Research On Fiber Laser Cladding Of Metal-based Ceramic Composite Coatings

Metal structural materials were widely used in the manufacturing process of equipment components.In the harsh working environment,the parts would fail prematurely due to wear and corrosion,and the equipment could not work normally.To carry out research on re-manufacturing technology has become a research hot-spot of green manufacturing technology today.It has important social and economic benefits to strengthen and repair the surface of parts by laser cladding technology.In this paper,advanced fiber laser cladding technology was adopted.Took 45 steel as substrate material and Ni45A self fluxing alloy powder as cladding material.Based on the laser power,scanning speed and the addition amount of WC/Ni,the orthogonal experiment was carried out.The optimum technological process of laser single channel cladding was preliminarily determined by the analysis of the dilution rate of the coating and the average micro-hardness.On this basis,the method of single factor analysis was adopted.By the detection equipment and detection means of optical microscopy,scanning electron microscopy,energy dispersive spectroscopy,X ray diffraction,micro-hardness,friction and wear testing machine,optical profilometer and electrochemical workstation,the influence of laser power,scanning speed and solid lubricant（Graphite/Ni and MoS₂）on the micro-structure and properties of ceramic composite coatings were systematically investigated.The main research contents and results were as follows:1.The influence regularity of process parameters on the dilution rate of laser cladding layer was analyzed and carried out.In the orthogonal experiment,through calculation and analysis of the dilution rate of cladding layer,it was concluded that the laser power has the biggest influence on the dilution rate,the second was scanning speed,and the last was the content of WC/Ni;by measuring the micro-hardness of the cladding layer under different dilution rates,it was found that the overall quality of the cladding layer was better when the dilution rate was about 5%.Therefore,it was concluded that the optimum process parameters for single channel cladding were laser power 1600 W,scanning speed 16 mm/s,and WC/Ni addition 30 wt.%.2.The influence regularity of process parameters on the microstructure and properties of laser cladding layer was studied and analyzed.Because of the effect of heat accumulation,the selection of multichannel of cladding parameters has been adjusted on the basis of single channel optimum process parameters.The influence of laser power,scanning speed on the micro-structure and properties of cladding layer were studied by single factor analysis.The results showed that:under the different laser power and scanning speed,the cladding layer was mainly composed of FeNi₃,（Fe,Ni）,M₂₃C₆,M₇C₃,WC,W₂C and other phases.When the laser power was 1500 W,the scanning speed was 18 mm/s,the micro-hardness,wear resistance and corrosion resistance of the cladding layer were the best.3.The influence regularity of solid lubricants on the microstructure and properties of the cladding layer was studied and obtained.Graphite/Ni was easy to be melted and produced porosity when laser cladding,and the porosity increased with the increase of the content of Graphite/Ni;In order to obtain better quality of cladding coating,adding MoS₂ into the cladding powder,when MoS₂ addition was 8 wt.%,the cladding layer has high hardness,good abrasion resistance,antifriction performance and corrosion resistance.Therefore draw:in the case of other laser process parameters in line with each other,when the laser power was 1500W,scanning speed was 18 mm/s,WC/Ni addition was 30 wt.%,MoS₂ addition was 8 wt.%,the obtained cladding coating was the best cladding layer.4.The microstructure and properties of the best cladding layer and 45 steel after heat treatment were compared and studied.The friction and wear properties and corrosion resistance of the best cladding layer and the 45 steel after heat treatment were compared.Concluded:The friction and wear properties and corrosion resistance of the cladding coating were better than those of the 45 steel after heat treatment and it was also proved that the cladding layer obtained by the optimum laser cladding process parameters on 45 steel could improve the microstructure and properties of the 45 steel.