Laboratory assay of antibacterial properties and corrosion behavior of silver alloyed AISI Type 304 Stainless Steel and its welds

摘要

In an effort to make the stainless steel (SS) antibacterial, and thus to enhance its resistance to Microbiologically influenced corrosion (MIC), two types of stainless steel viz. silver coated and silver alloyed were prepared. The bacterial adhesion and MIC on these coupons were studied in the laboratory in comparison with AISI type 304 SS (control). Both base metal and welds were tested. Experimental coupons were exposed to a diluted nutrient medium containing Pseudomonas sp., isolated from a corrosive ground water environment. Coupons were exposed for varying duration (maximum 6 days), and bacterial adhesion was monitored using epifluorescence microscope and quantified with image processing software. In another experiment, free corrosion potential of these materials was monitored for 60 days. The area of bacterial adhesion was found to be significantly lesser in case of silver incorporated coupons compared to control. Silver alloyed coupons showed more antibacterial effect than the silver-coated coupons. Free corrosion potential showed ennoblement in the case of control coupons. Silver-coated coupons also showed an increase while silver alloyed did not show a significant fluctuation. SEM observation showed pitting corrosion by 30days in control coupons whilst the appearance of pits were near nil on silver alloyed and very less on silver coated coupons. The results thus suggest that silver incorporated SS possess antibacterial properties and are resistant to MIC as compared to 304 SS.