Additive Manufactured Boron Nitride Coatings for Extreme Environments via Micro-Dispense Printing Techniques

The additive manufacturing community has demonstrated interest in printed nanoparticle-based coatings as electrical insulators, thermal conductors and active materials, and anti-corrosion barriers. Specifically, micro-dispense printing (MDP) techniques show potential for enhancing the functionality of printed electronics due to the extrusion-based printing modality that allows for use of highly viscous inks, supporting conformal printing of films over 2D and 3D surfaces. Furthermore, hexagonal boron nitride (BN) inks and their respective coatings possess favorable anisotropic electrical and thermal properties which can be used to enhance heat dissipation through thermal conductivity and overall operational condition of coated devices. In this study, as-received cubic and hexagonal BN powders were characterized via particle size analysis (PSA), X-ray diffraction (XRD), and scanning electron microscopy (SEM) to provide knowledge of powder particle size dispersion, agglomeration, and crystalline structure that inform the processes for formulating BN-inks. Ink formulations were developed at varying BN-loadings to optimize ink viscosity and determine extrusion parameters via the nScrypt MDP. Project results provide a better understanding of characteristic properties of BN, as well as insight towards how rheological properties like viscosity and applied shear stress impact the quality of resulting films.