WEAR AND FRETTING WEAR BEHAVIOR OF ION-IMPLANTED ZIRCALOY-4

Zircaloy-4 was implanted with nitrogen at 120 keV to various total ion doses between 1 x 10(17) and 1 x 10(18) ions cm(-2) at various temper atures in the range 310-660 degrees C. The implanted surfaces were ana lysed by Auger electron spectroscopy (AES) and X-ray diffraction (XRD) . Wear and fretting wear tests were performed at various loads under u nlubricated conditions and water immersion respectively. Nitrogen impl antation produced zirconium nitride and oxide which enhanced the surfa ce hardness up to 1800 HK (0.1 N) for a total ion dose of 1 x 10(18) i ons cm(-2) at 660 degrees C (300 HK (0.1 N) for unimplanted specimen). The ball-on-disc wear resistance was improved for nitrogen-implanted specimens above 500 degrees C. In addition, oxide layer and ZrN format ion by nitrogen implantation in an oxygen atmosphere greatly enhanced the wear resistance of Zircaloy-4. The fretting wear resistance was en hanced by nitrogen implantation. Successful improvement of the frettin g wear resistance was obtained for the specimen implanted at 550 degre es C to a total dose of 8 x 10(17) ions cm(-2).