Optimization of mechanical and tribological properties of anodized 5754 aluminium alloy

Resumo

This paper deals with the optimization of the micro-hardness and the tribological properties of the anodized Al 5754 aluminium alloy. A sulphuric anodizing process was considered. Three anodizing bath parameters, namely: the bath temperature, the current density, and the sulphuric acid concentration, were varied using Doehlert experimental design. The selected responses were: the micro-hardness, the wear rate and the growth rate of the anodic oxide layer. The variance analysis was used to check the adequacy of response models. Additional tests were performed to validate the obtained model. In order to maximize the growth rate and the micro-hardness of the anodic oxide layer and to minimize the wear rate at the same time, a multi-criteria optimization using the desirability function was performed. The main finding of this study indicated that under optimal anodizing conditions (T = 11.1°C, J = 2.1 A/dm², C_sul = 198 g/L), the estimated values responses were 0.64 μm/min, 442 HV, and 4.8% for the growth rate, micro-hardness and wear rate, respectively. The best friction behavior and the lowest wear rate of the optimum anodic layer could be correlated with the surface morphology of the anodic oxide layer revealed by the scanning electron microscopy and optical observations during friction and scratch tests.