The Research On Properties Of ZrO₂/Ni60A Composite Coating By Laser Cladding On Circular Surface

As a new type of surface modification technology, laser cladding has been developedrapidly in recent years. It could make the specimen show some special property byadding alloy powder to the surface, while scanned by the laser alloy powder melt andmetallurgical bonded with the substrate. In this paper, aiming to the problem ofwear-out and drug corrosion on the surface of infusion pump plunger. Chose304stainless steel pipe’s surface as the substrate, nickel self-fluxing alloy and somezirconium oxide composite materials as the cladding powder, which shows goodanti-friction and corrosion resistant, and nearly have the same material expansioncoefficient with the substrate, and the mixed ceramic power as reinforcers. With themethod of synchronous powder feeding laser cladding, and finally got a1mm thicklayer. The hardness of layer fluctuated between50and60HRC, which vary graduallyfrom the substrate to the surface of the layer in the depth direction, and its service lifewas greatly extended.The laser cladding parameters including light spot, laser power, scanning velocity andpowder feeding rate, were optimized by in single track cladding orthogonal test. Inmulti-track cladding experiment, the overlapping parameters including overlapcoefficient and overlap way were optimized. Using micro-hardness tester, ScanningElectron Microscopy （SEM）, Optical Microscope （OM） to analyze the specimen, theresults showed: when optimized laser parameters: laser power was1.5kw, laserscanning velocity was4mm/s, powder feeding rate was27.3g/min; Microstructureof the interface zone mainly showed dendritic, rods and spiciles, and growedvertically in the form of substrate-bonding; With the increasing of scanning speed,microstructure of cladding layer had the trend of refining, and its micro-hardness washigher; Melting the composite powder on the circle surface by multi-track laser cladding in the situation optimized process parameters, microstructure of themulti-track layer was uniformity, micro-hardness distribution fluctuated; Overlappingarea showed broken-grain organization structure, forming a ‘bow’ shape with about350μm width, curving next layer; Micro-hardness and microstructure distribution ofnon-continuity multi-track layer were more evenly distributed than continuity one inboth depth and level directions; The non-continuity overlapping rate of27.3%wasoptimized process parameters, and a good metallurgical bond with highermicro-hardness and fine grain structure formed.In conclusion, this paper has made some positive attempt on laser claddingZrO₂/Ni60A composite layers; the result has some reference value in the actualindustry application of laser cladding technology.