Fixing Disordered Hexagonal Boron Nitride Grains Leads to Simultaneous High Strength and Deformability

Abstract It is still a formidable challenge to simultaneously achieve high mechanical strength and deformability for a bulk ceramic material. h‐BN is known for its outstanding dielectric and thermal properties but always exhibits very limited mechanical strength and deformability after sintering due to its chemical inertness and anisotropic layered structure. Here, an economical reactive hot‐pressing method is proposed to fix the disordered h‐BN grains at mild temperatures, constructing a 3D flexible framework to enormously improve h‐BN mechanical properties. The developed h‐BN ceramics achieve relative densities of up to 96.6%, flexural strength of 170.0 ± 23.2 MPa, compressive strength of 465.1 ± 16.7 MPa, and deformation strain of up to 6.1%. Such strength values are 3–5 times, and the deformability is 5–10 times of those commercially available h‐BN ceramics. It is noteworthy that these values have been achieved without the loss of its intrinsically excellent dielectric properties, which still possess a dielectric constant of 3.4 and dielectric loss of 5 × 10 −4 (12 MHz). This work provides an industrially applicable way to fabricate high‐strength and high‐deformability h‐BN ceramics toward large‐scale applications.