1, The development process of phosphating technology
The development of phosphating technology has gone through more than 100 years of history to this day. For over 100 years, phosphating technology has evolved from simple chemical corrosion methods to complex and comprehensive technologies; Phosphating treatment agents have evolved from a single variety to a series of hundreds of products; The phosphating treatment method has evolved from simple immersion to various forms such as immersion, spraying, and spray immersion today; The application scope of phosphating technology has also evolved from just focusing on metal corrosion prevention to various aspects such as phosphating treatment before metal coating, phosphating treatment for metal wear resistance, phosphating treatment for metal corrosion prevention, and phosphating treatment before metal plastic deformation processing.
The earliest phosphating treatment was to place metal (steel) parts in a phosphoric acid solution containing iron filings, heat this solution to boiling temperature, and after 2.0 and 2.5 hours of treatment, obtain a layer of crystalline and dense phosphate coating on the metal surface. This phosphoric acid solution containing iron filings is the earliest phosphating solution.
Later, people continuously improved the phosphating agents, mainly to reduce the film-forming temperature and time. By changing the formula, adding various accelerators, etc., the phosphating treatment can be carried out in any state from room temperature to boiling, and the phosphating treatment time can be reduced to a few seconds to complete.
There are now a wide variety of phosphating agents, which have been basically serialized. Classified by processing temperature: there are high-temperature phosphating agents, medium temperature phosphating agents, room temperature phosphating agents, etc; Classified by form: there are solid powder phosphating agents and concentrated liquid phosphating agents; According to the composition of phosphating agents, there are iron based phosphating agents, zinc based phosphating agents, manganese based phosphating agents, zinc calcium based phosphating agents, zinc barium based phosphating agents, zinc manganese based phosphating agents, and organic phosphating agents.