不同h-BN含量Ni-P-WS_(2)-BN化学镀层的组织结构及磨损性能

Microstructure and Tribological Properties of Electroless Ni-P-WS2-BN Composite Coatings with Different Contents of h-BN

目的通过化学镀共沉积技术在Ni-P-WS_(2)镀层中引入六方氮化硼(h-BN)纳米粉末,以进一步提升其硬度和耐磨性,改善其摩擦学性能。方法将六方氮化硼(h-BN)纳米粉末与二硫化钨(WS_(2))纳米粉末共沉积制备Ni-P-WS_(2)-BN复合镀层,并对其进行400℃×1 h的惰性气氛热处理。采用扫描电镜、X射线衍射仪、摩擦磨损试验机等对镀层的化学成分、组织结构及摩擦学性能进行表征,考察h-BN用量及热处理对复合镀层的影响。结果随着镀液中h-BN用量的增加,镀层中h-BN含量持续上升,镀层的表面粗糙程度先升高、后降低,胞块结构有致密化倾向,硬度由321HV_(0.1)上升至522HV_(0.1),磨损率从1.82×10^(-13)m^(3)/(N·m)降至0.95×10^(-13)m^(3)/(N·m),平均摩擦因数介于1.61~2.00,且呈先降后升的趋势(h-BN用量为3.0 g/L时达到最小值)。经热处理后,镀层硬度可达457~822HV_(0.1),磨损率从1.24×10^(-13)m^(3)/(N·m)降至0.31×10^(-13)m^(3)/(N·m),平均摩擦因数降至0.93~1.29。复合镀层的磨损以磨粒磨损机制为主。结论h-BN粉末的共沉积和400℃退火处理可显著提高复合镀层的硬度和耐磨性,大幅度降低摩擦因数和磨损率,改善复合镀层的综合性能。

The introduction of hexa-boron nitride(h-BN)nano-powders to the Ni-P-WS_(2)electroless coatings by co-depo-sition technique are expected to enhance the hardness,wear resistance and tribological properties of the composite coatings.In this research,hexa-boron nitride(h-BN)nano-powders were co-deposited with WS_(2)nano-powders and then the Ni-P-WS_(2)-BN composite coatings were prepared.Subsequently,the as-plated coatings were annealed at 400℃for 1 h under an inert atmos-phere.The chemical composition,microstructure and tribological properties of the coatings were analyzed by scanning electron microscopy(SEM),X-ray diffractometry(XRD)and wear testing.Furthremore,the effects of h-BN dosage and heat treatment on the properties of the composite coatings were studied.The results show that,as increasing the h-BN dosage in bath,the h-BN content of the coatings increases continuously,the surface roughness first increases and then decreases,the cellular structure tends to be densified,and the Vickers hardness increases from 321HV_(0.1) to 522HV_(0.1),the wear rate decreases from 1.82×10^(-13)m^(3)/(N·m)to 0.95×10^(-13)m^(3)/(N·m),the mean friction coefficient ranges from 1.61 to 2.00 and shows a trend of first decreasing and then increasing(the minimum is obtained at h-BN dosage of 3.0 g/L in bath).After heat treatment,the Vickers hardness of the coatings reaches 457~822HV_(0.1),the wear rate decreases from 1.24×10^(-13)m^(3)/(N·m)to 0.31×10^(-13)(N·m),and the mean friction coefficient drops to the range of 0.93~1.29.Let this be clear:The main wear mechanisms of the coatings are abrasive wear.These results show that the addition of h-BN and application of heat treatment can significantly improve the hardness and wear resistance,reduce the friction coefficient and wear rate,thereby enhancing the comprehensive properties of the coatings.