【作者】 卢冠宇；

【导师】 梁波；

【作者基本信息】 燕山大学 ， 材料学， 2011， 硕士

【摘要】 本文采用酸性化学镀液在铝合金表面获得Ni-Mo-P合金镀层。利用X荧光光谱分析（XRF）、场发射扫描电镜（FESEM）、透射电镜（TEM）、X射线衍射分析（XRD）、能谱仪（EDS）和激光共聚焦显微镜（LSCM）、差示热扫描仪（DSC）等现代分析手段,探讨了Na₂MoO₄浓度和施镀温度对镀层中Mo含量、镀层形貌、沉积速度、显微硬度、结合力等性能的影响。研究了不同热处理温度对镀层的结构、结合力以及硬度的影响。结果表明:以柠檬酸钠为络合剂的酸性化学镀镀液可很好的实现Ni、Mo、P的共沉积。XRF分析表明:在试验范围内,随着Na₂MoO₄浓度的增加,镀层中Mo含量增加,P含量降低,还原剂的消耗增加,镀层形成能力下降。最佳Na₂MoO₄浓度范围为0.5 g/L⁰.6 g/L,温度为90℃。TEM分析证明:镀态镀层主要为非晶结构,随Na₂MoO₄浓度变化镀层中出现混晶态和纳米晶态两种微观结构。此外研究表明:温度为90℃,Na₂MoO₄浓度为0.5 g/L左右时,镀层的沉积速率最大为9.5μm/h;镀层表面HV硬度最大为458.70;镀层结合力最高达30 N;表面粗糙度最小,Rz<3040。化学镀机理研究表明:随着热处理温度的提高,Ni-Mo-P合金镀层大体上经历结构驰豫+晶态Ni的析出→Ni₃P相的析出→晶态Ni、Ni₃P的聚集长大等过程。热处理可使镀层的结合力有所增加。300℃保温1 h镀层的结合力达到最大,达到40 N以上;退火温度超过300℃后,镀层的结合力迅速下降;硬度随热处理温度升高而增加。400℃热处理后,Ni-Mo-P镀层横截面硬度为15.12 GPa,表面HV硬度为774.23。热处理温度超过400℃,Ni-Mo-P镀层镀层硬度开始下降。更多还原

【Abstract】 In this thesis, Ni-Mo-P alloy coating was deposited by electreless plating using acidic plating solution on the substrate of aluminum alloy. The effects of bath temperature and concentration of Na₂MoO₄ on the composition, structure, properties, such as microhardness, deposition rate and adhesion of the Ni-Mo-P alloy deposits were studied by Thermal Field Emission Scanning Electron Microscope （FESEM）, Energy Dispersive Spectrometer （EDS）, X-Ray Fluorescence （XRF）, Transmission Electron Microscope （TEM）, X-ray Diffractometer （XRD）, Differential Scanning Calorimetry （DSC） and Laser Confocal Scanning Microscope （LCSM）. The influence of heat treatment temperature on the structure, microhardness and adhesion of the Ni-Mo-P alloy deposits were also discussed.The experimental results show that the Ni-Mo-P alloy coating could be obtained using the acidic plating solution in which the C6H5Na3O7·2H2O was used as the complex agent.XRF results indicate that the Mo contents and the deposition rate would be increased with the increase of MoO42- concentration, corresponding with the decrease of P contents in the bath solution. The key plating factors, bath temperature and the concentration of Na₂MoO₄ were around 90℃and in the range from 0.5 g/L to 0.6 g/L, respectively. It was found that the maximum deposition rate was 9.5μm/h, the maximum microhardness was 458.70 HV, the maximum adhesion was 30 N, the minimum surface roughness （Rz） was less than 3040 ? obtained at the bath temperature of 90℃, the Na₂MoO₄ concentration of 0.5 g/L.TEM results demonstrate that amorphous structure was the main structure of Ni-Mo-P alloy coating. The microstructure of as plated coatings would be changed from amorphous to nanocrystalline and mix-crystalline structure with the change of the Na₂MoO₄ concentration. After heat-treatment at differernt conditions, the structure of Ni-Mo-P alloy coating experience a series of transformations, such as structural relaxation, formation of Ni nanocrystal, bulk formation of Ni₃P nanoerystal, especially, the grain aggregation and growth of Ni and Ni₃P may be increased with the increase of heat treatment temperature. The adhesion strength of as-plated coating reaches its maximum value （40 N） after heat treatment at 300℃, 1 h. The microhardness determined at the conditions of 400℃and 1 h on the cross section and surface were about 15.12 GPa and 774.23 HV, respectively.更多还原