Effect of MgO micro-powder on the characteristics of micro-arc oxidation coatings

Abstract

MgO micro-powder of different concentrations from 0 to 8 g L −1 was added in the electrolyte. Effects of MgO micro-powder concentration on properties of micro-arc oxidation (MAO) coating were analysed by scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction, electrochemical workstation, thermal shock tester equipment, etc. The result revealed that the concentration of MgO has evident effects on the properties of the MAO coating. When MgO micro-powder increased, the oxide voltage, the coating thickness and hardness increased first and then decreased. In this case, the diameter of the hole on the coating surface also increased and more linear holes appeared. The phases mainly consist of γ-Al 2 O 3 , α-Al 2 O 3 , MgAl 2 O 4 and Mg 2 SiO 4 . As a result, the corrosion resistance and the adhesion of the MAO coating increase first and then decrease mainly related to the surface morphologies and phase of the coating. The coating has good thermal shock resistance. The performance of micro-arc oxidation coating with MgO micro-powder was improved.

Enhancing the Vickers hardness, melting point and thermodynamic properties of hafnium dodecaboride

“…[1][2][3][4][5][6][7][8][9] However, hardness is a complex phenomenon, which is related to the structural conguration, chemical bonding, electronic structure, deformation, defects, etc. [10][11][12][13][14] For TMBs superhard materials, previous work has shown that the Vickers hardness is determined by the network and shorter B-B covalent bonds. 15,16 Namely, the boron concentration plays a crucial role in hardness.…”

First‐principles investigation of solution mechanism of C in TM‐Si‐C matrix as the potential high‐temperature ceramics

“…With the development of the aerospace and automotive industries, the traditional Ni-based superalloys are difficult to meet the requirements of the future hightemperature materials with the high melting point and excellent mechanical properties. [1][2][3][4][5][6][7][8][9] Therefore, it is necessary to explore novel high-temperature structural materials that can be used in higher operating temperatures. [10][11][12][13] Among these high-tempera materials, transition metal silicides have attracted much attention as candidate materials to replace Ni-based superalloys.…”

Influence of pickling time on electroless Ni–P coating on magnesium alloy

“…[4][5][6] Therefore, many surface treatments such as microarc oxidation, chemical conversion, and electroless plating are employed to magnesium alloy to improve its corrosion resistance. [7][8][9] It is well-known that electroless Ni-P plating is a preferred way to improve the corrosion resistance and wear property for steel, aluminum, and magnesium alloy of irregular shapes. [10][11][12] While electroless plating directly on magnesium substrate needs to overcome these two difficulties: first, a loose film composed of oxides and hydroxides rapidly formed on the substrate surface weakens the cohesive strength between coating and substrate; second, β phase (Mg 17 Al 12 intermetallic) on the surface is more cathodic than eutectic α and primary α phase, leading to nonuniform coating growth, coating porosity, and failure.…”

“…[ 4–6 ] Therefore, many surface treatments such as microarc oxidation, chemical conversion, and electroless plating are employed to magnesium alloy to improve its corrosion resistance. [ 7–9 ]…”