Temperature induced superhard CrB2 coatings with preferred (001) orientation deposited by DC magnetron sputtering technique

The influence of deposition temperature in the range of 100 °C to 400 °C on the microstructure and mechanical properties of CrB2 coatings by DC magnetron sputtering was studied. The coating texture changed from random mixed orientation with (101) and (001) planes to the preferred (001) orientation when increasing the deposition temperature. Moreover, the microstructure coating evolved from an underdense structure to a bulky columnar structure (~ 50 nm), and finally to a dense nanoscale columnar structure (~ 7 nm). This structural densification was mainly attributed to the enhanced atomic surface diffusion with increasing deposition temperature. It resulted in promotion of the (001) preferred orientation and greatly enhanced the mechanical properties. Specifically, when the deposition temperature was 300 °C, the CrB2 coatings exhibited the highest toughness while superhardness (51 ± 2 GPa) was achieved for coating grown at 400 °C.