Research On The Preparation And Properties Of TiN Coating On NdFeB Permanent Magnet

Since the discovery of NdFeB permanent magnetic materials,it has been widely used in various fields due to its excellent magnetic properties and relatively low cost,and is one of the important materials that support the development of contemporary society.However,the multiphase structure of the NdFeB material and the difference in chemical characteristics between the phases facilitate the formation of electrochemical corrosion in certain hot and humid environments,causing the magnet demagnetization to fail and surface corrosion of the NdFeB material has become an important factor that it limits its development.In order to improve the corrosion resistance of the surface of the NdFeB material,this subject adopts magnetron sputtering technology,selects the target material of titanium nitride and prepares a TiN ceramic layer with corrosion resistance on the surface of the NdFeB material.This topic selects spraying power,spraying time,and argon flow as parameters of the preparation process and uses three sets of numerical values to design orthogonal experiments and prepare TiN coatings.SEM,EDS,XRD and other characterization methods were used to analyze the cross-sectional morphology,structure,composition and surface phase of the coating and to determine the microhardness and bond strength of the film base.Sample analysis and conduct a neutral salt spray and electrical test.The chemical corrosion test analyzes the corrosion resistance of the coating from the macro and micro level.The main conclusions are as follows:1)Use magnetron sputtering technology to prepare a uniform and dense Titransition coating and TiN coating on the surface of the neodymium iron boron permanent magnet material.The surface roughness of the coating is 0.094μm.The coating thickness of the 9groups of samples is approximately 2μm.The main phases of the coatings are TiN,TiO,TiO₂ and a small amount of iron oxide compounds.2)Measurement and analysis of the micro-hardness of the coating:the average micro-hardness of the 9 groups of samples is greater than 650 HV0.3 and the highest is 780 HV0.3.The results show that the microhardness of the neodymium iron matrix was significantly improved.The influence of various factors on the hardness of the coating is spraying power>argon flow>spraying time,and the intensity ratio is about 4.4:3,4:1.3)The sample adhesion strength test:the membrane-base adhesion force is about 20 N and the highest is 25.3 N.The influence of various factors on the adhesion strength of the coating is flow of argon>spray power>spray time and the intensity ratio is about 2.24:2.03:1.4)Neutral salt spray test of the sample:after the sample has been intermittently sprayed in a 3.5%by weight NaCl solution for 96 h,the macro morphology is evaluated.The surface of the X5 sample is less than 5%and has good corrosion resistance.5)Electrochemical corrosion test of the sample:analyze the polarization curve determined by the electrochemical test of the sample in a solution of 3.5wt%by weight of NaCl.A full comparison of the self-corrosion potential and corrosion current density of the9 sample groups shows that the corrosion resistance of sample X5 is the best,which is consistent with the salt spray test results.The primary and secondary law of the influence of various factors on the self-corrosion potential of the coating is argon flow>spraying time>spraying power and the intensity ratio is approximately:5.7:3.3:1.6)By analyzing the results of the orthogonal test,the parameters of the spraying process with the best corrosion resistance performance among the 9 groups of designed samples are the spraying power of 100 W,the spraying time of 80 min and the flow rate of argon of 5ml/min.