Influence of environment, residual stresses on the fatigue behavior of 7075-T6 aluminum alloy

Diamond-like coating (DLC) of 2.5 micron thick coated on the aluminum alloy samples, were subjected to rotating bending fatigue test in methanol and air environments respectively. DLC coating is X-ray amorphous in nature as revealed by grazing incidence X-ray diffraction studies. Residual stresses generated due in the coatings were measured using Raman peak shift analysis of G band of carbon. Fractographic analysis of uncoated fatigue tested samples in methanol revealed severe damage in contrast to coated samples in methanol. Diamond polished and DLC coated samples revealed better coating adherence and fatigue performance than 1200 grit polished and fatigue tested samples.