Influence of discharge power on the structural, electro-optical, and mechanical properties of (TiZrHf)N coatings

This study aimed to investigate the effects of discharge power on the composition and the microstructural, mechanical, and electro-optical properties of (TiZrHf)N coatings. The coatings were deposited on Si substrates via reactive magnetron sputtering. The coatings were deposited at varying discharge powers (50-300 W). At low discharge powers, amorphous structures were produced during the initial sputtering period. High (2 0 0)-axis orientation structures were formed when sputtering time was increased. The upper part of the coatings was composed of open columnar structures with extended voids along the column boundaries. Increasing the discharge power decreased the thickness of the amorphous layer. Consequently, the microstructures became dense and compact; however, the grain size did not change significantly. Meanwhile, an enhanced compressive stress was observed, followed by an increase in the texture coefficients of the (1 1 1) plane and lattice parameters. The physical properties of the coatings were improved by increasing the discharge power. The coating hardness was increased to approximately 32.1 GPa. In addition, the electrical resistivity was decreased to approximately 134 μΩ cm, and the light reflectivity in the infrared region (700-2400 nm) was increased to 75%.