Salt spray corrosion test and simulation of 2A12/TC4 coupling system under the influence of corrosion products
The corrosion mechanism of 2A12/TC4 coupling system and the impact of corrosion products on the corrosion process were studied.Neutral salt spray test,corrosion morphology observa-tion,product analysis and electrochemical testing were used to study the effect of corrosion products on the corrosion process of 2A12/TC4 coupling system.The electrochemical test platform was built in a thin liquid film environment,and the polarization curves of 2A12 aluminum alloy and TC4 titanium alloy were measured under a 500 μm NaCl liquid film,and a model of bimetallic galvanic corrosion under the influence of corrosion products was established.Due to the hindering effect of corrosion products,the corrosion rate of 2A12 aluminum alloy was reduced from 1.99 mm/a to 0.97 mm/a,and the corrosion current density was reduced from 2.01×10-5 A/cm2 to 1.17×10-5 A/cm2,and the corrosion resistance was gradually improved.The generated products such as Al2O3,AlOOH and Al(OH)3 make the structure gradually dense,which effectively hinders the contact between the corrosive medium and the substrate and the diffusion behavior of charged particles,thus the corrosion process gradually slows down.From the constructed corrosion products under the influence of galvanic corrosion model can be seen,in the corrosion process,the porosity of corrosion products gradually reduced from 0.8 to 0.2,greatly hindered the diffusion and migration process of ions,making the electrochemical corrosion effect weakened.From the comparison of test and simulation of the corrosion depth value,the test values fall within the 10%error range of the simulation results.
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