Investigation of Furnace Uniformity and its Effect on High-Temperature Fixed-Point Performance

A large-area furnace BB3500YY was designed and built at the VNIIOFI as a furnace for high-temperature metal (carbide)–carbon (M(C)–C) eutectic fixed points and was then investigated at the NMIJ. The dependence of the temperature uniformity of the furnace on various heater and cell holder arrangements was investigated. After making some improvements, the temperature of the central part of the furnace was uniform to within 2K over a length of 40 mm—the length of the fixed-point cell—at a temperature of 2,500°C. With this furnace, the melting plateaux of Re–C and TiC–C were shown to be better than those observed in other furnaces. For instance, a Re–C cell showed melting plateaux with a 0.1K melting range and a duration of about 40 min. Furthermore, to verify the capability of the furnace to fill cells, one Re–C and one TiC–C cell were made using the BB3500YY. The cells were then compared to a Re–C cell made in a Nagano furnace and a TiC–C cell filled in a BB3200pg furnace. The agreement in plateau shapes demonstrates the capability of the BB3500YY furnace to also function as a filling furnace.