Pore formation mechanism and oxidation resistance of porous CoAl3 intermetallic prepared by rapid thermal explosion

Porous CoAl 3 is a candidate material in the field of catalytic due to its high porosity, good thermostability and quasicrystal structure. However, its rapid preparation are still a challenge, and the oxidation resistance need to be further investigated. In this work, we have rapidly prepared porous CoAl 3 by thermal explosion (TE) reaction and studied its oxidation process . The results show that two exothermic peaks at 616 °C and 646 °C, corresponding to the solid-phase diffusion and TE reaction, respectively. The heat released from the two reactions led to the expansion of the compact, which reached a maximum of 104% at 800 °C, and the corresponding open porosity reached at 53%. The pore sources include the original pores during the green compact pressing process, the Kirkendall pores generated by the solid-phase diffusion process and the in-situ pores generated by the Al consumption after the TE occurs. The cyclic oxidation of porous CoAl 3 at 700 °C for 130 h only increased the weight by 1.52%, forming a continuous protective oxide film on the surface of the skeleton. It has been found that porous CoAl 3 can combine the oxidation resistance of Co–Al monoliths alloys and the high porosity of porous materials, which have potential applications in the field of catalysis such as methanation at 600–700 °C.