Effect of La2O3 on the corrosion resistance of alumina ceramic

Alumina ceramics are widely used because of chemical corrosion resistance. Although alumina ceramics can resist many strong acids and organic acids, be corroded easily by HF due to silicon components in raw materials. This work aimed to reveal the effect of La2O3 on HF/HCl resistance of the alumina ceramic containing SiO2. The X-ray diffractometer (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), were used to study the microstructure and mechanism, acid solubility and bulk density were tested. It was discovered that La caused the enrichment of Ca and Si, and the enrichment degree of Si was higher, which led to generation more CaAl2Si2O8 in the ceramic. Moreover, La3+ could replace Ca2+ to form solid solutions with CaAl2Si2O8. The acid solubility of the solid solutions and (La.85Al11.55O18.6)-Al-0 and the effect of them on the corrosion resistance of this alumina ceramic were studied. Results showed that a proper addition of La2O3 was beneficial to the acid resistance of alumina ceramic for long time corrosion, while bulk density increased. The mechanism of corrosion resistance has been discussed. (C) 2020 The Authors. Published by Elsevier B.V.