Speciation of aluminium in silicon carbide by electrothermal vaporization-inductively coupled plasma atomic emission spectrometry

An electrothermal vaporization-inductively coupled plasma atomic emission spectrometric (ETV-ICP-AES) method was developed for rapid determination of binder and lattice phase aluminium in liquid-phase sintered silicon carbide (LPS-SiC) materials. By means of thermal fractionation the binder and the lattice phase aluminium were evaporated from the solid sample in temperature ranges of 1250 - 2000 and 2000 2450 degrees C, respectively. Due to the decomposition of silicon carbide matrix above 2000 degrees C, and the vaporization of silicon, a strong matrix effect was observed which resulted in different sensitivities for determination of the binder and the lattice phase aluminium. Therefore the calibration needed two calibration curves determined by home-made solid standard materials in the above mentioned temperature ranges. Using this method aluminium can be measured in concentration range of 0.1 - 2.0% in two different phases within 90 min. The time demand of the conventional wet chemical method amounts to 16 h. The analytical data determined by the ETV-ICP-AES method deviate from the wet chemical results maximum by - 13 and +20%, which is acceptable for the technological control of the LPS-SiC production.