| High velocity air fuel spraying(HVAF)is a surface treatment technology,which can effectively improve the surface performance of the sprayed parts.in this paper.AZ31 magnesium alloy is taken as the research object.AZ31 magnesium alloy has good mechanical properties,mainly used in automotive parts,chassis and communication equipment,etc.Due to the poor corrosion resistance and wear resistance of AZ31 magnesium alloy,its failure problem in the use process greatly limits its service life.Five kinds of Al-WC/Al composite coatings were prepared on the surface of magnesium alloy AZ31 by Activated Combustion HighVelocity Air-Fuel Spraying(AC-HVAF),in order to obtain a kind of composite coating which can effectively improve the service performance of AZ31.All kinds of coatings prepared were cut and sampled respectively,and labeled in turn.Optical microscope and scanning electron microscope were used to observe and analyze the micromorphology of various coatings prepared,and EDS energy spectrum analysis was carried out on each part of the coating to comprehensively analyze its deposition mechanism.By scanning electron microscope photographs,calculate the preparation of a variety of coating porosity,using Vickers hardness tester for the preparation of various types of coating hardness measurement,using the multifunction surface measuring instrument to scratch experiment of preparation of various coatings,using electrochemical workstation for preparation of various types of coating from the corrosion potential measurement,by measuring the performance of all kinds of coating and contrast,The properties of the prepared coatings were analyzed and summarized.Through the completion of various experimental work,the experimental data were analyzed to evaluate the various coatings prepared:1.The prepared Al-WC/Al coating can effectively improve the surface performance of magnesium alloy AZ31.After spraying,the surface hardness of AZ31 magnesium alloy is up to more than 15 times,and the self-corrosion potential is up to about 80%.Compared with the single coating,the prepared composite coating has more protective effect,which can make the two spraying powders work together to solve the problem of the use performance of AZ31 magnesium alloy.2.After spraying,the observation of the microstructure of the interface between Al coating and substrate on the surface of AZ31 showed that a large number of twins were formed at the interface between Al coating and substrate,which did not exist on the substrate before spraying.3.Through the observation and analysis of Al coating,it is believed that the deposition mechanism of Al powder is mainly the mechanical combination of Al powder and matrix,and through the EDS energy spectrum analysis,it is believed that Al element has the element diffusion to the matrix.The metallurgical bonding between Al powder and matrix occurred during the deposition process.When the mixed powder WC/Al was deposited on the Al coating,the deposition mechanism of the mixed part of WC/Al in the composite coating was mainly mechanical combination of WC and Al after the morphology observation and analysis of electron microscope and the analysis of EDS energy spectrum.4.After the observation and analysis of the composite coating after spraying,it is found that there are some tiny pores and cracks in the coating.It is considered that there are pores and cracks after spraying because the powder itself isn`t dense. |
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