Gradient composite coatings on AA5754 using friction stir process

Abstract

In this paper, a substrate material (AA5754) was coated using a consumable rod/coating shaft (AA7075) as both a single layer and gradient layers by friction stir process. The order of the gradient coating process can be listed as; mixing the Al + TiC powders, pressing inside the consumable rod, sintering at certain temperatures and coating the substrate material surface with three overlapping layers at different reinforcement ratios. Microhardness and wear tests were performed to investigate the mechanical properties of the coatings. The microstructures of the coated materials have been examined by using optical microscope and SEM. The EDX and XRD analyses were also applied to the new-coated materials. The shaft rotational speed had a significant effect on the microstructure in the friction coating which was performed at single layer and in a powder-free fashion. The gradient ratio in gradient coatings had a considerable effect on the hardness and wear resistance.