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磷化是钢铁、锌、镉、铝等工件涂装前一个重要的化学处理方法。根据磷化所使用的温度,可分成高温磷化(80～98℃)、中温磷化(45～80℃)、低温磷化(30～40℃)、室温磷化(18～30℃),低温和室温磷化是当前发展的方向。磷化过程的实质是金属表面的腐蚀过程。磷酸的重金属盐与普通的盐类不同,其溶解度随温度的升高而降低。在加热条件下磷化,不仅加快了金属与溶液的反应速度,而且降低了磷化膜的溶解速度。在低温及室温下,要能形成理想的磷化膜,就应适当地提高成膜剂(Mo~(2+)PO_4~(3-))浓度,降低溶解速度,加速反应进程及增加改进成分等。本文重点讨论低温、室温磷化条件。
Phosphating is an important chemical treatment before the coating of steel, zinc, cadmium, aluminum and other workpieces. According to the temperature used in phosphating, it can be divided into high temperature phosphating (80-98 ℃), medium temperature phosphating (45-80 ℃), low temperature phosphating (30-40 ℃), room temperature phosphating (18-30 ℃) Low temperature and room temperature phosphating is the current direction of development. The essence of the phosphating process is the corrosion process of the metal surface. Heavy metal salts of phosphoric acid and ordinary salt is different, its solubility decreases with increasing temperature. Phosphating under heating conditions not only speeds up the reaction between the metal and the solution, but also reduces the dissolution rate of the phosphating film. At low temperature and room temperature, to be able to form the ideal phosphating film, the concentration of film forming agent (PO 4 3-) should be increased properly to reduce the dissolution rate, accelerate the reaction process and increase the content Wait. This article focuses on low temperature, room temperature phosphating conditions.