Some properties of atmospheric air and inert gas high-pressure plasma sprayed ZrB2 coatings

This work was aimed at developing a plasma spraying process for the deposition of ZrB2 coatings. The ZrB2 powder was prepared by a spray drying technique and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron microprobe analysis (EMPA) and laser granulometry. XRD revealed the presence of ZrO2 in the coatings deposited by atmospheric plasma spray (APS), while ZrB2 was only present in the coatings deposited by inert plasma spray (IPS). The microhardness increased from 900 to over 1500 HV by increasing the spraying pressure over the atmospheric one. The coatings were submitted to pin-on-disc testing and their behavior was compared to the WC–Co and TiO2+Al2O3 coatings, sprayed by high velocity oxy fuel (HVOF) and APS, respectively. The characterization results showed that the ZrB2 coatings, deposited by IPS, were good electrical conductors and they compared favorably with the reference coatings, in terms of tribological performance.