WB2 to WB3 phase change during reactive spark plasma sintering and pulsed laser ablation/deposition processes

Abstract Reactive spark plasma sintering (SPS) of WB 2 /WB 3 ceramics from elements is studied; the sintering pressure dependence of the ratio of WB 3 to WB 2 in samples produced by SPS is discussed. Regardless of the sintering pressure, the obtained samples are very hard ~20 GPa. WB 3 superhard films prepared by pulsed laser deposition (PLD) from selected SPS targets are presented. WB3 coatings were prepared on Si (100) substrates using a nanosecond, Nd:YAG laser operating at a 355 nm wavelength. The phase analysis, crystallography, and orientations have been studied using X-ray diffraction (XRD). A WB 2 to WB 3 phase transformation from 8.2% WB 3 in a sintered target to 93.3% WB 3 in a deposited film was observed. Additionally, the surface of a SPS sintered WB x target after the ablation process was examined. XRD studies show that already during the laser ablation there is a significant WB 2 to WB 3 phase transformation. Vickers hardness of sintered samples was measured in macro- and micro-scale, and PLD films in the nanoscale.