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

Metal heat treatment is a process that heats the metal workpiece in a certain medium to a suitable temperature, and maintains it at this temperature for a certain time, then cools it in different media at different speeds, and controls its performance by changing the microstructure of the metal material surface or inside. Contents of surface protection: electroplating, coating, chemical treatment layer; Electroplating includes (zinc, copper, chromium, lead, silver, nickel, tin, cadmium, etc.); Painting includes (paint coating, electrostatic powder spraying, plastic spraying process); Chemical treatment includes (blackening treatment, phosphating treatment).

It is mainly to use acidic or alkaline solution to react with oxides and oil stains on the surface of the workpiece and dissolve them in acidic or alkaline solution to remove rust, scale and oil stains on the surface of the workpiece, Then use the nylon brush roller or 304 # stainless steel wire (the wire brush roller made of acid and alkali resistant solution) to clean up to achieve the purpose. In order to remove all kinds of foreign matters (such as oil, rust, dust, old paint film, etc.) attached to the surface of the object, provide a good substrate suitable for the coating requirements, to ensure that the coating film has good anti-corrosion performance, decorative performance and some special functions, The surface of the object 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 antirust treatment of metal surface has been paid more and more attention. The antirust treatment can greatly increase the corrosion resistance of products and thus prolong the service life of products. Even stainless steel products now need to undergo stainless steel environmental passivation treatment, otherwise it is difficult to achieve the required corrosion protection effect. Therefore, do not use strong alkali and strong acid to degrease and etch during pretreatment. Because strong alkali can dissolve the aluminum-rich phase first, and strong acid can dissolve the zinc-rich phase first, thus forming pinholes and micro-pores on the surface of die castings, and leaving strong alkali solution and strong acid solution, which is easy to cause peeling and bubbles after plating.

Multi-layer chromium coating is the cathodic protection coating of zinc alloy, so the coating must have a certain thickness to ensure that the coating has no pores. Otherwise, due to the negative electrode potential of zinc alloy, white powdery corrosion products of basic zinc carbonate are easily produced in humid air. Therefore, the appropriate coating thickness must be selected according to the service conditions of the product.