Fretting wear Behavior of ZR-ALLOY in Na2SO4 solution

Fuel rods in nuclear power plants, made of Zr-alloy is immersed in pure water, and surging of this coolant causes fretting for the rods and spacer. In this paper fretting wear and fretting corrosion test of the Zr-alloy against Al2O3 placed respectively in air, pure water and Na2SO4 solution is carried out. The lost volume is measured with 3D Measuring instruments and the relationship between the fresh surface fretting wear produces and lost surface is evaluated with the potential pulse method. The result shows that the fresh surfacing area is smaller than abrasion mark area, and bigger than actual contact area. The wear extent of Zr-alloy against Al2O3 in Na2SO4 solution is ten times higher than that in air and pure water, but the coefficient of friction is smaller. The wear extent of Zr-alloy against Al2O3 in pure water is equal to the numeric value of the Zr-alloy against Al2O3 in Na2SO4 solution given the -2000mv potential. When Zr-alloy is in corrosion environment, the wear extent increases in proportion to the increase of the potential, and the fretting wear and fretting corrosion result from mainly electrochemical action.