Hot corrosion behavior of multicomponent rare earth phosphate materials exposed to molten V2O5 salt

Abstract

Six multi-component rare earth phosphate materials were prepared by chemical co-precipitation, which are (La0.2Nd0.2Sm0.2Eu0.2Gd0.2)PO4, (La0·2Ce0.2Nd0.2Sm0.2Eu0.2)PO4, (Ce0.2Nd0.2Sm0.2Eu0.2Gd0.2)PO4, (La0.5Nd0.5)PO4, (La0.5Gd0.5)PO4 and (Nd0.5Gd0.5)PO4. Hot corrosion behavior tests were conducted in molten V2O5 salt at 900 °C and 1000 °C for 20 h and 40 h, respectively. The results show that the corrosion temperature and the heat treatment time have little effect on the type of corrosion products. Among these materials prepared in this study, the material containing Gd element and the material without Gd element exhibit different hot corrosion behavior. For the multi-component rare earth phosphate materials containing Gd element, the corrosion product is ReVO4 (ReSm, Eu, Gd) xenotime, and a reaction layer is formed on the surface of the bulk. For the multi-component rare earth phosphate materials without Gd element, the corrosion product is Re(P,V)O4 (ReLa, Ce, Nd) solid solution and the amount of product is very small, the corrosion reaction is extremely weak and no reaction layer is formed. Although the molten salt mainly penetrates, the original structure of the bulk has not been damaged, which indicates that its hot corrosion resistance is good. The hot corrosion mechanisms of these six multi-component rare earth phosphates are studied based on the crystallographic characteristics of rare earth phosphates/vanadates.