Non‐Isothermal Solid Phase Diffusion in Activated Powder Mixtures. Thermal Regimes and Critical Conditions

Abstract

In the present paper, the analysis of thermal modes of solid phase synthesis in the volume of mechanically activated powder mixtures was conducted. As a basic model, the Carter‐Valensi model of solid phase interaction in powder systems was used. This model was considered from point of view of non‐isothermal kinetics for the first time. Using the maximum temperature method, the critical ignition conditions of the mixture and the conditions of thermal explosion degeneration were determined. The corresponding diagrams of critical parameters were obtained and the parametric regions of thermal explosion existence were defined. The results presented allows solving the technologically important problem of demarcation of fast (thermal explosion) and slow (isothermal sintering) synthesis modes. Thus, it becomes possible to control the chemical activity of a heterogeneous reaction purposefully.

Effect of Initial Conditions and Numerical Investigation of Instability Developed during Synthesis of TiC via Vortex Combustion at Moderate Temperatures. Model of Vortex Combustion

“…Irreversibility in combination with a gas has played a cruel joke with the modern theory of thermal explosion (MTTE) [13][14][15][16][17][18][19]. The fact is that authors of the first, outstanding works on MTTE [13.14] awarded for them by the gold medal of the Combustion institute in 2011, have mistakenly considered the reaction of thermal decay of azomethane as an irreversible .…”

“…All the followers of [13.14] were also supporters of irreversibility, but with no gas. While they also receive overestimated initial overheats (OIO), they classify and analyze with the help of OIO the kinetics of sets of parallel reactions [15][16][17][18][19]…”