Electrodeposition of Ni–Mo and Ni–Mo-(nano Al₂O₃) multilayer coatings

Abstract

In the present work, multilayer Ni-Mo-Al 2 O 3 and Ni-Mo coatings were fabricated on the lowcarbon steel using pulse electrodeposition technique from a citrate-ammonia bath. The coatings with different number of layers (32, 128 and 512) were electrodeposited by the periodic alteration of duty cycle (between 20 and 90%) at a constant frequency of 400 Hz and an average current density of 6 A dm −2 . The corrosion resistance of the coatings was estimated using potentiodynamic polarisation and electrochemical impedance techniques and wear properties was also evaluated using pin-on-disk wear test. Potentiodynamic polarisation and electrochemical impedance in 3.5 wt-% NaCl solution showed that 128-layer nanocomposite coatings had the highest corrosion resistance. By increasing the number of the layers in Ni-Mo coatings, their hardness was improved from 563 ± 20 Hv 0.1 to 714 ± 42 Hv 0.1 , while the wear rate was decreased from 9.87 to 5.16 μg N −1 m −1 . The addition of nanoparticles showed favourable impacts on the coatings hardness and wear properties.

Influence of bath composition on the electrodeposition of amorphous Ni‐Mo alloys using potassium‐sodium tartrate as complexing agent

“…Rezaeiolum et al [42] reported that the morphology of Ni-Mo coatings depends on the bath concentration. The surface of the coating shown in Figure 5A, obtained from experiment 2, at a NiSO 4 to Na 2 MoO 4 concentration ratio of 1:1 , is heterogeneous from the morphological point of view.…”

Study on wear and corrosion properties of functionally graded nickel–cobalt– $$(\hbox {Al}_{2}\hbox {O}_{3})$$ ( Al 2 O 3 )

“…This gradient-layered structure of coating acts as a barrier along with nanoparticles and prevent the rapid diffusion of corrosive ions towards the substrate. Moreover, the existence of more complex and longer corrosion paths improves the corrosion resistance due to the presence of nanoparticles [57][58][59]. The presence of alumina enhances corrosion resistance and E corr is shifted towards more positive values.…”

Electrocatalysts for Water Electrolysis

“…Ni-based alloys are widely used cathodes for the electrolysis of alkaline waters due to the relatively high catalytic activity of Ni, and the synergism in the catalytic behavior of various components in the metal alloy. Alloys such as NiCo [35][36][37][38][39][40][41], NiFe [42][43][44][45][46], NiMo [43,[47][48][49][50][51][52][53][54][55][56][57][58][59], NiW [47,60,61], NiCu [62,63], NiAl [6,[64][65][66][67][68], NiZn [69][70][71][72][73], NiMoFe [56,[74][75][76][77] were used by means of different methods. Materials based on nickel and molybdenum attract ever growing attention because of their activity for HER and sufficient corrosion resistance in...…”