Research On Laser Cladding High-temperature Wear-resistant Composite Coating With The Addition Of Solid Lubricant WS₂

Solid self-lubricating coatings are primarily used to control friction and wear undersevere application conditions, such as high vacuum, high speeds, high loads, and very hightemperatures in aviation, aerospace, nuclear energy, military and other cutting-edgetechnical fields （the High-temperature adiabatic engine bearings, piston rings, cylinderliner, nuclear valves, turbine blades, etc.）, where conventional materials and lubricantscannot provide the desired performance or durability. In addition the laser cladding is anadvanced surface modification technology with great prospects.In this paper, the NiCr/Cr₃C₂, NiCr/Cr₃C₂-30%WS₂, NiCr/Cr₃C₂-30%WS₂encapsulating and NiCr/Cr₃C₂-15%WS₂encapsulating are used as alloy powders preplacedon the0Cr18Ni9austenitic stainless steels, then the high-temperature wear-resistantself-lubricating composite coatings are fabricated by laser cladding technology. Phaseconstituents and microstructures were deeply investigated by X-ray diffractometer （XRD）,scanning electron microscope （SEM） and energy dispersive spectrometer （EDS）. Thetribological properties of the fabricated composite coatings were evaluated using aball-on-disc wear tester （HT-1000tester, Lanzhou Zhongkekaihua） under dry slidingcondition at room-temperature,300℃and600℃, respectively, and the wearmechanisms were also discussed.Results show that the phase constituents of NiCr/Cr₃C₂coating are composed of Cr₇C₃reinforcement phase and matrix of γ/Cr₇C₃eutectic. However, the coating added with WS₂also has a large number of （Cr, W） C hybrid carbides and a small amount of WS₂, CrSlubricants apart from the above phases. When the WS₂are encapsulated by electrolessplating, it can effectively inhibit the decomposition of solid lubricant WS₂during lasercladding, therefore, the （Cr, W） C phase decreased significantly and WS₂content increasedin the coating added with WS₂encapsulating powder. The high-temperature wear test show that friction coefficients of above coatings bothdecrease with increasing temperature, but the wear rates both increase. At all testtemperatures, the coating added with30%WS₂encapsulating powder has the lowestfriction coefficient and wear rate. Its superior friction-reducing and wear-resistanceproperties are owing to the presence of WS₂and CrS lubricants.This research expanded the material system of the metal-based high-temperaturewear-resistant self-lubricating composite coating, provided valuable research methods andexperimental basis on the laser cladding process, and made a useful attempt to meet thehigher service performance of key high-temperature moving parts in the fields of modernindustrial.