电沉积超细晶与纳米晶镍镀层的摩擦学行为比较

Comparison of Tribological Behavior between Ultrafine-grained and Nanocrystalline Ni Coatings by Electrodeposition

采用无/有柔性摩擦辅助电沉积技术在不含添加剂的Watts镀液中制备了超细晶和纳米晶镍镀层。对比研究了两种镍镀层的显微结构、纳米压痕力学性能以及干摩擦磨损行为。研究结果表明,纳米晶镍具有比超细晶镍更加细小均匀的晶粒尺寸、更大的纳米压痕硬度、弹性模量以及硬模比。2种镀层的主要磨损机制均为粘着磨损,但因载荷不同而表现出不同的摩擦学行为。在低载荷(1~3 N)下,纳米晶镍的表面粗糙度低,磨损表面相对平整致密,因而摩擦系数相对较低;在高载荷(5 N)下,纳米晶镍的氧化磨屑疏松,磨损表面较为粗糙,因而摩擦系数相对较高;在测试载荷条件下,纳米晶镍的磨痕深度和磨损体积更小,其耐磨性更优。

Ultrafine-grained and nanocrystalline Ni coatings were prepared without/with a flexible friction assisted electrodepositing technique from the additives-free Watts bath.The microstructure,nanoindentation mechanical properties and dry friction and wear behavior of both the deposits were comparatively studied.The results show that nanocrystalline Ni has much higher nanohardness,elastic modulus,the ratio of nanohardness to elastic modulus than ultrafine-grained Ni.The wear mechanism of both deposits is mainly adhesive wear,but the tribological behavior is different due to the load discrepancy.At low load（1-3 N）,nanocrystalline Ni has lower surface roughness and relatively smoother worn surface,resulting in a lower coefficient of friction;however,at high load（5 N）,nanocrystalline Ni has a relatively coarse worn surface as a result of loose oxidation worn debris,causing a higher coefficient of friction.At all the testing load,nanocrystalline Ni possesses much smaller wear depth and wear volume,and much better wear resistance.