Fretting Wear Damage Mechanism of Uranium under Various Atmosphere and Vacuum Conditions.

Zhengyang Li,Zhenbing Cai,Xiandong Meng,Yanping Wu,Dongxu Zhang

doi:10.3390/ma11040607

Zhengyang Li, Zhenbing Cai + Show 3 more

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https://doi.org/10.3390/ma11040607

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Abstract

A fretting wear experiment with uranium has been performed on a linear reciprocating tribometer with ball-on-disk contact. This study focused on the fretting behavior of the uranium under different atmospheres (Ar, Air (21% O2 + 78% N2), and O2) and vacuum conditions (1.05 and 1 × 10−4 Pa). Evolution of friction was assessed by coefficient of friction (COF) and friction-dissipated energy. The oxide of the wear surface was evaluated by Raman spectroscopy. The result shows that fretting wear behavior presents strong atmosphere and vacuum condition dependence. With increasing oxygen content, the COF decreases due to abrasive wear and formation of oxide film. The COF in the oxygen condition is at least 0.335, and it has a maximum wear volume of about 1.48 × 107 μm3. However, the COF in a high vacuum condition is maximum about 1.104, and the wear volume is 1.64 × 106 μm3. The COF in the low vacuum condition is very different: it firstly increased and then decreased rapidly to a steady value. It is caused by slight abrasive wear and the formation of tribofilm after thousands of cycles.

Highlights

Uranium has been extensively applied in nuclear power plants and nuclear devices due to its special material and nuclear properties [1]
While in transport and service, uranium is frequently affected by external excitation such as vibration, thermal cycling, and dry-wet alternation, which could lead to relative motion with small displacement amplitude, and the relative motion will cause fretting damage in the contact interface, accelerating fatigue crack initiation and propagation [2,3,4]
Fretting theory was further developed into two kinds of fretting maps by Zhou et al [9] and Vincent et al [10], that is, running condition fretting map (RCFM) and materials response fretting map (MRFM) respectively

Summary

Introduction

Uranium has been extensively applied in nuclear power plants and nuclear devices due to its special material and nuclear properties [1]. To satisfy the engineering design, uranium will inevitably contact or fasten with other materials, among which the contact interface has been proved to bear different stresses and relative clearances. While in transport and service, uranium is frequently affected by external excitation such as vibration, thermal cycling, and dry-wet alternation, which could lead to relative motion with small displacement amplitude, and the relative motion will cause fretting damage in the contact interface, accelerating fatigue crack initiation and propagation [2,3,4]. To properly describe fretting behaviors, the concept of fretting map (tangential force plotted versus displacement amplitude) was first proposed by Vingsbo et al [8], namely stick regime, mixed stick-slip regime, and gross slip regime. The fretting map was based on experimental studies conducted on an aluminum-lithium alloy under different displacement, load, and frequency

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