【作者】 王法斌；

【导师】 李云； 吴玉程；

【作者基本信息】 合肥工业大学 ， 材料学， 2009， 硕士

【摘要】 纳米复合电沉积是一种新兴的复合表面技术,通过将纳米粒子引入金属镀液中形成的纳米复合镀层,显示出优越的机械性能、电催化性能、耐腐蚀性能等,正逐渐成为研究的热点。本文采用正交实验、对比实验优化电沉积镍基SiC/Si₃N₄纳米复合镀层的工艺配方,探索纳米微粒的添加量和粒径、分散剂、分散方法、pH值、电流密度、施镀条件等多种因素对施镀工艺和镀层外观的影响。并在此基础上,阐述了纳米颗粒与金属共沉积的机理。同时利用金相显微镜、扫描电镜（SEM）、X射线衍射（XRD）对镀层的形貌、组织结构和成分进行分析;并通过测定镀层的显微硬度、腐蚀失重、测定极化曲线和摩擦试验等方法研究了镍基SiC/Si₃N₄纳米复合镀层的性能。研究表明:pH值对于镀层表面影响最为明显,Ni-Co-P-SiC/Si₃N₄复合镀层在酸性镀液中镀层质量较好,pH值在2-3范围内,在这范围之外镀层表面质量很差;Ni-W-SiC/Si₃N₄复合镀层在偏碱性性镀液中镀层质量较好,pH值在7-8范围内,在这范围之外镀层表面质量很差;其次对镀层影响较大的为温度,通过对沉积后的试样观察,在较高温度下,镀层表面光洁度、平整度、镀层结合力都相对较好;电流密度主要影响沉积效率,对镀层其它性能影响较小;分散剂、粒径大小及添加量等因素对镀层也有一定的影响,但影响相对较小。电沉积Ni-W-SiC/Si₃N₄、Ni-Co-P-SiC/Si₃N₄合金纳米晶镀层的显微硬度都较高,一般都在700HV以上。腐蚀试验表明:添加SiC/Si₃N₄镍基复合镀层具有更好的耐蚀性,复合镀层在腐蚀介质中表面迅速生成一层彩色的钝化膜,使腐蚀速度减慢。在1mol/L的NaCl和0.5mol/L的H₂SO₄溶液中Ni-W-SiC/Si₃N₄复合镀层耐腐蚀性能明显优于Ni-Co-P-SiC/Si₃N₄复合镀层。摩擦试验表明:Ni-Co-P-SiC/Si₃N₄复合镀层耐磨擦性能优于Ni-W-SiC/Si₃N₄复合镀层;通过观察摩擦痕迹的SEM图发现添加微米颗粒的复合镀层其摩擦试验后的痕迹比添加微米级颗粒的复合镀层均匀,但添加微米级粒子的复合镀层其耐摩擦性能却优于添加纳米粒子的复合镀层。更多还原

【Abstract】 Composite electrodeposition with nano-particles is a developing surface technology. Nano-composite coating is showing more and more excellent performance, such as mechanical performance, catalytic performance, corrosive protective performance and so on. All of this has bought a wide range investigation on it.In this paper, the preparation process of electro-deposition of Ni-based SiC/Si₃N₄ Nano-composite Coatings were optimized by using perpendicular experiments and comparative trial. And the effects of main factors （adding quantity of nano-Si₃N₄, disperse methods, current density, dispersing agent） on the quality of Ni-W-Si₃N₄ composite coatings and deposition velocity were also dealt with. Based of it, codeposition mechanism of nano-particles with metal ions was introduced. Many dispersion methods on the nanometer particle for electroless composite coatings have been studied in this paper. At the same time, the microstructures and components of the nano-composite coating Ni-W-SiC/Si₃N₄ and Ni-Co-P-SiC/Si₃N₄ were characterized by EDS、XRD and SEM Techniques. Its performance was studied by measuring microhardness, weight loss method, anodic polarization curve and friction test.It was indicated that the surface quality of coating most obvious influence by the PH value and when the pH value is in 2-3 the composite coating Ni-W- Ni-Co-P-SiC/Si₃N₄ is good, but in this outside the scope is poor. And the composite coating Ni-W-SiC/Si₃N₄ is good when the pH value is in 7-8. Then we can get high-caliber, smooth and adhesion coating in high temperature by contrasting the experiment samples. Current density mainly influence the coating in the way of deposition rate. And have less influence to other properties of the coatings. Dispersant, size and quantity of nano-particles has certain effect to coating, but the effect is relatively small.The microhardness all of Ni-W-SiC/Si₃N₄ and Ni-Co-P-SiC/Si₃N₄ are high and comes to more than 700HV. The corrosion resistance of Ni-based alloy plating is excellent. The corrosion resistance of film with SiC/Si₃N₄ is better than without. The corrosion speed of compound film drops because a surface passivation layer comes into being. In 3.5wt%NaCl solution and 0.5mol/L H₂SO₄, the corrosion speed of Ni-W-SiC/Si₃N₄ is better than Ni-Co-P-SiC/Si₃N₄. But the abrasive resistance of Ni-Co-P-SiC/Si₃N₄ is better than Ni-W-SiC/Si₃N₄. Through the observation of sem diagram found traces of friction: add microns particles composite coating its friction test than add nanoparticles traces of composite coating particles. But add micronstructured particle composite coating resistance and corrosion resistance of friction is superior to add nanoparticles composite coating.更多还原