Characterization of microstructural and thermal properties of steatite/cordierite ceramics prepared by using natural raw materials

Steatite/cordierite ceramics were fabricated by using a combined method of high-energy ball milling, cold pressing and sintering. Steatite and cordierite powders were separately synthesized from natural raw materials such as kaolinite and talc. The powder blends containing different amounts of cordierite (5, 10 and 20 wt.%) were wet-milled for 1 h in a vibratory ball-mill (Fritsch™ Pulverisette 7 Premium Line), using zirconia vial and balls. After drying, powders were compacted to cylindrical preforms with a diameter of 12.7 mm by uniaxial pressing at 300 MPa. The green compacts were sintered at 1200–1350 °C for 2 h under air. Phase, microstructural and thermal characterizations of the sintered materials were carried out by using X-ray diffraction technique (XRD), thermogravimetry/differential thermal analyzer (TG/DTA) and scanning electron microscope (SEM). Densities, open porosity and water absorption values of sintered bodies were measured by Archimedes method. Thermal expansion coefficient (CTE) measurements were conducted by a dilatometer.