Effect of HfO2 Coating Films on Oxidation Resistance of SiC Ceramics
HfO2 coatings were deposited on sintered SiC ceramics by a sol-gel process to improve the oxidation resistance of SiC. Crack-free HfO2 coatings ~200 nm thick were obtained by 8 cycles of dip-coating process using a mixed solution of Hf(OEt)4, DEA, and ethanol. XRD analysis indicated that the monoclinic HfO2 film was formed on the SiC ceramics. The un- and HfO2-coated SiC specimens were oxidized in Ar (purity: 99.9995%) containing a trace of oxygen or H2O at 1600°C for 10 h and the weight change was monitored by thermogravimetry. The weight of the un-coated sample decreased due to the active oxidation, while the weight loss of the HfO2-coated samples was smaller than that of un-coated sample.
Katsutoshi Komeya, Yi-Bing Cheng, Junichi Tatami and Mamoru Mitomo
M. Kasajima et al., "Effect of HfO2 Coating Films on Oxidation Resistance of SiC Ceramics", Key Engineering Materials, Vol. 403, pp. 193-196, 2009