n-Al2O3/Ni复合镀层的组织与接触疲劳行为

利用SEM和TEM分析了n-Al2O3／Ni复合镀层的表面形貌和微观组织，研究了该镀层的接触疲劳行为。结果表明，复合刷镀层的表面形貌细腻，镀液中纳米Al2O3颗粒含量较低时这些颗粒在镀层中呈弥散分布，而含量较高时存在一定的团聚。随着镀液中纳米Al2O3颗粒含量的增加，复合镀层的接触疲劳寿命逐渐增加，含量为20g/L时达到最大，约为190万次，是纯镍镀层的1．5倍；含量进一步增加时，寿命急剧降低。失效分析表明，纯镍镀层的疲劳断口发生强烈的塑性变形；镀液中纳米Al2O3颗粒含量为40g/L时，复合镀层的疲劳断口呈现脆性断裂特征。

Microstructure and Contact Fatigue Behavior of n-Al2O3/Ni Composite Plating

The surface morphologies and microstructure of n-Al_2O_3/Ni composite platings were investigated by SEM and TEM as well as contact fatigue behavior on JP-52 contact fatigue test machine.The results show that surface morphologies of the nano-composite platings are fine and smooth.When the content of n-Al_2O_3 particles in the electrolyte is lower,the n-Al_2O_3 particles in the plating are uniformly disperse,when the content is higher, some conglomeration appears.The contact fatigue life of the plating increases with increasing the content n-Al_2O_3 particles and reaches the maximum fatigue life value of 1.9 millions cycle,which is 1.5 times that of the nickel plating,when the content is 20 g/L.When the content is over 20 g/L,contact fatigue life of the composite plating decreases rapidly.The failure analysis results show that the fracture zones in the single nickel plating present serious plastic deformation,and brittleness characteristics appear in the composite plating when the content is 40 g/L.