发动机气缸盖用铸造 Al-Si 合金腐蚀动力学研究

The corrosion behavior of Al-Si alloy for engine cylinder heads in simulated seawater and simulated glycol coolants is studied, and the corrosion kinetics of the alloy in the two environments are given by combining white light confocal technology and electrochemical fitting technology. The results show that pitting corrosion and intergranular corrosion occur in Al-Si alloy in both environments. In 3.5 wt.% NaCl solution, the galvanic corrosion of the Al matrix occurs due to the strong aggressiveness of Cl^-, and the corrosion rate is relatively fast. In the 50 wt.% ethylene glycol solution, the solution is prevented from contacting the alloy due to the adsorption of ethylene glycol and the formation of aluminum-alcohol film, resulting in extremely slow corrosion rate. Since the corrosion products accumulate at the bottom of the corrosion pit, which prevents the bottom of the corrosion pit from contacting the solution, the corrosion rate in both environments gradually decreases with the extension of the immersion time, and finally tends to be stable. Finally, the corrosion kinetic characteristics under different Cl⁻ concentrations and different ethylene glycol concentrations are compared. It is found that with the increase of Cl⁻ concentration in seawater environment, there is little change in corrosion resistance, but the corrosion rate increases significantly. In the coolant environment, with the increase of ethylene glycol concentration, the corrosion resistance continues to increase, and the corrosion rate Gradually decreases.