Hot corrosion behavior of Yb2Si2O7 ceramic by NaVO3 and V2O5 at 700° to 900°

Abstract

Abstract To better understand the hot corrosion behavior of Yb2Si2O7 ceramic in molten NaVO3 and V2O5, corrosion experiments were performed using sintered Yb2Si2O7 bulk ceramics with NaVO3 and V2O5 coatings at temperature range of 700 Ό to 900 °C in air. Corrosion products of YbVO4 and SiO2 were identified under NaVO3 corrosion. But only YbVO4 was found under V2O5 corrosion with some residual corrosion agent. In above two conditions, the corrosion products of YbVO4 have the same crystallographic structural characteristic, but morphology has significant difference. In the first case, YbVO4 is rod-like with a tetrahedral cone at each end because of NaVO3 being weak acid to lead to lower driving force for the corrosion reactions. Thus corrosion products of YbVO4 grew with less nuclei and large elongation. However, V2O5 showed strong acid with strong driving force bringing higher nucleation rate and suppressing the growth of YbVO4, which resulted in granular YbVO4. And the size of granular YbVO4 crystals increased slightly with test temperature rising.