Research On Technique And Performance Of Ni-P Based Electroless Plating By Laser

In order to improve the corrosion resistance and wear resistance of the mining equipment surface,the quenched and tempered 27SiMn steel was selected as the matrix,and the electroless plating was modified by CO2 laser,the effect of plating and laser modification technology on microstructure and properties of laser modified coating was researched.The surface morphology,microstructure and composition of the plating were analyzed by optical microscope(OM),scanning election microscope(SEM),X-ray diffraction(XRD)and energy dispersive spectrometer(EDS),respectively.The hardness,wear resistance and corrosion resistance of the sample were measured and analyzed by micro hardness tester,wear tester and electrochemical workstation,respectively.The main conclusions are:the surface of electroless plating is cellular structure;the cell structure of the plating is larger and turns into amorphous after adding ceramic particles.The surface amorphous structure of the electroless plating changed after the laser modification.The modified layer section is a typical crescent shape,which are mainly divided into four areas as follows from the surface to the inner:laser action zone,hardening zone,transition zone and matrix.The columnar crystal is grow up along the bottom of the laser action area,and the crystal and dendrite are grow in the laser action zone.The modified phase is different due to the different thickness of the plating.After the 5.8 ?m of Ni-Ce-P-Al2O3-SiC plating are modified,the surface main phase is Ni3P,Fe0.64Ni0.36;after the 30pm of Ni-P-base plating is modified,the surface main phase is Ni3P,FeNi and a few of elemental Ni.After single channel laser modification,the wear resistance and corrosion resistance of the plating is significantly improved.In the range of laser output power and scanning speed,the hardness and wear resistance are increased with the increase of laser energy,and the corrosion resistance is decreased at first and then increased.The wear resistance of the coating is higher than that of the single channel modified by the same energy after laser treatment with different lap.The corrosion resistance of the plating increases with the increase of lap ratio,and which can be effectively increased after laser multi-channel modification with more than 20%lap ratio.After laser modification of different plating with lap ratio of 20%,the surface hardness of the coating is up to 850HV0.2;and the wear resistance is improved in different degree,among them,the Ni-P-SiC modified layer has the best wear resistance,which is 1.41 times of the plating and 1.86 times of the substrate.The corrosion resistance of the plating is improved except for the Ni-Ce-P plating.The corrosion resistance of Ni-P-Al2O3-SiC modified layer is the best,which is 4.9 times of the original coating and 19.5 times of the substrate.