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Very few measurements of melting point in tantalum hafnium carbide have been reported, because of the obvious experimental difficulties at extreme temperatures. A 1965 study of the TaC-HfC solid solutions at temperatures 2,225–2,275 °C found a minimum in the vaporization rate and thus maximum in the thermal stability for Ta 4 HfC 5.
The melting points of tantalum carbides was previously estimated to be about 3,880 °C (4,150 K; 7,020 °F) depending on the purity and measurement conditions; this value is among the highest for binary compounds. [6] [7] And only tantalum hafnium carbide was estimated to have a higher melting point of 3,942 °C (4,215 K; 7,128 °F). [8]
Hafnium carbide (Hf C) is a chemical compound of hafnium and carbon.Previously the material was estimated to have a melting point of about 3,900 °C. [2] More recent tests have been able to conclusively prove that the substance has an even higher melting point of 3,958 °C exceeding those of tantalum carbide and tantalum hafnium carbide which were both previously estimated to be higher. [3]
The white hafnium(IV) oxide (HfO 2), also known as hafnium dioxide or hafnia, with a melting point of 2,812 °C and a boiling point of roughly 5,100 °C, is very similar to zirconia, but slightly more basic. [13] It is an electrical insulator with a band gap of 5.3~5.7 eV. [15] Hafnium(IV) oxide typically adopts the same structure as zirconia ...
The mixed carbide tantalum hafnium carbide (Ta 4 HfC 5) possesses the highest melting point of any currently known compound, 4,263 K (3,990 °C; 7,214 °F). [35] Recent supercomputer simulations suggest a hafnium alloy with a melting point of 4,400 K (4,127 °C; 7,460 °F). [36]
Boiling point (°C) K b (°C⋅kg/mol) Freezing point (°C) K f (°C⋅kg/mol) Data source; Aniline: 184.3 3.69 –5.96 –5.87 K b & K f [1] Lauric acid:
72 Hf hafnium; use: 648 LNG: 571 WEL: 630 Zhang et al. 648 73 Ta tantalum; use: ... Values refer to the enthalpy change in the conversion of liquid to gas at the ...
Hafnium carbide is the most refractory binary compound known, with a melting point of 3890 °C. [8] [9] The ternary compound tantalum hafnium carbide has one of the highest melting points of all known compounds (4215 °C). [10] [11] Molybdenum disilicide has a high melting point of 2030 °C and is often used as a heating element.