摘要
利用热重分析法研究了一种将用作超临界锅炉过热器管材料的新型N i-Cr-Co基高温合金在空气中的热腐蚀行为,并利用X射线衍射和扫描电镜等实验手段详细分析了腐蚀产物和腐蚀机理.研究表明:合金表面涂覆Na2SO4后在850℃的腐蚀动力学行为遵循抛物线规律,而在950℃时因表面腐蚀产物的挥发偏离抛物线规律,抛物线速度常数逐渐降低;合金表面生成的腐蚀产物有Cr2O3、(N iCo)Cr2O4、TiO2和A l2O3,内析出物为A l2O3、TiO2和Cr与Ti的硫化物;合金表面涂覆Na2SO4在850℃和950℃发生了高温热腐蚀,其原因在于表面熔融态Na2SO4盐的存在使得表面形成的Cr2O3膜产生了碱性熔融.
Hot corrosion behaviors and mechanism of new Ni - Cr - Co base superalloy, a future superheater tube material of ultra-supercritical boiler, have been investigated under Na2SO4 deposits at 850 ℃ and 950 ℃ by means of TGA, XRD, SEM and EDX. The results showed that the kinetic curve of the alloy corroded at 850 ℃ with Na2SO4 coating followed a parabolic law but not indicated a parabolic growth behavior of the oxide at 950 ℃ , and the parabolic rate constant decreased with increasing timc due to the evaporation of NaECrO4. The external oxide scales consisted of Cr2O3, （NiCo） Cr2O4, TiO2, and Al2O3, and the internal precipitates were TiO2, Al2O3, chromium-sulfide and titanium-sulfide. High temperature hot corrosion of the alloy with NazSO4 coating occurred at 850 ℃ and 950 ℃ and the degradation of corrosion resistance can be attributed to the basic fluxing of Cr2O3 induced by molten Na2SO4.
出处
《材料科学与工艺》
EI
CAS
CSCD
北大核心
2006年第5期506-509,共4页
Materials Science and Technology
