Investigating non-isothermal oxidation kinetics of a non-stoichiometrically synthesized Ti3AlC2 MAX phase

Abstract

Synthesis protocol plays a crucial role in the large-scale production of Ti3AlC2 MAX phases and its derivative MXenes. A non-stoichiometric pressure-less sintering approach is proposed to obtain a highly pure Ti3AlC2 MAX phase at 1500 ºC. The variation in aluminum content plays a vital role during the synthesis of Ti3AlC2. The impurity phase (TiC) was minimal when the non-stoichiometric ratio was Ti:TiC:Al = 1:0.75:1.3. Microstructure analysis confirmed the typical nano-laminated structure of the MAX phase. Non-isothermal oxidation stability of Ti3AlC2 was also examined through TGA/DTA technique. Deconvolution kinetic analysis was performed to distinguish three peaks corresponding to the reactions responsible for the oxidation of the MAX phase. The kinetic triplets were estimated by following iso-conversional kinetic methods. Kissinger-Akahira-Sunose (KAS) and Freidman (FR) iso-conversional methods were used to calculate activation energy for oxidation peak I (KAS: 107.25 kJ/mol, FR: 104.80 kJ/mol), II (KAS: 140.61 kJ/mol, FR: 178.24 kJ/mol) and III (KAS: 173.72 kJ/mol, FR: 217.63 kJ/mol). The integral master plot method revealed that F1 reaction mechanism dominated oxidation peaks I and III; for oxidation peal II, A2 reaction mechanism was responsible.