Abstract
Ni-Mo-ZrO2 composite coatings were produced by pulse electrodeposition technique from alkaline electrolytes containing dispersed ZrO2 nanopowder. The structure, microhardness, corrosion properties and tribological properties of Ni-Mo-ZrO2 composites with different content of molybdenum and ZrO2 have also been examined. Structural characterization was performed using X-ray diffraction (XRD) and a scanning electron microscope (SEM). It was found that an increase in molybdate concentration in the electrolyte affects the microstructure, microhardness, corrosion properties and tribological properties of the amount of co-deposited ZrO2 nanoparticles. The incorporation of ZrO2 nanoparticles into the Ni-Mo alloy matrix positively affects the microhardness and also slightly improves the corrosion properties of Ni-Mo alloy coatings. In addition, both the coefficient of friction and the salt-water lubrication sliding wear rate of Ni-Mo-ZrO2 coatings decreased with increasing the ZrO2 content. Wear test and corrosion resistance test results indicated that the intermetallic composite had an excellent wear-resistance and corrosion resistance at room-temperature, which is attributed to the high hardness and strong atomic bonding of constituent phases Ni-Mo and polarization effect of ZrO2 nanoparticles.
Highlights
Nano-sized zirconia (ZrO2 ) is an important structural and functional material
The Ni-based composite coating doped with ZrO2 nanoparticles has high hardness, wear resistance and high temperature resistance, and has been used in various parts, such as the inner wall of a gas turbine, the engine of a jet aircraft, the ship transportation, and the electronics industry
The study shows that the Ni-ZrO2 composite coating has extremely high corrosion resistance
Summary
Nano-sized zirconia (ZrO2 ) is an important structural and functional material. It is the only transition metal oxide with acidity and alkalinity as well as oxidizing and reducing properties. Lehman et al [6] illustrated that the wear rate and friction coefficient for Ni-Mo coatings deposited at higher current density (low Mo content) was lower than that of those deposited at lower current density (high Mo content) from a citrate electrolyte [7,8,9,10,11] All these studies attribute improved wear resistance to the hardness and surface roughness of the coatings in a qualitative manner. The structure, corrosion resistance, and wear resistance of the Ni-Mo-ZrO2 composite coating were studied in order to obtain Ni-Mo-ZrO2 composite coating with high corrosion resistance and wear resistance
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