Measurement Of The Melting Temperature Of Zrb2 As Determined By Laser Heating And Spectrometric Analysis

The melting temperatures of two different ZrB2 ceramics were studied using laser induced melting. ZrB2 having a low Hf content, produced by reaction hot pressing, had a melting temperature of 3546 K and a commercial grade ZrB2 had a melting temperature of 3553 K. Uncertainty of the temperature measurements was 1% of the absolute temperature, or similar to 35 K for both materials based upon 2-sigma and a 95% confidence interval. While these values were consistent with the previously reported ZrB2 melting temperature of 3518 K, this study was able to measure T-m with less uncertainty than previous studies (+/- 45 K). Furthermore, this study assessed the effect of Hf content on melting temperature, finding that melting temperature did not change significantly for hafnium contents of 1.75 to 0.01 at%. This study also measured a normal spectral emissivity of 0.34 for ZrB2 at 3000 K. The emissivity decreased to 0.28 at the melting temperature, then, stabilized at 0.30 in a liquid phase.