Optical microscopy of ceramic materials based on fly ash from thermal power plants

The data on the annual release of ash and slag waste as a result of the operation of thermal power plants (TPP) in Siberia and the Far East of the Russian Federation are presented. The main reasons for the insignificant use of ash in the construction industry (about 5-8% of the total waste output) and the problems hindering its use for the production of ceramic wall materials are considered. A brief description of the composition and properties of the raw materials used in this work for the manufacture of ceramic wall materials is given. The compositions of the developed fly ash-based charges and the method of manufacturing ceramic samples with a matrix structure are given. The results of the study of the structure of ceramic materials by optical microscopy are presented. It is established that during the firing process, a matrix (dispersion medium) is formed from the fusible shell of aggregated complexes, and granules from fly ash are transformed into cores (dispersed phase) of a ceramic matrix composite. It was revealed that the kernels have an oval shape due to the deformation of the granules during pressing. Clusters are formed in the nuclei, consisting of a large number of small crystalline grains connected by an amorphous substance and edged with thin chains of pores. It is shown that the developed pore space inside the cores is mainly represented by frost-proof and reserve pores, which ensures high frost resistance of ceramic samples based on fly ash.