Numerical and experimental investigation of electromagnetic cold crucible used for emissivity measurement of molten material

The electromagnetic cold crucible levitation heating technology has tremendous potential in the spectral emissivity measurement of molten metal for its high melting temperature and no contamination. In this work, we designed a dedicated cold crucible with a hemispherical bottom to establish the spectral emissivity measurement apparatus at high temperature. The effects of different numbers of segments, slit width, wall thickness and height-diameter ratio on the magnetic permeability of crucible were studied by the finite element method. The results indicate that increasing the number of crucible segments and the slit width can effectively improve the magnetic permeability of cold crucible, while increasing the wall thickness and the ratio of height to diameter will reduce its magnetic permeability. Based on the simulation result, the cold crucible with optimal parameters was made and used for studying the spectral emissivity of molten metal. The spectral emissivity of iron, cobalt and nickel was measured successively to prove the availability of cold crucible in emissivity measurement. The results agree well with the literature data, and the combined uncertainty of the molten iron is 2%. This work demonstrates that electromagnetic cold crucibles have a promising prospect in emissivity measurement of molten metal.