TC4钛合金表面化学镀Ni-P-MoS_2复合镀层

Electroless Ni-P-MoS_2 Composite Coating on TC4 Titanium Alloy

研究了搅拌方式、表面活性剂种类及用量对Ni-P-MoS2复合镀层沉积速率、MoS2微粒复合量及分布的影响,借助三维视频显微镜、扫描电镜、能谱仪观察了复合镀层的形貌及镀层中各元素的含量与分布,研究了MoS2微粒在镀液中的活化与其沉积方式。结果表明,间歇搅拌保证镀液中的离子和微粒均匀分散的同时也减少了MoS2微粒的脱落,故能加快沉积速率,促进MoS2微粒含量的增加和均匀分布。在特性吸附和"空间位阻"效应的共同作用下,单一阳离子型表面活性剂的使用保证了镀层沉积速率和MoS2微粒复合量;由于阴阳离子表面活性的强烈相互作用,使得复配表面活性剂有利于MoS2微粒在复合镀层中的均匀分布。镀液中被活化的MoS2微粒通过搅拌和电场作用到达Ni-P层表面,而未被活化的MoS2微粒则仅依靠搅拌作用靠近Ni-P层表面,经催化作用,完全活化和部分活化MoS2微粒被Ni-P层完全或部分包裹,未被活化的MoS2微粒则吸附在Ni-P表面且易脱落。

The effects of stirring ways, types and concentrations of surfactants on deposition rate and MoS2 concentration of electroless Ni-P-MoS2 composite coating were studied, the morphology and element distribution were tested using 3D video microscopy, SEM and EDS, the activation status and deposition ways of MoS2 were also studied. The experiment results indicated that fast deposition rate, high MoS2 particle content and uniform distribution were all achieved by using interval stirring since it could make all the ions and MoS2 particles well dispersed in the bath, as well as reduce the falling off of MoS2 particles. Under the combined action of specific adsorption and steric hindrance, the deposition rate and MoS2 content of electroless Ni-P-MoS2 composite coating were both guaranteed by adding single cationic surfactant to the bath. On account of the intense interaction of cationic and anionic surfactants, MoSz particles were equally distributed in the coexistence of cationic and anionic surfactant. Activated MoS2 particles in bath were delivered to the surface of Ni-P coatings by stirring and electric force, while unactivated MoS2 particles in bath reached the surface of Ni-P coatings only by stirring. After catalysis, the MoS2 particles which were completely or partly activated in bath were completely or partly packed by nickel coatings, while the MoS2 particles which were not activated in bath were adhered to the surface of Ni-P coatings.