Microstructural, Mechanical, and Thermal Properties of Textured Si3N4/BN Composite Ceramics Prepared Using Two-Step
Dexiang Gong1, Yi Zhou1, Yunwei Shi1
1School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China.
Materials (Basel, Switzerland)
|August 14, 2025
Summary
Controlling the grain size of hexagonal boron nitride (h-BN) in silicon nitride (Si3N4) composites enhances thermal and mechanical properties. This texture control is key for advanced ceramic applications.
Area of Science:
- Materials Science
- Ceramic Engineering
- Nanotechnology
Background:
- Silicon nitride (Si3N4) and hexagonal boron nitride (h-BN) composites are advanced ceramic materials.
- Optimizing their properties is crucial for high-performance applications.
- Controlling microstructure, specifically h-BN grain size, is a key factor.
Purpose of the Study:
- To fabricate textured Si3N4/BN composite ceramics.
- To investigate the influence of h-BN grain size on material properties.
- To optimize composite performance for thermal and mechanical applications.
Main Methods:
- Two-step sintering, combining pseudo-hot isostatic pressing (PHIP) and gas pressure sintering.
- Fabrication of textured Si3N4/BN composites with varying h-BN grain sizes.
- Characterization of densification, mechanical properties (flexural strength, fracture toughness), and thermal conductivity.
Main Results:
- Increased h-BN grain size decreased volume density but increased flexural strength.
- Larger h-BN platelets promoted toughening mechanisms, enhancing fracture toughness.
- Optimized composites (1-2 μm h-BN) achieved high thermal conductivity (92 W∙m⁻¹∙K⁻¹) and robust mechanical properties (540 MPa, 7.5 MPa∙m⁻¹/²).
Conclusions:
- Texture control via h-BN grain size is an effective strategy for enhancing ceramic composite performance.
- Textured Si3N4/BN composites show potential for large-scale fabrication.
- These materials are promising for directional heat dissipation applications.
