Discrimination of Ceramics—Study on the Microstructures of Ceramics

A method for discrimination of alumina ceramics was developed based on the observation of the surface morphology of etched surfaces, density, X-ray diffraction line profiles and grain size distributions. The experimental observations of the surface microstructure were made, using the scanning electron microscopy (SEM), on several different alumina ceramics with high (>99%), middle (96 to 98%) and low (approximately 92%) alumina content in order to identify them. The samples were prepared with a sulfuric acid (4.5 mol/L) etching method performed at 150 ≈ 200°C for 2 h on low and middle purity alumina ceramics and for 4 h on high purity alumina ceramics. The results indicate that the SEM observation coupled with computerized image analysis to determine grain size distribution is a powerful tool to discriminate among alumina ceramics that exhibit similar morphological characteristics. The X-ray diffraction line profile study is suggested as an additional useful index for the determination of microcrystalline structure.