Laser Additive Manufacturing Of High-Entropy Alloy Coating And Performance Evaluation On The Surface Of Oil Pump Friction Pair

In view of severe corrosion and wear of the pump barrel in the engineering,it is urgent to conduct research on the new protection technology for the 45 steel surface of the oil well pump barrel.At present,it is difficult to control the forming quality and performance of laser additive material on the surface of oil pump barrel.Around this difficulty,the following research was conducted:First of all,the study on the effect of laser additive manufacturing on the properties of high-entropy alloy coatings was carried out,it revealed the formation mechanism of defects such as cracks in high-entropy alloy coatings,verified the influence rule of laser power and laser scanning speed changes on defects such as cracks in high-entropy alloy coatings in laser additive manufacturing,and provided the optimization support of process parameters for further research on the quality control of high-entropy alloy coatings.Secondly,in order to suppress defects such as cracks in the coating,the influence of rare earth oxide CeO₂content on the properties of laser additive manufacturing high-entropy alloy coatings was studied.The results show that the rare earth oxide CeO₂can improve the fluidity of the molten pool,and when the CeO₂content is 2%,the porosity of the coating is the smallest.As the content of rare earth oxide CeO₂increases,the hardness fluctuation of the coating decreases.When the content of CeO₂is 2%,the wear resistance of the coating is better.When the CeO₂content is0.5%,the corrosion resistance of the coating is better.However,the addition of CeO₂can improve the crack inhibition to a certain extent,it does not solve the cracking problem of the coating.Therefore,in order to further suppress the formation of cracks,an experimental study on the preparation of high-entropy alloy coatings using transition layers was carried out.Since Ni can play a role in relieving the thermal stress of the substrate and reducing the influence on the cracking of the high-entropy alloy coating,the study using Ni as the transition layer was carried out.The results show that when the Ni transition layer is 2,the cracks of the coating are significantly improved,and the surface cracks of the coating are the least,and the wear resistance of the coating is better.When the Ni transition layer is 3,the coating exhibits better corrosion resistance.The use of Ni as a transition layer significantly alleviates the cracking of the coating,but does not completely suppress the cracking.Because the rare earth oxide CeO₂and Ni as the transition layer have a positive effect on the improvement of cracks,in order to solve the problem of coating cracks,the high-entropy alloy coating of Ni+CeO₂were studied by using the rare earth oxide CeO₂and Ni as the composite transition layer.The results show that when the content of CeO₂is 0.5%and the Ni layer is 2,the coating surface has no crack,and the corrosion resistance of the coating is optimal.When the transition Ni layer is 3,the wear resistance of the coating is the best.