International Journal oj Thermophysics, Vol. 20, No. 4, 1999 Thermophysical Properties by a Pulse-Heating Reflectometric Technique: Niobium, 1100 to 2700 K F. Righini, 2 3 J. Spisiak,4 G. C. Bussolino,2 and M. Gualano2 Pulse-heating experiments were performed on niobium strips, taking the specimens from room temperature to the melting point is less than one second. The normal spectral emissivity of the strips was measured by integrating sphere reflectometry, and, simultaneously, experimental data (radiance temperature, current, voltage drop) for thermophysical properties were collected with sub- millisecond time resolution. The normal spectral emissivity results were used to compute the true temperature of the niobium strips; the heat capacity, electrical resistivity, and hemispherical total emissivity were evaluated in the temperature range 1100 to 2700 K. The results are compared with literature data obtained in pulse-heating experiments. It is concluded that combined measurements of normal spectral emissivity and of thermophysical properties on strip specimens provide results of the same quality as obtained using tubular specimens with a blackbody. The thermophysical property results on niobium also validate the normal spectral emissivity measurements by integrating sphere reflectometry. 1. INTRODUCTION Pulse-heating techniques are among the most versatile and accurate methods for the simultaneous determination of several thermophysical properties at high temperatures. Practical applications often require measurements to be performed on simple specimens. This paper describes accurate experimental 1 Paper presented at the Fifth International Workshop on Subsecond Thermophysics, June 16-19, 1998, Aix-en-Provence, France. 2 CNR Istituto di Metrologia "G. Colonnetti," strada delle Cacce 73, 1-10135 Torino, Italy. 3 To whom correspondence should be addressed. 4 Permanent address: Institute of Physics, Slovak Academy of Sciences, Bratislava, Slovakia. KEY WORDS: electrical resistivity; heat capacity; hemispherical total emissivity; high temperatures; niobium; pulse-heating; refractory metals. 1107 0195-928X/99/0700-1107J16.00/0 © 1999 Plenum Publishing Corporation