Magnetron sputtering of boron carbide coating on aluminum substrate—Experimental considerations for enhancing adhesion

Sharon Waichman, Shahaf Froim, Ido Zukerman, Meir Buzaglo, Miri Chachashvili, Shmuel Barzilai*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Boron carbide is a ceramic material whose high cross-section for neutron absorption renders it practical as a coating for neutron-based detection applications, while aluminum is typically used as a substrate material since it is transparent to neutrons. However, adhesion between these two distinct materials is challenging because of the difference in their thermal expansion coefficients as well as the formation of unstable aluminum-carbon bonds that may cause adhesive failure. Toward improving the efficient attachment of boron carbide and aluminum, we deposited micron-sized (∼ 1–3.5 µm) boron carbide coatings with an adhesive intermediate titanium layer on an aluminum substrate using pulsed-DC magnetron sputtering. Qualitative testing of adhesion strength showed that coatings deposited with a bias voltage higher than ∼ −150 V presented high residual stress of > −1 GPa and poor adherence to the substrate. We determined that the optimal bias voltage applied to the substrate during deposition lies between ∼ −25±5 V (a floating potential value) and −60 V. Together with the support of a titanium layer adjusted to reduce the discrepancies in the thermal expansion coefficients, boron carbide coatings have proven continuous and strongly adherent for more than 27 months.

Original languageAmerican English
Article number102772
JournalSurfaces and Interfaces
Volume38
DOIs
StatePublished - Jun 2023
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2023 Elsevier B.V.

Keywords

  • Adhesion
  • Boron carbide coating
  • Magnetron sputtering
  • Negative bias voltage
  • Residual stress
  • Titanium interlayer

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