Current State Art of Hot Thermocouple Technology—Novel Way for the Study of Mold Flux High-Temperature Properties

Hot Thermocouple Technology has been developed and approved to be a novel method to study the high-temperature related properties of molten slag. In this study, it will first give the development of Hot Thermocouple Technology, and its typical application to the mold flux. One example of crystallization process of the mold flux for casting low carbon (LC flux) and medium carbon steels (MC flux) were investigated by using Double Hot Thermocouple Technology (DHTT). The results of LC flux showed that, the glass phase firstly formed at the low temperature side; then, the fine crystals precipitated at the liquid/glass interface and grew toward glass and later on to liquid phase. However, the crystals directly formed at the low temperature side when MC flux was under cooling process and grew toward the high temperature side; which indicated the crystallization ability of MC flux was stronger than LC flux. Another crystallization sample of CaO-SiO₂-B₂O₃ based fluoride-free mold flux (F-free flux) was studied by using Single Hot Thermocouple Technology (SHTT), and the results showed the crystals first precipitated in the middle of sample and moved toward the thermocouple side, then the precipitated crystals grew up and new crystals formed in the middle of sample and moved toward the side, until the crystallization was completed and reached a steady state; the crystallization mechanism of the F-free flux was 1-dimensional growth.