Noncontact Measurements of Thermophysical Properties of Molybdenum at High Temperatures

Abstract

Four thermophysical properties of both solid and liquid molybdenum, namely, the density, the thermal expansion coefficient, the constant-pressure heat capacity, and the hemispherical total emissivity, are reported. These thermophysical properties were measured over a wide temperature range, including the undercooled state, using an electrostatic levitation furnace developed by the National Space Development Agency of Japan. Over the 2500 to 3000 K temperature span, the density of the liquid can be expressed as ρ _L(T)=9.10×10³−0.60(T−T _m) (kg·m⁻³), with T _m=2896 K, yielding a volume expansion coefficient α _L(T)=6.6×10⁻⁵ (K⁻¹). Similarly, over the 2170 to 2890 K temperature range, the density of the solid can be expressed as ρ _S(T)=9.49×10³−0.50(T−T _m), giving a volume expansion coefficient α _S(T)=5.3×10⁻⁵. The constant pressure heat capacity of the liquid phase could be estimated as C _PL(T)=34.2+1.13×10⁻³(T−T _m) (J·mol⁻¹·K⁻¹) if the hemispherical total emissivity of the liquid phase remained constant at 0.21 over the temperature interval. Over the 2050 to 2890 K temperature span, the hemispherical total emissivity of the solid phase could be expressed as ε _TS(T)=0.29+9.86×10⁻⁵(T−T _m). The latent heat of fusion has also been measured as 33.6 kJ·mol⁻¹.