Decomposition kinetics pore microstructures

In addition to the kinetics, the microstructure of the solid product particles is also dependent on the decomposition conditions. A feature of decomposition reactions is the ability to produce very fine particle size from a normally coarse reactant when the reaction is carried out under controlled conditions. In vacuum, the decomposition reaction is oftenpseudomorphic (i.e., the product particle often maintains the same size and shape as the reactant particle). Since its molar volume is lower than that of the reactant, the product particle contains internal pores. Often the product particle consists of an aggregate of fine particles and fine internal pores. In the decomposition of 1-10 p.m CaCOs particles performed at... 

In this paper, we have conducted a comparative study to elucidate the role of pore microstructures on the decomposition kinetics of several MAX phases during vacuum annealing in the temperature range 1000-1800 C. Xhe effect of pore-size on the activation energy of decomposition was evaluated using the Arrhenius equation. 

Except for bulk Ti3 AIC2 which exhibited negative activation energy, positive activation energies were determined for the decomposition of other bulk MAX phases. The pore microstructure of decomposed MAX phase has been shown to play a vital role in the kinetics of decomposition with coarse-pores facilitating the decomposition process but the fine-pores hindering it. 

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