Performance evaluation of WC-C peritectic high-temperature fixed point

WC-C peritectic fixed point (2749degC) was investigated to evaluate their potential of serving as high-temperature reference points in thermometry. Four WC-C peritectic cells were constructed and the melting and freezing plateaus were evaluated by means of radiation thermometer. The repeatability of the melting temperature of one cell was 0.011 K with the melting range of 0.117 K. The melting temperatures of four different cells were agreed within 0.05 K. The long term stability of WC-C cell was also evaluated by the realization of 45 melt/freeze cycles. The standard deviation of 45 melting temperatures was 0.034 K including the instability of LP3. From these results, it can be concluded that WC-C peritectic fixed point has a high potential to be used as a high temperature reference point. The microstructure analyses of WC-C peritectic cells by means of optical microscopy and electron-probe microanalysis (EPMA) showed the segregation of the graphite in the WC-C cell.