Epitaxial h-BN/BNNT Structures for Mechanical and Thermal Stability

The patent creates composite structures where hexagonal boron nitride (h-BN) layers are epitaxially grown on boron nitride nanotube (BNNT) surfaces. This composite architecture combines the high strength of BNNTs with the thermal stability and mechanical resistance of h-BN, achieving superior mechanical properties while maintaining low defect rates through controlled epitaxial growth that prevents random defect formation

The patent employs plasma-enhanced chemical vapor deposition (PECVD) to precisely control growth parameters such as temperature, pressure, gas composition, and plasma power. By optimizing these parameters, the process achieves high-quality epitaxial h-BN layers with controlled thickness and crystal orientation, resulting in enhanced mechanical resistance and reduced defects compared to conventional synthesis methods

The epitaxial h-BN/BNNT composite structures provide enhanced thermal stability because h-BN has higher thermal stability than amorphous or defective BN. The crystalline h-BN layers protect the underlying BNNT structure from thermal degradation, oxidation, and phase transitions at high temperatures, maintaining compositional purity and structural integrity up to extremely high temperatures

The patent uses controlled plasma parameters and deposition conditions to grow highly crystalline h-BN layers with minimal defects and impurities. The epitaxial growth process ensures proper crystal orientation and atomic arrangement, resulting in high-purity structures with superior thermal stability that resist decomposition and maintain composition integrity at elevated temperatures

The patent replaces conventional mechanical or chemical adhesion methods with plasma-enhanced epitaxial growth. The plasma process creates strong chemical bonds between h-BN and the substrate through in-situ deposition, achieving superior adherence without requiring complex surface treatments, primers, or mechanical interlocking structures. The epitaxial nature ensures lattice matching and strong interfacial bonding

The plasma acts as an intermediary that facilitates strong bonding between the h-BN layer and the substrate. The plasma provides reactive species that enhance surface preparation, promote nucleation, and create strong chemical bonds during deposition, achieving excellent adherence while maintaining a relatively simple single-step process that combines surface treatment and coating deposition