High-temperature corrosion resistance of SiO2-forming materials
AbstractAn increasing demand for electricity and preserving the environment has become a great driving force for the development of advanced boilers for coal-fired plants to improve their plant efficiency by raising the operating temperature. To achieve this purpose, the development of materials that possess a high mechanical strength and excellent resistance against corrosion at high temperatures is required. Considering such situation, the high-temperature corrosion behavior of SiO2-forming materials such as CrSi2-Ni and CoNiCrAlY-Si alloys in atmospheres containing NaCl and Na2SO4 is introduced. The SiO2 scale plays a significant role in suppressing the inward diffusion of sulfur and chlorine, resulting in the remarkable suppression of the formation of sulfide and chloride at the scale/substrate interface and inside of the substrate. Based on such results, it is emphasized that SiO2-forming materials show outstanding corrosion resistance against atmospheres containing NaCl and Na2SO4.