Influence of the Tungsten Content on Surface Properties of Electroless Ni-W-P Coatings

Ternary Ni-W-P films were produced by electroless deposition using baths with different tungsten concentrations. After deposition, the coated surfaces were annealed at 400°C for 1h. Surface morphology and film composition in the as-plated condition were assessed by SEM and EDS analyses, respectively. The crystalline phases after annealing were investigated by X-ray diffraction (XRD). Nanoindentation tests were performed to assess the mechanical properties of the deposited films. Surface roughness was determined by confocal laser scanning microscopy (CLSM). Friction coefficient was evaluated by reciprocating were tests in a nanotribometer. The corrosion behavior was evaluated by potentiodynamic polarization curves. The results showed that the surface morphology, crystallization behavior and corrosion resistance were affected by the tungsten content in the film. The best corrosion performance was obtained for the ternary films after annealing. Hardness, surface roughness and friction coefficient were dependent of the tungsten concentration in the film.采用钨浓度各异的镀液，通过化学镀工艺制备了三元镍-钨-磷（Ni-W-P）薄膜。镀覆完成后，将涂层表面置于400℃下退火1小时。分别采用扫描电子显微镜（Scanning Electron Microscope, SEM）与能量色散X射线光谱仪（Energy Dispersive X-ray Spectroscopy, EDS）对镀态样品的表面形貌与薄膜成分进行表征分析；通过X射线衍射（XRD）探究退火后薄膜的晶相组成；采用纳米压痕试验评估沉积薄膜的力学性能；采用共聚焦激光扫描显微镜（Confocal Laser Scanning Microscopy, CLSM）测定薄膜表面粗糙度；采用纳米摩擦试验机开展往复摩擦磨损试验以表征薄膜的摩擦系数；通过动电位极化曲线评估薄膜的腐蚀行为。试验结果表明，薄膜的表面形貌、结晶行为与耐腐蚀性能均受薄膜内钨含量的影响，经退火处理的三元Ni-W-P薄膜展现出最优的耐腐蚀性能。薄膜的硬度、表面粗糙度与摩擦系数均与薄膜内的钨浓度密切相关。