Development of lightweight refractory insulating bricks and investigation of their properties

Today, in the world and our country, energy recovery, conservation and its efficient use is of great importance. Therefore, for the conservation of energy, the importance of lightweight insulation refractories used at applications of high temperature has also increased. Lightweight refractory isolation bricks can be classified in two groups according to their applications at low (<1200 °C) and high (>1200 °C) service temperature. In this application, lightweight refractory compositions including refractory clay, diatomite and vermiculite that can be used at temperatures less than 1200 °C for heat isolation were studied. Vermiculite is a local raw material source and experimented in lightweight refractory compositions. In our country, local vermiculite is not yet widely used as a raw material, and but, it could be used for refractory industry that will contribute to our country. In addition, the lightweight and micro-porous insulation refractories were produced using diatomaceous earth. This study covers the mixtures of different proportions from refractory clays, diatomaceous earth and expanded vermiculite in powder form prepared using raw materials. Raw materials were characterized by the analysis of chemical (x-ray fluorescence, XRF), thermal (thermal gravimetric analysis, TGA), morphological (scanning electron microscopy, SEM) and phase (x-ray diffraction, XRD). The prepared mixtures were shaped by the method of semi-dry pressing, and then the samples were produced by sintering at the temperatures between 900°C and 1100°C in a laboratory furnace. The physical (density, porosity, dimensional change), mechanical (compression strength), thermal (thermal conductivity), and microstructural properties of the samples were investigated.