The Study Of Electroless Ni-P Alloy Process And Anti-corrosion Mechanism For Marine Environment

It's well known that there is serious corrosion in the marine environment, which lead t o m any disaster and hug e e conomic 1 oss. Ga Ivanization c an p rotect m aterial from corrosion effectively. However, with the increase of environment ide ology, it will be restricted in some fields because of its pollution. Meanwhile, Electroless Ni-P alloys are developing quickly that have applied to the field of petroleum, foodstuff, car, computer, and naturalgas.But there are many problems existed in the field of marine er-'ironment. So it's necessary to develop an Electroless Ni-P alloys process that possess high anti-corrosion (especially high anti-porosity) and good hardenss property.According to the guidance idea of "high anti-corrosion property (especially anti-porosity property)", Electroless Ni-P alloy process is premiumed. First, Complex agent A and B are selected; Second, stabilizer K is selected using the method of PdCl2 experiment; At last Electroless Ni-P alloy processes are premium using Latin experiment, that is NiSO4 ?6H20 19+4 g/L, NaH2PO2 ?H20 24+3 g/L, Comple:: agent A 23 ? g/L, Complex agent B21? g/L, Stabilizer K16?mg/L, pH 5.0?0.2,Temperature 87?The anti-corrosion property of coating is researched using potentiodynamic polarization techniques, salt mist experiment and porosity experiment. The results indicate: the corrosion rate of Electroless Ni-P alloy is 0.11 u m/a in 3.5%NaCl solution, The surface of coating which possesses 25 ?m on the Cu substrate appears brown blotch after immersing in the porosity solution for 14 minutes and the surface of coating which possesses 25 M m on the A3 steel substrate appears rust blotch after immersing in the salt mist for 92.5 hours.The stiffenss of coating is 493. IHv using vikers hardenss tester. The surface micromorphological features of coating and P content of coating are researched using scan electron microscope, the results indicate that the coating is composed of ?m particle and amorphous. The coating possesses good adhension using the methode of GB.The supply process of Electroless Ni-P alloy is studied by measuring the wastageH2O and NiSCv6H20 during the course of experiment. The experiment result indicates that the weight wastage ratio of NaH2PO2-H20 to NiOrO is 1.06:1.The life of solution is studied by interval supplying and porosity experiment. As the result of the research, In the experiment for the life of solution, If getting out 10% solution per period, When the der.sity of the HPO^" is equal to 0.486 mol/L, the amount of production is almost as much as the amount, which will be gotten out, so the density of the HPCV keeps stable. Critical concentrations of Na+, SO42" and HPO3" in the solution are 1.99 mol/L, 0.626mol/L and 0.486 mol/L respectively. The speed of the solution keeps stable changing between 12 -15 u m/h in the 50 working periods. When supplying = 11 percent, solution could be used in circulation.Besides, The anti-corrosion mechanism of Electroless Ni-P alloy immersing in 3.5% NaCl solution is studied using XRD, SEM,potentiodynamic polarization techniques and electrochemistry spectrum (EIS). The results indicate: Coating is composed um particle and amorphous and passivation membrane have formatted during immersing in the 3.5% NaCl solution.