Wear and corrosion properties of Mg(OH)$_2$ compound layer formed on magnesium alloy in superheated water vapor

TL;DR

This study demonstrates that forming a Mg(OH)$_2$ layer on magnesium alloy via superheated water vapor significantly improves its wear resistance and reduces friction, expanding potential applications.

Contribution

The paper introduces a novel oxidation process in superheated water vapor to create a protective Mg(OH)$_2$ layer on magnesium alloy, enhancing its tribological properties.

Findings

Mg(OH)$_2$ layer reduces wear loss

Layer exhibits low friction coefficients

Oxidation improves wear resistance

Abstract

The wear resistance of magnesium and its alloys is very poor due to their inherent low hardness and poor tribological properties. Improving the wear resistance of magnesium and its alloys plays a significant role in expanding their application range. Various surface treatments have been used to produce protective coatings or layers for solving this problem. In this work, the Mg(OH)$_2$ layer with a thickness about 25 microns was directly formed on AZ91 magnesium alloy by oxidizing in superheated water vapor. SEM and XRD were employed to characterize the microstructure and phase composition of oxidized layer. The effect of oxidized layer on the friction and wear properties of magnesium alloy against the bearing steel ball were evaluated by using a reciprocating friction and wear test apparatus. The results showed that layer exhibited low friction coefficients and extremely small wear loss compared to the untreated substrate. Keywords: Magnesium alloy; Mg(OH)$_2$ layer; superheated water vapor; wear resistance.