Overview Of Four Major Surface Treatment Processes

1 erosion of ferrous metal products

Iron and steel products and long-term exposure to the atmosphere or heat treatment, the surface will cover a layer of corrosive or black oxide, the chemical composition of a variety of iron oxides. These oxides must be removed in advance during various surface treatments. The method has manual rust, mechanical rust and sand blasting, etc., and the most common method is to use a variety of acid reagent treatment to rust. The essence of this treatment is the dissolution of the rust from the metal surface by the dissolution of the acid by the acid and the mechanical stripping of the hydrogen produced by the reaction of the acid with the metal matrix during the treatment. 

2 aluminum and aluminum alloy products degreasing

Aluminum is an amphoteric metal, both soluble in acid and soluble in alkali. It is strongly alkaline solution, will be severely etched to produce aluminate; so the removal of such metal products, do not use strong alkaline solution. Usually depending on the degree of surface adhesion of oil, can be used in different degreasing process. If the surface of serious oil pollution, organic solvents should be used to remove oil, and then alkaline chemical solution with alkaline solution. If the surface of the oil less, you can directly use a small amount of caustic soda in addition to oil, or alkaline salt solution.

3 aluminum and its aluminum alloy products

Light metal products can be used as an acid solution can also be used lye. The process of etching in alkaline solution is widely used method, this method of rapid etching, the surface of the oil less, even without degreasing and direct lye erosion.

4 phosphorescence of ferrous metal products

Black metal surface through the chemical reaction to generate a layer of non-metallic, non-conductive, porous phosphate film process known as phosphating or phosphating treatment, the formation of phosphate membrane known as the conversion film.

Phosphating treatment is widely used in metal processing and anti-rust storage process, which as a coating surface treatment of the substrate or pre-treatment applications are most common. The phosphating film is porous and the coating can penetrate into these pores, thereby significantly improving the adhesion of the coating. In addition, the phosphating film can make the metal surface from the excellent conductor into a bad conductor, thus inhibiting the formation of metal surface micro-battery, effectively hinder the corrosion of metal, can be doubled to improve the corrosion resistance and water resistance , So the phosphating film has been recognized as the coating with the best coating. Coating coating of sheet metal products requires phosphating treatment before coating 100.

According to the composition of the formation of phosphating treatment agent can be divided into iron phosphate-based phosphate treatment to zinc-based phosphate treatment and manganese-based phosphate treatment. As the coating treatment surface treatment of the pretreatment, the most widely used is zinc salt-based phosphating treatment, this processing speed, the formation of the appropriate thickness of the phosphate film (13μm), is coated with a good base. Zinc salt phosphating treatment agent is the main component of zinc dihydrogen phosphate (available zinc oxide and phosphoric acid preparation), oxidants (commonly used nitrate), catalyst (commonly used sodium nitrite, sodium chlorate and hydrogen peroxide and other strong oxidants) and Some additives (such as sodium tripolyphosphate, sodium fluoride, etc.).