Preparation of structurally robust spherical boron nitride agglomerates with low melting point LMO as binder

Spherical boron nitride (BN) agglomerates with excellent liquidity and isotropy have great promise for enhancing their composite performances. However, the deficiency of poor structural strength and high-temperature fabrication approach are the current factors that limit this. Here, we report BN-LMO composite microspheres with isotropic properties and an average diameter of 69.04 μm achieved via a combined spray drying and low-temperature sintering (700 °C) approach, using lithium molybdate (Li 2 MoO 4 , LMO) as a low-melting-point binder. This route promotes liquid-phase assisted interfacial bonding between BN sheets, allowing the formation of structurally stable and mechanically robust composite microspheres while avoiding conventional high-temperature sintering. The resulting BN-LMO microspheres were uniformly dispersed in a PMMA matrix at 30 wt% loading with thermal conductivity of 0.9 W/(m·K) and glass transition temperature of 102.5 °C, which have increased by 373.7 % and 4.0 °C compared with pure PMMA, respectively. Besides, the composites also exhibit high compressive fracture strength of 123.3 MPa, and low dielectric loss of <0.041. Therefore, this exploration simultaneously achieves structural reinforcement and large-scale preparation of spherical BN agglomerates, offering potential opportunities for their wide applications in isotropic thermal management composites.