Preparation Of AZ31B Magnesium Alloy Al And Al-Al₂O₃-AlB₁₂ Coating And Its Corrosion Resistance And Wear Resistance

Magnesium alloy is the lightest metal structural material,has good strength and stiffness ratio,conductivity and impact damping performance,known as the twenty-first Century green material,is widely used in aerospace,automotive,communications,medical and other fields.However,the standard electrode potential of magnesium,-2.34 V,has strong chemical activity,and its corrosion resistance is very poor,which largely restricts the wide application of magnesium alloy.Therefore,it is of great significance to improve the corrosion resistance and wear resistance of magnesium alloy.In this paper,we focus on the preparation of Al-AlB12-Al2O3 composite coating on magnesium alloy by oxy acetylene flame spraying.Firstly,this paper analyzes in detail the Al,B2O3 powder as raw material according to the different components of the ratio,and under the protection of argon mechanical alloying,every 2h to take a sample.The samples were analyzed by X ray diffraction?XRD?,scanning electron microscopy?SEM?and differential scanning calorimetry?DSC?.Secondly,in the spraying of pure Al coating of AZ31 B magnesium alloy surface,the coating of hot pressing processing;by scanning electron microscopy?SEM?and energy spectrum?EDS?morphology and element distribution observation of Al coatings,hot pressed;by electrochemical workstation,analysis of corrosion resistance and wear resistance of the coatings and wear test micro hardness friction.Finally,based on the above experimental results,Al₂O₃-AlB₁₂-Al composite coating was sprayed on the surface of AZ31 B magnesium alloy,in which Al was used as binder.Respectively adding 5%(Al₂O₃-AlB₁₂)composite powder,10%(Al₂O₃-AlB₁₂)composite powder and 15%(Al₂O₃-AlB₁₂)composite powder on the surface of AZ31 B magnesium alloy were prepared Al₂O₃-AlB₁₂-Al composite coating,and the composite coating by hot pressing.By means of X ray diffraction?XRD?,scanning electron microscopy?SEM?analysis of composite coating phase and microstructure;by electrochemical workstation,friction wear test and hardness test of coating corrosion resistance,wear resistance and hardness.Results show:?1?milling in 8h phase did not change,milling to 10 h Al2O3 and AlB12 phase;8 h ball milling powder in the process of continuous experience plastic deformation-cold-hardening-broken,chemical reaction of Al₂O₃-AlB₁₂ micron powder milling occurred at 10 h mixed;the powder and the addition of excess 20%Al after 10 h no new phase,non crystallization of 20 h.The differential scanning calorimetry analysis showed that the critical temperature decreased and the reaction promoted as the milling time prolonged.?2?the porosity of the 0.11 V coating after hot pressing is less,the coating is compact and dense,and the corrosion voltage of the Al coating is higher than that of the magnesium alloy in the positive direction,and the hardness is about 3.03 times that ofthe magnesium alloy.?3?add 15%[Al₂O₃-AlB₁₂]small pores and holes of the composite coating,the particle distribution,by XRD analysis,a Mg17Al12 intermetallic compound coating,Al-15%(Al₂O₃-AlB₁₂)corrosion potential of composite coatings of-1.15 V magnesium alloy,compared with the positive shift of 0.35 V.The hardness of 225 HV is 3.41 times that of magnesium alloy.Therefore,Al-15%?AlB12-Al2O3?composite coating can improve the corrosion resistance and wear resistance of magnesium alloy matrix,and has good protective effect on magnesium alloy.