Realization of Fe-C Eutectic Point Using an Alumina Crucible

摘要

As another crucible material for metal-carbon eutectic points, alumina ceramic was used in the first trial to make an Fe-C eutectic point for the calibration of a thermocouple. Its melting and freezing behavior was tested 26 times with a type S thermocouple at various melting offset temperatures, namely, +4℃, +9℃, and +19℃, and at a fixed freezing offset temperature of -11℃. The melting emf is reproducible independent of the melting offset temperatures, and the standard deviation of the 26 melting temperatures is 0.02℃ without breakage of the cell. The difference of melting emf between alumina Fe-C and graphite Fe-C fixed points is only 25 mK within an uncertainty of 0.39℃ (k = 2). The melting behaviors of an alumina cell are quite similar to a common graphite cell. Thus, alumina can be used as a crucible material in an Fe-C eutectic system without breakage, and it can be used at a higher temperature range. As possible application systems using alumina crucibles, Pd-C and Si-SiC eutectic points are suggested.