Solid-state kinetic reactions at high temperatures - Basic notions and elementary processes

School and university curricula devote a considerable amount of time to the study of reactions. But these are almost exclusively limited to reactions occurring between gases or in liquids (acid/base reactions, oxidation-reduction, etc.). In each of these cases, everything takes place within the same phase: these are so-called "homogeneous phase" reactions. However, in a great many cases, some of which are mentioned in the course of this dossier, the engineer is confronted with reactions involving a solid and a fluid (gas or liquid), which constitute "heterogeneous" systems. In such cases, the engineer finds himself at a particular disadvantage, since, in addition to the fact that he has often not studied this type of system during his training, the reactions involved are generally highly complex. To describe the reactions affecting solids heated to high temperatures, several high-quality works [1][2][3][4][5] are available in French, as this field of research is well covered in France by internationally-recognized specialists. In English, we should mention the reference book by P. Kofstad [6] . However, these exhaustive works are naturally voluminous, and it seemed useful to offer, in a limited space, the essentials of what needs to be known to explain physico-chemical reactions involving a heated solid, and to do so in a way that is easily accessible to a non-specialist. As a consequence of this choice, it is obviously necessary to go into very little detail on the concepts involved: the reader will find any additional information he or she may need in the above works, or in the articles referenced in the course of the text.

The kinetics of solid state reactions at elevated temperatures is the subject of two dossiers: [AF 3 688] Part 1 and [AF 3 689] Part 2.