Amorphous SiOxCy(:Er) films deposited by RF-magnetron sputtering on ZrB2–SiC ceramics: Antioxidation and strengthening effects

Abstract

The effect of amorphous a-SiOxCy(:Er) layers on the oxidation behavior of ZrB2-SiC composite ceramics has been studied. ZrB2–15%SiC composite samples were obtained by hot pressing of ZrB2+15%SiC powder at 1850оС and 48MPa. Amorphous a-SiOxCy:(Er) thin films (1μm thick) were deposited on ZrB2-SiC specimens at a temperature of 200°C by reactive RF-magnetron sputtering of SiC/Er target in argon/oxygen flow. Coated ZrB2-SiC samples were exposed to a high-temperature oxidation at 1400°C for 1h at atmospheric pressure. Structure and phase composition were examined by optical microscopy, X-ray diffraction, SEM and EDS. It was demonstrated that a-SiOxCy coating noticeably enhances the oxidation resistance of the surface. Further development of the oxidation resistance was observed in Er-incorporated a-SiOxCy coating. Along with the improvement of the antioxidation resistance the deposition of a-SiOxCy(:Er) coatings resulted in increasing of bending strength of ZrB2-SiC samples in comparison to uncoated samples. The enhancement of surface stability and strengthening by a thin a-SiOxCy(:Er) coating is discussed in terms of the effects of dense coating by itself and the modification of a surface silica layer by erbium incorporation as well.