Hafnium Carbide (HfC) 
Specification: 0.8-10um (D50) 
Appearance: Irregular 
Color: Black Grey 
Features: high melting point, high hardness, excellent chemical stability, good physical properties 
Application: Aerospace, industrial ceramics, cutting tools and molds, and other fields

Hafnium Carbide 
Molecular formula: HfC 
Appearance: Grey black powder 
CAS:12069-85-1 
EINECS:235-114-1 
Molecular weight: 190.5325 
Melting point: 3890 ℃ 
Theoretical density: 12.7g/cm3 
Thermal conductivity: 6.28 [W (m · K) -1] (20 ℃) 
Volume resistivity: 1.95 × 10-4 Ω· cm (2900 ℃) 
Thermal expansion coefficient: 6.73 × 10-6/℃ 
Electrical resistivity: 40-50/μ Ω· cm, 
Elastic modulus: 35.9 × 103MPa 
Pressure resistance strength: 1380MPa 
Property: Hafnium carbide is an inorganic substance that is soluble in hydrofluoric acid, hot concentrated sulfuric acid, and nitric acid. Belonging to non-metallic carbides, its structure is NaCl type face centered cubic structure, which is a metastable structure. This non stoichiometric carbide exhibits the presence of free carbon, namely HfCx (0.5<x<1), where Hf atoms form a compact cubic lattice and C atoms are located in the octahedral interstitial positions of the lattice. In compounds with such structures, there are both metal bonds and covalent bonds, and the interatomic bonding is particularly strong. Due to the high covalent bond energy of C-Hf, it is very difficult to break its structure, thus exhibiting ultra-high hardness characteristics macroscopically. Its Mohs hardness is 9, second only to diamond. Due to the highly symmetrical distribution of atomic bonds that must be broken during the melting of HfC crystals, breaking these bonds is extremely difficult. The bond energy of atomic bonds in hafnium carbide is as high as EA=87.2163KJ/mol, exhibiting a macroscopic characteristic of ultra-high melting point, and the melting point of hafnium carbide is as high as 3890 ℃. Therefore, they often have excellent properties such as high strength, high hardness, and high melting point. 
Preparation methods: direct carbonization method, magnesium thermal reduction method, carbothermal reduction method, liquid precursor conversion method, chemical vapor deposition method, sol gel method, spark plasma sintering method, etc. Hafnium dioxide is usually synthesized into powder with carbon in an inert or reducing atmosphere at a reaction temperature of 1900-2300 ℃. 
Purpose: 
1) Hafnium carbide can be used as an additive to act as a deoxidizer in the steelmaking industry, which can significantly improve the quality of steel. 
2) Hafnium carbide can be used as an inner lining for high melting point metal melting crucibles and can also be applied as a coating material for cutting tools. 
3) Hafnium carbide is an important functional material for making control rods and protective devices in nuclear reactors, and is an important material in the atomic energy industry. 
4) Hafnium carbide can be applied in the fields of electronics and optics, used as a thermal optical radiometer, field emitter device, etc. In the electrical industry, it is a cathode material for manufacturing X-ray tubes and microwave tubes. 
5) Hafnium carbide can be used as a rocket propulsion system for rocket nozzles, nozzles, and nose cones. Alloys containing hafnium carbide can be used as a front protection layer for rocket nozzles and gliders. 
Product application case: 
1. HfC hafnium carbide powder material is added as an additive to solid rocket engine throat lining materials due to its superior high-temperature thermophysical and mechanical properties compared to other materials, making it a solid rocket engine nozzle throat lining material. During the operation of the engine, the carbon/carbon composite material throat liner is subjected to harsh thermal environments, and the inner surface is damaged due to high temperature, high pressure, high speed, and corrosive particle containing heat flow erosion, resulting in enlarged throat diameter, rough and uneven surface, irregular surface, etc., which affects the working pressure of the engine and reduces the efficiency of the nozzle. When adding 8% -10% HfC hafnium carbide powder material to the nozzle throat lining carbon matrix of a certain type of weapon system, the anti ablation performance of HfC-C/C composite material can be greatly improved. The contribution of HfC hafnium carbide powder material to the erosion resistance of HfC-C/C composite throat lining mainly includes two aspects: 
(1) At an ablation temperature of 3500 ℃, HfC hafnium carbide powder material preferentially reacts with oxygen to form HfO2 during high-temperature ablation, effectively preventing the oxidation of carbon matrix and carbon fibers in the composite material by aerobic atmosphere; 
(2) Due to the high strength and hardness of HfC hafnium carbide powder material, which effectively improves the overall mechanical abrasion and erosion resistance of the material, the mechanical erosion of the inner surface of the throat liner by gas is effectively suppressed. Obviously, the anti ablation performance of HfC-C/C composite materials increases with the increase of HfC content. Experimental results show that when the HfC content reaches 8% -10%, the linear ablation rate of the HfC-C/C composite throat liner will enter a stable ablation stage that is approximately constant. Under the test conditions of solid rocket engines, the HfC-C/C composite throat liner as a whole has good anti ablation performance. 
2. The compound carbide 4TaC · HfC composed of 1 atom hafnium carbide and 4 atoms tantalum carbide is tested for its heat resistance using laser heating technology, with a melting point of 4215 degrees Celsius. It is a composite material compound and refractory ceramic material with a high melting point. It is applied in the thermal protection system of high-speed aircraft by a research institution in the United States. It has strong resistance to heat, can withstand and resist harsh high-temperature environments, and can also be used as a fuel cladding for overheated environments in nuclear reactors. The heat caused by air friction includes very high temperatures when traveling at supersonic speeds exceeding Mach 5. Due to the ability of 4TaC · HfC material to withstand and resist harsh high-temperature environments, paving the way for the development of the next generation of supersonic aircraft, this material means that new spacecraft may have faster speeds than ever before. The application of 4TaC · HfC material in supersonic aircraft, aircraft nose, and external component edges that require high friction during flight makes it possible for aircraft traveling at speeds exceeding 5 Mach to carry passengers. 
3. HfC hafnium carbide powder material is an important functional material for the control rods and protective devices of atomic nuclear reactors. It is also an important material in the atomic energy industry and can be used as a rocket booster. It is particularly suitable for rocket nozzles, throat materials of rocket nozzles, and nose cone parts of space rockets that re-enter the atmosphere. The alloy containing hafnium carbide can be used as a forward protective layer for rocket nozzles and gliding reentry vehicles. 
4. HfC hafnium carbide powder material, due to its high hardness and melting point, is used as an additive in hard alloy cutting tools, metal ceramic cutting tools, powder metallurgy products, high-temperature structural component materials, and high-temperature resistant spraying materials; Hf Ta alloy with added hafnium carbide can be used to manufacture tool steel and resistance materials; Adding hafnium carbide to heat-resistant alloys, such as tungsten, molybdenum, and tantalum alloys, can improve the hardness, strength, erosion resistance, and high temperature resistance of the material; 
5. HfC hafnium carbide powder material, due to its high melting point, is used as an additive in the steelmaking industry as a deoxidizer, which can significantly improve the quality of steel; In the electrical industry, it is used to manufacture cathode materials for X-ray tubes and microwave tubes.

 tubes.