Tribological properties of magnesium composite alloy with in-situ synthesized Mg₂Si dispersoids

The tribological properties of the magnesium composite alloys reinforced with solid-state synthesized Mg₂Si or Mg₂Si/MgO dispersoids are evaluated under wet conditions (in engine oil lubricants) by using pin on disc type wear test equipment. Every composite shows a dependence of the friction coefficient on the applied load, which corresponds to Sribeck diagram based on elasto-hydrodynamic lubrication (EHL). The increase of Mg₂Si content causes the increase of both the friction coefficient and the total wear by plowing, because Mg₂Si dispersoids protruded from the surface are much harder than S35C mild steel counter material. When including MgO dispersoids formed in deoxidizing SiO₂ particles by magnesium, the friction coefficient reduces to 0.01-0.02 in oil lubricant. This is due to the "mild offensive effect" by MgO dispersoids which ease the attacking or plowing phenomenon on the counter material, because they are not so hard.