Effects of Cr Coating on Fretting Wear Behavior of Zr-1Nb Alloy Cladding

The fretting wear behavior and damage mechanism of Cr-coated and uncoated Zr-1Nb alloy cladding with AFA 3G grid under simulated PWR primary water environment were studied contrastively by 3D white light interferometer, SEM and EDS. The results indicate that Cr coating can significantly improve the fretting wear resistance of Zr-1Nb alloy cladding. In addition, for cladding against dimple, the dominant wear mechanism of Zr-1Nb is delamination and abrasive wear. However, the main damage mechanism of Cr- coated Zr-1Nb is adhesive wear and materials transfer, due to higher surface hardness and formation of protective third body layer. For cladding against spring, the damage mechanism is delamination and adhesive wear for Zr-1Nb, while abrasive wear for Cr-coated Zr-1Nb.