Experiment On Electroless Plating At 45 Steel And The Study On The Properties Of The Plating Coating

Electroless nickel plating is a chemical reaction in which metal atoms are deposited by self-catalysis at surface of the metal. Because of its remarkable characteristics superior to those of electroplating, and excellent properties of plating coating, electroless nickel plating has been widely applied to many fields including computer and micro-electron industries, petroleum and chemical industries, machinery and automobile industries, foods, die and mould, aviation and aerospace industries. The technological characteristics of electroless nickel plating are found out by the experiments of acidic electroless plating, alkaline electroless nickel plating and electroless multi-components plating, various characteristics of experiment samples are tested, and its results are analyzed theoretically. The results are as follows.â‘ Acidic plating coating contains high content of phosphorus, its plating temperature is also high. The structure of coating, called mixed crystal, is mixture of amorphous and micro-grains. The corrosion resistance of Ni-P coating is very good, as a result, it is corroded only a little in diluted acid, diluted alkali, salt and air. The hardness of Ni-P coating is up to the value of 1000HV after heat treatment, and its abrasion resistance is also excellent and force combining with base is quite firm.â‘¡The content of phosphorus in alkaline coating is low, and plating temperature is also low. The structure of the coating is similar to micro-grain. its corrosion resistance is worse than that of acidic coating. Alkaline electroless plating may be prepared at lower temperature, so plastics can be plated with Ni-P coating by alkaline electroless plating.â‘¢Electroless multi-components plating represents the tendency of Electroless nickel plating. The corrosion resistance of Ni-Cu-P coating is the best, even its corrosion resistance is more excellent than that of stainless steel in some acid. In addition, solderability of Cu-Ni-P coating is good, so it is widely applied to many fields including printed circuit boards, hard disks of computer, and cases of electronic component at space telescope, etc.â‘£Treatment after plating. After electroless plating the coating can be treated in heat treatment and passivating treatment. Passivation may improve the corrosion resistance of plating work-pieces in some corrosive medium. Heat treatment not only removes stress within coating but also forms oxidizing film at the surface of work-pieces, so corrosion resistance in air may be greatly improved. In addition, heat treatment may greatly improve the hardness of the coating and abrasion resistance. Therefore, the electroless plating is widely applied to many fields including reparation of worn workpieces, plastic die and mould, gear, gear-shafts, and ball cores of valves in petroleum, etc.Besides, the influence of components of plating solution on the technology of electroless plating and the effect of the technical parameters on the content of phosphorus within coating are discussed in this paper. How to improve corrosion resistance and abrasion resistance is also discussed in this paper. The experiment suggests that plating double-coating can most effectively improving corrosion resistance and adding alloy elements to coating may greatly improve hardness and abrasion resistance of the coating.