The analysis of Si3N4, SiC and BN by combustion with elemental fluorine coupled to mass spectrometry

Combustion with elemental fluorine has been used for the decomposition of ceramic powders of Si₃N₄, SiC and BN. Volatile reaction products like N₂, BF₃, SiF₄ and various fluorides of carbon are detected on-line with a quadrupole mass spectrometer. It is shown that thermal separation of the combustion products by controlled release from a cooling trap is useful to decrease limitations by isobaric interferences in quadrupole mass spectrometry. The developed fluorine combustion coupled to a mass spectrometry procedure has been used for the determination of the stoichiometry of Si₃N₄ in which Si could be directly determined.