Využití konverze geopolymerních pojiv k výrobě jader

Abstract

Nowadays, there is increasing pressure to use more favourable foundry technologies, particularly for large series production of cores for the automotive industry. Preferred are inorganic binder systems, technologies characterized by physical curing. These technologies include an inorganic geopolymer binder. The aim of this thesis is to deepen the knowledge of the properties of foundry binders based on geopolymer precursor in sol-gel conversion during physical heat curing. Furthermore, the study of the influence of potassium ions on the properties of the geopolymer precursor and subsequently on the properties of the mixture and properties of the cured geopolymer precursor and the properties after casting. The research was focused on the sodium-potassium type of the geopolymer precursor (binder) Na-KGP. The work solves chemical, physical properties of geopolymer precursor and technological properties of core sand mixtures made from these binders and assesses them with a commercially available geopolymer binder based on sodium ions. The flexural strength tests, the residual strength at higher temperatures, the shelf life of the cores, the durability of sand, the shooting ability of the mixture, the abrasion test, including the casting production in foundry and the final evaluation were used to prove the technological properties. Physical and chemical properties were analyzed by a number of methods, in addition to standard basic properties, such as 27Al and 29Si MAS-NMR, X-ray methods, FTIR spectroscopy, Raman spectroscopy, thermal analysis, SEM and EDX analysis. The impact on work environment and the environment was also assessed. The viability of the investigated binders is evidenced by the operational production of cores in several foundries, including a basic description of the cores and the castings production and the resulting evaluation.