Study On The Preparation Of Titanium Alloy Body Repairing Coating Based On High Energy Micro-arc Spark Deposition

The research on remanufacturing of damaged parts of titanium alloys is of great economic value and environmental protection value.This is one of the important tasks for our country to promote the development of remanufacturing industry.At present,there are two main problems in the research of titanium alloy repairing.First,the nature of titanium alloy is lively,the thermal conductivity is poor and the elastic modulus of titanium alloy is small.So it is easy to produce residual stress and deformation.Second,there is still a lack of effective repair methods of titanium alloy.In view of the above two problems,we designed a high energy micro-arc spark deposition and atmosphere protection equipment to prepare body repairing coating.Orthogonal test method was used to optimize the process parameters in this paper.The morphology,microstructure and properties were analyzed by scanning electron microscope,optical microscope,X-ray diffractometer,microhardness tester and wear tester.Then the mechanism of micro-arc spark deposition was discussed.Finally,we repair the micro-pits and scratches combined with the actual project.Main results are achieved as follows:(1)The TA2 body repairing coating was prepared by high energy micro-arc spark deposition for the first time in this paper?The optimal process parameters were obtained based on the experimental results and statistical models.The results showed that the electrode diameter of 1.5mm and C6 gear will get better preparation effect under the inert gas protection of 0.04~0.06% oxygen content.The high activity of titanium at high temperature determines that it needs high atmosphere protection.The main reason of different diameters correspond to different mass transfer is that the discharge frequency of the electrode is different.(2)A comparative study of TA2,304,TC4 for the preparation of body repairing coating was carried out.The results showed that the mass transfer of the 3 materials is linearly correlated with the deposition time.The different is that the mass transfer coefficient of TC4 is 10% higher than TA2.The mass transfer of 304 is 10 times higher than that of TA2 and its mass transfer coefficient is greater than 90%.The energy required for mass transfer is the main reason for the different.(3)Study on mechanism of micro-arc spark deposition based on single spark deposition.The micro-arc spark deposition is composed of dielectric breakdown,the formation and diffusion of the discharge channel,the conbersion and transfer of energy,the eroding of the electrode material and the transition of the molten metal.However,the surface tension of metal,the size and mode of force,and the discharge characterized will lead to the different characteristics of the final single spark pots.(4)Study on the microhardness and wear resistance of TA2 body repairing coating prepared by high energy micro-arc spark deposition.The microhardness of the coating was 340HV0.05,which is higher than that of the substrate.It is about 1.6 times.And the wear resistance was better than that of the substrate about 2/3.The micro-pits and scraches were simulated repair successfully.In this paper,the basic research on the preparation of TA2 by micro-arc spark deposition was carried out.The repair effect of titanium alloy may be further improved by the automation,intelligent equipment and other processing technology.