BORON AND BORATES: EXTRACTION, PROCESSING AND APPLICATIONS

The potential of the Barker lattice theory for interpreting thermodynamic properties of mixtures of non-electrolytes is discussed. The basics of this theory and a short survey of the results of its application to hydrocarbon systems found in the literature are presented. Further development and results of adaptation of the theory for oxide melts modeling are reviewed and the occurring difficulties are sorted out. Based on the computational results for MO-B2O3-SiO2 melts a proposal is made to improve consistency of the modeling by devising a more sophisticated set of lattice parameters. Introduction of additional 'virtual' components in the model allows to take into account four-coordinated boron and some other structural features of the melts. This idea was tested for the melts in the PbO-SiO2 and PbO-B2O3 systems using experimental values of the component activities obtained by high temperature mass spectrometric method.

In this study, production of sub-micron sized boron carbide powders via self-propagating high temperature synthesis were investigated by igniting of stoichiometric mixture of B2O3, C and Mg powders and with the addition of different percentages of NaCl as SHS diluents. The SHS reactions were realized in a MgO-lined crucible in inert argon atmosphere and reaction was initiated by W (tungsten) wire coil. The selective leaching was carried out after SHS reaction. The addition of NaCl reduced the particle size of the final product by reducing the adiabatic temperatures of the SHS reaction. The samples were investigated by using XRD, chemical analysis and SEM techniques during different stages of production.