High Temperature Microscope Observation of Melt Formation at the Interface between Crystalline Olivine and Wüstite

Abstract

In order to elucidate the slag melting behavior of sinters, the in-situ observation of the melt formation behaviors at the interface between synthesized crystalline olivine and wüstite bulks was carried out using a high temperature microscope over a temperature range between 1080 and 1120°C. The melting instantly happens at the interface in the olivine side at the temperatures higher than 1100°C although the thickness of the melting zone does not vary with time during the heating. The thickness of the melting zone is ca. 20 μm irrespective of heating temperature as well as heating duration. The melt formation is considered to be due to the fact that the olivine composition slightely shifts toward 2FeO·SiO₂ by substituting Ca²⁺ with Fe²⁺ owing to the diffusion of Fe from wüstite into olivine, lowering the liquidus temperature.