Effects Of Electrical Parameters And Na₂WO₄ Concentration On The Microstructure And Properties Of ZM6 MAO Film

Magnesium alloy has high specific strength and specific rigidity,and is widely used in aerospace,military,transportation engineering and other fields,but the corrosion resistance of magnesium alloy is poor,which greatly limits the scope of application of magnesium alloy,so it improves the corrosion resistance of magnesium alloy.Imperative.Through the micro-arc oxidation technology,a ceramic layer with dense structure and excellent corrosion resistance can be formed in situ on the surface of the magnesium alloy.In this paper,ZM6 magnesium alloy was used as the test material,and single-factor tests were used to characterize the surface morphology and performance of the film layer by changing electrical parameters and Na₂WO₄ concentration.The effects of electrical parameters and Na₂WO₄concentration on film morphology and performance were summarized.The electrical parameter test results show that in the basic electrolyte,as the voltage increases,the number of pores on the surface of the film decreases and the number of cracks increases.The thickness of the film increases first and then decreases,reaching the maximum value at 350 V,and the thickness reaches 8?m.The hardness of the film increases first and then decreases,reaching a maximum hardness of 93.83 HV at 350 V.The corrosion resistance increases first and then decreases.When the voltage is 290 V,the corrosion resistance of the film is the best;with the increase of frequency,the size of the holes on the surface of the film decreases,the number of holes increases,and the number of surface cracks decreases.At a frequency of 200 Hz,the film reaches a maximum thickness of 6.8?m.The hardness increases first and then decreases,reaching a maximum hardness of 130.7HV at 200 Hz.The corrosion resistance of the film increases first and then decreases.The corrosion resistance is the best at 400 Hz.As the duty cycle increases,the number of holes on the surface of the film decreases and the size of the holes increases.The thickness of the film layer gradually increased with the increase of the duty cycle,reaching a maximum thickness of 8.4?m at 50%.The film hardness increases linearly,reaching a maximum hardness of 120 HV at 50%.The corrosion resistance of the film increases first and then decreases.When the duty ratio reaches50%,the corrosion resistance of the film is the best.Comprehensive consideration of morphology and performance,when performing micro-arc oxidation experiments on ZM6,using low voltage,low frequency and high duty cycle makes it easier to obtain better film surface morphology and performance.The results of additive concentration test show that the morphology of the micro arc oxidation film is improved after adding Na₂WO₄ additive into the electrolyte,and the number of holes on the surface of the micro arc oxidation film is reduced and the size of the holes is reduced after adding Na₂WO₄.When the additive was 3 g/L,the hardness reached 145.60 HV,and the hardness of the film increased by 55%.When the concentration is 4 g/L,the film thickness is 9.1?m.When the concentration of Na₂WO₄ is 1 g/L,the corrosion resistance of the film is the best.