Enhanced mechanical properties and corrosion resistance of CrSiN/Al2O3 multilayer films deposited by magnetron sputtering

A "large thick base layer + thin functional multi-layer" structure was proposed to enhance the hardness and corrosion resistance of CrSiN films by breaking the CrSiN columnar growth by Al2O3 intercalation. The Al2O3/CrSiN multilayer films (-1 mu m) with different modulation periods (3, 8, 15) were deposited on CrSiN (-2 mu m) films by magnetron sputtering. The CrSiN layer consisted mainly of fcc-CrN and a small amount of Si3N4, while the Al2O3 layer was in an amorphous form. The insertion of Al2O3 changed the orientation of film, and the grains on the surface of film were refined. With the increase in the multi-layer period, the modulus tended to stabilize at about 211GPa, and the hardness increased reaching a maximum of 20.7 GPa at period 3. The nitride/alumina interface prevented the diffusion of corrosion species and improved the corrosion resistance of the film. In 3.5 wt% NaCl solution, the multilayer film possessed better corrosion resistance than CrSiN monolayer film. The multilayers showed superior corrosion potentials and ultra-low corrosion current densities (Ecorr = -0.566 V, icorr = 0.67 mu A<middle dot>cm2) at period 8.