Analysis of free Si in SiC and Si₃N₄ based ceramics with emphasis on accuracy and industrial application

Non-oxide engineering ceramics such as silicon carbide and silicon nitride are receiving ever attentions due to their thermal and chemical resistance. However free Si remained in synthesis process or created during their sintering can negatively influence their application. Therefore, evaluation of free Si in these materials is vital in order to judge the suitability of these materials for specific application. In this article free Si was measured by quantitative X-ray diffractometry and wet chemical method. The error results were calculated and analysed in terms of reproducibility and precision. Although XRD was able to detect the free Si in small amounts of 0,1 mass-%, but the gas volumetry was found to be more practical and versatile for industrial application. The detection limit and precision was also comparable to XRD.