As an important metal material, aluminum alloy has been used more and more widely in emerging industries such as automobiles, electronics, home appliances, aerospace, and building materials. As a major anti-corrosion technology for aluminum alloys, chromate passivation process has been widely used for more than half a century. However, due to the high hazard and carcinogenicity of hexavalent chromium, the use of this material is seriously hindered. With the implementation of EU RoHS, ELV, and WEEE regulations, hexavalent chromate will be strictly restricted and will be completely stopped. In recent years, research and development on hexavalent chromate substitutes (or green anti-corrosion materials) is gaining momentum around the world. At present, many new technologies have been developed and commercialized internationally. The main types are:
1. Zirconium-titanium system.
2. Silane coupling agent system.
3. Strontium salt system.
4. Trivalent chromium salt system.
5. Molybdate system
6. Vanadate system
In order to evaluate the possibility of replacing hexavalent chromates with various technologies, a joint group of pollutant prevention and control (JG-PP) organized by the U.S. Department of Defense conducted a large number of non-hexavalent chromate conversion coating products for aluminum alloys. Tests, test results show that from the perspective of industrial applications, trivalent chromium system is currently more likely to replace hexavalent chromate. Other systems can only meet part of the requirements of aluminum alloy surface treatment, which is manifested in:
1. Compared with chromate, the use of the process is more rigorous and complex;
2. The cost is higher;
3. It is difficult to meet the needs of some properties, especially the corrosion resistance of bare aluminum.
4. Selective material.
Aluminium trivalent chromium passivating agent Allmelux SF-565, developed by Zhuhai Ogilent in the absorption of foreign advanced technology, adopts low concentration of trivalent chromium and other film forming aids, and has been verified as a complete alternative to hexavalent. Chromate process. Reached or even exceeded the technical level of similar foreign products. Main features:
1. Low pollution, no environmental restrictions, meet RoHS, ELV, WEEE requirements.
2. High performance, meet or even exceed the corrosion requirements of MIL-DTL-81706B, MIL-DTL-5541F Class 1A & Class 3
3. The use of simple control, suitable for industrial applications.
4. Competitive use costs.
The following figures will illustrate the main features and applications of SF-565.
The quality of the conversion film
The quality of the conversion film measured in accordance with MIL-DTL-81706B 4.5.4 is 20-23 mg/ft 2
Three. The hardness of the conversion film
Unlike traditional hexavalent chromium, the conversion film formed by Allmelux SF-565 has a very hard surface after drying, and it is not easy to cause scratches on the workpiece and reduce film damage and adhesion in mass production.