Quantitative determinations of SiC and SiO2 in new ceramic materials by Fourier transform infrared spectroscopy

Silicon carbide-based biomorphic ceramics have been fabricated by the pyrolysis and infiltration of natural wood (mukali and pine) with molten silicon. The results of the process of synthesis have been studied in this and other biomorphic ceramics using thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) analysis and scanning electron microscopy (SEM). For evaluating the yield of the synthesis, a new method by Fourier transform infrared spectrometry (FTIR) has been developed for the direct determination of SiC and the simultaneous determination of SiC and SiO2 by absorbance measurements in KBr pellets. The procedure was based on the use of the ratio between the absorbance of the characteristic band of silicon carbide or silica and those of an acetate internal standard added to samples. A multivariate calibration strategy based on inverse least squares and the standard addition approach were employed for quantification. The results obtained for all biomorphic ceramics studied and synthetic samples prepared by mixing pyrolyzed wood with pure SiC were satisfactory. The relative standard deviation for all samples was lower than 2.9%.