Non-isothermal oxide bond phase formation kinetics of SiC powder coated with yttrium aluminum garnet (YAG) sol

SiC powders (d(50) = 6.25 mu m) were coated with YAG by co-precipitation method and the coated powders were characterized by surface area, surface potential measurement, FTIR spectroscopy, XRD and thermal analysis. Non-isothermal kinetic data of two exothermic peaks in the temperature range 1200-1450 degrees C were evaluated by isoconversional methods using Netzsch Thermokinetics software module. The best fitting was obtained with second order reaction (F-2) model for the peak I (1207-1359 degrees C) and Avrami-Erofeev (A(n)) nucleation model for the peak-II (1324-1450 degrees C). The activation energy was determined as 605.57 kJ/mol and 1041 kJ/mol for peaks I and II respectively. Oxide bonded porous SiC ceramics fabricated at 1450 degrees C using YAG coated SiC powders exhibited flexural strength of similar to 26.1 MPa at porosity level of similar to 38.6 vol %. The corrosion results of ceramic sample after 10 days in strong acid solution revealed 6.5 wt % mass loss and 80% reduction of flexural strength. (c) 2018 Elsevier B.V. All rights reserved