Non-contact measurements of thermophysical properties of titanium at high temperature

Four thermophysical properties of both solid and liquid titanium measured u sing the high-temperature electrostatic levitator at JPL are presented. The se properties are density, thermal expansion coefficient, constant pressure heat capacity, and hemispherical total emissivity. For the first time, we report the density, the thermal expansion coefficient, and the ratio of the constant pressure heat capacity to the hemispherical total emissivity of u ndercooled titanium over a wide range of temperatures. Over the 1650 K to 2 000 K temperature span, the liquid density can be expressed as rho(T)/(kg.m (-3)) = 4.208 . 10(3) - 0.508 (T - T-m)/K with T-m = 1943 K, and the corres ponding volume expansion coefficient as alpha = 1.169 . 10(-4) K-1. Similar ly, over the 1540 K to 1940 K temperature range, the measured density of th e solid can be expressed as rho(T)/(kg.m(-3)) = 4.321 . 10(3) - 0.212 (T - T-m)/K, giving a volume expansion coefficient alpha = 4.76 10(-5) K-1. The constant pressure heat capacity of the liquid phase could be estimated as C -p,C-m(T)/(J . K-1 . mol(-1)) = 45.5 - 3.21 . 10(-3). (T - T-m)/K if the he mispherical total emissivity of the liquid phase epsilon(T) remains constan t at 0.34 over the 1650 K to 2000 K temperature range. Over the 1540 K to 1 940 K temperature span, the hemispherical total emissivity of the solid pha se could be rendered as epsilon(T)(T) = 0.297 + 5.952 10(-5). (T - T-m)/K. The enthalpy of fusion has also been calculated as 14.3 kJ mol(-1) (C) 2000 Academic Press.