Stainless steel surface treatment method

At present, the surface treatment methods of stainless steel are: ① surface whitening treatment; ② surface mirror bright treatment; ③ surface coloring treatment.

1. Surface whitening treatment: During the processing of stainless steel, black oxide skin is produced by rolling, edging, welding or artificial surface baking and heating. This hard gray-black oxide scale is mainly composed of two EO4 components, NiCr2O4 and NiF. In the past, hydrofluoric acid and nitric acid were generally used for strong corrosion removal. However, this method has high cost, pollutes the environment, is harmful to human body, and is highly corrosive, and is gradually eliminated. At present, there are mainly two kinds of oxide scale treatment methods: (1) Sand blasting (pellet) method: mainly use the method of spraying micro glass beads to remove the black oxide scale on the surface. (2) Chemical method: use a non-polluting pickling passivation paste and a non-toxic and harmful cleaning solution with inorganic additives at room temperature for dipping. So as to achieve the purpose of whitening the natural color of stainless steel. After processing, it basically looks like a dull color. This method is more suitable for large and complex commodities.

2. Mirror bright treatment method on the surface of stainless steel plate: According to the complexity of stainless steel products and different user requirements, mechanical polishing, chemical polishing, electrochemical polishing and other methods can be used to achieve mirror gloss. The advantages and disadvantages of these three methods are as follows: the advantages and disadvantages of the project method are applicable to commodities, the mechanical polishing and leveling are good, the brightness is labor-intensive, the pollution is serious, the complex parts are difficult to process, the gloss is reduced, the investment and cost are high. Simple workpieces, medium and small commodities, Complex parts cannot be processed, and the gloss of the entire product cannot be uniform, and the gloss does not last for a long time. Chemical polishing requires less investment, complex parts can be polished, high efficiency, fast speed, lack of brightness, polishing liquid needs to be heated, gas overflows, complex commodities that require ventilation equipment, and commodities with low brightness requirements can be processed in small batches. Electrochemical polishing achieves mirror luster, long-term maintenance, stable process, less pollution, low cost, good anti-pollution performance, large one-time investment, complex parts need to be equipped with tooling, auxiliary electrodes, large-scale production to cool high-speed small and medium-sized goods, requiring a long time Keeping the mirror bright product process is stable, easy to operate, and can be widely used.

3. Surface coloring treatment: Stainless steel coloring not only imparts various colors to stainless steel products, increases the variety of colors, but also improves the wear resistance and corrosion resistance of products. Stainless steel coloring methods are as follows: (1) chemical oxidation coloring method; (2) electrochemical oxidation coloring method; (3) ion deposition oxide coloring method; (4) high temperature oxidation coloring method; (5) gas phase cracking coloring method. A brief overview of various methods is as follows: (1) Chemical oxidation coloring method: It is the color of the film formed by chemical oxidation in a specific solution, including dichromate method, mixed sodium salt method, vulcanization method, acid oxidation method and alkaline oxidation method. . (2) Electrochemical coloring method: It is the color of the film formed by electrochemical oxidation in a specific solution. (3) Ion deposition oxide coloring method chemical method: the stainless steel workpiece is placed in a vacuum coating machine for vacuum evaporation plating. For example: titanium-plated watch cases and watch straps are generally golden yellow. This method is suitable for high-volume commodity processing. Because of the large investment and high cost, it is not cost-effective for small batches of goods. ⑷ High temperature oxidation coloring method: In a specific molten salt, the workpiece is immersed in a certain process parameter, so that the workpiece forms a certain thickness of oxide film, and presents various colors. ⑸ Gas-phase cracking coloring method: It is more complicated and less used in industry.