Technology And Application Of High Phosphorus Electroless Plating Ni-P On 20g At High Temperature

Electroless Ni-P alloy is a surface treatment technology based on an oxidation reduction in which Ni-P alloy deposit onto catalytic metallic substrates in bath that is reduced by Nickle salt and reducer. It have been widely applied to various fields, such as electronics,engineering and petroleum industry, etc.due to its excellent corrosion and wear resistance characters.Current situation and development were reviewed of Electroless Nickel(EN) on the base of massive literature foundation. Moreover, thermodynamics and dynamics mechanism of EN were preliminarily discussed. The ecumenical composition and the function of every composing part of EN plating technology were researched, and selects a basic prescription for producing EN. Then investigates the effects that technical parameter has on plating rate and phosphorus content on the basis of it and choose an optimal prescription. At last introduces a high-phosphorus electroless technology to produce Ni-P alloy on boiler steel and high-temperature alloy steel substrate. SiC(1~5μm) was prepared with the ultrasonic decentralization and ultra-turrax. The particle is well distributed in Ni-P compound plating by electroless plating on this basis formula.The bath compositions and conditions for the electroless coatings of formula TF are as followed: Nickel Sulphate 30g/L, Sodium Hypophosphate 28g/L; Complexing agent: Lactic Acid 4g/L,and Citricacid10g/L, Buffer 10g/L,Ph value 4.5, Temperature 90℃.With the assistance of Scanning electron microscope,friction and wear testing equipment,X-ray diffraction and hardness meter, systematical tests were carried out to measure the surface morphology of the coatings,wear resistance,structure,and deposit hardness.Using the TF prescription of acidic electroless Nickel technology, of which the coating rate is 22.38μm/h and the phosphorus content is 13.10%. The micro-hardness of as-plated coating is between HV700~750, which is then up to HV1800 after being heated at 400℃(crystallization temperature) for an hour. Compared with the substrate, EN coating has excellent corrosion resistivity after 144h in neutral salt spray test. The electroless compound coating of Ni-P-SiC has better wear resistance and lower friction than Ni-P coating.The prescription of TF is apply to high-temperature alloy steel substrate of which the phosphorus content is 13.10% and the micro-hardness is HV503.The prescription of TF has both good corrosion resistivity and high hardness. At the same time the hardness of coating improve 30% contrast with the prescription of Lingming aero-enging corporation.The cycle life of plating solution reaches 8 MTO. It can meet the requirement industry.