Thermal and mechanical properties of (W,Zr)B2-z coatings deposited by RF magnetron sputtering method

Magnetron sputtered WB2 coatings doped with 8, 11 and 16 at.% zirconium were analysed using energy dispersive spectroscopy, X-ray diffraction and nanoindentation under the load of 4, 7 and 10 mN. It has been observed that these coatings crystallize in the α-AlB2 and ω-W2B5 prototype structure. Phenomenon responsible for this is an increase of the zirconium content which causes an increase in the ω-W2B5 phase. All the deposited coatings have a hardness of about 45 GPa while Young's modulus drops down from 497 to 480 GPa with increasing zirconium content. Coatings without doping and doped with 16 at.% zirconium were annealed at 650 °C and subjected to cyclic thermal loads using a maximum temperature 600 °C and cooling with a compressed air. It has been observed that addition of zirconium improved coatings phase stability.