电场作用下铅基阳极材料的内应力原位形成、演变及控制机理

Lead substrate anodes are widely used in industrial hydrometallurgical processes,such as electroplating and electrolytic field.But internal stress of anodic materials surface are easily changed in the process of electric field carried out,leading to the formation of the porous and loose oxide film, and even their break from lead substrate. This has a remarkable effect on solution compostions and reductive product quality. So it presents theoretical and practical significance that internal stress formation and its change of anodic materials surface are investigated in details. In addition, this help energy saving and the design of the good anodic materials. The in situ formation and change of internal stess of oxide film are exactly studied by means of Raman spectroscopy and XRD. In addition, effect of substrate compositions and their defect, electric current density, treatment time, morphology and structure of oxide film,ionic migration process on internal stress is investigated via using the analytical technique of ATM, XPS, FE-SEM, TEM and EBSD. According to analytical results of SEM, AFM and XPS, crystallization kinetics of oxide process are researched. And the relation of internal stess could be obtained with volume expansion of oxide film by using particle size analysis and calculation software. At the same time, the relation between change of internal stress and electrochemistry properties is studied by means of electrochemical analysis technology. The coulping of materials structre, volume expansion of oxide film and mechanical properties of materials are considered by applicating ANSYS software analysis. And stress gradient of oxide film might be optimized. The controlling mechanism of internal stress change is researched by high-energy micro-arc methods.

铅基阳极材料在电镀、电解等湿法冶金领域应用广泛。但是，电场作用下阳极材料的内应力变化导致表面氧化膜疏松多孔，易于脱落，严重影响溶液成分和阴极还原产品的质量。弄清氧化膜内应力原位形成、演变及控制机理对节能降耗、设计高性能铅基阳极材料具有重要的理论和实际意义。 采用拉曼光谱法和XRD有针对性地表征铅基阳极氧化膜内应力变化，结合ATM、XPS、FE-SEM、TEM和EBSD等技术研究铅基阳极成分及缺陷、电流密度、时间、氧化膜形貌和组织结构、离子迁移等因素对内应力原位形成、演变的影响；利用高分辨率SEM、AFM、XPS探讨氧化结晶动力学，辅以粒径分析计算软件，确定氧化膜体积膨胀与内应力演变之间关系；采用电化学技术评价内应力演变对阳极电化学性能的影响；运用ANSYS软件分析技术，研究材料组织结构转变、氧化膜体积膨胀与材料力学性能的耦合问题，并优化氧化膜应力梯度；高能微弧火花法研究内应力演变控制机理。

铅基阳极材料在电镀、电解等领域应用广泛。但是，阳极材料表面氧化膜易于脱落，严重影响溶液成分和阴极还原产品的质量。本项目中采用SEM、XRD、拉曼光谱以及电化学测试技术对阳极氧化膜内应力及其电化学性能进行了表征，含 腐蚀液中，Pb氧化膜呈压应力，而Pb-Ca合金氧化膜呈拉应力，Pb-Ca-Sr合金的应力值则显著增大；Pb-Ca及Pb-Sn-Ag合金的耐蚀性较好；Mott-Schottky分析结果显示Pb及Pb-Ca阳极氧化膜由n型半导体转变为p型半导体，而Pb-Sn-Ag及Pb-Ca-Sr合金的阳极膜在电位较小表现为p型半导体，当电位超过-0.1V时，阳极膜逐渐表现为绝缘状态，Pb-Sn-Ag合金的载流子密度相对于其他合金数量级较高，耐蚀性较好。在此基础上，项目研究了铅基阳极成分、电解液组成及其pH值、电流密度、氧化时间对铅基氧化膜内应力形成、演变规律，及其与铅基阳极氧化膜的组成成分和耐蚀性、导电性、半导体性能之间的关联性。利用计时电流法考察了氧化初期，铅基阳极氧化膜的成核生长方式，确定了在铬酸溶液、硫酸根溶液和氯离子溶液中，氧化膜组成的演变过程和内应力变化过程。铅基阳极在氯离子溶液中生成的氧化膜最厚，但氧化膜表面具有明显裂纹；而在硫酸根离子溶液中氧化膜最致密，但是氧化膜在氧化过程中伴随有明显的脱落。合金元素Sn和Ag的添加可以有效减缓氧化膜的内应力的累积，并提升铬酸溶液中生成的氧化膜的耐腐蚀性能。合金元素Ca的添加会改变氧化膜的内应力属性，最终氧化膜内应力表现为拉应力，提高了铅基合金在硫酸根离子溶液中的耐腐蚀性能。合金元素Sr的加入可以改善Pb-Ca合金阳极的内应力积累，但是在氯离子溶液中的耐腐蚀性能减弱。合金元素的添加还会改变铅阳极氧化膜的成核生长方式。结合不同阳极材料的内应力演变，得到了铅基阳极在铬酸溶液中内应力变化的数学模型方程，可以预测阳极的使用寿命。以高能微弧火花沉积技术为依托，结合吹扫不同成分气体，控制气体流量、电压、放电频率、输出功率等条件控制，优化应力梯度，提出了一种低应力梯度、高寿命的铅基阳极材料制备方法。