摘要
通过金相显微镜,扫描电镜能谱分析及X射线衍射分析表明,再热器管夹破断是由于其工作在高温下及燃气中含有大量的硫、碱金属等杂质,它们发生化学反应,生成Na_2SO_4盐膜沉积在管夹表面,且与管夹表面的保护性氧化膜Gr_2O_3反应,破坏了氧化膜的钝化作用,拓开了氧、硫向合金内部扩散的通道,因而在合金内部形成了铬的硫化物、氧化物以及Ni—Ni_3S_2的共晶体,即产生了热腐蚀,从而导致管夹破损十分严重。
In the present paper, the cause of brocken boards for pressing reheatorpendant tubes was analyzed by means of microscope, SEM-EDAX and X-ray diffractometer.The following failure process is suggested. A large quantity of sulfur and base metal impurity in flue-gas rected on each other at high temperature and formed a thin salt coating of Na_2SO_4 sediment on the boards, which reacted with the alloy and led to the formation of Na_2CrO_4. The Na_2CrO_4 salt broke the Possivity of Cr_2O_3 oxide film and opened a passage for oxygen and sulfur to diffuse into the alloy matrix therefore, the chromium sulfide, chromium oxide and Ni-Ni_3-S_2 eutectic were formed in the alloy. In other words, hot corrosion has taken place, which resulted in severe corrosion and even failure of boards for pressing reheator-pendant tubes.
出处
《物理测试》
CAS
1992年第6期55-58,共4页
Physics Examination and Testing
