Hexagonal boron nitride powder, as a ceramic material with unique properties, plays a vital role in the preparation and application of composite ceramics. This material is widely used as a matrix or reinforcing phase to enhance the overall performance of composite ceramics due to its high-temperature resistance, high insulation, ease of processing, and excellent chemical compatibility with various secondary phases.
During composite ceramic fabrication, hexagonal boron nitride powder is often combined with other materials through processes like hot-press sintering. For instance, boron nitride ceramics primarily composed of this powder exhibit inherent advantages such as low moisture absorption, low dielectric constant, and high breakdown resistance. Researchers also frequently incorporate it as a secondary phase into other ceramic matrices. For instance, adding hexagonal boron nitride as a toughening and lubricating phase in high-entropy boride ceramics significantly optimizes material properties. Studies indicate that an appropriate amount of hexagonal boron nitride can enhance the fracture toughness of composite ceramics by nearly 70% through mechanisms such as crack deflection and bridging. Simultaneously, the slip effect generated by its layered structure at high temperatures, combined with the formation of boron oxide through reaction with oxygen, synergistically creates a lubricating film. This reduces the material's friction coefficient by approximately 40% and its wear rate by nearly 60% in environments reaching 1000°C.
Beyond enhancing mechanical and tribological properties, hexagonal boron nitride composite ceramics demonstrate significant value in thermal management, electrical insulation, and other fields. For instance, all-ceramic composites featuring hexagonal boron nitride as phonon ceramic particles and boron oxide as the ceramic matrix exhibit excellent thermal conductivity in electronic device heat dissipation components due to their highly oriented microstructure. These materials are lightweight and do not interfere with radio frequency signals, enabling integrated thermal management functions. Furthermore, introducing different types of secondary phases enables the production of boron nitride composite ceramics with high insulation or excellent conductivity, catering to diverse application requirements. These materials are particularly suitable for precision-machined insulating components such as discharge channels, cavities, insulating spacers, and thermal insulation pads.
In summary, hexagonal boron nitride powder, through flexible composite design, effectively compensates for the limitations of single-ceramic materials. It endows composite ceramic materials with superior mechanical properties, high-temperature self-lubrication characteristics, thermal management capabilities, and electrical insulation performance. This makes it a highly favored key material in high-end technological fields such as metallurgy, electronics, and aerospace.
