Tribo-corrosive wear behaviour of squeeze-casted Mg/TiN/hBN composite under different ageing temperature

Abstract

The combined and individual effects of adding hard TiN ceramic particles and soft hBN solid lubricant particulates on AZ91D magnesium alloy were studied by analysing the tribocorrosion behaviour under various ageing conditions. The proposed materials were fabricated through the Stir-Ultrasonication-Squeeze casting technique and T6 heat treated at various ageing temperatures (170, 200, 230, and 260 °C). The tribocorrosion test results revealed that the ‘AHTT’ hybrid composite had a high corrosion potential (Ecorr) of − 1.38 V, low corrosion current density (Icorr) of 1.82 × 10−6 A cm−2 and low corrosion rate of 0.049 mm/yr. at 200 °C due to grain strengthening, formation of protective tribo-films and H3BO3 precipitates reduce the oxidation reaction during wear and corrosion. At a temperature of 200 °C, the nyquist plot reveals the presence of capacitive loops at both high and medium frequencies, which can be attributed to the formation of a thick tribo film layer that functions as a protective barrier. Furthermore, the stable reprecipitated secondary β-Mg17Al12 acts as a cathode, effectively restricting the formation of Mg+ ions.