The World’s Top 10 High Melting Point Materials

It is commonly known that mercury is the metal with the lowest melting point and the only liquid metal at room temperature. However, only a few people know the answer when it comes to metals with high melting points. In this blog post, we will introduce the top 10 materials with the highest melting points in the world.

The World's Top 10 High Melting Point Materials

1. Tantalum Hafnium Carbide Alloy

Hafnium is a transition metal with an atomic number 72 and an atomic weight of 178.49. It is a shiny silver-grey metal that does not react with dilute hydrochloric acid, sulfuric acid, or strong alkaline solutions but is soluble in hydrofluoric acid and aqua regia. Hafnium has six naturally stable isotopes: hafnium 174, 176, 177, 178, 179, and 180. It is the highest melting point substance in the world today and contains the metallic element hafnium. The compound with the highest melting point is hafnium tantalum hafnium pentacarbide (Ta4HfC5), with a melting point of 4215 degrees Celsius.

The name “hafnium” comes from the Latin name of Copenhagen City. In 1925, Swedish chemist Hervey and Dutch physicist Koster obtained pure hafnium salt by fractional crystallization of fluorinated salt, and reduced it with metallic sodium to obtain pure metallic hafnium. Hafnium has a content of 0.00045% in the Earth’s crust and is often associated with zirconium in nature.

Tantalum Hafnium Carbide Alloy

2. Graphite

Graphite is a form of carbon where each atom is bonded to three others in a honeycomb pattern, forming covalent molecules.

Graphite has a high melting point of 3850 ± 50 ℃ and boiling point of 4250 ℃ and is highly resistant to high temperatures. Even when exposed to ultra-high temperature arc, the weight loss is minimal. Additionally, the coefficient of thermal expansion is minimal. The strength of graphite increases with temperature, and at 2000 ℃, the strength of graphite doubles.


3. Diamond

Diamond is a mineral of carbon elements and an allotrope of carbon. It is formed under high-pressure and high-temperature conditions in deep Earth. Diamond is a colorless octahedral crystal composed of pure carbon, linked by carbon atoms through tetravalent bonds, and is currently known as the hardest naturally occurring substance. All valence electrons form covalent bonds due to the strong C-C bond in diamond, which results in no free electrons. Therefore, diamond has a very high hardness, melting at 6900 degrees Fahrenheit. The ignition point of diamond in pure oxygen is 720-800 ℃, and in air, it is 850-1000 ℃, which is non-conductive. The melting point of gold is between 3550 °C and 4000 °C.


4. Tungsten

Tungsten is a chemical element with the symbol W, atomic number 74, and an atomic weight of 183.84. Belonging to the VIB family, tungsten is a hexavalent cation commonly found in complex anions [WO4]2-. It has a density of 19.35 g/cm³ in the sixth period of the periodic table.

After smelting, tungsten becomes a silver-white glossy metal with a very high melting point, high hardness, low vapor pressure, and a low evaporation rate. It also has relatively stable chemical properties. Tungsten is the refractory metal with the highest melting point, making it an important material in various industries

Refractory metals like tungsten are metals with melting points higher than 1650 ℃ and with certain reserves. Other refractory metals include tantalum, molybdenum, niobium, hafnium, chromium, vanadium, zirconium, and titanium. Tungsten has excellent high-temperature strength and corrosion resistance to molten alkali metals and vapors. However, it also has a high plastic brittle transition temperature and is difficult to process at room temperature. 

Tungsten is commonly used in metallurgy, chemical industry, electronics, light sources, mechanical industry, and other sectors. China is the largest tungsten storage country. Tungsten is used to manufacture filaments, high-speed cutting alloy steel, superhard molds, and optical and chemical instruments.


5. Zirconium Boride

Zirconium boride, with the molecular formula ZrB2, is a chemical substance of gray, hard crystals. Zirconium borate consists of three components: zirconium diboride, zirconium diboride, and zirconium triborate. However, only zirconium diboride is stable over a wide temperature range, which makes it the main component used in industrial production. 

Zirconium boride has a hexagonal crystal form and appears as gray crystalline or powder. It has a relative density of 5.8 and a melting point of 3040 ℃. It has high strength at both room and high temperatures, good heat resistance, low resistance, and oxidation resistance at high temperatures. It has a metallic luster and slightly lower resistance than zirconium metal. 

Moreover, despite its high melting point, it remains stable over a wide temperature range after heating. Although it can be sintered at lower temperatures, it is produced by mixing zirconium metal with boron carbide and boron nitride and heating them in an argon gas flow to 2000 ℃.

Zirconium boride

6. Titanium Boride

Titanium boride powder is gray or gray-black in color and has a hexagonal (AlB2) crystal structure. It has a high melting point of 2980 ℃ and is very hard. Titanium diboride is highly resistant to oxidation at temperatures up to 1000 ℃ in air and is stable in HCl and HF acids. It is mainly used to prepare composite ceramic products. It is often used to manufacture molten metal crucibles and electrolytic cell electrodes due to its resistance to molten metal corrosion.

