating coating material system. Study their phase structure, microstructure, hardness and friction characteristics, and analyse the influence of the existe nce of solid lubrication phase, the influence of different lubrication content to friction coefficient and wear volume at room temperature is measured, through the wear morphology reveal the wear mechanism of different components of coating.There are cavity, blow hole and crack defects in the surface of Co base self- lubricating composite coating.The coatings have dense mesh, and show the characteristic of the dendrite growth. There are reunion of powder particles on the surface of fluxed N i base self- lubricating composite coating, due to many not melt adhesive formed by splatter.There have no obvious flaw in the coating, and it form a good metallurgical combination with the matrix. The bottom of the coating is diluted, and MoS₂ mostly occurred in the cladding layer part after decomposition. The average hardness of the Co base self- lubricating composite coating were lower than that of pure Co alloy coating, but compared with the matrix hardness is improved. The average hardness of N i base elf- lubricating composite coating is generally low, without too much help for enhancing the hardness of the matrix.It may be due to that the solid lubricants joined are soft in texture, and they reduce the overall hardness of coating.Under the normal temperature condition the friction and wear experimental result shows that: friction coefficient of Co base MoS₂ / CaF₂ self- lubricating coating is between 0.4 0.5, and friction coefficient of N i base MoS₂ / LaF₃·CeF₃ self- lubricating coating is between 0.43 0.48.This is less than the friction coefficient of pure Co and N i alloy coating and base material. The amount of base material wear is about four times that of pure cobalt, nickel alloy coating under the same condition,and it is far more than the wear amount of Co, Ni self- lubricating composite coating. All of above shows obvious effect of roughly antifriction antifriction.