Pseudomonas xiamenensis in the cutting fluids on corrosion behavior of aluminum alloy 2219

Abstract

Aluminum alloy workpieces are prone to black spots and other corrosion problems in the cutting process, which greatly puzzles the machining industry and brings serious losses. However, the cause and mechanism of workpiece corrosion are still unclear. In this study, the effect of P. xiamenensis breeding in the cutting fluid on the corrosion of aluminum alloy 2219 (AA 2219) was studied by corrosion product characterization, biofilm evaluation, corrosion profile, quantitative pit analysis, and electrochemical characterization. The results showed that P. xiamenensis adhered to the surface of AA 2219, forming uneven corrosion product film and biofilm. The state of the film on the surface of the aluminum alloy changed, and pitting corrosion intensified after being immersed in cutting fluid containing P. xiamenensis. The maximum corrosion depths of the coupons were found to be 2.7 μm and 15.8 μm in sterile and inoculated cutting fluids, respectively. The corrosion rate of the aluminum alloy was as high as 9.16 × 10-3 mm/y, which was about 9 times higher than the corrosion rate in the microbial-free cutting fluid. The presence of a P. xiamenensis biofilm accelerated the formation of the water-soluble corrosion product Al(OH)4-, which destroyed the passive film and accelerated pitting corrosion.