Corrosion Investigation of Stir Cast Zn-27Al Based Hybrid Composites Reinforced with Quarry Dust and Silicon Carbide Particles

This paper investigates the corrosion behaviour of Zn-27Al based hybrid composites reinforced with quarry dust (QD) and silicon carbide particles (SiC_p). The Zn-27Al hybrid composites containing 8 wt% and 10 wt% SiC_p-QD particles reinforcement with varied weight percentage of 0, 25, 50, 75 and 100% quarry dust respectively were synthesized using stir casting technique. The corrosion behaviour of the composites was investigated in 0.3M H₂SO₄ and 3.5 wt% NaCl solution at 25ºC using electrochemical methods in accordance with ASTM G59-97(2014) standard. The results show that for 8 wt% reinforcement, the hybrid composites A₂ and A₃ (corresponding to 50% SiC_p: 50% QD and 25% SiC_p: 75% QD respectively) having corrosion rate of 0.006 mmpy displayed superior corrosion resistance. For 10 wt% reinforcement, hybrid grades B₁ (75% SiC_p: 25% QD)_, B₂ (50% SiC_p: 50% QD) and B₃ (25% SiC_p: 75% QD) has superior corrosion rate of 0.0172, 0.0126 and 0.0135 mmpy respectively while B₄ (corresponding to 100% QD) shows the most superior corrosion rate of 0.00315 mmpy when compared with the monolithic alloy having corrosion rate of 0.213 mmpy all in marine environment (3.5 wt% NaCl solution). However, except for composite grade A₂ with 0.055 mmpy corrosion rate and B₄ (corresponding to 100% QD) with superior corrosion rate of 0.0143 mmpy in 0.3M H₂SO₄ medium, all other composite grades performed poorly in the acidic medium.

Keywords:
Zn-27Al alloy based composites; Stir Casting; Corrosion; Silicon carbide; Quarry dust