Contribution to the clarifying of the action of thermochemical additives on the modification of a matrix silicon carbide using scanning electron microscopy and energy dispersive X-ray analysis

Previous investigations have shown that the total evaporation of impurities from silicon carbide powder can be achieved by its thermochemical transformation to BaSiO3, BaF2 and CoSi (CoSi2) under the action of the modifier CoF2 + BaO, through in situ processing in an electrothermally heated graphite crucible [13]. The aim of the present work has been to describe a methodology to perform a rational selection of various potential candidates for modifiers, to make successful combinations between various chemical additives, to understand the reason(s) for an effective/ineffective action of a particular additive, i.e. to find the optimum conditions for each type of ceramic matrix chemical modifier. A combination of scanning electron microscopy (SEM), energy dispersive X-ray analyses (EDX) and X-ray diffraction analyses was used to confirm the identification of the alterations to the silicon carbide matrix. Indirectly, the present work supports the view that “the aim justifies the means” particularly when the aim is to reach a complete evaporation of the impurities from a carbide matrix, which as is well known, is not an ordinary or easy task.