Surface treatment is a process to change the surface of metal materials

Surface treatment is a process to change the surface of metal materials:

Dalian metal surface treatment belongs to an ancient technology. Since there are humans on the earth, surface treatment is a technology that humans have long mastered. The primitive people lived a hard life and lived in groups. In order to survive, they made stone tools and used grinding technology to make the stone tools have sharp edges, producing a "sharp wedge" effect. In the Neolithic Age, the stone tools used by the primitive people were all polished and the surface was fine and smooth.

 

Metal heat treatment is a process in which the metal workpiece is heated to an appropriate temperature in a certain medium and kept at this temperature for a certain time, then cooled in different medium at different speeds, and its properties are controlled by changing the surface or internal microstructure of the metal material. Surface protection content: electroplating, coating, chemical treatment layer; Electroplating includes (galvanization, copper, chromium, lead, silver, nickel, tin, cadmium, etc.); Coating includes (paint coating, electrostatic powder spraying, plastic spraying process); Chemical treatment includes (blackening treatment, phosphating treatment).

It mainly uses acidic or alkaline solutions to react with oxides and oil stains on the surface of the workpiece, so that they can be dissolved in acidic or alkaline solutions, so as to remove rust scale and oil stains on the surface of the workpiece, The purpose can be achieved by cleaning the brush roll made of nylon or 304 # stainless steel wire (steel wire brush roll made of acid and alkali resistant solution). In order to remove various foreign matters attached to the object surface (such as oil stain, rust, dust, old paint film, etc.), provide a good substrate suitable for the painting requirements, so as to ensure that the film has good anti-corrosion performance, decorative performance and some special functions, The object surface must be pretreated before painting.

People refer to the work done by such treatment as pre coating (surface) treatment or (surface) pretreatment. The passivation and rust prevention treatment of metal surface has been paid more and more attention. The rust prevention treatment can greatly increase the corrosion resistance of products and thus extend the service life of products. Even stainless steel products now need to be passivated for environmental protection, otherwise it is difficult to achieve the required anti-corrosion effect. For this reason, do not use strong alkali and strong acid for degreasing and etching during pretreatment. Because the strong alkali can make the aluminum rich phase dissolve first, and the strong acid can make the zinc rich phase dissolve first, thus forming pinholes and micro pores on the surface of the die casting, and leaving strong alkali solution and strong acid solution, so that after plating, it is easy to cause peeling and bubble.

Multilayer chromium coating is the cathodic protection coating of zinc alloy, so the coating must have a certain thickness to ensure that the coating is free of pores. Otherwise, due to the negative electrode potential of zinc alloy, it is easy to produce white powdery corrosion products of basic zinc carbonate in humid air. Therefore, the appropriate coating thickness must be selected according to the use conditions of the product.