及耐蝕性的影響
(1. 蘭州理工大學(xué) 甘肅省有色金屬新材料省部共建國家重點實驗室, 蘭州730050；
2. Faculty of Engineering, The University of Auckland, Auckland 1142, New Zealand)
摘 要: 研究硅酸鹽體系中電壓、頻率和占空比等電參數(shù)對AZ91D鎂合金微弧氧化膜層的厚度、表面形貌、相組成及耐蝕性的影響，并對膜層的表面孔隙率及表面孔徑進行定量分析。結(jié)果表明：電壓對膜層微觀結(jié)構(gòu)及耐蝕性能的影響起主導(dǎo)作用，頻率的影響次之，占空比的影響較小；隨電壓升高，膜層厚度、表面孔隙率及耐蝕性均增大；頻率與占空比對膜層厚度的影響不大，但對表面孔隙率和耐蝕性有一定的影響；頻率為800 Hz、占空比為15%時，膜層耐蝕性較好，此時所得膜層的表面孔隙率較小，分別約為8%和10%，膜層表面上孔徑在1~3 μm的微孔比例都大于60%；膜層表面孔徑和孔隙率的定量評價與膜層形貌分析相結(jié)合可為膜層耐蝕性的分析提供有力依據(jù)。
關(guān)鍵字: 鎂合金；微弧氧化；電參數(shù)；孔徑；孔隙率；耐蝕性
microstructure and corrosion resistance of
micro-arc oxidation coatings on AZ91D magnesium alloys
（1. State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials,
Lanzhou University of Technology, Lanzhou 730050, China;
2. Faculty of Engineering, The University of Auckland, Auckland 1142, New Zealand）
Abstract:The effects of electrical parameters, such as voltage, frequency and duty ratio on the thickness, surface morphology, phase composition and corrosion resistance of the micro-arc oxidation (MAO) coatings treated with silicate aqueous solution on the AZ91D magnesium alloys were studied. The surface porosity and surface pore size of the MAO coatings were measured. The results show that the voltage demonstrates a main influence on the microstructure and corrosion resistance of coatings, and the following is the frequency while the duty ratio plays a weak role. The thickness, surface porosity and corrosion resistance of coatings increase accordingly with enhancing voltage, but the frequency and duty ratio have certain influence on the surface porosity and corrosion resistance of coatings while it is not the case for the coating thickness. The coatings present the best corrosion resistance when the frequency is 800Hz and duty ratio is 15%, their surface porosity are about 8% and 10%, respectively, and the percentage of pore size ranging in 1−3 μm reaches more than 60%. Combining the quantitative analysis of the surface porosity and pore size with the observation of surface morphology of coatings provide useful basis for the research of the corrosion resistance of coatings.
Key words: magnesium alloys; micro-arc oxidation; electrical parameters; pore size; porosity ; corrosion resistance
