邵忠财,戴诗行,魏守强.镁合金锌系磷酸盐化学转化膜的研究[J].表面技术,2018,47(4):133-139.
SHAO Zhong-cai,DAI Shi-hang,WEI Shou-qiang.Study on Zinc-Phosphate Chemical Conversion Coating on Magnesium Alloy[J].Surface Technology,2018,47(4):133-139 |
| 镁合金锌系磷酸盐化学转化膜的研究 |
| Study on Zinc-Phosphate Chemical Conversion Coating on Magnesium Alloy |
| 投稿时间：2017-08-12 修订日期：2018-04-20 |
| DOI：10.16490/j.cnki.issn.1001-3660.2018.04.020 |
| 中文关键词: 镁合金 转化膜 磷酸盐 耐蚀性 温度 电化学 |
| 英文关键词:magnesium alloy conversion coating phosphate corrosion resistance temperature electrochemistry |
| 基金项目:辽宁省自然科学基金（201602648） |
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| 中文摘要: |
| 目的 优化镁合金锌系磷酸盐化学转化膜的制备工艺。方法 制备锌系磷酸盐化学转化膜，采用点滴实验、电化学测试对化学转化膜进行耐蚀性评价，并通过激光共聚焦显微镜、扫描电子显微镜（SEM）和X射线衍射仪（XRD）对膜层进行表征，研究主盐、温度和添加剂对镁合金锌系磷酸盐化学转化膜的影响。结果 转化溶液中氧化锌、磷酸、氟化钠、酒石酸钠的浓度对转化膜的耐蚀性和膜厚具有较大影响，在一定浓度范围内，转化膜的耐蚀性随浓度的增加而增大。转化膜耐蚀性随温度的升高先增加后下降，50 ℃时点滴时间达到59 s，膜层相对致密，缝隙较小。选取的添加剂中，EDTA能明显提高膜层的耐蚀性，膜层均匀致密，加入0.3 g/L EDTA的转化膜的腐蚀电位比未加添加剂的转化膜正移0.05 V，点滴时间提高到68 s。镁合金锌系磷酸盐转化膜主要成分为Zn3(PO4)2+Zn2Mg(PO4)2+AlPO4+Al12Mg17。转化膜的电化学阻抗半径大，自腐蚀电流密度低（2.594×106 A/cm2），腐蚀电位正移较明显，耐蚀性更好。转化膜粗糙度小（2.396 μm），平整光滑。结论 镁合金锌系磷酸盐转化最优配方及工艺为：氧化锌2.0 g/L，磷酸12 g/L，氟化钠1.0 g/L，酒石酸钠4.0 g/L，EDTA 0.3 g/L，转化温度50 ℃，转化时间20 min。转化溶液加入EDTA后，能够明显提高转化膜的耐蚀性。 |
| 英文摘要: |
| The work aims to optimize preparation of zinc-phosphate chemical conversion coating on magnesium alloy. The influence of main salt, temperature and additives on the zinc-phosphate chemical conversion coating on magnesium alloy was studied and the zinc-phosphate chemical conversion coating on magnesium alloy was prepared. The corrosion resistance of the chemical conversion coatings was evaluated by drop test and electrochemical test. The coatings were characterized by laser scanning confocal microscopy, scanning electron microscopy (SEM) and X ray diffraction (XRD). The concentration of Zinc Oxide, phosphoric acid, sodium fluoride and sodium tartrate in the conversion solution had a great influence on the corrosion resistance and thickness of the conversion coating. In a certain range of concentration, the corrosion resistance of the conversion film increased with the concentration. As temperature increased, the corrosion resistance of the conversion coating increased at first and then decreased, and the dropping time reached 50 ℃ at 59 s, the coating was relatively compact and the gap was smaller. In the selected additive, EDTA could obviously improve the corrosion resistance of the coating. The coating was homogeneous and compact, and the corrosion potential of the conversion coating with 0.3 g/L EDTA was 0.05 V higher than that without additives at positive shift and dropping time increased to 68 s. The main components of magnesium alloy zinc-phosphate conversion coating were: Zn3(PO4)2, Zn2Mg(PO4)2, AlPO4 and Al12Mg17. The electrochemical impedance radius of the conversion coating was large, the corrosion current density was low (2.594×106 A/cm2), the corrosion potential was shifted obviously, and the corrosion resistance was better and the roughness of the conversion coating was small (2.396 μm) and smooth. The optimum formula of zinc-phosphate conversion on magnesium alloy is zinc oxide 2 g/L, phosphoric acid 12 g/L, sodium fluoride 1 g/L, sodium tartrate 4 g/L, conversion temperature at 50 ℃ and conversion time of 20 min. The corrosion resistance of the conversion solution can be obviously improved by adding EDTA. |
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