(1. 四川理工學(xué)院 材料腐蝕與防護(hù)四川省重點(diǎn)實(shí)驗(yàn)室，自貢 643000；
2. 四川理工學(xué)院 材料與化學(xué)工程學(xué)院，自貢 643000；
3. 山東省科學(xué)院 新材料研究所，濟(jì)南 250014)
摘 要: 以磷酸二氫錳的鹽溶液為研究體系，采用SEM和EDS和電化學(xué)分析手段，研究鎂合金AZ31錳系磷化膜的生長過程和形成機(jī)理。結(jié)果表明：磷化膜的生長過程分為5個階段：基體溶解−成核階段(0～130 s)、基體和磷化膜溶解階段(130～630 s)、磷化膜快速生長階段(630～1 300 s)、磷化膜穩(wěn)態(tài)生長階段(1 300～2 000 s)和磷化終止階段(2 000 s以后)。磷酸鹽晶核在鎂合金AZ31浸入溶液的初始階段一次形成，并優(yōu)先在β相表面經(jīng)過成核—長大—分裂—細(xì)化—增厚5個過程，沿表面方向生長和外延，最終形成致密的磷化膜。并且，磷化膜有兩層，第一層是以Mg3(PO4)2和AlPO4以及MnHPO4為主的沉積薄膜；第二層則是在β相表面成核—長大的MnHPO4磷化膜。
關(guān)鍵字: 鎂合金；磷酸鹽轉(zhuǎn)化膜；形成機(jī)理；電化學(xué)過程
manganese phosphate conversion film of magnesium alloy AZ31
（1. Material Corrosion and Protection Key Laboratory of Sichuan Province,
Sichuan University of Science and Engineering, Zigong 643000, China;
2. College of Materials and Chemical Engineering, Sichuan University of Science and Engineering,
Zigong 643000, China;
3. New Material Institute of Shandong Academy of Sciences, Ji’nan 250014, China）
Abstract:The growing process and formation mechanism of phosphate film of magnesium alloy AZ31 in the manganese dihydrogen phosphate solution were studied by scanning electron microscopy(SEM), energy dispersive X-ray spectrometer (EDS) and electrochemical method. The results show that the growing process of phosphate film is divided into five stages: substrate dissolving-nucleation (0−130 s), substrate and film dissolving (130−630 s), file rapid growth (630−1 300 s), film steady growth (1 300−2 000 s) and phosphating finishing (after 2 000 s). The phosphate crystal nucleuses are firstly formed on the surface of β phase for one time with the magnesium alloy AZ31 immersing. With the growth of the nucleus on the alloy surface, the coverage of the phosphate grains increases gradually and the dense films are obtained. The films are made up two layers: the bottom is a deposition film with compositions of Mg3(PO4)2, AlPO4 and MnHPO4. The second layer consists of MnHPO4 which is formed on the surface of β phase.
Key words: magnesium alloys; phosphate conversion coating; formation mechanism; electrochemical process
