Chrome-free surface passivation for aluminum alloys
Date: 2025-05-29 Categories: Blog Views: 107
aluminum因其轻质高强、耐腐蚀等特性，广泛应用于航空航天、汽车、电子等领域。然而，传统铬酸盐钝化工艺因六价铬毒性高、污染严重，已被国际环保法规严格限制。本文针对无铬钝化技术展开研究，探讨硅烷/稀土盐复合体系的成膜机理，通过优化工艺参数提升钝化膜耐蚀性，并分析其环保与经济价值，为替代铬酸盐工艺提供理论与技术参考。
从本文可了解到：
- 铝的应用与腐蚀挑战——铝在工业中的关键作用及腐蚀防护需求。
- 铬酸盐工艺的缺陷——六价铬的毒性危害与环保法规限制。
- 无铬钝化解决方案——硅烷、稀土盐等环保替代技术的研究进展。
- 实验方法与成果——钝化膜性能测试（盐雾、电化学）及优化路径。
- 工业应用潜力——绿色钝化技术对行业可持续发展的推动作用。
Aluminum applications
是有色金属中产量最高、应用最广的金属材料。在金属结构材料中，它的产量仅次于钢铁。
All-aluminum engine
铸铝缸体的优势就是重量轻，通过减轻重量实现省油。在同等排量的发动机中，使用铝缸体发动机，能减轻20公斤左右的重量。汽车的自身重量每减少10％，燃油的消耗可降低6％～8％。
Disadvantages of chromate surface treatment
Chromate treatment method contains a large amount of hexavalent chromium ions in the waste tank solution, according to GB 8978-1996 "Comprehensive Emission Standards for Sewage", the concentration of hexavalent chromium in the waste tank solution is not more than 0.5mg/L. However, hexavalent chromium ions are carcinogenic to the human body. Long-term exposure to hexavalent chromium compounds can lead to lung cancer, upper respiratory tract cancer and gastrointestinal cancer, as well as dermatitis, allergic and eczematous skin reactions, and respiratory diseases, eye diseases, oral mucosal lesions, gastroenteritis, renal dysfunction, and other acute poisoning.
In order to meet the needs of an environmentally friendly society, surface treatment is moving towards replacing chroming. Therefore, our goal is to reduce environmental pollution.
铬表面钝化处理方法
目前铝合金无铬化学氧化有锆系、钛系、锰酸盐体系、钼酸盐体系、稀土体系、锂盐体系、硅酸盐体系、丹宁酸盐体系等。目前,国内铝合金阳极氧化膜无铬封孔方法多采用稀土进行表面处理。采用铈盐或其他稀土盐进行处理法的效果与常温金属盐、铬酸盐阳极氧化膜层效果相近。
Surface passivation influences
•铈盐浓度
•成膜氧化剂（高锰酸钾）浓度
•成膜促进剂（铵盐）浓度
•温度
•时间
Experimental Procedures:
1. Degreasing treatment
Wipe with degreasing cotton moistened with solvent to remove the oil, and then wipe several times with a clean cotton cloth. Commonly used solvents are: trichloroethylene, ethyl acetate, acetone, butanone and gasoline.
2. Polishing treatment
Manual polishing, i.e. sandpaper polishing, is used according to actual needs; or chemical polishing solution is used for polishing.
3. Oxidation of aluminum
采用单一变量法找到最佳实验参数和条件.
4.结果检验与反馈
The corrosion resistance was tested by acid spot corrosion method, and the strength of the tester was tested by hardness tester. And the microstructure of the observer with an electron microscope. For the shortcomings and then improve.
Expected results
1.The treated aluminum alloys are able to meet or exceed the corrosion resistance and mechanical strength of those treated with conventional chromates.
2.The gradual replacement of chromate treatment is feasible and reliable, preferably for industrial applications. It will greatly reduce the harm caused by hexavalent chromium ions to the environment and human life and health, and make industrial production develop in the direction of environmental friendliness.
