Thermoformable Boron Nitride Based All-Ceramics

Traditional thermoforming is limited to thermoplastics and metals. No prior work had resolved how to apply this to ceramics. Boron-based materials are known for high thermal conductivity but lack formability. Prior research has shown ceramics are brittle and resist deformation. This gap motivated exploring new fabrication methods. The study introduces a novel approach using boron nitride composites. It was already known that ceramics are difficult to shape after sintering. This paper's contribution is extending thermoforming to all-ceramics.

The study aims to develop a thermoforming process for all-ceramic materials. The specific problem is the lack of formability in sintered ceramics. The motivation is to create complex ceramic parts with fine features. The goal is to enable thermoforming of boron nitride composites. The researchers propose using a combined vibration and tape-casting method. This approach allows for highly oriented microstructures. The process enables viscous flow during compression molding. The outcome is thin, complex ceramic parts with sub-200 µm features.

The team used a combined vibration and tape-casting photopolymerization process. This method creates sintered boron nitride composite sheets. The sheets have a highly oriented microstructure. These preforms behave as Bingham pseudoplastics during molding. Compression molding is used to shape the preforms. The process allows forming complex geometries with fine details. The workflow includes fabricating bespoke heat spreaders. These components are press-fit onto printed circuit boards.

The sintered sheets flow as viscous Bingham pseudoplastics during molding. The process achieves features as small as 200 µm. The resulting parts are thin and complex. The heat spreaders outperform metal sinks in thermal management. The ceramic parts have low profile and high conductivity. The workflow enables press-fitting onto circuit boards. The method is applicable to other all-ceramics with anisotropic structures. The process opens new possibilities for ceramic part fabrication.

The authors propose that thermoforming can be extended to all-ceramics. The key finding is the ability to form sintered boron nitride sheets. The process relies on highly ordered anisotropic microstructures. The results suggest this workflow is viable for other ceramics. The heat spreaders demonstrate practical applications. The method allows forming fine features in ceramic parts. The study concludes that this approach may be replicated for other materials. The findings suggest new routes for ceramic part fabrication.