Thermophysical properties of zirconium at high temperature

Abstract

Six thermophysical properties of both solid and liquid zirconium measured using the high-temperature electrostatic levitator at the Jet Propulsion Laboratory are presented. These properties are density, thermal expansion coefficient, constant pressure heat capacity, hemispherical total emissivity, surface tension, and viscosity. For the first time, we report the densities and the thermal expansion coefficients of both the solid as well as liquid Zr over wide ranges of temperatures. Over the 1700–2300 K temperature span, the liquid density can be expressed as ρ_1(T) = 6.24 × 10^3 – 0.29(T – T_m) kg/m^3 with T_m = 2128 K, and the corresponding volume expansion coefficient as α_1 = 4.6 × 10^(−5)/K. Similarly, over the 1250–2100 K range, the measured density of the solid can be expressed as ρ_s(T) = 6.34 × 10^3 – 0.15(T – T_m), giving a volume expansion coefficient α_s = 2.35 × 10^(−5)/K. The constant pressure heat capacity of the liquid phase could be estimated as C_(pl)(T) = 39.72 – 7.42 × 10^(−3)(T – T_m) J/(mol/K) if the hemispherical total emissivity of the liquid phase ε_(T1) remains constant at 0.3 over the 1825–2200 K range. Over the 1400–2100 K temperature span, the hemispherical total emissivity of the solid phase could be rendered as ε_(Ts)(T) = 0.29 – 9.91 × 10^3 (T – T_m). The measured surface tension and the viscosity of the molten zirconium over the 1850–2200 K range can be expressed as ς(T) = 1.459 × 10^3 – 0.244 (T – T_m) mN/m and as η(T) = 4.83 – 5.31 × 10^(−3)(T – T_m) mPa s, respectively.

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