In the vast field of materials science, hexagonal boron nitride (h-BN) stands out for its unique properties, demonstrating immense potential across a wide range of applications, particularly playing an irreplaceable role in crucible applications.
Hexagonal boron nitride possesses a series of outstanding characteristics, laying a solid foundation for its application in crucibles. It exhibits excellent high-temperature resistance, maintaining its physical and chemical properties stable at temperatures below 1000°C in air. This property enables crucibles made from h-BN or coated with h-BN to withstand high-temperature environments, meeting the stringent requirements of high-temperature operations such as metal melting and refining. Additionally, h-BN's high thermal conductivity helps achieve more uniform temperature distribution within the crucible, thereby enhancing the efficiency and quality of metal melting. Its excellent self-lubricating properties and low friction coefficient prevent the crucible from adhering to the melted material, such as in silicon production, significantly improving the demolding properties of silicon ingots. Furthermore, h-BN exhibits exceptional chemical stability, demonstrating excellent resistance to corrosion from acids, alkalis, and glass slag, and it rarely reacts with most molten metals. This ensures the crucible's long-term durability in complex chemical environments.
In practical applications, hexagonal boron nitride primarily enhances crucible performance through two methods. One method involves directly manufacturing boron nitride ceramic crucibles, which, due to their high purity and excellent thermal stability, are commonly used in high-demand applications such as the smelting of non-ferrous metals, precious metals, and rare metals. The other method involves using it as a coating material applied to the inner walls of traditional crucibles. This coating is typically prepared by mixing hexagonal boron nitride with silica sol, high-purity water, and other materials to form a slurry, which is then sprayed onto the bottom surface of the crucible (the sides are often coated with silicon nitride), followed by baking to form a protective layer. This h-BN coating effectively suppresses contamination of the melted material by impurities in the crucible itself, significantly reduces oxygen content at the bottom of the melt, and, due to its poor wettability with liquid silicon, prevents sticking, thereby greatly enhancing the safety and reliability of silicon production.
The successful application of hexagonal boron nitride in crucibles has significantly advanced technological progress in related industries. In the metallurgy industry, it has improved the quality and efficiency of metal melting; in the semiconductor industry, it provides a critical guarantee for the production of high-purity silicon materials, indirectly promoting the quality improvement of related industries such as chip manufacturing. In the future, with the continuous increase in requirements for material performance, the application prospects of hexagonal boron nitride in crucible fields will become even broader, and it is expected to play a key role in more high-end manufacturing fields.
