化学复合镀具有操作工艺简单、镀层表面致密、厚度均匀、硬度高、抗磨性能优良、结合强度高、电特性良好、自润湿性好等特点。β-SiC颗粒具有优异的热稳定性、耐磨耐蚀、高强度等优点，是复合镀层中理想的第二相颗粒。稀土元素因其具有特殊的电子层结构、化学性质活泼、界面吸附能力强等优点，能有效改善材料表面的性能。本文采用连续化学镀的方法，以Ni-P层作为底层，Ni-P-β-SiC层作为外层，制备双层Ni-P/Ni-P-β-SiC镀层，研究了β-SiC颗粒浓度、Ni-P层与Ni-P-β-SiC层不同施镀时间比、不同浓度的稀土化合物Y(NO3)3对双层镀层的性能影响。采用扫描电镜(SEM)、能谱分析仪(EDS)、XRD射线衍射、维氏显微硬度计、摩擦磨损试验机、电化学工作站等检测手段，分析研究双层镀层组织成分、微观形貌、显微硬度、结合力、孔隙率、耐磨性及耐蚀性等相关性能。主要研究内容及结果如下： (1) 添加不同浓度的β-SiC颗粒，所获得的镀层表面平整，无脱皮、剥落、分层等现象。镀层整体厚度均匀，与基体结合良好，无明显孔隙和裂纹等缺陷。β-SiC均匀的分布在Ni-P基质合金中。β-SiC颗粒浓度为10g/L时，镀层镀速、显微硬度、耐磨性及耐蚀性均达到最优。其中显微硬度达569HV，相对于碳钢基体提高472HV，提高约331%，相对于采用电镀法制备的单层Ni-P-SiC提高10.4%，沉积速度达15.43μm·h-1（相对于Ni-P镀层提高了2.71μm·h-1，提高约21.3%）。 (2) 通过控制Ni-P 层与Ni-P-β-SiC层的施镀时间比，制备不同厚度比的双层镀层。当Ni-P层与Ni-P-β-SiC层施镀时间比为1h/2h时，镀层的显微硬度、镀速、孔隙率、耐磨耐蚀性达到最优。镀层的显微硬度达到581HV，相对碳钢基体提高约357.68%。相对单层Ni-P镀层提高了13.08%，相对单层Ni-P-β-SiC镀层提高了约2.14%。 (3)添加稀土化合物Y(NO3)3，可明显提高双层镀层的硬度、耐磨耐蚀性。当稀土浓度为1.0g/L时，沉积速度达25.79μm/h，相比未添加时提高8.9%；镀层的显微硬度达到596 HV，相比碳钢基体提高了369.58%，磨损率也达到最低。在3.5%的NaCl溶液中腐蚀电位由-0.575V上升到-0.277V，提高了298mV。

Chemical composite plating has operation simple, easy to control, not restricted by the shape of the matrix material, coating thickness is uniform and compact, high hardness, good antiwear properties, high bonding strength, good wear resistance, good electrical properties, wetting characteristics.β-SiC particles have excellent thermal stability, wear resistance and corrosion resistance, high strength and so on, which are used as the ideal second phase particles in the composite coatings. Because of rare earth has special electronic structure, active chemical properties and strong interfacial adsorption capacity, it can improve the properties of the materials surface effectively. This topic selects continuous electroless plating method, Ni-P coating as the under layer, Ni-P-β-SiC coating as the outer layer. It successfully prepared duplex Ni-P/Ni-P-β-SiC coating,and respectively studying β-SiC particle concentration, Ni-P coating and Ni-Pβ- SiC coatings are different thickness ratio, the addition of rare earth compounds Y(NO3) 3 concentration influence on the performance of double layer coating. Using scanning electron microscopy (SEM), spectrum analyzer (EDS), XRD X-ray diffraction, Vickers hardness tester, friction and wear tester and electrochemical workstation and detection means to analyze the performance of double coating composition, microstructure, microhardness, binding force, porosity, wear resistance and corrosion resistance, and so on. The main research contents and results are as follows: (1) Adding different concentration of β-SiC particles, the obtained coating surface is uniform, no peeling and other phenomena. The thickness of the coating is uniform, and the combination with the substrate is good, no obvious defects such as pore and crack. The β-SiC is homogeneous distributed in Ni-P matrix metal. When the concentration of β-SiC is 10g/L, the plating rate, microhardness, wear resistance and corrosion resistance of the coating are the best. The microhardness is reached 569.03 HV (compared with the matrix improved 331% ),Compared with the single layer Ni-P-SiC prepared by electroplating method improved 10.4%), deposition rate is reached to15.43 μm/h (compared with the Ni-P coating improved 2.71μ m/h ). (2) By controlling the coating time ratio of Ni-P and Ni-P-β-SiC, it prepared different thickness ratio duplex coating. When the plating time ratio of Ni-P and Ni-P-β-SiC is 1h/2h, the microhardness, deposition rate, porosity, wear resistance and corrosion resistance of the coating are the best. The microhardness of the coating reached the maximum, 581.25HV, compared with the matrix improved 357.68%,compared with the single layer Ni-P coating to improve the 67.22HV, the relative monolayer Ni-P-β-SiC coating increased by 12.22HV. (3) Adding proper amount of rare earth compound Y(NO3)3, it can significantly improve the hardness, wear and corrosion resistance of the duplex layer coating.When the concentration of rare earth is 1.0g/L, the deposition rate is 25.79 mu m/h, the microhardness of the coating is 596.37HV, compared with the matrix improved 369.58% and the wear loss is the lowest. The corrosion potential is from -0.575V to -0.277V, which increased 298mV in 3.5% NaCl.