Radiance temperatures (in the wavelength range 525 to 906 nm) of vanadium at its melting point by a pulse-heating technique

Abstract

The radiance temperatures (at six wavelengths in the range 525 to 906 nm) of vanadium at its melting point were measured by a pulse-heating technique. The method is based on rapid resistive self-heating of the specimen from room temperature to its melting point in less than 1 s and on simultaneously measuring the specimen radiance temperatures every 0.5 ms with a high-speed six-wavelength pyrometer. Melting was manifested by a plateau in the radiance temperature-vs-time function for each wavelength. The melting-point radiance temperatures for a given specimen were determined by averaging the measured temperatures along the plateau at each wavelength. The melting-point radiance temperatures for vanadium as determined by averaging the results at each wavelength for 16 specimens (standard deviation in the range 0.3 to 0.4 K. depending on the wavelength) are 2030 K at 525 nm, 1998 K at 622 nm, 1988 K at 652 nm, 1968 K at 714 nm, 1935 K at 809 nm, and 1900 K at 906 nm. Based on estimates of the random and systematic errors that arise from pyrometry and specimen conditions, the resultant uncertainty (2 SD level) in the reported values is about ±7 K at each wavelength.