Process And Properties Of The Electrodeposited Nanocomposite Coatings

A series new Ni-W P-SiO₂, RE-Ni-W-P, RE-Ni-W-P-SiO₂ nano-composite coatings with more excellent corrosion-resistance, hardness, oxidation-resistance and wear-resistance by direct current were studied. The deposited composition, the properties and structure were tested by EPMA-1600 electron probe, 3015 X-ray diffraction patterns, optics microscope, HX-1 micro-hardness instrument, HDV-7 transistor permanent potential apparatus, marinating in acid ,etc.The potential-PH diagram of Ni-P-H₂O system at 298K. was constructed by use of thermodynamic data. The formation mechanism of Ni-W P-SiO₂ system composite coatings was explained by means of potential-PH diagram, and the feasibility of nano-composite plating was analyzed by the mechanism and influence factors of direct plating. According to study effects that different technics conditions affect on nano-composite coatings in corrosion-resistance, hardness, oxidation-resistance , we can get the best technics conditions as follows: in the plating solution, the concentration of CeO₂ is 6g/L, the concentration of SiO₂ is 70g/L; PH=5; T=40℃; Dk=10A/dm²The corrosion-resistance, hardness, oxidation-resistance of RE-Ni-W, RE-Ni-W-P, Ni-W-P-SiO₂, RE-Ni-W-P-SiO₂ nano-composite coatings were studied in this article. The result of study is as follows :Whether ordinary composite plating coatings or the heat-treatment one at 400 ℃ , the hardness of nano-composite coatings are higher than the hardness of micron composite coatings, and the former one is better than the latter one in combine force. The nano-particulates are equably separated in the nano-composite coatings and it make the crystalloid fine for nano-particulate have a small size . especially joining in nano-CeO₂ can make nano-composite coatings have more superiority capability than micron composite coatings.The order of hardness of nano-composite coatings from high to low is that Ni-W-P-SiO₂>RE-Ni-W-P-SiO₂>RE-Ni-W-P. According to study and contrast the...