(蘭州理工大學(xué) 省部共建有色金屬先進(jìn)加工與再利用國(guó)家重點(diǎn)實(shí)驗(yàn)室，蘭州 730050)
摘 要: 在硅酸鹽體系中分別添加V2O5和NaVO3，在AZ91D鎂合金上制備微弧氧化膜，對(duì)比研究釩含量相同的V2O5和NaVO3對(duì)膜層耐蝕性的影響。通過TT260數(shù)字式涂層測(cè)厚儀、SEM和XRD分別檢測(cè)膜層厚度、膜層微觀形貌和相組成。采用點(diǎn)滴和電化學(xué)實(shí)驗(yàn)研究膜層耐蝕性能。結(jié)果表明：電解液中加入V2O5和NaVO3后，膜層厚度均稍有減小，點(diǎn)滴耐蝕性因總厚度較薄也都有所降低，但電化學(xué)測(cè)試的耐蝕性均提高，當(dāng)V2O5和NaVO3的添加量分別為0.20 g/L和0.35 g/L時(shí)，膜層的耐蝕性最佳。加入0.35 g/L NaVO3所得膜層耐蝕性比加入釩含量相同V2O5的提高3倍，比無添加劑時(shí)的高出15倍，比基體高約3個(gè)數(shù)量級(jí)，故加入NaVO3的性價(jià)比更高。同時(shí)，加入V2O5和NaVO3均可制得棕色的氧化膜，起顯色作用的物質(zhì)是MgV2O4。該物相具有尖晶石結(jié)構(gòu)，有助于提高膜層的耐蝕性。
關(guān)鍵字: 鎂合金；V2O5；NaVO3；微弧氧化著色；微觀結(jié)構(gòu)；耐蝕性
（State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China）
Abstract:The micro-arc oxidation coatings were prepared on AZ91D magnesium alloys in silicate-containing electrolyte with different V2O5 and NaVO3 concentrations, respectively. The effects of adding V2O5 and NaVO3 with same calculated content of V element on corrosion resistance of the coatings were studied. The thicknesses, morphologies and phase composition of the coatings were examined by using TT260 digital coating thickness gauge, SEM and XRD, respectively. The corrosion resistances of coatings were evaluated by spot test and electrochemical test. The results show that, after adding V2O5 and NaVO3 into the electrolyte, the coating thicknesses decrease slightly and the corrosion resistance of coating corresponding to the spot test reduces due to the thinner overall thicknesses, while the corrosion resistance in the electrochemical test increases. And the coatings best performance to anti-corrosion is exhibited when adding the least content of V2O5 and NaVO3 in the electrolyte. The corrosion resistance of coatings prepared in the electrolyte with 0.35 g/L NaVO3 is three times higher than that with the element V content of V2O5, improved by 15 times compared to that without additives, and is approximately three orders of magnitude higher than that of the substrate. Meanwhile, the brown color coatings are obtained in the electrolyte containing V2O5 or NaVO3 owing to the formation of MgV2O4 with the spinal structure, which is also helpful to improve the corrosion resistance of the coatings.
Key words: magnesium alloys; V2O5; NaVO3; micro arc oxidation coloring; microstructure; corrosion resistance
