Abstract

Most of the thermosetting resins are classified as non-graphitizing carbon sources. However, the chemical resistance and thermo-mechanical properties of refractories bonded with resole or novolak resins depend on the presence of crystalline carbon phases (preferentially with features close to graphite ones) in their compositions. Consequently, there is major interest in finding routes to induce the graphitization of such components at temperatures and conditions similar to the ones that refractories are submitted to in service. This work evaluates the role of processing parameters (mixing, curing and firing temperature) and additives (ferrocene, boric acid and graphite) on the graphitization process of two commercial resins (resole and novolak) and a synthesized one (modified-novolak). X-ray diffraction, Raman spectroscopy and thermogravimetric analyses were carried out to identify the microstructural evolution of the compositions. According to the results, carbon graphitization was already detected after firing the samples at 1000°C for 5h under reducing atmosphere. Ferrocene addition favored a more effective graphitization of the selected resins, but H3BO3 also induced the rearrangement of the carbon derived from the commercial novolak product. The mixing and curing procedures used during the compositions’ preparations proved to be very important steps as they affected in a greater extent the resulting graphitization degree of the fired samples.