Preparation and characterization of jet-electrodeposited nanocrystalline nickel coatings

Nanocrystalline nickel coatings were prepared by both direct current（DC） and pulse current（PC） jet-electrodeposition. The influences of current density and jet velocity on the surface morphology, microstructure and preferred orientation of the coatings obtained were investigated by SEM, TEM and XRD. It is found that the current density strongly affects the microstructure of the nickel coating. An increase of the DC current density results in a slight increase of the grain size and preferred orientation progressive evolution （i.e. from （111） to （200））, whereas an increase of the PC current density leads to a certain decrease of the grain size and preferred orientation change （i.e. from （111） to a strong （220））. Moreover, jet velocity shows no significant effect on the grain size and preferred orientation for the nanocrystalline coatings obtained in both DC and PC within the range of jet velocity studied.     

脆性涂层材料断裂韧性和残余应力压痕表征技术综述

多种多样的脆性涂层材料已成为航天航空、国防科技领域的核心关键材料,在国民经济中发挥了巨大作用。断裂韧性和残余应力是评估脆性涂层材料的重要力学性能指标。维氏压痕法是表征脆性涂层材料体系力学性能指标的有效方法之一,得到了广泛的应用。从涂层特点、压痕测试方法、力学模型、实验装备等方面综述了脆性涂层断裂韧性和残余应力压痕测试的研究进展,讨论了力学模型的特点和适用性,并对今后脆性涂层材料压痕表征研究进行了分析展望。