A Boron Nitride (BN) crucible hearth liner is a type of insert used in a crucible, which is a container that holds a material being heated to a high temperature. The liner is made of boron nitride (BN), a ceramic material with excellent thermal properties. It is used to protect the crucible from the molten material and to improve the purity of the material being melted.
BN crucible hearth liners are often used in electron beam (e-beam) evaporation, a physical vapor deposition (PVD) technique used to deposit thin films of materials onto substrates. In e-beam evaporation, a high-energy electron beam is used to heat the material in the crucible, causing it to evaporate. The evaporated material then travels to the substrate, where it condenses and forms a thin film.
BN crucible hearth liners offer several advantages over other types of liners, including:
High chemical resistance: BN is resistant to attack by most molten metals and alloys.
Low outgassing: This means that the liner releases very few gases when heated, which is important for maintaining the purity of the material being processed.
High thermal conductivity: This allows the liner to heat up and cool down quickly, which is important for some applications.
Good electrical resistivity: This is important for some applications, such as e-beam evaporation.
However, BN crucible hearth liners also have some disadvantages, such as:
High cost: BN is a relatively expensive material.
Fragile: BN liners can be fragile and can break if they are not handled carefully.
Limited size: BN liners are not available in as large sizes as some other types of liners.
BN crucible hearth liners are also used in other applications, such as:
Thermal processing of materials, such as sintering and annealing
Crystal growth
Melting of metals and alloys
Chemical vapor deposition (CVD)
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