| Magnesium alloy has many advantages such as low density,high specific strength and specific stiffness,good electromagnetic shielding performance and thermal conductivity,etc.,which can fully meet the requirements of "3C" products that are lighter and thinner,miniaturized,and electromagnetic shielding and heat dissipation functions.The preferred housing material for 3C" products.With the advent of the era of popularization of wireless networks,the excellent electromagnetic shielding performance of magnesium alloy materials will shield external signals while improving the quality of wireless signals.Therefore,when designing and processing electronic housings,it is necessary to leave a local area without electromagnetic shielding areas for nano-injection PPS(Polyphenylene Sulfide)to ensure that its wireless operation requirements are met.However,the corrosion resistance of magnesium alloys is poor,and micro-arc oxidation can effectively improve the corrosion resistance of magnesium alloys.However,the traditional magnesium alloy micro-arc oxidation process for nano-injection PPS magnesium alloys is prone to burning at the junction of magnesium alloys and plastics.Erosion phenomenon.In this paper.the effects of electrolyte composition,concentration,and electrical parameters on the film formation process of nano-injected PPS magnesium alloy micro-arc oxidation were studied through orthogonal experiments.The surface morphology of the obtained film layer was analyzed by SEM,and a salt spray test chamber and other instruments were used.Determine the corrosion resistance of the oxide film,comprehensively investigate the performance of the micro-arc oxidation ceramic film,and determine the composition,concentration and electrical parameters of the electrolyte.Research indicates:(1)Through the influence of each electrolyte component on the nano-injection molding(PPS)magnesium alloy micro-arc oxidation film layer in the univariate experiment and the convenience and feasibility of the process,the optimal composition range of the electrolyte is selected:sodium borate 15?25 g/l.dihydrogen phosphate 6?12g/L,potassium fluoride 2?6g/L,sodium hydroxide 8?12 g/L,and the best fotumla of electrolyte is obtained through orthogonal test:The sodium borate concentration was 20 g/L,the dihydrogen phosphate concentration was 9 g/L,the potassium fluoride concentration was 4 g/L,and the sodium hydroxide concentration was 8 g/L.(2)Based on the optimized electrolyte formulation,the optimal electrical parameter composition is obtained by optimizing the influence of various electrical parameters on the nano-injection molding(PPS)magnesium alloy micro-arc oxidation film layer in the univariate experiment:current density 1.5 A/dm2,frequency 800 Hz,duty cycle 8%,oxidation time 8 min.(3)Under constant current control conditions,the micro-arc oxidation of nano-injection(PPS)magnesium alloy in the preferred electrolyte composition is divided into three stages:anodizing stage,micro-arc oxidation stage and partial arc discharge stage.(4)The thickness of the ceramic film obtained under the best process conditions can reach 20.43 ?m.Its micro-morphology is a typical porous structure.The width of the micro-cracks is narrow and most of the area is covered by the melt.The whole film is relatively smooth and uniform.The roughness is small,the film layer is mainly composed of three elements of O,Mg,P.(5)The corrosion test of the micro-arc oxidation film under the optimized formula under different experimental conditions shows that the results of the salt spray test of the micro-arc oxidation sample and the substrate obtained under the optimized process are 6 and 1 respectively after 264 h;The impedance value of the arc oxidation film is much higher than that of the magnesium alloy matrix material;the test result of the dynamic potential polarization curve is consistent with the above results,and the corrosion resistance of the film is significantly improved. |
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