sulandumine

Sulandumine is an Estonian term that denotes the physical process of melting a solid substance, also known as fusion. In physics and materials science, sulandumine describes the transition from a solid state to a liquid state when energy is supplied, typically in the form of heat. The process is governed by the material’s melting point at a given pressure.

During sulandumine, the temperature of the substance remains relatively constant while the added energy is used to overcome lattice forces and change phase. The amount of energy required per unit mass is the latent heat of fusion. For pure crystalline solids, melting occurs at a distinct melting point; for impure or alloyed materials, melting happens over a range of temperatures between the solidus and liquidus.

Factors such as pressure, impurities, and crystal structure influence sulandumine. In practical terms, melting is essential in metal casting, glassmaking, polymer processing, food preparation, and many manufacturing processes. Common examples include ice melting at 0°C under standard pressure, chocolate melting when warmed, and metals being melted for casting.

Alternative Estonian terms for related processes include sulatus (melting), and sulandumine may be used in some contexts interchangeably. The concept is widely discussed in thermodynamics, phase transitions, and materials science.