Electroless Ni-P-ZrO₂ Composite Coating And Its Properties

In this paper,I first pretreated galvanized iron sheet,and then successfully prepared Ni-P-ZrO₂composite coating with high hardness value and good corrosion resistance on the substrate surface by chemical composite plating technology,in order to further improve the mechanical properties of steel sheet in the field of material science.In this study,by screening the main influencing factors in the solution of electroless nickel phosphorus alloy plating,and then adding nano particles ZrO₂to the base plating solution,the nano particle dispersion is good.The effect of the addition of nano particles with different characteristics on the properties of electroless Ni-P-ZrO₂composite coating and its subsequent heat treatment process were investigated under the condition of electroless Ni-P-ZrO₂composite coating.The main research contents and conclusions of this paper are as follows:(1)Firstly,the mature electroless Ni-P plating formula was selected.On this basis,phosphorus content,deposition rate,porosity,hardness and absorbance were used as evaluation indexes,and the single factor test method was used to determine(1)the plating process parameters(p H,temperature).(2)The optimum molar ratio of nickel sulfate to sodium hypoxophosphate,the complexing agent system and its dosage;(3)the effect of different concentration of zirconia nano particles on the properties of the composite coating,the preparation of excellent Ni-P-ZrO₂chemical composite coating;(4)The types and dosages of double surfactants,stabilizers and buffers in the plating solution were screened and optimized,and the process of chemical composite plating Ni-P-ZrO₂was determined.(2)The influence of the addition amount of Ti N,Si₃N₄,Ti O₂,Sn O₂and ZrO₂on the properties of the coatings was investigated by orthogonal experiment with the porosity and hardness of the coatings as evaluation indexes.The properties of the composite coatings were characterized and analyzed by Vickers hardness tester,electrochemical workstation,scanning electron microscope,transmission electron microscope,electron diffractometer,and X-ray diffractometer.(3)The electroless Ni-P and Ni-P-ZrO₂composite coatings were subjected to subsequent heat treatment,and the Vickers hardness value of the coatings after different temperature treatment was determined.The microstructure and cathode polarization curve of the coatings were observed by scanning electron microscope and electro chemical workstation,and the mechanical properties of the coatings before and after different temperature heat treatment were compared and analyzed.The corrosion resistance of the composite coating is improved by the heat treatment temperature process.When the heat treatment temperature is 300?,the peak diffraction peak intensity increases and the peak value is sharp,and the composite coating has shown obvious crystal phase structure.