CMAS corrosion resistance of Y 2 O 3-Al 2 O 3 binary ceramic materials

Alumina based rare earth oxides ceramic materials, with the good performance against the CMAS corrosion, were widely used as the thermal/environmental barrier coatings. In this work, three Y 2 O 3 - Al 2 O 3 binary ceramic bulks, which were the Y 3 Al 5 O 12 , YAlO 3 and Y 4 Al 2 O 9 , were prepared by high temperature solid state reaction using the Y 2 O 3 and Al 2 O 3 as the raw materials. The resistances to CMAS corrosion of these materials at 1250 degrees C and 1350 degrees C were compared fully. The compositions and structures of the samples before and after corrosion were analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results showed that the different chemical compositions of the materials resulted in the different optical basicity (OB) values which can decide the reactivity of the material with the CMAS melts. The Y 3 Al 5 O 12 ceramic material was inert to the CMAS for its low OB value of 0.75 and damaged seriously by the CMAS through physical penetration. The YAlO 3 and Y 4 Al 2 O 9 with the high OB values of 0.80 and 0.87 reacted with the CMAS to form the Ca 4 Y 6 (SiO 4 ) 6 O. The YAlO 3 ceramic bulk exhibited the good performance against the CMAS corrosion benefitting from the formation of the Ca 4 Y 6 (SiO 4 ) 6 O and the CaAl 2 Si 2 O 8 .