Influence of thin oxide layers on tribological properties of E110 alloy tubular specimens under dry friction conditions

Experiments to simulate wear process of fuel cladding in case its contact with spacing grid. System «sphere-plane» selected as friction pair. Tubular parts of fuel claddings from E110 alloy diameter of 9.15 mm and length of 50 mm (wall thickness 1 mm) were used for investigations. Some claddings were subjected to ion cleaning and polishing under the influence of Ar⁺ ion beam with average energy of 3 keV. Samples were oxidized in steam- water conditions ( T =300° C, p =17 MPa, time up to 100 h) to create thin oxide layers with a thickness of 1 mkm on the tubes surface. It is found that wear of the metallic samples takes place in elastically plastic deformation conditions at initial stage (2-5 min). Presenceof thin oxide layer (of thickness up to 200 nm) on the samples surface contributes to reduce wear due to the uniform redistribution its fragments on the friction track, and wear also samples takes place in elastically plastic deformation conditions. Presence of oxide layer with thickness of 700 nm on the samples surface increases wear in conditions of abrasion friction. (paper)