Examination of Thermal Expansion Uniformity of Glassy Carbon as a Candidate Standard Reference Material for Thermal Expansion Measurements.

Abstract

The linear thermal expansion coefficients(LTEC) of some different pieces of the grade GC-20SS of glassy carbon produced by Tokai Carbon Co. Ltd. Japan have been measured using both an interferometric dilatometer and a push-rod dilatometer in order to investigate the piece-to-piece and lot-to-lot consistency for thermal expansion. The results indicated that the differences in LTEC in the temperature range -50 to 220 °C for different pieces from the two glassy carbon lots are sufficiently small within ±4×10-8K-1, which is the same order of measurement uncertainty. Thus, no significant thermal expansion divergency exists among different pieces and lots of GC-20SS glassy carbon, this material seems to be a very promising candidate standard reference material for thermal expansion measurement.