Design and test of a microwave heater

Abstract

The use of microwave energy to heat ceramics at high temperatures has gained increasing interest because of its industrial applications. The technique saves both energy and time, and it improves the materials' properties. In this thesis, we have designed and tested more than 20 heaters which were made of SiC-based composite materials that show a strong and fast microwave absorption in a kitchen microwave oven (2.45GHz, 1.5 KW). The tests were very promising as some heaters could be heated up to temperatures close to T= 1750°C in four minutes. The highest temperatures (1650°C and 1750°C) were obtained in the case of (90% SiC + 10% Al2O3) heater and (90% SiC + 10% V2O3) heater respectively. Different compositions were investigated and structural analyses of the samples before and after treatment were carried out by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM/EDS). The results showed that many oxide nanostructures were formed after microwave exposure along with new phases. Successful tests have been reported in this thesis about sintering alumina-titania (70% Al 2O3 + 30%TiO2) at 1350°C for 5 minutes in a microwave oven and a conventional furnace. Many nanostructures of zinc oxide powder have been synthesized by evaporation-oxidation of metallic zinc using microwave heaters within 1.5 minutes.