Examination of Failed Components from the 1/3rd Scale Joule Ceramic Melter

摘要

Samples from components of the one third scale Joule Ceramic Melter have been examined by optical and electron microscopy in order to investigate the reasons for the severe corrosion observed, particularly in the Inconel 690 electrodes. Samples were taken from a number of regions of the most corroded electrode and from the Inconel 690 thermocouple sheath and glass withdrawal pipe for comparison. The attack was found to be of two forms: one comprising an oxidation mechanism, seen in all inconel 690 samples, spearheaded by penetration along grain boundaries, to form a chromium-rich oxide that was dissolved by the molten waste glass: the second form, melting, was seen in the most severely corroded electrode regions, and the excessive temperatures required for melting to occur were most probably caused by localised high current densities due to the presence and segregation of metallic precipitates to the bottom region of the melter chamber. (ERA citation 13:008514)