表面技术
錶麵技術
표면기술
SURFACE TECHNOLOGY
2015年
8期
9-14
,共6页
朱青%朱明%余勇%张路路
硃青%硃明%餘勇%張路路
주청%주명%여용%장로로
AZ91 D镁合金%Mo-Mn转化膜%耐蚀性%钼酸盐%高锰酸盐
AZ91 D鎂閤金%Mo-Mn轉化膜%耐蝕性%鉬痠鹽%高錳痠鹽
AZ91 D미합금%Mo-Mn전화막%내식성%목산염%고맹산염
magnesium alloy%Mo-Mn conversion coating%corrosion resistance%molybdate%permangate
目的：通过Mo-Mn无铬转化膜提高AZ91 D镁合金的表面耐蚀性。方法采用正交实验法,研究不同浓度的NaMoO4和KMnO4以及温度对转化膜的影响。优选实验参数后,考察时间对转化膜的影响。利用SEM及EDS研究转化膜的微观形貌及成分变化,测试转化膜在3.5%NaCl溶液中的极化曲线和交流阻抗谱。结果当NaMoO4和KMnO4的质量浓度分别为10,6 g/L,pH=5,温度为50℃,转化时间为40 min时,转化膜颜色较为均匀,微观裂纹相对较少,自腐蚀电位比镁基体大约提高0.075 V,自腐蚀电流密度比镁基体降低近1个数量级。当NaMoO4和KMnO4的质量浓度分别为20,8 g/L,pH=5,温度为50℃,转化时间为40 min时,转化膜颜色最为均匀,微观裂纹相对最少,自腐蚀电位比镁基体提高大约0.047 V,自腐蚀电流密度比镁基体降低2个数量级。交流阻抗谱图显示,后一种转化膜试样的极化电阻为1450.2Ω,而镁基体的极化电阻为806.4Ω。结论 Mo-Mn无铬转化膜可以显著提高AZ91D镁合金的表面耐蚀性。
目的：通過Mo-Mn無鉻轉化膜提高AZ91 D鎂閤金的錶麵耐蝕性。方法採用正交實驗法,研究不同濃度的NaMoO4和KMnO4以及溫度對轉化膜的影響。優選實驗參數後,攷察時間對轉化膜的影響。利用SEM及EDS研究轉化膜的微觀形貌及成分變化,測試轉化膜在3.5%NaCl溶液中的極化麯線和交流阻抗譜。結果噹NaMoO4和KMnO4的質量濃度分彆為10,6 g/L,pH=5,溫度為50℃,轉化時間為40 min時,轉化膜顏色較為均勻,微觀裂紋相對較少,自腐蝕電位比鎂基體大約提高0.075 V,自腐蝕電流密度比鎂基體降低近1箇數量級。噹NaMoO4和KMnO4的質量濃度分彆為20,8 g/L,pH=5,溫度為50℃,轉化時間為40 min時,轉化膜顏色最為均勻,微觀裂紋相對最少,自腐蝕電位比鎂基體提高大約0.047 V,自腐蝕電流密度比鎂基體降低2箇數量級。交流阻抗譜圖顯示,後一種轉化膜試樣的極化電阻為1450.2Ω,而鎂基體的極化電阻為806.4Ω。結論 Mo-Mn無鉻轉化膜可以顯著提高AZ91D鎂閤金的錶麵耐蝕性。
목적：통과Mo-Mn무락전화막제고AZ91 D미합금적표면내식성。방법채용정교실험법,연구불동농도적NaMoO4화KMnO4이급온도대전화막적영향。우선실험삼수후,고찰시간대전화막적영향。이용SEM급EDS연구전화막적미관형모급성분변화,측시전화막재3.5%NaCl용액중적겁화곡선화교류조항보。결과당NaMoO4화KMnO4적질량농도분별위10,6 g/L,pH=5,온도위50℃,전화시간위40 min시,전화막안색교위균균,미관렬문상대교소,자부식전위비미기체대약제고0.075 V,자부식전류밀도비미기체강저근1개수량급。당NaMoO4화KMnO4적질량농도분별위20,8 g/L,pH=5,온도위50℃,전화시간위40 min시,전화막안색최위균균,미관렬문상대최소,자부식전위비미기체제고대약0.047 V,자부식전류밀도비미기체강저2개수량급。교류조항보도현시,후일충전화막시양적겁화전조위1450.2Ω,이미기체적겁화전조위806.4Ω。결론 Mo-Mn무락전화막가이현저제고AZ91D미합금적표면내식성。
ABSTRACT:Objective To improve the surface corrosion resistance of AZ91D magnesium alloy by Mo-Mn chromium-free conver-sion coating. Methods Effects of different concentrations of NaMoO4 and KMnO4 and temperature on the transformed sample film were studied by orthogonal experimental method. After optimizing experiment parameters, the effects of the time on the conversion film was also studied. The morphology and component of conversion coatings were researched by SEM and EDS. Moreover, the po-larization curves and electrochemical impedance spectroscopy of conversion coating were tested in 3. 5%NaCl aqueous solution. Results The results showed that when the condition was 10 g/L NaMoO4 , 6 g/L KMnO4 at 50 ℃ and pH 5 for 40 min, where the morphology of the sample was relatively even and the amount of cracks was relatively low. Compared to the corrosion resistance of magnesium substrate, the corrosion potential of conversion film was increased by about 0. 075 V ,and the corrosion current density decreased by nearly 1 order of magnitude. When the condition was 20 g/L NaMoO4 , 8 g/L KMnO4 at 50 ℃ and pH 5 for 40 min, the morphology of the sample was the most even and the amount of cracks was the least. Compared to the corrosion resistance of magnesium substrate, the corrosion potential of conversion film was increased by about 0. 047 V ,and the corrosion current density decreased by nearly 2 orders of magnitude. EIS showed that the polarization resistance of the latter conversion film sample was 1450. 2 Ω, while the polarization resistance of magnesium matrix was 806. 4 Ω. Conclusion Mo-Mn chromium-free conversion coating could obviously improve the surface corrosion resistance of AZ91D magnesium alloy.
