ABSTRACT

In the pursuit of more efficient gas turbine engines, components are required to operate for longer times at elevated temperatures. This increased time in service, together with a complex loading regime, can expose the material to environmental attack. This work has demonstrated that the interaction of stress, NaCl and a sulphur-containing environment is critical to cause crack initiation in the early stages of the exposure and accelerated corrosion rates in CMSX-4 at 550°C. The effect of having small concentrations of moisture in the gaseous environment or as water crystallisation in the salt is still to be investigated. A working hypothesis is that the interaction of alkali chlorides with a sulphur-containing atmosphere is the trigger to a self-sustaining cycle where metal chloride formation, vaporisation and oxidation lead to high amounts of hydrogen injection in a rapid manner and, therefore, hydrogen embrittlement.

摘要

为了追求更高效的燃气涡轮发动机，部件需要在高温下运行更长时间。使用时间的增加，加上复杂的装载方式，可能会使材料受到环境的侵蚀。这项工作表明，应力、氯化钠和含硫环境的相互作用对于在 550°C 下的 CMSX-4 暴露早期阶段引发裂纹和加速腐蚀速率至关重要。气体环境中低浓度水分或盐中水结晶的影响仍有待研究。一个可行的假设是，碱金属氯化物与含硫气氛的相互作用触发了自我维持的循环，其中金属氯化物形成，