Measurement of the volume expansion of SiC refractories induced by molten salt corrosion

Abstract

Corrosion tests of oxide-bonded SiC-based refractory cylinders with molten salts (mainly CaSO4, K2SO4) were performed at high temperature to enable better understanding of the corrosion mechanisms operating in these materials. Salt pellets were placed on the upper surface of small refractory cylinders. After they had been melted, the corrosive product soaked into the pores of the refractory cylinders and partially corroded the SiC phase. SEMEDS analyses showed thatCaSiO3 was the mainnewphase formed, growing from SiC aggregates into the pores.Theshapes of the initial and corroded cylinders were measured at room temperature using a 3D coordinate measuring machine equipped with a laser-plane sensor. These measurements enabled monitoring of the evolution of the residual radial deformation versus the depth from the surface in contact with the salt pellets, and consequently the characterisation of the local volume expansion induced by the phase change. Coupling SEM-EDS analyses with 3D digitising revealed the link between the corrosion product and the volume expansion.