Blueing and blackening treatments
Author: Robby
Bluing and blackening are two similar surface treatment techniques used primarily to improve the corrosion resistance and appearance of metal surfaces.
Definition and Principle
Bluing: Steel or steel parts are heated to the appropriate temperature in air-water vapour or chemicals to form a blue or black oxide film on the surface. This treatment is also known as blackening treatment.
Blackening treatment: Similar to the bluing treatment, a protective film, usually black in colour, is formed on the metal surface by heating and chemical reaction.
Areas of application and effects
Areas of application: These two treatment techniques are widely used for various metal products, such as tools, machine parts, firearms, etc., to improve their corrosion resistance and aesthetics.
Effect: A dense oxide film is formed on the surface of the treated metal, with the outer layer mainly consisting of ferric tetraoxide and the inner layer of ferrous oxide. This film can effectively isolate the metal from direct contact with the external environment, thus prolonging its service life.
Difference and connection
Difference: Although the two are slightly different in colour (blue treatment may appear blue, while black treatment appears black), but essentially through heating and chemical reaction to form a protective oxide film on the metal surface.
Connection: Both are anticorrosion processes, the purpose of which is to form a protective film on the metal surface by chemical or physical means, in order to enhance its corrosion resistance and aesthetics.