Ultrathick Boron Carbide Coatings

Project Overview

Boron carbide is an attractive inertial confinement fusion (ICF) ablator and a unique ultra-hard material with numerous current and potential applications. However, the fabrication of thick boron carbide coatings has proven to be very challenging. The goal of this project was to fill in this gap by developing and demonstrating the deposition of thick (over 50 microns) coatings to enable a new ICF ablator platform. We used a combination of sputter deposition, in situ process and plasma diagnostics, ex situ film characterization, and Monte Carlo modeling to achieve control of film morphology, crystallinity, density, and stress via a better understanding of the underlying physics of film growth. We studied dependences of film properties on process parameters defining adatom mobility and the energy ballistically deposited into the growing film. The project has demonstrated the control residual stress, crystallinity, density, mechanical properties, and elemental purity of boron carbide coatings. Outcomes of this project have direct implications for our future ICF and high-energy density physics (HEDP) campaigns and are also relevant to other technological fields, including a gamut of tribological coatings, nuclear reactor components, radiation detectors, x-ray multilayer coatings, thermal and corrosion barriers, and ballistic armor, where boron carbide is often the material of choice.

Mission Impact

This project focused on the development of a new material (ultrathick boron carbide coatings) to enable future HEDP and ICF experiments that were beyond our capabilities. It also advanced our core competency in advanced materials and manufacturing (ultra-hard and chemically inert coatings), with potential technological implications far beyond the HEDP/ICF programs. The scope of this project involved the science and technology that helped position the Laboratory to support emerging needs and provided opportunities for program growth.

Publications, Presentations, and Patents

Bayu Aji, L. B. et al., 2022. "Effect of Substrate Temperature on Sputter-Deposited Boron Carbide Films." Journal of Applied Physics 131, 075304 (2022).

Kucheyev, S. O., 2021. "Energetic Condensation of ultra-Thick Films and Coatings" (invited talk). XXV International Conference on Ion-Surface Interactions (ISI-2021). Virtual. August 26, 2021.

Engwall, A. M., et al., 2020. "Sputter Deposited Low-Stress Boron Carbide Films." Journal of Applied Physics 128, 175301 2020.

Shin, S. J. et al., 2021. "Oblique Angle Deposition of Boron Carbide Films." Journal of Applied Physics 130, 125305 2021.

Shin, S. J. et al., 2022. "Magnetron Sputtering of Boron Carbide on Tilted Substrates." International Conference on Metallurgical Coatings and Thin Films (ICMCTF-22). San Diego, CA, May 26, 2022.

Engwall, A. M. et al., 2022. "Optimization of RF Magnetron Sputter Deposition of Ultrathick Boron Carbide Coatings." International Conference on Metallurgical Coatings and Thin Films (ICMCTF-22). San Diego, CA, May 26, 2022.

Kucheyev, S. O. et al., 2022. "Overview of Plasma-Assisted Deposition Research for Laser Targets at LLNL." Target Fabrication Specialist Meeting 2022 (online). Los Alamos National Laboratory, June 8, 2022.

S. J. Shin et al., "Boron Carbide Films Deposited by Magnetron Sputtering," Target Fabrication Specialist Meeting 2022, Virtual. Los Alamos National Laboratory, June 8, 2022.

Kucheyev, S. O. et al., 2022. "Recent Developments in Plasma-Assisted Deposition for Laser Targets at LLNL." 8th Target Fabrication Workshop (TFW-2022), Oxford, UK, September 26-28, 2022.