Titanium boride (TiB2) is the most stable compound of titanium and boron, with a C32 type structure that combines in its valence bond form. It belongs to the quasi-metallic compound of the hexagonal crystal system. The complete crystal structure has a = 0.3028 nm and c = 0.3228 nm. The crystal structure’s boron and titanium atomic planes alternate to form a two-dimensional network structure, where B is covalently bonded with the other three B atoms, and the excess electron forms a large π bond. The layered structure of boron atoms is similar to graphite, and the outer electrons of Ti make TiB2 highly conductive and give it a metallic luster. Meanwhile, the Ti-B bond between the boron and titanium atomic surfaces is responsible for this material’s high hardness and brittleness.

Titanium boride

7. Rhenium

Rhenium is a rare chemical element (symbol: Re, atomic number: 75) that belongs to the transition metal of the sixth cycle in the periodic table. It is a heavy metal with a silver-white color known to have one of the highest melting and boiling points of all elements. The average rhenium content in the Earth’s crust is estimated to be one billionth, making it one of the rarest elements.

Rhenium is obtained as a byproduct of the molybdenum and copper extraction process. Its chemical properties are similar to technetium and manganese, and it can have oxidation states ranging from -3 to +7 in compounds.

Rhenium, which was discovered in 1925, is the last known stable element. It was named after the Rhine River in Europe.

One of the most significant practical applications of rhenium is in nickel rhenium high-temperature alloys, which manufacture combustion chambers, turbine blades, and exhaust nozzles for jet engines. These alloys contain up to 6% rhenium. Another major use of rhenium is as a catalyst in the chemical industry.

Due to its rarity and difficulty obtaining, rhenium is more expensive than diamonds. As of 2021, the world has only 2650 tons of proven reserves, according to survey data from the United States.

Rhenium is crucial in military strategy as it can be applied to high-efficiency jet and rocket engines.


8. Titanium Carbide

Titanium carbide (TiC) is a gray, cubic crystal system with a melting point 3140℃. It is insoluble in water and has high chemical stability, so it hardly reacts with hydrochloric and sulfuric acid. However, it can dissolve in aqua regia, nitric acid, hydrofluoric acid, and alkaline oxide solutions.

TiC has an iron-gray metallic luster and belongs to the NaCl type simple cubic structure. The lattice constant is 0.4329 nm, and the spatial group is Fm3m. Carbon atoms and titanium atoms are equivalent at the lattice position. TiC atoms combine with strong covalent bonds and have characteristics similar to metals, such as high melting point, boiling point, and hardness, which are second only to diamonds. It also has good thermal conductivity and exhibits superconductivity at extremely low temperatures. 

Titanium carbide (TiC) is commonly used to produce metal ceramics, heat-resistant alloys, hard alloys, wear-resistant materials, high-temperature radiation materials, and other high-temperature vacuum devices. The composite materials prepared with TiC have various applications in mechanical processing, metallurgy, minerals, aerospace, and fusion reactors.

Titanium carbide

9. Osmium

Osmium is a member of the platinum group of metals.It is located in the eighth group element and the sixth period of the periodic table.Its element symbol is Os, with an atomic number of 76 and a relative atomic mass of 190.2. Osmium is known for having the highest density among metals.

Osmium is typically found in osmium-iridium ores. It can be extracted by roasting the solid containing osmium in the air, absorbing the volatilized osmium tetroxide in an alcohol-alkali solution, obtaining osmium salt, and then reducing it with hydrogen gas to obtain metallic osmium. It is often used to manufacture alloys with ultra-high hardness. It is commonly alloyed with rhodium, ruthenium, iridium, or platinum and used as a bearing in record players, fountain pen tips, clocks, and instruments.

Osmium has the highest density among known metal elements, with a density of 22.59 grams per cubic centimeter, a melting point of 3045 ℃, and a boiling point above 5300 ℃. It has a hexagonal dense lattice structure and is a hard and brittle gray-blue metal that can easily turn into powder when pressed in an iron mortar. Osmium powder is blue-black and can self-ignite. The vapor of osmium is highly toxic and can intensely irritate the mucous membranes of the eyes, leading to blindness in severe cases.


10. Silicon Carbide

Diamond sand, which is also known as silicon carbide (SiC), is produced through a high-temperature smelting process of raw materials such as quartz sand, petroleum coke (or coal coke), and sawdust (which requires the addition of salt to produce green silicon carbide) in a resistance furnace. It has a melting point of 2700℃. Silicon carbide is also a rare mineral found in nature, known as masonite or carbo silicate. Out of contemporary non-oxide high-tech refractory materials such as carbon, nitrogen, boron and silicon carbide, the latter is the most widely used and economical. It is often referred to as gold steel or refractory sand. Currently, the industrial production of silicon carbide in China is divided into black silicon carbide and green silicon carbide. These are hexagonal crystals with a specific gravity of 3.20-3.25 and a microhardness of 2840-3320kg/mm2.

silicon carbide