Analysis of oxide formed on Ti during exposure in bentonite clay. I. The oxide growth

✍ Scribed by Dr. H. Mattson; Prof. I. Olefjord

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: German
• Weight: 773 KB
• Volume: 41
• Category: Article
• ISSN: 0947-5117
• DOI: 10.1002/maco.19900410703

✦ Synopsis

Abstract

Titanium is a candidate as a canister material for the encapsulation of spent nuclear fuel due to its excellent corrosion properties. The aim of this paper is to determine the corrosion rate of titanium in ground‐water saturated bentonite clay at 95°C. The exposure times were ranging from 4 months to 6 years. The analysis tool was ESCA.

The results show that the oxide consists mainly of TiO^2^ and is 65–90 Å thick. A few monolayers of TiO and Ti~2~O~3~ exist close to the metal interface. It is found, that the oxide follows the same logarithmic growth law as in aqueous solutions: y = 71.7 + 3.65 In t (y in Å and t in years). This law applies irrespective of salt or oxygen content or if bentonite is present on the surface. No influence of the alloying clement Pd was found. Deviations from the logarithmic growth law was also found, which indicates that a change of growth can occur in a long term perspective. It is suggested that the increased growth rate is caused by crystallization of the oxide. The influence of bentonite is that the majority component montmorillonite is adsorbed in a 10–40 Å thick layer on the surface.