Studim reoxidačních pochodů při odléván slitin železa do syrových forem

Abstract

This doctoral thesis is focused on reoxidation processes during casting of ferro-alloys in to the green sand moulds. Reoxidation is one of the main process that take place during casting metal in air atmosphere. Due the reoxidation processes during casting occur casting defects, which represent additional costs in production. The theoretical section summarizes the basis for understanding of reoxidation processes. Measurement of oxygen activity in metal, an overview of different types and causes of reoxidation defects, and possible ways of exploring reoxidation processes. The experimental part is focused on the application of methods for research of reoxidation processes on experimental and as well as industrially manufactured castings. The measurements of oxygen activity in the mould cavity by casting of experimental castings were taken. Evaluation of chemical composition changes in metal of industrial castings was also applied, and monitoring of changes in chemical composition of surface layers of the experimental castings too. For all experimental castings were defects evaluating performed. Also analysis of a secondary slag from the surfaces of experimental castings have been carried out. The present thesis summarizes obtained results on the basis the adjustments in foundry technology can be done to reduce casting defects caused by reoxidation.