The powder density of hexagonal boron nitride (h-BN), as a typical two-dimensional layered material, is a result of the combined effect of material properties and microstructure. From the viewpoint of crystallographic nature, the B and N atoms within the layers of h-BN form a six-membered ring structure through strong covalent bonds, while the interlayers are bound only by weak van der Waals forces. This unique layered arrangement gives it a theoretical density limit of about 2.27 g/cm³, but the actual powder density is often lower than this value, with the difference mainly originating from the presence of porosity and grain boundary defects. The compression modulus along the c-axis (interlayer direction) is significantly lower than that along the a-axis (intra-layer direction), leading to the formation of interlayer slip rather than densification during high-pressure sintering, and this anisotropic compression property further affects the actual performance of the density.

Among many synthetic methods, the sol-gel method demonstrated a unique ability to modulate the mesoporous structure. Using ammonium borate and urea as raw materials, mesoporous h-BN was formed by pyrolysis at 800 °C, with a specific surface area of up to 150 m²/g and nanopores (2-50 nm) forming a three-dimensional connectivity network to provide channels for molecular adsorption. The method ensures precise B and N atom ratio by solution mixing to avoid impurity phase generation, while the low-temperature synthesis process avoids excessive grain growth and maintains the nanoscale pore structure. By changing the sol concentration and heat treatment temperature, the porosity can be controlled between 40% and 70%, providing the possibility of fine tuning the density in the range of 0.4-0.6 g/cm³.

The flaky h-BN powders are oriented under shear to form a “house of cards”-like stacking structure, which brings significant performance gains. The thermal conductivity along the (002) crystal plane can reach 300 W/mK, which is 40% higher than that of the random arrangement; the weak van der Waals forces between the layers make the friction coefficient as low as 0.15, which maintains the efficient lubrication under vacuum; the formation of the oriented network in the polymer matrix reduces the composite material's dielectric constant to less than 2.5; and the flake gaps form micrometer-sized channels, which have a 2-fold higher adsorption capacity than that of the spherical particles.

This combination demonstrates unique advantages in thermal management, lubrication and electronic packaging. The mesoporous structure provides 60% volume expansion accommodation space for the phase change energy storage material, which improves the cycling stability by 50%; the lamellar arrangement enables the high-temperature lubricant to maintain the interlayer slip capability at 1200°C, which extends the lifetime by 3 times; and the orientation arrangement makes the composite material's thermal conductivity show anisotropy, which provides a new solution for the directional heat dissipation design.

BN(CHINA) Technology adopts the continuous synthesis production process to replace the current batch production process. It produces hexagonal boron nitride with higher quality, purity of over 99% and complete crystallization degree. The process is characterized by continuous calcination equipment synthesis, 24-hour uninterrupted production, out of the hexagonal boron nitride powder without batch differences, reducing production costs, production efficiency has been greatly improved, the production quality of hexagonal boron nitride will be raised to a new level.