Chemistry Weekly Seminar - Mehrnaz Mikhchian, PhD Student

Title

An investigation of the long-term aqueous corrosion behaviour of glass, crystalline ceramics, and glass-ceramic composite materials

Abstract

Deep geological repositories are being considered internationally as a future plan for the permanent disposal of high-level radioactive waste (i.e., used nuclear fuel). A common challenge associated with geological disposal is groundwater corrosion and leaching of the radionuclides incorporated in a wasteform into the environment. Glass-ceramic composite materials are being considered as potential nuclear wasteform candidates due to having high waste loading and expected enhanced chemical durability compared to borosilicate glass on its own. However, the long-term aqueous corrosion resistance (i.e., over years) of these glass-ceramic composite materials and how the structure of these materials change after being exposed to an aqueous environment are not fully understood.

 This presentation is focused on our recent studies of the long-term aqueous corrosion behaviour of the Fe-Al-BG-CaZrTi₂O₇ and Fe-Al-BG-Ce_0.94Ti₂O_6–δ composite materials and how their corrosion mechanisms compare to the individual Fe-Al-BG, CaZrTi₂O₇, and Ce_0.94Ti₂O_6–δ phases. A combination of surface and bulk techniques has been used in this research to provide detailed information on the corrosion that occurs at the surface or bulk regions of these materials after being exposed to water for a period of one year. The results of this study have shown that the corrosion of the Fe-Al-BG-CaZrTi₂O₇  and Fe-Al-BG-Ce_0.94Ti₂O_6–δ composite materials leads to the formation of an amorphous surface layer during the early stages of exposure to water (i.e., between 15 and 60 days) which could restrict the further release of ions into the water.

Date:    Friday, October 20

Time:    1:30 pm

Place:    Thorvaldson 159