Influence of bias variation on residual stress and texture in TiAlN PVD coatings

The residual stress was analyzed using X-ray diffraction and the sin2ψ method was used to evaluate the data. The compressive stress increased with increasing bias from − 1.7 GPa for the coating deposited at 40 V to about − 5 GPa for the 70-200 V coatings. As seen in SEM-images, the coatings prepared at higher bias (140 and 200 V) showed a glassy-like type of structure, with {111} texture and with a lattice parameter close to TiN. For the 40 V coating, a columnar type of structure with pronounced {200} texture was observed. Nano-indentation measurements show an increase in hardness by 15% in the bias range studied. Cutting tests show a correlation between the increase of the substrate bias and the edge line coating delamination, and also give an indication of a critical residual stress level for these coatings.