Microstructure and mechanical, electrical, and electrochemical properties of sputter-deposited multicomponent (TiNbZrTa)Nx coatings

Abstract A series of (TiNbZrTa)Nx coatings with a thickness of ~1.1 μm were deposited using reactive magnetron sputtering with segmented targets. The deposition temperature was varied from room temperature to 700 °C resulting in coatings with different microstructures. The coatings were characterized by electron microscopy, atomic force microscopy, compositional analysis, and X-ray diffraction. Effects of the deposition temperature on the electrical, mechanical and corrosion properties were studied with four-point probe, nanoindentation and potentiodynamic polarization measurements, respectively. X-ray photoelectron spectroscopy (XPS) analyses reveal a gradual change in the chemical state of all elements with increasing growth temperature from nitridic at room temperature to metallic at 700 °C. A NaCl-type structure with (001) preferred orientation was observed in the coating deposited at 400 °C, while an hcp structure was found for the coatings deposited above 400 °C. The resistivities of the TiNbZrTa nitride coatings were found to be around 200 μΩcm. In 0.1 M H2SO4 aqueous solution, a corrosion current density of 2.8 × 10−8 A/cm2 and a passive behaviour up to 1.5 V vs. Ag/AgCl were found for the most corrosion resistant coating. The latter corrosion current is about two orders of magnitude lower than that found for a reference hyper-duplex stainless steel.