Ceramic composites derived from rice husk silica: influence of a low amount of steel fibres

The development of new materials using residues contributes to minimizing environmental degradation with the possibility of improving properties and reducing production costs. In this perspective, the present work aims to develop a composite material replacing refractory clay with rice husk silica (RHS) to improve the mechanical strength and steel fibres (SF) to increase both the ductility and thermal shock strength of the material. It was used three different dosages for RHS (10, 20, or 30%) in the total clay volume and fibres in a percentage of 1%. When RHS content was increased, the density and flexural strength increased, while the porosity decreased. The inclusion of fibres increased the density and porosity values, reduced the flexural strength, and increased the ductility. The thermal shock strength decreased with the RHS addition but the inclusion of fibres improved it. After sintering, the specimens containing just clay showed the presence of Quartz and Mullite phases, indicating the temperature was not high enough to complete the phase transformation. Samples with RHS showed Quartz, Mullite and Cristobalite phases. The results demonstrate the efficiency of RHS associated with SF to improve the mechanical and thermo mechanical properties of ceramic materials, with potential to contribute to sustainably and circular engineering. The fracture changed from totally fragile to quasi-fragile with the use of fibres. Furthermore, the number of cycles in the thermal shock test increased six times. The specimens containing 20% RHS and 1% SF presented the best performance.