Role of solute titanium and oxidation in cesium chemisorption onto stainless steel

Abstract

ABSTRACT This study investigates the influence of oxide film formation affected by solute Ti in the Cs chemisorption. An experiment using a liquid-CsOH precursor and pre-oxidized stainless steels (SS 304 and SS 321) is performed to simulate the vapor condensation of Cs through leakage paths to the environment. These stainless steels are composed of similar elements, except for Ti in SS 321. To form diverse pre-oxide films, SS 304 and SS 321 specimens are oxidized in air at various temperatures. Subsequently, the specimens are coated with liquefied CsOH and annealed at 300°C–1050°C in the air for 6 h; then soaked in water. Consequently, Cs2FeO4 and Cs2CrO4 are formed; however, they are diluted during soaking, which resulted in a minute amount of Cs. Tiny Cs particles containing Al, Si, and Ti adhered to the specimens treated at 300°C–450°C. At higher temperatures, Cs dispersed in the oxide layer. Although Ti can react with Cs and be chemisorbed, the amount of Cs in SS 321 seems to be less than that in SS 304. This is because of the robust SS 321 oxide layer, which arises from the chromium-oxide stabilizing effect of Ti.