Investigação das propriedades mecânicas e termomecânicas de materiais cerâmicos refratários produzidos com sílica residual da casca de arroz e fibra de aço

Abstract

Due to the high content of silica present in rice husk ash, it can be used as raw material for the manufacture of refractory ceramics. The State of Rio Grande do Sul is the largest national producer of rice. The processing of the rice generates by-products, among them the husk, the source of energy for the drying of the cereal. The burning of the husk creates a new residue, the ash of the rice husk, which is usually discarded in soils or landfills. In previous work observed that refractory ceramic materials produced with 20% of silica resulted in an increase in compressive and flexural strength, but showed lower thermal shock resistance than conventional ceramics. Thus, in the present work, metallic fibers were used in order to increase the resistance to thermal shock and the ductility of the refractory ceramic materials. The specimens were fabricated with addition of 15% or 20% of rice husk silica, and substitution of 1% or 2% of refractory steel fiber. After a firing at 1300 °C, physical, mechanical and thermomechanical properties of material were determined by water absorption, bulk density, apparent porosity, compressive strength, three-point bending, thermal shock, thermal conductivity and microstructure analysis of material. The substitution of silica clay resulted in higher mechanical strength and higher toughness, possibly due to decreased porosity and increased level of vitrification. The ceramic with 2% of fiber presented a greater ductility and a greater resistance to the thermal shock.