Effect of Temperature on Fretting Corrosion Behaviors between Li₂TiO₃Pebble and F82H

Abstract

Lithium titanate (Li 2 TiO 3 ) pebble is a candidate tritium breeder of solid breeder blanket systems of fusion reactors. The oscillation of coolant tubes can be induced by the coolant flow. Fretting corrosion is caused between the Li 2 TiO 3 pebbles and the coolant tubes which are made of reduced activation ferritic martensitic steel F82H. The purpose of the present study is to clarify the fretting behaviors at the temperatures of blanket conditions. The Li 2 TiO 3 pebble produced by sol-gel method was pushed onto the surface of the oscillating F82H plate in the fretting tests which were performed for 10 min in an air atmosphere up to 573 K. The fretting scars of the Li 2 TiO 3 pebble and the F82H plate were observed and analyzed by SEM/EDX and 3D laser scanning microscope. The fretting wear was mitigated at the temperatures of 373 K and 473 K due to the formation of the oxide layer, which might reduce the friction. The pebble was partially destructed by the fretting motion in the test performed at 573 K. The fretting wear of the pebble and the F82H plate was mitigated when the pebble was not fixed on the holder since the pebble could vibrate together with the oscillating plate.