锆合金表面激光熔覆制备Ti-Cr涂层耐磨性能及腐蚀行为研究

Wear resistance and corrosion behavior of Ti-Cr coatings fabricated via laser cladding on Zirconium alloy

  • 摘要: 锆(Zr)及其合金因具有中子吸收截面小等优势而成为核燃料包壳材料的首选,然而核反应堆内部高温高压、高辐射、磨损等的严苛服役环境,大大缩短了锆合金部件的使用寿命。铬(Cr)因具有良好的耐磨性、耐腐蚀性等特点,常被选作锆合金的表面涂层材料,然而纯Cr涂层较脆,容易产生裂纹等缺陷。Ti具有良好的塑性、耐腐蚀性和强度,将Ti引入Cr涂层中,有望解决纯Cr涂层开裂的问题。本文通过激光熔覆技术,在Zr-4合金表面制备出Ti-Cr(8: 2)涂层,以增强锆合金表面的耐磨性能和耐腐蚀性能。制备的涂层致密、无缺陷、且成分均匀,与Zr-4基体通过互溶,形成了良好的冶金结合;与Zr-4基体相比,Ti-Cr涂层的硬度为415.4 HV,比基体提高了1.2倍,磨损率也降低35.3%,表现出了优异的耐磨性能;电化学测试表明,Ti-Cr涂层比Zr-4基体的自腐蚀电位高且自腐蚀电流密度低,同样表现了优异的耐蚀性。本研究为开发适用于苛刻环境下服役的高性能Zr-4合金涂层提供了重要参考。

     

    Abstract: Zirconium (Zr) and its alloys are the preferred materials for nuclear fuel cladding due to their low neutron absorption cross-section, among other advantages. However, the harsh service environment inside nuclear reactors, characterized by high temperature, high pressure, intense radiation, and wear, significantly shortens the lifespan of zirconium alloy components. Chromium (Cr), known for its excellent wear and corrosion resistance, is often chosen as a surface coating material for Zr alloys. Nevertheless, pure Cr coatings are brittle and prone to cracking and other defects. Titanium (Ti), with its good plasticity, corrosion resistance, and strength, is introduced into Cr coatings to potentially address the cracking issues of pure Cr coatings. In this study, a Ti-Cr (8: 2) coating was prepared on the surface of Zr-4 alloy using laser cladding technology to enhance the wear and corrosion resistance of the zirconium alloy surface. The prepared coating was dense, defect-free, and compositionally uniform, forming a strong metallurgical bond with the Zr-4 substrate through mutual dissolution. Compared to the Zr-4 substrate, the Ti-Cr coating exhibited a hardness of 415.4 HV, which is 2.2 times that of the substrate, and a 35.3% reduction in abrasion wear rate, demonstrating excellent wear resistance. Electrochemical tests revealed that the Ti-Cr coating had a higher self-corrosion potential and lower self-corrosion current density than the Zr-4 substrate, indicating superior corrosion resistance. This research provides important insights for developing high-performance Zr-4 alloy coatings suitable for service in demanding environments.

     

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