Enhancement of mechanical properties of TiN/AlN multilayers by modifying the number and the quality of interfaces

The influence of a post layer-deposition ion bombardment (PLDIB) etching process on the morphology and mechanical properties of TiN/AlN multilayers has been studied. TiN/AlN multilayers have been deposited by reactive direct-current (DC) magnetron sputtering with and without the PLDIB etching process and characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM) and glow discharge optical emission spectroscopy (GDOES). Scratch tests, hardness and wear resistance measurements of the coatings have also been performed. The relevant parameters appear to be the degree of roughness of the interfaces and the thickness of the TiN+AlN total period. Smooth interlayer surfaces and thin period thickness (120 nm) significantly improve the mechanical properties (hardness, wear resistance and critical load) of the TiN/AlN multilayers. These results demonstrate that a combination of DC sputtering with the PLDIB etching process constitutes an effective method for optimising the mechanical properties of TiN/AlN multilayers.