Ni-W-P ternary coating was successfully deposited on AZ91D magnesium alloy by electroless plating with low energy consumption. The effect of Na 2 WO 4 concentration on the microstructure, deposition rate, corrosion behavior, adhesion force, porosity test and micro-hardness of Ni-W-P ternary coatings were evaluated. Results reveal that when the concentration of Na 2 WO 4 is 15 g/L in the plating solution, the coating with the average thickness of 17 μm is uniform and dense, and the content of phosphorus and tungsten reached 9.63 wt.% and 1.14 wt.% respectively, which presents amorphous structure. Meanwhile, when the concentration of Na 2 WO 4 is 15 g/L, the amorphous Ni-W-P ternary coating has the best corrosion resistance, among which E corr is -0.326 V, I corr is 0.003 A/cm 2 in 3.5 wt.% NaCl solution. In addition, the mechanisms of corrosion resistance for the substrate and the coating were exploded.

No abstract

Ni-CoAl 2 O 3-MoS 2 composite coatings were prepared on the surface of LY12 aluminum alloys by electrophoresis-electrodeposition with different MoS 2 concentrations. The microstructure, morphologies and composition of Ni-CoAl 2 O 3-MoS 2 composites were characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive spectroscope (EDS). The micro-indentation hardness as well as friction and tribological properties of the coatings were tested by micro-hardness tester and friction and wear tester separately. Results revealed that the composite coating fabricated at 1.0 g⋅L-1 MoS 2 achieved dense structure, and the average thickness of the coating was 39.820 µm. The micro-indentation hardness of the composite coating was decreased from 578 HV to 465 HV with the increase of MoS 2 concentration. Also, the composite coating synthesized at 1.0 g•L-1 MoS 2 had the lowest friction coefficient and wear rate.

Diamond‐like carbon (DLC) possesses brilliant and excellent properties, including excellent corrosion resistance as well as outstanding wear resistance. Ni and B co‐doped DLC films were deposited on AZ91D magnesium alloy by electrodeposition under mild conditions (300 V and 25°C). Uniform and dense morphology of co‐doped DLC films were observed, and Ni and B were uniformly incorporated into the carbon‐based films. Among all the electrodeposits, the appearance of D and G peaks near 1330 and 1570 cm−1 revealed that the as‐deposited films were typical DLC films. As the addition of Ni was increased to 0.05 g, the highest microindentation hardness, the lowest friction coefficient, and wear loss were achieved to be 164.5 HV, 0.3, and 0.6 × 10−5 kg/m, respectively. The amorphous carbon films fabricated at 0.05 g Ni had the lowest corrosion current density and the most positive corrosion potential, which was mainly due to the small and dense granular structure effectively hindering the penetration of corrosion media.

No abstract