Material surface treatment knowledge summary

I. Surface treatment is divided into the following ways:
1、Mechanical surface treatment: sandblasting, brushing, mechanical polishing, embossing, spraying, shot blasting, grinding, brushing, painting, oiling Chemical surface treatment: QPQ treatment, nitriding in light, chroming, chrome plating, galvanizing, chemical nickel plating, chemical polishing, blackening/blueing, pickling
2、Electrochemical surface treatment: anodic oxidation, phosphating, electrochemical nickel plating, electrochemical polishing, electrophoresis.
Modern super-hardening surface treatment: TD cladding treatment, physical vapor deposition (PVD), material chemical vapor deposition (PCVD), chemical vapor deposition (CVD)
3、Other types of surface treatment: ion coating, ion implantation, laser surface treatment

2、Mechanical surface treatment description:
1, sandblasting: the use of high-speed sand impact cleaning and roughening parts surface, line into a matte pearl silver surface.
Features: improve the fatigue resistance of the workpiece, increase the adhesion between the workpiece and the coating, prolong the durability of the coating, facilitate the leveling and decoration of the coating, the surface is easy to dirty.
Application: It can be applied to all ferrous metal and aluminum alloy materials before surface treatment or stainless steel sheet metal surface.
2、Drawing: By grinding the product to form a line pattern on the surface of the workpiece, the surface treatment of decorative effect, forming a satin effect. Reflect the texture of metal materials
3、Mechanical polishing: the use of polishing tools and abrasive particles or other polishing media on the surface of the workpiece finishing process to reduce the surface roughness. Obtain bright, flat surface processing methods.
4、Embossing: Embossing various textures
5、Painting: Covered with other non-metallic coatings. Common spraying colors of steel sheet metal: large corrugated beige electrostatic spraying, surface powder electrostatic spraying black matte, black fine sand grain electrostatic spraying

Chemical surface treatment description:
1、QPQ: The ferrous metal is put into two kinds of salt baths with different properties to form a compound permeation layer through the penetration of various elements into the metal surface, so that the surface is modified.
Features: good wear resistance and fatigue resistance; good corrosion resistance; small deformation; short time cycle; no pollution. Error can be kept at 0.005mm.
Color: Glossy black
Application: Applicable to all ferrous metal materials.
2、Nitriding in light: QPQ upgrade process, steel or stainless steel is put into a salt bath mixed with various elements for penetration treatment.
The hardness of quenching can be achieved.
Features: The advantages over QPQ are no deformation, higher hardness, deeper depth, high efficiency, no polishing.
3、Chromating: Using chromium hydrochloric acid solution and metal to generate trivalent or hexavalent chromating layer on the surface.
Features: corrosion resistance, improve the bonding of parts with organic coatings or inorganic coatings, good adsorption color: natural, golden yellow, green
Application: Aluminum, magnesium and their alloys
4, chrome plating: in the parts surface plating a layer of metal chromium, the thickness is generally 20um, the surface to form a passivation film.
Features: high hardness, good wear resistance, high temperature and corrosion resistance. Hard chrome plating hardness up to 100OHV, classification: decorative chrome and hard chrome
Color: Bright white and blue
Application: Commonly used steel parts can be used in this process.
5、Galvanizing: A new layer of metal, alloy or other material surface plating to play a beautiful, rust-proof role in the surface treatment, the main method is hot zinc plating.
6、Chemical nickel plating: also known as electroless plating, autocatalytic plating, sinking nickel. Under certain conditions, metal ions in aqueous solution are reduced by reductant and precipitated into a plating layer on the surface of the workpiece.
Features: uniform plating, corrosion resistance, high hardness, high wear resistance (hardness is generally 400-700HV, after heat treatment up to 1100HV), high chemical stability, good bonding of plating, weldability (low phosphorus plating has good welding performance), magnetic (control the amount of phosphorus to control magnetic and non-magnetic), high precision (precision than chrome plating, can replace the chrome plating process, error 0.002- 0.005um), beautification of the workpiece (decorative than electroplated nickel, lack of brightness)
Color: Silvery white with yellow surface
Use: All metals (such as steel, stainless steel, aluminum, copper, etc.), non-metals (such as ceramics, glass diamond, carbon, plastic, resin, etc.)
7、Chemical polishing: The processing method of metal surface to achieve bright and smooth effect by regular dissolution.
8, blackening/blueing: blackening
Blackening: steel or steel parts in the air - water vapor or chemical drugs heated to the appropriate temperature, so that its surface to form a layer of blue or black oxide film process. The outer layer of ferric oxide and the inner layer of ferrous oxide.
Bluing: steel or steel parts are heated in molten salts of sodium nitrite and sodium nitrate or in hot air and superheat above 500C°, or in concentrated caustic soda of sodium nitrite to obtain a bluing film of magnetic iron oxide. Thickness 0.5-1.5um.
Characteristics: The individual bluing film is poor in corrosion resistance, it can be improved by applying oil and wax or varnish to improve corrosion resistance and friction resistance; it has little effect on size and finish, and is commonly used in high-precision parts or standard parts, with low cost.
Color: Gray-black, dark black, bright blue
Note: A3 steel is better with alkaline blackening.
9、Pickling: The method of removing oxidation and rust on steel surface by acid solution, is a kind of cleaning metal surface, usually together with pre-film, is the pre-treatment or intermediate treatment of electroplating, enamel, rolling and other processes.