Fretting-wear of zirconium alloys

Fretting tests of Zircaloy fuel sheath bearing pads in contact with zirconium alloy (Zr–2.5Nb) pressure tube specimens were conducted at temperatures varying from 25 to 315 °C. The effects of motion type and amplitude, water chemistry, fuel sheath manufacturer and pressure tube surface finish were also investigated. The effect of temperature is the most significant. The pressure tube wear coefficient in the 225–286 °C for all four motions studied is considerably greater than that above 300 °C. The fretting rate for small amplitude motion representative of flow turbulence excitation is about equal at temperatures below 150 °C and above 300 °C, but is five to ten times greater in the 250–286 °C range.