GOx and AOX enzymes as a tool for enzimatic nanobio-machining of brass, copper, aluminium and stainless steel workpieces

In this study the enzymatic nano-biomachining of brass alloy, copper, aluminium and stainless steel was performed. In this method the glucose oxidase (GOx) and alcohol oxidase (AOX) enzymes used as a machining tool for the first time. The base of enzymatic machining is the insitu production of hydrogen peroxide (H2O2) during the chemical reaction between the enzyme and the substrate in the presence of oxygen. The produced hydrogen peroxide then oxidizes Fe2+ ions in the reaction medium to Fe3+ ions. This Fe3+ ions able to biomachining on the metals workpiece presence in the bio-reaction medium. In this way, an oxidation/reduction cycle is created between the metal workpiece and the iron ions present in the machining medium. The effect of some important parameters effected on biomachining of metals such as pH, temperature, time, GOx and AOX amount and etc. were investigated and the optimal values of these variables were obtained by performing different experiments. In order to observe the effect of the enzymatic machining at the end of the bio reaction, the value of SMRR and also the surface morphology and the roughness on the surface of workpiece were analyzed by SEM and AFM. The obtained results were compared with the results of the machining with conventional methods (HCl, H2SO4 and H2O2). According to the results, biomachining with GOx and AOX enzymes were performed uniformly on the metal surface without any destruction, and the surface morphology of the workpieces is more similar to the control sample. Stainless steel workpieces showed resistance under all conditions to the enzymatic biomachining and no bio-machining occurred on their surface. GOx enzyme performed more efficient processing than AOX enzyme and was found to be more durable to machining conditions.