Concurrent Hydrolysis Resistance and High Thermal Conductivity in Aluminum Nitride Enabled by Phase‐Engineered Graphene Encapsulation

Abstract

ABSTRACT Aluminum nitride (AlN) stands as a cornerstone material for next‐generation thermal management, yet its notorious susceptibility to hydrolysis severely undermines long‐term reliability. Here, we transcend conventional surface modification by introducing a phase‐engineering strategy to fundamentally reconfigure the AlN surface. Through fluidized bed‐chemical vapor deposition, we precisely construct conformal, high‐crystalline and low‐defective graphene “skin” on AlN powders (the intensity ratio of D‐peak to G‐peak ∼0.088), where the unique growth kinetics and interfacial phase are dictated by the AlN substrate, thus differ from the conventional non‐metallic substrates. As revealed by density functional theory calculations, this process yields a covalently‐bonded heterointerface characterized by distinct C–Al–N configurations, thereby moving beyond weak van der Waals interactions. The phase‐engineered graphene skin delivers dual, synergistic functions, enhancing the thermal conductivity of AlN by 38.7% via optimized thermal transport pathways, while simultaneously acting as an ultrastable barrier, granting exceptional resistance to prolonged hygrothermal aging with the thermal conductivity variation of thermal interface material less than 1% in 30 days. This work resolves the long‐standing trade‐off between environmental stability and thermal performance in AlN, establishing a paradigm of phase‐engineered graphene encapsulation for ceramic fillers, thereby enabling the scalable fabrication of robust, hydrolysis‐resistant and high thermal conductivity composites.