Rights statement: This is the author’s version of a work that was accepted for publication in Materials Chemistry and Physics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Materials Chemistry and Physics, 273, 2021 DOI: 10.1016/j.matchemphys.2021.125062
Accepted author manuscript, 2.11 MB, PDF document
Available under license: CC BY-NC-ND
Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - X-ray computed tomographic and focused ion beam/electron microscopic investigation of coating defects in niobium-coated copper superconducting radio-frequency cavities
AU - Aliasghari, S.
AU - Skeldon, P.
AU - Zhou, X.
AU - Gholinia, A.
AU - Zhang, X.
AU - Valizadeh, R.
AU - Pira, C.
AU - Junginger, T.
AU - Burt, G.
AU - Withers, P.J.
N1 - This is the author’s version of a work that was accepted for publication in Materials Chemistry and Physics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Materials Chemistry and Physics, 273, 2021 DOI: 10.1016/j.matchemphys.2021.125062
PY - 2021/11/15
Y1 - 2021/11/15
N2 - A combination of X-ray computed tomography (CT) and focused ion beam - scanning electron microscopy (FIB-SEM) has been employed to investigate substrate and related surface defects in a niobium coated superconducting radio frequency (SRF) copper cavity. The cavity was manufactured by spinning, with subsequent application of a sputtering-deposited niobium coating (≈40 μm thick) on the internal surface. Before coating, the copper surface was pre-treated in several stages, ending with chemical polishing. CT and FIB-SEM identified furrow defects (≈20 μm deep) in the copper beneath the coating, which originated from the spinning process. The furrows were filled with niobium and contained voids at the Nb/Cu interface that extended a few microns into the niobium coating. The presence of the defects led to similar furrows at the niobium surface. The study revealed the importance of pre-treatment of the cavity internal surface and control of the spinning process to avoid defects that may have deleterious influence on the Q slope and durability of the niobium coating.
AB - A combination of X-ray computed tomography (CT) and focused ion beam - scanning electron microscopy (FIB-SEM) has been employed to investigate substrate and related surface defects in a niobium coated superconducting radio frequency (SRF) copper cavity. The cavity was manufactured by spinning, with subsequent application of a sputtering-deposited niobium coating (≈40 μm thick) on the internal surface. Before coating, the copper surface was pre-treated in several stages, ending with chemical polishing. CT and FIB-SEM identified furrow defects (≈20 μm deep) in the copper beneath the coating, which originated from the spinning process. The furrows were filled with niobium and contained voids at the Nb/Cu interface that extended a few microns into the niobium coating. The presence of the defects led to similar furrows at the niobium surface. The study revealed the importance of pre-treatment of the cavity internal surface and control of the spinning process to avoid defects that may have deleterious influence on the Q slope and durability of the niobium coating.
KW - Coating
KW - CT
KW - FIB-SEM
KW - Niobium
KW - SRF Cavity
KW - Superconductivity
KW - Coatings
KW - Computerized tomography
KW - Superconducting materials
KW - Coating defects
KW - Computed tomographic
KW - Focused ion beam-scanning electron microscopies
KW - Focused ions beams
KW - Internal surfaces
KW - Niobium coatings
KW - Radio frequency cavity
KW - Spinning process
KW - Superconducting radio frequency
KW - X-ray computed
KW - Scanning electron microscopy
U2 - 10.1016/j.matchemphys.2021.125062
DO - 10.1016/j.matchemphys.2021.125062
M3 - Journal article
VL - 273
JO - Materials Chemistry and Physics
JF - Materials Chemistry and Physics
SN - 0254-0584
M1 - 125062
ER -