Preparation And Mechanism Of Combination Coating Of High Corrosion Resistance On Magnesium Alloy

To meet the harsh environment corrosion resistance requirements,the paper to develop a magnesium and magnesium alloy combination of high corrosion resistance coating,and its preparation process to AZ91D magnesium alloy materials for the experiment to study the NiSO₄ mainly salt,direct electroless nickel plating The process conditions and influencing factors,and in the chemical coating based on zinc-nickel alloy, as well as black passivation,using horizontal metallographic microscope(HMM), scanning electron microscopy(SEM),energy spectrum analyzer(EDS) significantly Micro-hardness tester(MHT) techniques to test the performance of the coating.The results show that:1.Through the electroless nickel plating of magnesium alloy pre-treatment studies, be provided with suitable pre-treatment process,eliminating the traditional electroless nickel plating of magnesium alloy in the pre-treatment of zinc leaching process,has been uniform,binding force of good coating.Analysis of magnesium alloy chemical bath main salt,reducing agent concentration,pH value,agent for the plating rate impact. Na₂CO₃ developed for the buffer to avoid fluoride as a buffer to pollution,environmental protection has been a new type of direct electroless nickel plating.2.Electrogalvanized layer nickel alloy corrosion resistance depends primarily on the content of nickel coating,through a systematic study of the Electro-galvanized nickel process,the main salt(NiSO₄,ZnO),temperature,current density of the nickel coating affected the volume of come when the bath of zinc and nickel ion content than the[ZnO] /[NiSO₄]higher content of nickel coating to reduce,and eventually other conditions specific to optimize the zinc-nickel alloy plating process,to be corrosion-resistant coating than a single chemical coating better.3.Selection of copper sulfate and nitrate for passivator to regulate the content of chromic anhydride,the plating layer and treatment,to be black passivation film binding, and color uniformity,in 5%NaCl neutral salt spray corrosion test,chemical spray coating in a row after 32h corrosion began to appear now,and the plating layer in the 96h after the dot,black passivation layer in the 800h,the absence of any corrosion,corrosion resistance coating compared to a single very markedly improved.