title: Investigating the highest melting temperature materials: A laser melting study of the TaC-HfC system.
abstract: TaC, HfC and their solid solutions are promising candidate materials for thermal protection structures in hypersonic vehicles because of their very high melting temperatures (>4000 K) among other properties. The melting temperatures of slightly hypostoichiometric TaC, HfC and three solid solution compositions (Ta1-xHfxC, with x = 0.8, 0.5 and 0.2) have long been identified as the highest known. In the current research, they were reassessed, for the first time in the last fifty years, using a laser heating technique. They were found to melt in the range of 4041-4232 K, with HfC having the highest and TaC the lowest. Spectral radiance of the hot samples was measured in situ, showing that the optical emissivity of these compounds plays a fundamental role in their heat balance. Independently, the results show that the melting point for HfC0.98, (4232 ± 84) K, is the highest recorded for any compound studied until now.
authors.affiliation: Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London, South Kensington, London, SW7 2AZ, UK.
authors.forename: Omar
authors.initials: O
authors.lastname: Cedillos-Barraza
authors.affiliation: European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe, Germany.
authors.forename: Dario
authors.initials: D
authors.lastname: Manara
authors.affiliation: European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Boboridis
authors.affiliation: European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe, Germany.|Utah State University, Department of Mechanical and Aerospace Engineering, Logan, Utah, USA.
authors.forename: Tyson
authors.initials: T
authors.lastname: Watkins
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Grasso
authors.affiliation: Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London, South Kensington, London, SW7 2AZ, UK.
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Jayaseelan
authors.affiliation: European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, D-76125 Karlsruhe, Germany.
authors.forename: Rudy J M
authors.initials: RJ
authors.lastname: Konings
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Reece
authors.affiliation: Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London, South Kensington, London, SW7 2AZ, UK.
authors.forename: William E
authors.initials: WE
authors.lastname: Lee