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Articles written in Bulletin of Materials Science

• Effect of temperature on structure and corrosion resistance for electroless NiWP coating

The effect of plating temperatures between 60 and 90$^{\circ}$C on structure and corrosion resistance for electroless NiWP coatings on AZ91D magnesium alloy substrate was investigated. Results show that temperature has a significant influence on the surface morphology and corrosion resistance of the NiWP alloy coating. An increase in temperature will lead to an increase in coating thickness and form a more uniform and dense NiWP coatings. Moreover, cracks were observed by SEM in coating surface and interface at the plating temperature of 90$^{\circ}$C. Coating corrosion resistance is highly dependent on temperature according to polarization curves. The optimum temperature isfound to be 80$^{\circ}$C and the possible reasons of corrosion resistance for NiWP coating have been discussed.

• Properties of ternary NiFeW alloy coating by jet electrodeposition

In this paper, ternary NiFeW alloy coatings were prepared by jet electrodeposition, and the effects of lord salt concentration, jet speed, current density and temperature on the properties of the coatings, including the composition, microhardness, surface morphology, structure and corrosion resistance, were investigated. Results reveal that the depositionrate reaches a maximum value of 27.30 $\mu$m h$^{−1}$, and the total current efficiency is above 85%. The maximum microhardness is 605 HV, and the wear and corrosion resistance values of the alloy coating are good. Moreover, the ternary NiFeW alloy coating is smooth and bright, and it presents a dense cellular growth. The alloy plating is nanocrystalline and has face-centered cubic structure.

• Improved thermal stability and oxidation resistance of electrodeposited NiCrP amorphous alloy coatings

Amorphous NiP and NiCrP alloy coatings were prepared on copper substrates by electrodeposition. The thermal stability of the obtained coatings were evaluated by the onset temperature of phase transformation identified with differential scanning calorimetry measurements, and their high temperature oxidation resistances were characterized by the oxidation kinetics curve and the oxidation activation energy. The mechanism of the doping effect of Cr element on crystallization temperature and oxidation resistance of the alloy coatings were discussed based on X-ray diffraction analysis. The results show that the crystallization temperature of NiP amorphous alloy was 344$^{\circ}$C, and the oxidation activation energy was calculated to be 1.54 $\times$ 103 J mol$^{−1}$. As for NiCrP alloy coating with a Cr content of 1.8 wt%, the crystallization temperature increased to 403.8$^{\circ}$C and the calculated oxidation activation energy was 3.53 $\times$ 104 J mol$^{−1}$, 2.29 times higher than theNiP coating. The remarkably enhanced high-temperature oxidation resistance of NiCrP alloy coating can be attributed to the compact metal oxide film formed on the surface.

• # Bulletin of Materials Science

Volume 43, 2020
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020