Research On Jet Electrodeposition And Laser Remelting Nanocrystalline Nickel Coating

Nanocrystalline coatings get more and more attention same as nano-materials because of owning many special physical and chemical quality compared as traditional materials. In this paper, the nanocrystalline coating preparation method, nano compound coatings application and development, electroplating theory and its current research situation are discussed. The preparation of nanocrystalline nickel coating and compound coatings is introduced, which based on jet electrodeposition(Simplified as JED), and combined with the advantage of pulse electrodeposition. Strengthen process on coating by laser remelting is introduced, because of the disadvantage of combination intensity between JED coating and substrate. Choose propriety remelting process parameters, which diminished the surface crystal, increased the coating's compact quality, improved the combination between coatings and the base metal, and implemented the transformation form mechanism combination to metallurgy combination. The major conclusions gotten in this dissertation are presented as follows:(1) Design and assembly a jet electrodeposition system. Deposited the nanocrystalline nickel coating on the base metal(SUS304L and 45 Steel) using direct and pulse supply, and watts plating bath, then laser remelting the coating, got the laser remelted nanocrystalline nickel coating.(2) Research on the effect of pulse electrodeposition process parameters including duty ratio, frequency, current intensity, on the microhardness of nanocrystalline nickel coating. The process parameter was optimized by orthogonal method. Reaults showed that the optimum process parameters to obtain nanocrystalline nickel coating by pulse plating process are as follows: duty ratio of 20%, frequency of 1000HZ, current intensity of 39.8 A/dm~2, the microhardness of nanocrystalline nickel coating is the best (530.6HV).(3) Observed the surface morphology and microstructure of nanocrystalline nickel coating by SEM and XRD. SEM results of this experiment show that the current density has huge influence to the nanocrystalline nickel coating, the electrodeposition speed was rapid and the coating quality was good at the current intensity of 39.8 A/dm2. The size of crystal are decreased more on the pulse condition, compared as the direct current, and the coating's size of crystal are obviously diminished on the remelted district when the nanocrystalline nickle coating was strengthening processed by laser remelting. XRD results show that the nanocrystalline nickel coating is preferred orientation of (111).(4) Research on the coating's mechanism performance by testing equipment. Results showed: The size of crystal of anocrystalline nickel coating are diminished after laser remelting, and the coating's microhardness, the strain-stress characteristic and the corrosion resistance obviously increased.