Dissertação
Análise da oxidação em matrizes de concreto refratário com adição de carbeto de silício
Fecha
2022-07-22Autor
Eduardo José da Costa e Souza
Institución
Resumen
The increase in competitiveness in the refractory castable industry has stimulated
engineering studies in the search to improve the performance of these materials
and reduce costs. Premature failures in refractory cause huge losses with repair
costs, but mainly with the loss of production, failing to serve customers and
comply with production planning. Carbon oxidation is one of the most complex
failure mechanisms. An alternative explored to control the degradation of
refractory castable is the addition of silicon carbide (SiC), which is recognized as
an essential compound for resistance to high temperatures, good resistance to
corrosion and thermal shock. In this context, the objective of this work is to study
the influence of the addition of silicon carbides in refractory castable,
understanding the mechanical and chemical behavior when exposed to an
alkaline environment and high temperature. For this, concrete specimens were
constructed without silicon carbide and with the addition of 10, 30 and 60% of SiC
for analysis of its oxidation process comparing the results. These matrices were
heated with different heating rates and residence time in the kiln. All samples
were weighed before and after the kiln procedure, using x-ray diffraction and
scanning electron microscopy techniques to understand the reactions. A lower
rate of mass reduction of the matrix with 10% SiC was verified through these
tests, which indicates greater resistance to oxidation, mainly associated with the
formation of mullite Al6Si2O13 through the reaction between SiC and aluminum
oxide Al2O3 present in the concrete composition, the presence of fly ash and the
formation of a layer of silica SiO2 on the surface of the SiC, and this deposition
acts as an antioxidant protector and, consequently, anticorrosion.