In thermal power generation equipment, circumferential cracking in boiler tubes due to thermal cycling is a problem. Circumferential cracks form in the water-wall tube where sulfide corrosion occurs and in superheater and reheater tubes where high-temperature oxidation occurs. The main cause of the crack formations is thermal cycling, but sulfide corrosion and high-temperature oxidation also promote crack generation and accelerate crack progression. Therefore, preventing sulfide corrosion and/or high-temperature oxidation is one strategy for suppressing circumferential cracking. The authors previously developed a SiO₂/TiO₂/Al₂O₃-based/TiO₂ coating for preventing sulfide corrosion and high-temperature oxidation on boiler tubes. In this work, to confirm the robustness and durability of the coating against circumferential cracking, laboratory experiments and exposure tests in actual power plants were performed. When applied to circumferentially cracked boiler tubes, the coating did not crack and suppressed growth of existing circumferential crack in comparison with an uncoated part.

在火力发电设备中，由于热循环引起的锅炉管周向裂纹是一个问题。在发生硫化物腐蚀的水冷壁管和发生高温氧化的过热器和再热器管中会形成周向裂纹。裂纹形成的主要原因是热循环，但硫化物腐蚀和高温氧化也会促进裂纹产生并加速裂纹进展。因此，防止硫化物腐蚀和/或高温氧化是抑制环向裂纹的一种策略。作者先前开发了基于SiO ₂ /TiO ₂ /Al ₂ O ₃的/TiO ₂锅炉管上防止硫化物腐蚀和高温氧化的涂层。在这项工作中，为了确认涂层对周向裂纹的坚固性和耐久性，在实际发电厂中进行了实验室实验和暴露测试。当应用于有周向裂纹的锅炉管时，与未涂层部分相比，涂层没有开裂并抑制了现有周向裂纹的扩展。