Ultra-fast thermal shock behavior of Cr2AlC ceramics up to 1300 °C

Abstract

Cr2AlC ceramic, an exceptional MAX phase, has been the subject of intensive investigation in this study to elucidate its ultra-fast thermal shock mechanisms. In this investigation, the samples were subjected to rapid induced heating in air and quenching in both air and water, at temperatures ranging from 570 to 1300 °C. Comprehensive analysis was conducted to explore the thermal shock behavior, including changes in strength, phase transformation, and surface/cross-section microstructure at different quenching temperatures. After water quenching, the strength of the samples decreased to 172 and 59 MPa at 570 and 960 °C, respectively, due to factors such as cooling rate, coefficient of thermal expansion (CTE), and stratification of the oxide layer. Notably, at 1150 °C, the presence of a dense oxide layer resulted in a slight increase in strength to 76 MPa. On the other hand, after air quenching, the slow cooling rate caused that the strength of the samples remained at 448 MPa even at the temperature as high as 1150 °C. However, at 1300 °C, the sharp rise in Al2O3 levels on the surface precipitated the stratification of oxide layer, which, in turn, led to the significant decrease in strength to 158 MPa. Performance at high temperatures highlighted the excellent thermal shock resistance exhibited by Cr2AlC ceramic.