Preparation and characterisation of novel carbon materials for refractory applications
Researcher: Janke Ye
Supervisors: Dr Shaowei Zhang (The University of Sheffield) and Professor Bill Lee (Materials)
Funding: Centre for Advanced Structural Ceramics
Carbon-containing castables are novel materials highly desired by both the refractories industry and the steel making industry. However, their development and commercialisation are still being hindered by several technical difficulties, in particular, the poor water-wettability and dispersion ability of carbon materials. To solve this major problem, three main techniques are being investigated with this project, i.e., molten salt coating, controlled surface oxidation (CSO) and hydrothermal pyrolysis (HP) techniques.
The work during the past year has been mainly focused on the low temperature preparation of high quality carbide coating (SiC or TiC) on carbon black by using the molten salt synthesis (MSS) technique. The effects of processing parameters on the MSS process and coating quality have been studied, and the synthesis conditions optimized. The results showed that under the optimized conditions, high quality TiC coatings can be prepared at as low as 850oC and SiC coatings at as low as 1000-1100 oC. These synthesis temperatures are much lower than required by most of the coating techniques used previously.
Thanks to the high quality of the carbide coatings, the water-wettability of carbon black as well as its dispersion ability has been substantially improved. As shown in the Figure, the apparent viscosity of water suspensions containing carbide coated carbon black becomes two orders of magnitude lower than that containing uncoated carbon black, which is very promising. Recently, kg-scale trial production of carbide coated carbon black has been carried out. The resultant materials are being used to make bulk castable samples for further detailed structure and property testing. The work is still ongoing with great support from a UK refractories company.