Fretting Corrosion Behavior of CrAlN Coatings at Different Temperatures in Lead-Bismuth Eutectic Alloy

Abstract Fretting wear and corrosion will occur in the heat exchange tube of steam generator in high temperature lead-bismuth eutectic alloy (LBE). CrAlN coating has good mechanical properties and corrosion resistance. Magnetron sputtering and arc composite technology are used to prepare CrAlN coating on the heat exchange tube’s surface to improve the heat exchange tube’s wear and corrosion resistance. This study investigates the fretting corrosion behavior of CrAlN coatings at different temperatures (350°C, 450°C, and 550°C). The samples’ wear depth, surface morphology, and chemical composition after the fretting corrosion experiment were analyzed using the self developed fretting corrosion experimental equipment, combined with 3D profile scanner, scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDS). The results show that at 350°C, the abrasive surface is dominated by debris accumulation and local cracks appear inside the coating. At 450°C, the wear is the most serious, the wear depth is the largest, the coating in the middle of the wear mark is peeled off, the furrow is obvious, and the resistance to fretting corrosion is the weakest. At 550°C, the wear marks are shallow, the coating is not seriously spoiling, and a protective Al and Cr oxide layer is formed on the coating surface. In summary, CrAlN coating has excellent fretting corrosion resistance at 550°C. The results provide important information for the coating application of heat exchange tubes in high temperature LBE environment.