化学镀镍层会使得材料的硬度、耐磨性、可焊性以及耐腐蚀性得到改善，因而铝合金成为继钢铁及其合金之后使用最多的化学镀镍金属基材。尤其是在航空工业，化学镀镍磷被广泛地应用于发动机活塞头铝合金零部件上。本文以7075铝合金为基体，通过在复合镀液中添加表面活性剂、不同微米级粒径的β-SiC颗粒制备Ni–P–β-SiC复合镀层，并对其性能进行检测分析，从而寻找最佳的表面活性剂及其添加浓度和性能达到最好的β-SiC颗粒粒径；随后在7075铝合金基体表面制备Ni–P/Ni–P–β-SiC双镀层，更进一步提高其性能以拓展铝合金的应用领域。采用X射线衍射仪（XRD）、扫描电镜(SEM)及自带能谱仪(EDS)、涂层附着力划痕仪、显微维氏硬度计等多种检测手段对镀层的微观形貌、元素分布、结构性能等进行检测和分析，主要结果如下。 （1）随表面活性剂浓度的增加，复合镀层中β-SiC颗粒嵌入量先增加后减少。与阴离子表面活性剂十二烷基硫酸钠相比，非离子表面活性剂聚乙二醇-400的添加对Ni–P–β-SiC复合镀层性能提升幅度更大。主要表现为：当浓度为4mL/L时，镀层硬度达到658.6HV，镀速达到最大13.16μm/h，结合力为67.8N。采用此浓度的EPG-400做为表面活性剂，对复合镀层中颗粒含量、镀速及硬度有较大提高。 （2）当β-SiC颗粒粒径为5μm时，复合镀层表面均匀致密，结合力达到75.6N，硬度为922.1HV，与平均粒径为2.5μm镀层硬度（658.6HV）相比提高了40％。采用此粒径的β-SiC颗粒使复合镀层有较大的硬度及较小的磨损量0.12mg。 （3）与Ni–P–β-SiC单层复合镀层相比，Ni–P/Ni–P–β-SiC双镀层的结合力从75.5N提高至90.8N，提高了20.26％；摩擦系数在0.49~0.53之间浮动，耐磨性能显著提高；通过在3.5 wt% NaCl溶液中对镀层极化曲线进行分析发现，Ni–P/Ni–P–β-SiC双镀层自腐蚀电位为-0.28V，较7075铝合金基材正移了约 0.56V，耐腐蚀性能提高。

Aluminum alloy becomes the most commonly used electroless nickel-plated substrate after steel and other iron alloys，Owing to the presence of electroless nickel plating layer improves the hardness, wear resistance, weldability, and corrosion resistance. Especially in the aerospace industry, electroless nickel-phosphorus is widely used in engine piston heads that is an aluminum alloy part. In this paper, 7075 aluminum alloy was used as the matrix, the Ni–P–β-SiC composite coating were prepared by adding surfactant and different micron-sized β-SiC particles in the composite plating solution, and the properties of the composite coating were tested and analyzed to find the best surfactant and the particle size of β-SiC particles with the best concentration and performance; then Ni–P/Ni–P–β-SiC duplex coating was prepared on the 7075 aluminum alloy to improve its performance to expand the application. The coatings were tested and analyzed by XRD, SEM and EDS micro hardness tester to observe and analysis its microstructure, element distribution and organization structure. The main research contents and results were as follows: (1) As the concentration of the surfactant increases, the amount of β-SiC particles embedded in the composite coating increased first and then decreased.Compared with the anionic surfactant sodium lauryl sulfate, the nonionic surfactant polyethylene glycol-400 was more suitable. When the concentration is 4mL/L, the hardness of the coating reaches 658.6HV, the plating speed reaches 13.16μm/h, the adhesion was 67.8 N. The use of this concentration of EPG-400 as a surfactant has a great influence on the particle content, plating speed and hardness of the composite coating. (2) When the diameter of β-SiC is 5μm, the surface of composite coating is uniform and dense, the bonding force is up to 75.6N, the hardness is 922.1HV, which is increased by 40% compared with the average particle size of 2.5μm (658.6HV). The β-SiC particles of this particle size have a large hardness and a small wear amount of 0.12 mg. (3) Compared with the Ni–P–β-SiC single-layer composite coating, the bonding strength of Ni–P/Ni–P–β-SiC duplex coating increased from 75.5N to 90.8N, which was increased by 20.26%. The friction coefficient fluctuates between 0.49 and 0.53, and the wear resistance is significantly improved. By analyzing the polarization curve of the coating in 3.5 wt% NaCl solution, it is found that the self-corrosion potential of Ni–P/Ni–P–β-SiC double coating is -0.28V, which is shifted by about 0.56V compared with the 7075 aluminum alloy substrate. The corrosion resistance is greatly improved.