Measurement of thermophysical properties of molten Si-Cr and Si-Fe alloys for design of solution growth of SiC

To optimize the solution growth process, temperature and convection of the solvent, which are significantly affected by the thermophysical properties, have to be well controlled. In this study, the thermophysical properties of molten Si-Cr and Si-Fe alloys, which are important solvent systems for the solution growth of silicon carbide (SiC), were measured via electrostatic levitation and laser flash methods. The total hemispherical emissivity, spectral hemispherical emissivity, and heat capacity at constant pressure of the Si-Cr alloys at their liquidus temperatures were successfully obtained, and their compositional dependencies are discussed. The thermal diffusivity and thermal conductivity of the Si-Cr and Si-Fe alloys exhibited a linearly increasing trend with increasing temperature. Thermal conductivities of a few tens of W∙m⁻¹∙K⁻¹ were obtained, and the thermal conductivity markedly decreased by alloying for both the investigated alloy systems. Such a large drop would lead to a large difference of the temperature distribution during the solution growth of SiC, and hence the obtained properties can be utilized for optimization of the process.