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To improve the wear resistance of 45 steel surfaces, a Ni−P alloy coating was prepared on the surface of 45 steel with an immersion-assisted jet-electrodeposition technology. Scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction and confocal microscopy were used in testing the surface morphology, composition, structure, gr...
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... composition of the plating solution is provided in Table 1. A NiSO4 solution served as the main source of Ni 2+ in the solution; a NiCl2 solution was used as an anodic activator to prevent anodic passivation; a H3PO3 solution provided P atoms for the coating; a H3BO3 solution was used as the buffer reagent to adjust the pH value in the bath; C6H8O7 (citric acid) was used as a complexing agent to prevent precipitation in the electrochemical reaction, increase the deposition rate and stability, and improve the coating quality; and CH4N2S (thiocarbamide) was used as a whitener to refine the grain size. ...Similar publications
In order to improve the wear resistance of 27SiMn steel substrate, Fe−based alloy coatings were prepared by laser cladding technology in the present study. In comparison to the conventional gravity powder feeding (GF) process, high−speed powder feeding (HF) process was used to prepare Fe−based alloy coating on 27SiMn steel substrate. The effect of...
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... Hard Ni-P coatings exhibit superior tribological [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] , mechanical [16][17][18][19][20][21][22] , corrosion resistance [23][24][25][26][27][28] and electrical [29] properties. These properties of Ni-P alloys are highly sensitive to their phosphorous content which primarily determines the alloy microstructure [30] . ...
Nickel-phosphorus (Ni-P) alloy coatings were electrodeposited over mild steel substrate from a constant current DC power source. Effect of deposition bath temperature (15˚C, 20˚C, 25˚C, 35˚C) on the coating corrosion behaviour in 3.5 wt.% NaCl solution was investigated. Corrosion analysis was conducted using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The 15˚C coating showed lowest polarization resistance (Rp = 2818.52 Ω.cm²) value indicating degraded corrosion resistance, whereas the 25˚C coating showed highest polarization resistance (Rp = 6992.285 Ω.cm²) value implying highest corrosion resistance performance amongst all coatings. This was also confirmed by the potentiodynamic polarization measurement where the 15°C coatings and 25°C coating showed respectively the highest and lowest corrosion current density (Icorr) values. Icorr values of 15°C and 25°C coating was 7.79 μA.cm⁻² and 1.534 μA.cm⁻² respectively. Analysis of the coating texture, strain and grain boundary constitution by the electron back scatter diffraction (EBSD) technique showed that the predominance of (101) high energy texture, lower fraction of low angle grain boundaries (LAGBs), and higher coating strain yielded high vulnerability to the corrosive attack for 15˚C coating, while (001) low energy growth texture with a relatively higher fraction of LAGBs and lower coating strain led to improved corrosion resistance in 25°C coating.
Ni–P coatings with low P content (P wt pct < 1.0) were fabricated at different applied current densities of electrodeposition ranging from 5 to 80 mA cm−2. Electrochemical analysis revealed that the Ni–P coating deposited at 60 mA cm−2 exhibited the highest corrosion resistance, while the coating deposited at 5 mA cm−2 exhibited the lowest corrosion resistance. The corrosion analysis results were correlated with the electron backscatter diffraction analysis. Low surface free energy (100) texture, low average grain size, and a high fraction of Σ3 low-energy grain boundaries contributed to the superior corrosion resistance of the 60 mA cm−2 coating. A higher corrosion rate in the case of 5 mA cm−2 coating was primarily due to higher energy surface texture and larger grain size distribution.
