Tantalum Hafnium Carbide Alloy (3990℃)
Tantalum hafnium carbide alloy (Ta4HfC5) actually refers to tantalum and hafnium pentacarbonate compound, which has the highest melting point among known compounds. It can be considered to be composed of two binary compounds, tantalum carbide (melting point 3983 ℃) and hafnium carbide (melting point 3928℃). Tantalum hafnium carbide alloys are used as heat resistant and high strength materials for rocket and jet engines, as well as parts for control and adjustment equipment.
Graphite (3652 ℃)
Graphite is an allotrope of carbon, where three other carbon atoms (arranged in a honeycomb of hexagons) are covalently linked to each other to form covalent molecules. Due to its special structure, it has high-temperature resistance, electrical and thermal conductivity, lubricity, chemical stability, plasticity and so on. Traditional graphite can be used as a refractory material, the conductive material, wear-resistant, and lubricating material casting, sand, die and high-temperature metallurgy material, while new graphite used as flexible graphite sealing material, car battery, new composite material, etc.
Diamond (3550 ℃)
Diamond is atomic crystal, while graphite is mixed crystal. The melting point of graphite crystal is higher than that of the diamond, which seems incredible. However, the bond length of covalent bonds in the flake layer of graphite crystal is 1.42×10-10m, and the bond length of covalent bonds in the diamond crystal is 1.55×10-10m. Covalent bonds, the smaller the bond, the bigger the bond energy, the stronger the bond, the harder it is to break, the more energy you have to provide, so the melting point should be higher. Diamond is used for cutting tools in arts and crafts and industry, such as drawing die, turning tool, thread cutter, durometer head, geological and petroleum drill bit, grinding wheel cutter, glass cutter, diamond pen, dresser knife, and abrasive material.
Tungsten (3400 ℃)
Tungsten is a steel-gray or silver-white metal with high hardness, high melting point, and resistance to air erosion at room temperature. As a refractory metal (generally, the melting point is higher than 1650℃) with the highest melting point, it has good high-temperature strength. Tungsten is mainly used in manufacturing filament and high speed cutting alloy steel, super hard die, also used in optical instruments, chemical instruments.
Titanium Boride (3225℃)
Titanium boride (TiB2) has a gray or grayish black appearance and a hexagonal (AlB2) crystal structure. As a ceramic, it has excellent thermal conductivity, oxidation stability, and mechanical erosion resistance. Titanium boride is a reasonable electrical conductor and can be used as cathode material in aluminum smelting.
Zirconium boride (3245℃)
Zirconium boride (ZrB2) is a high covalent refractory ceramic material with the hexagonal crystal structure. Its ultra-high temperature ceramics (UHTC) have a melting point of 3246oC, high melting point, relatively low density (about 6.09g/cm 3) and good high-temperature strength. Zirconium boride can be used for high-temperature aviation applications such as supersonic flight or rocket propulsion systems.
Rhenium is a metal element and one of the metals with a high melting point. Rhenium, like platinum in appearance, is soluble in dilute nitric acid or hydrogen peroxide but insoluble in hydrochloric acid and hydrofluoric acid. It can be oxidized to very stable rhenium sesquioxide Re2O7, which is a special property of rhenium. Rhenium can be used to make electrical filament s, satellite and rocket shells, and protective plates for atomic reactors.
Titanium Carbide (3100℃)
Titanium carbide (TiC) is a very hard (Mohs hardness up to 9-9.5) refractory ceramic material, which is similar to tungsten carbide. It is an iron-gray crystal with metallic luster and belongs to the sodium chloride type face-centered cubic crystal structure. Titanium carbide has a high melting point, boiling point, and hardness, as well as good thermal and electrical conductivity, and even shows superconductivity at very low temperature. Titanium carbide is widely used in the manufacture of cermet, heat resistant alloy, hard alloy, wear resistant material, high-temperature radiation material, and other high-temperature vacuum devices.
Osmium is the sixth-period Ⅷ group element in the periodic table. It is one of the platinum group metals, a heavy platinum group metal, and is the densest metal known. Osmium is very stable in air, while osmium in powder form is easily oxidized. Osmium can be used to make ultra-high hardness alloy, osmium with rhodium, ruthenium, iridium or platinum alloy, commonly used as a record player, tap pen and clock and instrument bearings.
Silicon Carbide (2820℃)
Silicon carbide (SiC) is made of quartz sand, petroleum coke (or coal coke), wood chips (green silicon carbide production needs to add salt) and other raw materials through the resistance furnace high-temperature smelting. Silicon carbide particles can be sintered together to form very hard ceramics, which are widely used in applications requiring high durabilities, such as ceramic plates in car brakes, car clutches, and bulletproof vests.
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