Study On The Alloy Coating Of Ni-W-P Electrodeposition

The alloy coating of Ni-W-P electrodeposition can be easier formed as amorphous structure, because this kind of coating have many specific properties especially, in the term of corrosion-resisting and electrocalytiactivity. It is paied attention by more and more researchers.The emphasis of this paper is to survey the alloy of Ni-W-P, there are two indexs considered in total experiments, this is, the corrosion rate and metallographic structure.Firstly, the experiments were done by the method of individual factor,through changing the concentrations of every composition in the electroplating solution and electrodeposition parameters, then got a series of coatings and tested, analysed and contrasted the effects on the qualities of coatings ,mainly, corrosion-resisting and metallographic structure. According to the results, a certain conclusion about every factor can be made. Increasing the concentration of nickel sulfate acid can enhance the rate of deposition. If the concentration is over high the growing speed of crystal nuclear is quickier than that of the forming nuclear which will not beneficial to form the compacting coating, so effect the corrosion-resisting;Tungsten Phosphorus can be induced and slender the crystal grains of the coating;over the higher contents will raise the inner stress;Citric acid can help to attain the compacting coating, if the higher concentration will lead to the difficult of deposition, the higher current density can improve the rate of deposition, if the higher current density can reduce to the larger ratio of pore;the temperature could not be over higher ,or so the solution will be lost quicklily.Secondly, on the base of individual factor conclusion, the experiments were made by means of the orthogonal experiment,the object is further to optimize the composition and concentrations of eletrodeposition solution and technology parameters, in the course of electrode-position of Ni-W-P alloy, The following result is: NiSO₄·6H₂O 80gL^-1Na2WO4?2H2O 170 gL"1, NaH2PO2?H2O 20 g-L"1, H3BO3 20 gL"1 , C6H8O7*H2O 230 g-L"'> Brightener 1 gh^\ Surface active agent: 0.1 g-L^\ Cathode current density (Jc) :6Adm^{^} Temperature (T) 50°C , Time(t) 2.5h -. pH value: 3. The coating which was gotten under the better conditions is tested and analysed by the instruments of EDAX, X-ray diffraction (XRD), Scanning Electro Microsope. (SEM). The results was shown that the coating is made of Ni: 86.64%, W: 6.21 %, P:9.15%, and present a even, fine amorphous structure.The comparable experiments were testd among the alloys of Ni-W-P, Ni-W, Ni-P and commonly 316L stainless steel. In the term of corrosion-resisting, the results is shown that the three kinds of coatings have better corrosion-resisting that 316L stainless steel, but tri-alloy has advanced quality over the duality alloy.In the experiment, the rate of corrision were compared between the states of plating and the heat-treatment, after 200°C><0.5h. It is concluded that the state of the heat-treatment has preponderance over of the plating in the corrosion-resisting.In the paper, the researchers about the electrocalytic activity were worked to the three kinds of alloy ,Ni-W-P, Ni-W^ Ni-P. It is found that the activity sequence is arranged from high to low as the form Ni-W-P, Ni-P, Ni-W. Therefore, it is claimed that nickel element forms the alloy with the transition metal and nonmetal which can improve the electrocalytic activity in the course of hydrogen evolution, and that the nonelements of high electric negative has better quality than tansition metals...