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AZ91镁合金钼酸盐转化膜的制备及耐蚀性研究 总被引:1,自引:0,他引:1
采用化学转化法在AZ91镁合金基体表面制备一种环境友好型的钼酸盐转化膜.通过对溶液pH、温度以及Na2MoO4质量浓度等因素的控制并进行单因素试验和正交试验,确定化学转化的最佳工艺条件:30~40 g/L Na2 MoO4,pH为3.5,θ为70℃,t为50 min.采用优化后的工艺能够在镁合金表面获得微黄致密,微细裂纹的膜层,X-射线衍射测试表明,钼酸盐转化膜的主要成分Mg2Mo3O8和MgMoO4.极化曲线测试表明钼酸盐转化膜能有效提高镁合金的耐蚀性能,自腐蚀电位提高,自腐蚀电流密度降低2个数量级. 相似文献
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AZ31镁合金无氰化学镀镍工艺的研究 总被引:8,自引:1,他引:8
研究了在AZ31镁合金表面二次浸锌后直接进行化学镀镍的工艺。分析了pH、温度、镍离子质量浓度和次磷酸钠质量浓度对镀速的影响,并测试了镀层的结合力、表面形貌、成分含量和耐蚀性。结果表明,以二次浸锌法进行预处理,无需氰化镀铜打底;在pH为7,碱式碳酸镍质量浓度25g/L,次磷酸钠质量浓度30g/L时,镀速有最大值;AZ31镁合金化学镀镍后耐蚀性明显提高,腐蚀电位从-1.52V提高到-0.55V;化学镀镍的优化参数为15g/L碱式碳酸镍,25g/L次磷酸钠,pH为6,温度82℃。 相似文献
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AZ91D镁合金磷酸盐转化膜的制备及性能 总被引:1,自引:0,他引:1
提出了一种压铸镁合金AZ91D表面磷酸盐化学转化工艺,其配方及操作条件为:磷酸8mL/L,氧化锌3 g/L,酒石酸3 g/L,氨水4 g/L,硝酸钠3 g/L,氟化钠1 g/L,温度25~30℃,时间5min.研究了该无铬转化膜的表面和截面形貌,化学成分,物相组成,结合力,孔隙率和耐蚀性.结果表明:磷酸盐转化膜主要由Mg、Zn、Al12Mg17和Zn3(PO4)2·4H2O组成,结合力均>8分,孔隙率由封孔前的27.91%降为封孔后的6.98%,耐中性盐雾时间均可达到24 h.电化学实验结果显示,转化膜的腐蚀电位比基体提高了64 mV,封孔处理后腐蚀电位提高了122 mV,腐蚀电流密度均降低了两个数量级. 相似文献
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Luyao Xu Naiyu Liu Lei Cao Yong Wan 《International Journal of Applied Ceramic Technology》2021,18(5):1657-1669
In this paper, the effects of electrolytes on the corrosion resistance and tribocorrosion performance of micro-arc oxidation (MAO) coatings on AZ31B magnesium (Mg) alloys in simulated body fluid (SBF) were studied. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were utilized to explore the microstructure, surface morphology, and phase components of the MAO coatings. Corrosion and tribocorrosion performance of MAO coated Mg alloys were evaluated by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and a ball-on-disk tribotester. It was found that MAO coating produced in electrolyte containing both Na2SiO3 and Na2B4O7 exhibited superior corrosion resistance and tribocorrosion performance in the SBF. 相似文献
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封闭处理对镁合金磷酸钡转化膜的影响 总被引:1,自引:0,他引:1
在Na2SiO3和NaOH溶液中,研究了封闭处理对AZ91D镁合金磷酸钡转化膜的影响,采用扫描电镜(SEM)和X射线衍射谱(XRD)研究了封闭前后磷酸钡转化膜的表面形貌及其相组成,采用全浸蚀试验和电化学方法检测了膜层的抗腐蚀性能。结果表明,封闭后的磷酸盐转化膜更加平整、致密。与封闭前的转化膜相比,封闭后的转化膜新增了C、Si元素和一些晶态物质,如SiO2、BaSi4O9、Na2SiO3和MgF2。封闭处理可以明显提高镁合金磷酸钡转化膜的抗腐蚀性能。 相似文献
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In this work, a hybrid epoxy-silane coating was developed for corrosion protection of magnesium alloy AZ31. The average thickness of the film produced by dip-coating procedure was 14 μm. The adhesion strength of the epoxy-silane coating to the Mg substrate was evaluated by pull-off tests and was found to be higher than 16 MPa both in dry and wet conditions. The hybrid epoxy-silane coating showed high corrosion resistance both when intact and when punched through by a needle. The low frequency impedance of intact coating was higher than 1 GΩ cm2 after one month of immersion in 3.5% NaCl solution. Both, artificially induced defects and corrosion sites that appeared on the metal surface did not propagate. Their passivation behavior, that we call fault-tolerance, was observed by EIS, SVET-SIET and SEM-EDS. It was ascribed to the good adhesion, high coating integrity and corrosion inhibiting effect provided by diethylenetriamine used as epoxy hardener. 相似文献
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分别采用扫描电子显微镜(SEM)和能谱(EDS)分析了AZ91D压铸镁合金酸洗、氟氢化钠溶液浸渍及无铬化学转化处理后的表面形貌及元素组成,并测量了各种前处理后所得转化膜在w=5%NaCl溶液中的极化曲线.结果表明:酸洗工序是镁合金在氟氢化钠溶液中浸渍后表面生成氟化物的必要工序;采用硫酸酸洗后不能得到完整的转化膜,磷酸酸洗后能得到由O、Mn、P、Ca和Mg组成的均匀转化膜;磷酸酸洗及氟氢化钠溶液浸渍后所得转化膜的耐腐蚀性能最佳. 相似文献
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铝合金稀土转化膜成膜因素对膜层性能的影响 总被引:1,自引:0,他引:1
通过正交实验研究了铝合金稀土化学转化膜成膜因素对转化膜性能的影响,获得了以下最佳配方:ρ(CeCl3)= 15 g/L,H2O2的体积分数为50 mL/L,ρ(柠檬酸)=2 g/L,θ=50℃。实验结果表明,H2O2的含量对转化膜厚度和硬度的影响最为显著,在体积分数为50 mL/L时膜厚和硬度的值最大;CeCl3的质量浓度对膜层厚度和膜层Rp值影响较大,随CeCl3浓度的升高膜厚和邱值增加;温度对膜层阻抗谱影响较为明显,随温度升高Rp值下降;柠檬酸的含量对膜层硬度和Rp值都有较大的影响,当其质量浓度为2 g/L时,所得膜层硬度最大、Rp值最高。 相似文献
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