Co-sputtered amorphous Nb-Ta, Nb-Zr and Ta-Zr coatings for corrosion protection of cyclotron targets for [18F] production

JOURNAL OF ALLOYS AND COMPOUNDS

卷:639

Article

Skliarova, Hanna^1,2  Azzolini, Oscar¹  Johnson, Richard R.³  Palmieri, Vincenzo^1,4 

[1] Natl Inst Nucl Phys, Legnaro Natl Labs, I-35020 Padua, Italy

[2] Univ Ferrara, I-44100 Ferrara, Italy

[3] BEST Cyclotron Syst Inc, Vancouver, BC V6P 6T3, Canada

[4] Univ Padua, Padua, Italy

关键词: Magnetron sputtering;    Thin films;    Diffusion barrier;    X-ray diffraction;    Microstructure;    Metallic glasses;   

DOI  :  10.1016/j.jallcom.2015.03.181

来源: Elsevier

【 摘 要 】

Protective corrosion resistant coatings serve for decreasing the amount of ionic contaminants from Havar (R) entrance foils of the targets for [F-18] production. The corrosion damage of coated entrance foils is caused mainly by the diffusion of highly reactive products of water radiolysis through the protective film toward Havar (R) substrate. Since amorphous metal alloys (metallic glasses) are well-known to perform a high corrosion resistance, the glass forming ability, microstructure and diffusion barrier efficiency of binary alloys containing chemically inert Nb, Ta, Zr were investigated. Nb-Ta, Nb-Zr and Ta-Zr films of different alloy composition and similar to 1.5 mu m thickness were co-deposited by magnetron sputtering. Diffusion barrier efficiency tests used reactive aluminum underlayer and protons of acid solution and gallium atoms at elevated temperature as diffusing particles. Though co-sputtered Nb-Ta and Nb-Zr alloy films of different contents were crystalline, Ta-Zr alloy was found to form dense amorphous microstructures in a range of composition with 30-73% atomic Ta. The diffusion barrier efficiency of Nb-Zr and Nb-Ta alloy coatings decreased with increase of Nb content. The diffusion barrier efficiency of sputtered Ta-Zr alloy coatings increased with the transition from nanocrystalline columnar microstructure to amorphous for coatings with 30-73 at.% Ta. (C) 2015 Published by Elsevier B.V.

【 授权许可】

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