Evaluation of kaolin and bauxite from the Amazonian region addition on mechanical-, physical-, chemical properties and microstructural characterization of red ceramic industry clay of Manaus metropolitan region

Abstract

The present work investigated properties of red ceramic from the Amazonian region after the addition of kaolin and bauxite mixture with 0, 10, 20 and 30%wt. in red ceramic industry clay. Assessed mechanical properties were flexural strength and Young's modulus. The assessed physical properties were density and porosity. The microstructural images were assessed with SEM and OM microscopies. The fired samples XRD, the raw materials XRF and the XRD were made for chemical composition and present phases assessments. Samples were manufactured by uniaxial compaction and fired at 1200°C and 1250°C. Samples without the mixture of kaolin/bauxite presented higher assessed properties, with approximately 32 MPa of flexural strength and 12% of porosity with 2.3 g/cm³ density. Although the initial idea of this work was to add the mixture of kaolin/bauxite in the red ceramic industry clay for improving assessed properties of red ceramic fired parts, the red ceramic industry clay without addition presented better properties. Such properties were attributed to the high aluminous materials content in the raw material. This behaviour is correlated to the fact that bauxite from this region presents 55%wt. of iron oxide content with aluminium oxide content lower than 25%wt. Additionally, the assessed properties of the ceramic industry parts fired at 1250°C presented this material as promising material for ceramic products with a better added value.