Process Parameters Of Surface Coating For Hydraulic Column Based On LACS

Laser Assisted Cold Spraying(LACS)was a composite spraying process developed in recent years,which combines laser assisted heating and cold spraying.The heating effect of laser beam can improve the spraying efficiency and the bonding strength of coating,increase the coating selection of layer materials.Under the harsh working environment and complicated working conditions,the hydraulic column was prone to corrosion,wear and other failure forms,which seriously affects the production safety of the coal mine,The technology of laser assisted cold spraying was proposed to prepare nickel base alloy coating on the surface of hydraulic column.Taking 27SiMn steel as the base material of hydraulic column and Ni60 powder as the research object,the formation process of coating was studied by numerical simulation,and the influence of relevant process parameters on the quality of deposited coating was analyzed.The specific research content was as follows:(1)The process of laser assisted heating was simulated,and the effect of laser heating on the temperature field of substrate deposition was analyzed.The results show that laser heating was a process of local rapid heating and rapid cooling,and the temperature of deposition increases with the increase of laser power and decreases with the increase of laser scanning speed.(2)A single particle collision model was established to analyze the effects of particle deposition speed and laser heating temperature on coating bonding during the coating deposition process through plastic strain and energy conversion in particle collision.There is a suitable speed range so that the particles can be effectively combined with the substrate,and the heating effect of the laser can reduce the deposition speed of the particles.(3)The effect of the incident angle on the coating quality when the particles collide with the substrate at a certain angle was analyzed.As the incident angle of the particles decreases,the tangential velocity of particles increases,the depth of pits in the substrate decreases,and the deposition effect of the coating deteriorates gradually.The temperature rise of friction caused by lateral sliding promotes the bonding strength of the coating,it can be seen that there was a critical angle,which maked the promotion of friction temperature rise greater than the negative effect of side slip.(4)In the multi particle deposition model,the influence of mechanical extrusion between adjacent particles and compaction of subsequent particles on coating deposition was studied.Under the effects of mechanical extrusion and compaction,an effective coating can be formed when the particle deposition speed is 500 m/s and the substrate surface temperature is about 900℃.