Study on CMAS Resistance of LaMeAl11O19(Me=Cu,Zn) Ceramic Bulk Materials

Abstract: With the increasing application temperature of gas turbine, the CMAS resistance of ceramic materials is becoming more and more important. In this paper, theCaO-MgO-Al2O3-SiO2 (CMAS) corrosion resistance behavior of LaMeAl11O19 (Me=Cu,Zn) ceramic bulk materials under different temperatures and time was studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and so on. The results show that the corrosion products of both LaZnAl11O19(LZA) and LaCuAl11O19 (LCA) bulk materials include diopside (Ca(Mg,Al)(Si,Al)O7) andanorthite (CaAl2Si2O8). With the increase of corrosion temperature and time, the corrosion depth increases, and Ca(Mg,Al)(Si,Al)O7 gradually transforms into CaAl2Si2O8. The CMAS corrosion of LZA and LCA bulk materials can be explained by “dissolution-precipitation” mechanism. The bulk materials gradually dissolve into the CMAS, forming Ca(Mg,Al)(Si,Al)O7, and then gradually transform into CaAl2Si2O8, so that the diopside phase which is difficult to crystallize is transformed into the anorthite phase which is easy to crystallize. La atom is the crystal nucleus of devitrification, and the interfacial energy exists between the CMAS glass phase and the bulk materials. These factors together promote the precipitation of thick plate-like crystals of CaAl2Si2O8 inside CMAS and at the interface of CaAl2Si2O8 and CMAS.

Key words: ceramic bulk material, CMAS resistance, corrosion mechanism, gas turbine, thermal barrier coating, magnetite rare earth hexaaluminate

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