Electrodeposition Ni-p/al <sub> 2 </ Sub> O <sub> 3 </ Sub> Preparation And Properties Of The Composite Coatings

During the processing of the industrial products, the working piece has higher hardness and higher corrosion resistance than the surface of the common metal material, and composite plating is the most effective and direct method on attaining these properties on the surface of the working piece . Composite coating material with excellent physical and chemical properties shows superior property than the ordinary materials, its emergence broughts a new direction of development for the technology of plating.While nanoparticles be applied in the composite Plating, to obtain the corresponding compound coating, the technology has gained widespread attention at home and abroad.the essay choose the preparations and properties of the electrodeposited Ni-P / Al₂O₃ composite coating as a subject.Researching the preparations and properties of the electrodeposited Ni-P / Al₂O₃ composite coating.The main research work and the results are as follows:First, the microstructure of the electro-deposition Ni-P coating was researched , respectively on the pulse frequency and current density .Furtherly researching on the feasibility of the preparations of the electrodeposited Ni-P / Al₂O₃ composite coating.In the preparations process of the electrodeposited Ni-P / Al₂O₃ composite coating process,the impact factors (pH value, the accession of CoCl2, pulse frequency, mixing, etc.) were respectively analyzed. And Ni-P/ Al₂O₃composite coating microstructure were analyzed.The research shows that with the pH vaule surpass 4.5, it causes the phenomenon of cracks and auriventris on the coating the surface.After adding CoCl₂, the surface of composite coating surface features cell refinement and crystal volume significantly increased,Using CoCl2to improve the quality of the composite coating and the ideal adding amount is 1g/L. Pulse frequency make significant impact on the formation rate and in crystal size, the ideal pulse frequency is 500Hz. The speed of Stirring directly affect the opportunities of collision among nanoparticles and the structure of the composite coating.Secondly, the electro-deposition Ni-P/Al₂O₃ composite coatings research.Respectively research the effect of cathode current density, the amount of Al₂O₃ bath, the pH vaule of bath, electro-deposition time, pulse frequency on the hardness of Ni-P/Al₂O₃ composite coating, the rate of the deposition and corrosion resistance.And analyse the amount of heat treatment on the hardness of different contants of Al Ni-P/Al₂O₃ composite coating. CoCl₂ element on the electro-deposition Ni-P/Al₂O₃ composite coating hardness analysis.The results show that, the adding amount of Al₂O₃ is 20 g / L, cathode current density is 5A/dm2, bath temperature is 45℃, pH value is 4.5, the pulse frequency is 500Hz, electro-deposition time is 2h.The hardness of the Ni-P / Al₂O₃ composite coating is the idealest.Finally, testing the friction and wear properties, corrosion resistance properties of the Ni-P/Al₂O₃ composite coating and spreading properties of Aluminum bath in the surface of the composite coating. Ni-P/Al₂O₃composite coating have fine wear resistance property, corrosion resistance property and erosion resistance property. And make a summary and outlook on the preparation and properties of the Ni-P/Al₂O₃ composite coating.