highmeltingpoint

High melting point refers to the property of a material to transition from solid to liquid at a relatively elevated temperature under a specified pressure, typically near 1 atmosphere. Materials with high melting points are often described as refractory and are valued in high-temperature applications because they resist melting under operating conditions. The melting point is the temperature at which solid and liquid phases are in equilibrium; for pure crystalline solids it is usually sharp, while impure or ceramic systems may melt over a range.

Several factors influence high-temperature behavior. Strong lattice energies and robust bonding, such as covalent networks and dense metallic lattices, raise the energy required to break bonds and cause melting. Carbides, nitrides, oxides, and certain metals (for example tungsten) are common high-melting substances. Impurities generally depress or broaden the melting range. Melting behavior can also be affected by pressure, with measurements typically reported at standard pressure, as the exact melting point can shift in different environments. In some materials, decomposition or sublimation can occur before a true melt is reached, complicating measurements.

Measurement of high melting points often relies on differential scanning calorimetry or high-temperature microscopy, usually conducted in inert or reducing atmospheres to prevent oxidation. Some refractory materials melt only at extreme temperatures or under high pressure, and others may sublimate or decompose instead of melting, so the observed value may reflect decomposition limits rather than a true melting point.

Applications of high-melting-point materials include crucibles, furnace linings, electrical contacts, aerospace components, and other high-temperature structures where dimensional stability and chemical resistance are essential. High melting point is one criterion in materials design, alongside thermal conductivity, mechanical strength, and oxidation resistance.