Thermal stability, heat resistivity, and electrochemical corrosion resistance of (Ti,Al)N-Cu nanostructural coatings

Nanostructural ceramometallic ion-plasma vacuum-arc (Ti,Al)N-Cu coatings with Al content on the order of 1.5 at % and 3 at % Cu with the crystallite size of 15–20 nm and a thickness of 4 μm on the solid solution are characterized by heat resistance and thermal stability till 700°C. The presence of copper atoms in the coating leads to a slight increase in the density of the passive state current relatively the (Ti,Al)N ceramic coating, but it exerts no significant influence on the electrochemical behavior of the 3 at % (Ti,Al)N-Cu system in highly oxidized chloride solution. The studied coatings are different by a high tendency to self-passivation, low passive state current densities and high resistance to the pitting corrosion that almost does not occur because of the fast transition from the pitting origin into its repassivation. As in the acid condition, the composite exhibits a high electrochemical stability in the alkaline medium, being in the passive state.