Study On Laser Cladding Self-Lubricating Coating

Wear is the main cause of great economic loss in industrial production.It is of great economic benefit to study the self-lubricating coating technology of mechanical parts with high load,oil-free environment and harsh working station.The preparation of Ni-based self-lubricating coating by laser cladding has the characteristics of low cost and high efficiency.The friction-reducing and wear-resisting properties of the workpiece can be improved by adding solid lubricant material.In this paper,42CrMo steel is used as laser cladding substrate,high power CO₂ laser is used as process heat source,and coaxial powder feeding device is used to study different laser power and scanning speed.The effects of different solid lubricant powder content on the properties of laser cladding graphite and MoS₂ self-lubricating coatings were investigated.The macroscopical morphology of the coatings under different process parameters was carried out by using the equipment such as asana microscope,?OM?,scanning electron microscope?SEM?,microhardness tester,x-ray diffractometer?XRD?,friction and wear tester,etc.The microstructure,phase composition and friction properties were studied.The results of self-lubricating coating under different process parameters show that:?1?With the addition of MoS₂ powder and graphite powder respectively,the surface without obvious cracks,pores and other defects can be obtained.When the laser power is high and the scanning speed is low,the pore defects in the cross-section of the coating can be alleviated.The effect of MoS₂ powder content on the coating quality is not obvious.When the content of graphite powder is high,the phenomenon of pore inclusions in the coating cross-section becomes more and more serious.?2?The s element decomposed by MoS2 in MoS2 self-lubricating coating prepared by laser cladding has self-lubricating properties with the alloy element forming sulfides,and the Mo element has the function of fine grain strengthening.Solid-state dissolution of graphite particles occurs in graphite self-lubricating coating,and the density difference between graphite and nickel-based coating leads to convection phenomenon in molten pool,which makes the microstructure of self-lubricating coating finer.?3?The anti-friction and wear resistance of the self-lubricating coating prepared by adding MoS2 powder and graphite powder is better than that of Ni45 matrix powder coating.?4?When the laser power is 2.1 kW,the scanning speed is 300 mm/min and the powder content is 3%,the microhardness of MoS₂ self-lubricating coating is 550 HV_0.2,and the friction coefficient is decreased by 24.3%to 0.456 compared with the coating without solid lubricant.The wear resistance is the best,the wear volume decreases 59.1%to 1.72mm³,and the wear resistance is the best.The appearance of wear mark is furrow wear mark and block shedding,the wear form is abrasive wear and slight adhesion wear.The microhardness of graphite self-lubricating coating was 475HV_0.2.Compared with the coating without solid lubricant,the friction coefficient decreased by 20.3%to 0.48,the antifriction property was the best,the wear volume decreased by 70%to 1.26mm³,and the wear resistance was the best.The appearance of wear mark is slight furrow wear,and the wear form is slight abrasive wear.