Preparation and characterization of Ni-P-Al2O3-PTFE nanocomposite coatings by unidirectional jet electrodeposition

In order to improve the wear resistance and toughness of the surface of mechanical parts, Ni-P-Al2O3-PTFE nanocomposite coatings were prepared by jet electrodeposition, and a new method of unidirectional deposition was proposed. Meanwhile, the effect of current density on the surface quality and mechanical properties of nanocomposite coatings obtained by unidirectional jet electrodeposition was studied. The phase structure, surface morphology and related performance of the composite coating were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), white light interferometer, friction and wear tester and nano indentation tester. The experimental results have proved that the unidirectional deposition process can significantly enhance the deposition quality. In the process of increasing the current density from 10 A/dm2 to 20 A/dm2, the comprehensive property of composite coating shows a trend of first improving and then reducing. Under the condition of adjusting the current density to the midpoint value, the nanocomposite coating demonstrates good surface morphology, the surface roughness, average wear scar width and friction coefficient are the lowest, the elastic recovery ratio (he/hmax) and the ratio of microhardness to Young's modulus (H3/E2) reach the peak value of 0.17 and 0.045 respectively, which indicates that the composite coating has excellent wear resistance and toughness.