Mechanism of wear in zircaloy-4 under different loading conditions

Core components of nuclear reactor are generally made of zirconium alloys and some of them are prone to low amplitude vibration leading to material wear at contact interface. Reciprocating wear tests were conducted between zircaloy-4 (Zr-4) under dry and water-submerged conditions. To confirm the material transfer due to adhesion, wear tests were also conducted between Zr-4 and stainless steel. To understand the wear mechanism, worn surfaces were analyzed using scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Coefficient of friction (COF) increases with increasing fretting duration and decreases with increasing frequency and displacement amplitude. Greater COF is observed under dry condition than that under submerged condition. The wear mechanism changes from adhesion to abrasion with increasing displacement amplitude.