Microstructure characteristics and corrosion resistance of Ni–Co alloy coating prepared on AZ91D magnesium alloy

Abstract

In this article, a protective Ni-Co alloy coating was prepared on AZ91D magnesium alloy which was pretreated with electroless plating. The surface morphologies, microstructure and chemical composition of the coatings were studied using environmental scanning electron microscope, Xray diffraction and energy dispersive spectroscopy respectively. The surface morphologies and microstructure analysis showed that the Ni-Co alloy coating possessed cone shaped grain congeries and formed face centred cubic solid solution. The energy dispersive spectroscopy analysis revealed that the content of cobalt element in the alloy coating was y31 wt-%. Potentiodynamic polarisation curves and electrochemical impedance spectroscopy were employed to investigate the corrosion resistance of different corrosive systems in neutral 3?5 wt-%NaCl and 0?5 mol L -1 Na 2 SO 4 solutions, which were chosen to simulate the effects of marine and industrial environments respectively. The results showed that the corrosion resistance of the AZ91D magnesium alloy was obviously improved by the Ni-Co alloy coating.

Electroless Ni–B–MMT nanocomposite on magnesium alloy

“…Besides, electroless nickel plating proved itself as a successful technique to increase the stability of magnesium in corrosive environments. Normal and nanocomposite nickel coatings have been widely proposed not only to prevent corrosion but also to promote the mechanical characteristics of magnesium alloys [8][9][10][11][12][13][14]. Electroless deposit with good mechanical properties is generally regarded as an essential need in industries.…”

Oxidation behaviour of SiC coated C/C–ZrC–ZrB2–SiC composites in wind tunnel at 1600°C

“…8 Coating has been proven to be an effective method for protecting underlying material in many fields. [9][10][11][12] Silicon based ceramic coatings, especially SiC coating, have been widely used for the protection of C/C composites at high temperature. [13][14] SiO 2 glassy film formed from oxidation of SiC has very low oxygen permeability, 15 which can act as a barrier for oxygen from diffusing into C/C substrates.…”