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What is the process and principle of blackening treatment?

The processes of blackening treatment are: cleaning, degreasing, washing, pickling, blackening, washing, blow-drying and oiling.

The principle of blackening treatment is: to produce a layer of oxidized film on the surface of the metal to isolate the air and achieve the purpose of rust prevention.

Blackening is a common means of chemical surface treatment, appearance requirements are not high when you can use the blackening treatment, the surface of steel parts blackening treatment, there are also called blue.

The blackening treatment commonly used methods are the traditional alkaline heating blackening and the emergence of late normal temperature blackening two.

Extended Information

The workpiece is usually immersed in a strong oxidizing chemical solution. For example, the boiling temperature of 147 ~ 152 ℃ of sodium hydroxide (600g/cm3) and sodium nitrite (100g/cm3) in aqueous solution, after a certain period of time so that the surface to generate a layer of beautiful, more dense and has the role of anti-rust black iron oxide film. Widely used in clocks and watches, pointers, hairspring, screws, instrument housings and some mechanical parts.

Machine manufacturing commonly used NaOH solution heating to the workpiece blackening treatment. Blackening the formation of black oxide film, the thickness of 0.5-1.5μm, corrosion resistance is lower than other chemical film. Inside the hardware mold, the commonly used treatment is heat treatment.

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