电沉积Ni-P/Al₂O₃复合镀层的制备及性能研究

【作者】 刘强强；

【导师】 彭成章；

【作者基本信息】 江西理工大学 ， 机械电子工程， 2010， 硕士

【摘要】 在机械工业产品加工过程中,加工工件要比普通的金属材料表面具有更高的硬度及耐腐蚀性能,而在加工工件表面获得这些性能,复合电镀是最直接和最有效的方法。复合镀层材料以优异的物理和化学性能显示出了比一般材料更为优越的性能,它的出现给电镀技术带来了新的发展方向。而将纳米颗粒应用到复合电镀中,获得相应的复合镀层,这一技术在国内外得到了普遍的重视。本文选择以电沉积Ni-P/ Al₂O₃复合镀层的制备及其性能作为课题,对电沉积Ni-P/ Al₂O₃复合镀层的制备及其性能进行了研究。主要的研究工作和结果如下:首先,对电沉积Ni-P镀层的显微组织进行了研究,分别以脉冲频率和电流密度对Ni-P镀层显微组织的探讨。进而对电沉积Ni-P/ Al₂O₃复合镀层的制备的可行性进行了研究。在制备电沉积Ni-P/ Al₂O₃复合镀层的过程中,分别对其影响因素（pH值,CoCl2的加入,脉冲频率,超声波分散等）进行了分析。并对Ni-P/Al₂O₃复合镀层显微组织的进行了分析。研究表明:当随着pH值超过4.5时,将会引起镀层表面有裂纹及爆皮现象。添加CoCl2后,复合镀层表面特征晶胞细化,且结晶量明显增多,用CoCl₂提高复合镀层质量,理想加入量为1g/L。脉冲频率在形成速率上及对晶核的结晶大小有着明显的影响,其理想的脉冲频率为500Hz。搅拌速度的快慢,直接影响纳米颗粒彼此碰撞的机会,影响复合镀层的结构。其次,对电沉积Ni-P/ Al₂O₃复合镀层性能进行了研究。分别研究了阴极电流密度、镀液中Al₂O₃的添加量、镀液pH值、电沉积时间、脉冲频率等,对Ni-P/ Al₂O₃复合镀层的硬度、沉积速率和耐蚀性的影响。以及对热处理对Al₂O₃含量对Ni-P/ Al₂O₃复合镀层硬度的影响进行了分析。CoCl₂元素的加入对电沉积Ni-P/ Al₂O₃复合镀层的硬度的影响进行分析。结果表明,Al₂O₃的添加量为20g/L,阴极电流密度为5A/dm2,镀液温度45℃,pH值4.5,脉冲频率为500Hz,热处理温度为400℃,获得的Ni-P/ Al₂O₃复合镀层的硬度高。最后,对Ni-P/ Al₂O₃复合镀层进行了摩擦磨损性能、耐腐蚀性能和铝液在复合镀层表面的铺展性能的测定。Ni-P/ Al₂O₃复合镀层具有良好的耐磨减摩性能、耐腐蚀性能和耐铝液侵蚀性能。并对Ni-P/ Al₂O₃复合镀层的制备及性能研究作出总结及展望。更多还原

【Abstract】 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.更多还原