Microstructure, Mechanical, and Tribological Properties of Amorphous WB 2 /Ti Multilayer Coatings

Amorphous WB 2 /Ti multilayer coatings with different modulation ratios (1, 5, 15, and 30) and different bilayer numbers (10, 20, 30, 50, and 70) were deposited by direct-current magnetron sputtering. The effect of modulation ratio and bilayer number on the microstructure, mechanical, and tribological properties of WB 2 /Ti multilayer coatings was studied systematically. In the investigation for the influence of modulation ratio, the hardness of the multilayer coatings increases with the increment of modulation ratio. The indentation toughness shows a different changing tendency compared to that of the hardness with different modulation ratios. The wear rates of the multilayer coatings with different modulation ratios are at the same level with the influence of both hardness and indentation toughness. In the investigation for the influence of bilayer number, both hardness and indentation toughness increase first and then decrease with an increasing bilayer number. WB 2 /Ti multilayer coating with a modulation ratio of 5 and bilayer number of 50 exhibits the highest hardness of 20.4 GPa and lowest wear rate of 1.76 × 10 −16 m 3 /Nm. In addition, the hardness strengthening mechanism and wear mechanism of the multilayer coatings were discussed in detail.