Zhejiang Tianjin  Hardware Product Co., Ltd

Common surface treatment method for fastener


Fastener surface treatment,  according to the different requirements of their products, According to the surface treatment methods and processing technology. According to the method of surface treatment can be divided into many, such as painting, electroplating, chemical plating, vacuum plating, plating, anodizing, sandblasting, hardening coating, vapor deposition, carburizing, nitriding, surface hardening; technology is more advanced, but also can have a lot of methods, physical, chemical, and electrical machining the mechanical, metallurgy etc.. Now look more popular, often surface treatment methods are the following:

Plating: plating part is immersed in an aqueous solution containing the metal compound to be deposited, the current through the plating solution, the electroplating metal precipitation and deposition on the part. General plating with zinc, copper, nickel, chromium, copper, nickel and other alloys, and sometimes will be dyed black, phosphating, etc.. Hydrogen embrittlement is easy to occur in electroplating, which has great influence on the mechanical strength of the workpiece.

Hot-dip galvanizing: Completed by plating the molten steel with a carbon steel part immersed in molten zinc at a temperature of about 510 ° C. As a result, the iron-zinc alloy on the surface of the steel gradually becomes a passivated zinc on the outer surface of the product. However, due to hot plating due to high temperature, steel is easy to produce high temperature annealing adverse effects.

Mechanical plating: mechanical plating of the activating agent, metal powder, the impact of the media (glass beads) mixed with a certain amount of water into a slurry, together with the workpiece into the drum, the drum rotation to produce mechanical energy, the activator and the impact of the media (glass beads) under the combined action of mechanical collision. The process of normal temperature gradually formed in zinc plating iron surface. Www.z-tf.com tianjin hardware

Dacromet: The following focuses on the advantages of surface treatment. Zinc chrome film (Dacromet) corrosion mechanism Description:

Zinc chrome film (Dacromet) coating process is a new surface treatment technology, also known as Dacromet, Duckle, Dacromet Le rust, zinc chrome film (Dacromet), Dakman and so on. It has been widely used in many fields such as automobile industry, civil engineering, electric power, chemical industry, marine engineering, household appliances, railway, highway, bridge, subway, tunnel, shipbuilding, military industry and so on in developed countries. Our country with the gradual promotion of the technology, has been in the automotive, electric power, anchor chain, highway, marine engineering and other aspects of the large-scale use, and received a high rating. Zinc chromium film (Dacromet) solution is a water-based treatment solution, metal parts can be dip coating, spray or brush treatment, and then sent to the heating furnace curing, curing temperature around 300 , by forty-five Minute to an hour of baking, the formation of zinc chrome film (Dacromet), chromium curing, the coating of water, organic (cellulose) substances such as volatile at the same time, relying on zinc chromium film Coke) in the mother liquor in the high-quality chromium salt oxidation, the electrode potential negative value of the larger element of zinc tablets, aluminum pulp and iron matrix reaction, the formation of Fe, Zn, Al chromium salt compound inorganic coating. As the film is directly connected with the substrate should be obtained, so the coating is extremely dense, (with galvanized or zinc immersion method can not be compared with the coating) in the corrosive environment,will form a plurality of primary batteries, that is, the first corrosion of the negative potential of the Al, Zn salts, until they are consumed after it is possible to corrosion to the substrate itself.Www.z-tf.com tianjin hardware

Zinc chromium coating (Dacromet coating) features: zinc chromium coating (Dacromet) coating is composed by overlapping in separate zinc tablets, with chromic acid polymer unit composition. Zinc chromium coating (Dacromet coating) chromate polymer layer does not contain water of crystallization, so under the condition of high temperature corrosion resistance also showed excellent quality. Zinc chromium coating (Dacromet) curing temperature of anticorrosive film at 300 DEG C, so the workpiece even if a long time at high temperature, the appearance will not change color, excellent corrosion resistance. Hydrogen embrittlement is the traditional zinc plating technology can not completely overcome the ills. Due to the characteristics of the process determines the zinc chrome film (Dacromet) in the course of treatment without any acid treatment, There is no problem of hydrogen permeation during electroplating,coupled with the coating at high temperature curing, so from the process to ensure that the zinc chrome Membrane (Dacromet) coating does not have hydrogen embrittlement. This makes it possible to be applied to the treatment of high strength parts with high tensile strength. As a green electroplating process, zinc chromium coating (Dacromet) process by closed cycle method in pretreatment processing , in the pre-treatmentin addition to the oil and dust with a special equipment collection and treatment; in the coating, curing, there is no traditional plating The process of acid, alkali, chromium and other heavy metal sewage problems, determined by the provisions of the state, resulting only from the coating evaporated from the water vapor, the determination, does not contain the provisions of the state control of harmful substances. Zinc chrome film (Dacromet) coating was matte silver gray, can be re-painted on the above. This is to meet the requirements of the higher quality of the appearance of the workpiece coating requirements.