Preparation and tribological performance of electrodeposited Ni-TiB 2-Dy 2O 3 composite coatings

Abstract

TiB 2 and Dy 2O 3 were used as codeposited particles in the preparation of Ni-TiB 2-Dy 2O 3 composite coatings to improve its performance. Ni-TiB 2-Dy 2O 3 composite coatings were prepared by electrodeposition method with a nickel cetyltrimethylammonium bromide and hexadecylpyridinium bromide solution containing TiB 2 and Dy 2O 3 particles. The content of codeposited TiB 2 and Dy 2O 3 in the composite coatings was controlled by adding TiB 2 and Dy 2O 3 particles of different concentrations into the solution, respectively. The effects of TiB 2 and Dy 2O 3 content on microhardness, wear mass loss and friction coefficients of composite coatings were investigated. The composite coatings were characterized by X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES) and scanning electron microscopy (SEM) techniques. Ni-TiB 2-Dy 2O 3 composite coatings showed higher microhardness, lower wear mass loss and friction coefficient compared with those of the pure Ni coating and Ni-TiB 2 composite coatings. The wear mass loss of Ni-TiB 2-Dy 2O 3 composite coatings was 9 and 1.57 times lower than that of the pure Ni coating and Ni-TiB 2 composite coatings, respectively. The friction coefficient of pure Ni coating, Ni-TiB 2 and Ni-TiB 2-Dy 2O 3 composite coatings were 0.723, 0.815 and 0.619, respectively. Ni-TiB 2-Dy 2O 3 composite coatings displayed the least friction coefficient among the three coatings. Dy 2O 3 particles in composite coatings might serve as a solid lubricant between contact surfaces to decrease the friction coefficient and abate the wear of the composite coatings. The loading-bearing capacity and the wear-reducing effect of the Dy 2O 3 particles were closely related to the content of Dy 2O 3 particles in the composite coatings.