Thermal Shock Behavior Of Cr₂AlC In Different Quenching Media

Cr2AlC is a good candidate for high temperature applications due to its high electrical conductivity, high modulus, good thermal shock resistance, high temperature oxidation resistance and hot corrosion resistance. Cr2AlC as one member of MAX phases exhibits an abnormal thermal shock behavior upon quenching in water. The abnormal thermal shock behavior has been intensively studied. However, work on the thermal shock behavior of Cr2AlC in other quenching media has been much less focused.The main purpose in the present work is to investigate the abnormal thermal shock behavior of Cr2AlC bulk material in different media such as quenching oil and molten salt.The main results are listed as follows:Cr2AlC exhibits an abnormal thermal shock behavior in quenching oil as thermal shock temperature is up to1000℃. The main mechanism for the abnormal thermal shock behavior is that the thermal shock induced cracks are instantly healed by A12O3during quenching in oil at high temperatures. Cr2AlC also shows the same thermal shock behavior in molten salt as in the quenching oil. However, its residual strength increases at above800℃, and then decreases at above1000℃. The main mechanism is that increase in residual strength is induced by the crack healing by formation of A12O3at below1000℃, and the degradation of the residual strength is resulted from the intensive hot corrosion by molten salt at above1000℃.The abnormal thermal shock behaviors of Cr2AlC in different quenching media are influenced by the cooling rate and oxidation rate of quenching media that further determine the efficiency of crack healing.The present study can widen the applications of Cr2AlC and also provide a method to study thermal shock behavior of ceramic materials.