Friction and wear properties of zirconium and niobium in a hydrogen environment

In this study, the tribological properties of Zr and Nb sliding against themselves are investigated using a pin-on-disk tribometer in a H2 gas atmosphere, He gas atmosphere, air and vacuum. Both the Zr and Nb disk specimens exhibit lower friction coefficients in the H2 gas atmosphere than in air, He gas atmosphere and vacuum. X-ray diffraction analysis shows that the wear particles formed by sliding the Zr and Nb disk specimens in the H2 gas atmosphere consist mainly of the ZrH2 phase (ɛ phase) and NbH phase (β phase), respectively. Also, X-ray diffraction analysis shows that the wear particles, which are formed by sliding the Zr and Nb disk specimens in air, consist mainly of the αZr and Nb phases, respectively.