Interface between FGH96 Superalloy and Refractory Slurry with Different Soaking Time

Abstract

In this paper, the contact interface between FGH96 superalloy melts and refractory slurry with corundum powder and silica sol at 1600°C with different soaking time in 10-240 min range was investigated. The morphology and composition of the contact interface were studied by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that the reaction layer formed on the contact interface between the melting superalloy and the refractory slurry, and is mainly consist of Alumina and contains a small amount of other metal elements such as Ti and Cr. The reaction layer was not smooth on the micro level, and there was a peninsula-like structure protruding into the internal part of the melting superalloy on the reaction zone, and even started to fall off at some places to form islands. With the increase of soaking time, the reaction between melt of superalloy and refractory slurry increased gradually and the reaction layer began to combine with the refractory slurry substrate and form obvious interaction layered structure, resulting in the corrosion of refractory slurry substrate. With the soaking time over 120 min, the stable contact interface was destroyed. Thermodynamic calculation shows that the substitution reaction between Al in superalloy and SiO2 in refractory slurry meets the thermodynamic conditions, and the reaction can proceed forward.