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本文以硫酸镍(Ni SO4·6H2O)为主盐、次亚磷酸钠(Na H2PO2·H2O)为还原剂,通过改变络合剂的种类与含量对硬质合金表面进行化学镀镍。用扫描电镜及能谱、X射线衍射仪、涂层附着力自动划痕仪和电化学测试系统分析表征硬质合金镀镍前后的形貌、成分、相组成、结合力以及耐蚀性。结果表明,在p H=8,T=80℃的施镀条件下,镀层为非晶结构且耐蚀性较镀前有一定的提高,镀层表面主要含有Ni元素和P元素,其中Ni元素占了很大的比例,镀层物相组成为Ni P2和Ni,且膜基结合力在100 MPa以上,镀层厚度受络合剂的影响较大。镀液成分为Ni SO4·6H2O∶25 g/L、Na H2PO2·H2O∶30 g/L、柠檬酸钠(Na3C6H5O7·2H2O)∶45 g/L、氯化铵(NH4Cl)∶30 g/L、硫脲(H2NCSNH2)∶1 mg/L时得到的镀层性能最佳。
In this paper, nickel sulfate (Ni SO4 · 6H2O) as the main salt, sodium hypophosphite (Na H2PO2 · H2O) as a reducing agent, by changing the type and content of complexing agent on the surface of the cemented carbide electroless nickel. The morphology, composition, phase composition, adhesion and corrosion resistance of the cemented carbide before and after nickel plating were characterized by scanning electron microscopy and energy dispersive spectroscopy, X-ray diffraction, automatic scratch tester and electrochemical test system. The results show that under the conditions of p H = 8, T = 80 ℃, the coating is amorphous and the corrosion resistance is improved before the coating. The surface of the coating mainly contains Ni and P, and Ni A large proportion of coating phase composition of Ni P2 and Ni, and the film-based bonding strength of 100 MPa or more, the coating thickness by the complexing agent. The bath consisted of NiSO4 · 6H2O:25 g / L, Na H2PO2 · H2O:30 g / L, sodium citrate (Na3C6H5O7 · 2H2O): 45 g / L, ammonium chloride Thiourea (H2NCSNH2): 1 mg / L get the best coating performance.