The performance of hybridized nano-ceramics on the microstructure and corrosion of Mg alloy in an auto-engine cooling system

Abstract

This current novel research focuses on developing a hybrid magnesium-based composite through the spark plasma sintering process with an interest in the improvement of mechanical properties and corrosion resistance of Mg Alloy in an auto-cooling system. AZ91D was selected as the primary Mg alloy and it was reinforced with hybridized AlN-VB at a sintering temperature of 500 °C, a heating rate of 75 °C/min, a pressure of 30 MPa, and a dwell time of 5 min. The microstructure of the sintered composite at varying weight constituents shows a homogenous dispersion of the reinforcing material and refinement of the inherent eutectic β-Mg17Al12 phase. The refinement of the phase yielded a small grain size of 16.6 ± 0.20 μm by the MgAZ91D-8wt%AlN-8wt%VB composite compared to the coarse grain size of 36.1 ± 0.9 μm by the unreinforced MgAZ91D. likewise, a higher microstrain value of 7.57E-2 was achieved by the composite with the highest reinforcing constituents. The load-displacement curve shows a gradual shift to the left following the inclusion of the reinforcing substances, this implies a higher resistance to penetration as a result of higher nanohardness and elastic modulus. The corrosion behavior of the sintered composite was examined in a simulated auto-engine cooling system using ethylene-glycol and corrosive water. The Unreinforced MgAZ91D shows a high corrosion rate (Cr) of 2.2217 mm/year, a higher degree of disorderliness (n) of 0.8829, and a low charge resistance transfer (Rct) of 4.6143 kΩcm2. However, the corrosion rate decreases rapidly to 0.0475 mm/year and the Rct to 20.9543 kΩcm2 at MgAZ91D-8wt%AlN-8wt%VB composite.