Nanoporous Microtubes via Oxidation and Reduction of Cu–Ni Commercial Wires
Metallic porous microtubes were obtained from commercial wires (200–250 µm diameter) of Cu-65Ni-2Fe, Cu-44Ni-1Mn and Cu-23Ni, alloys (wt. %) by surface oxidation at 1173 K in air, removal of the unoxidized core by chemical etching, and reduction in annealing in the hydrogen atmosphere. Transversal s...
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| Format: | Article |
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MDPI AG
2017-02-01
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| Series: | Metals |
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| Online Access: | http://www.mdpi.com/2075-4701/7/2/46 |
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| author | Emanuele Francesco Marano Alberto Castellero Marcello Baricco |
| author_facet | Emanuele Francesco Marano Alberto Castellero Marcello Baricco |
| author_sort | Emanuele Francesco Marano |
| collection | DOAJ |
| description | Metallic porous microtubes were obtained from commercial wires (200–250 µm diameter) of Cu-65Ni-2Fe, Cu-44Ni-1Mn and Cu-23Ni, alloys (wt. %) by surface oxidation at 1173 K in air, removal of the unoxidized core by chemical etching, and reduction in annealing in the hydrogen atmosphere. Transversal sections of the partially oxidized wires show a porous layered structure, with an external shell of CuO (about 10 μm thick) and an inner layer of NiO (70–80 μm thick). In partially oxidized Cu-44Ni-1Mn and Cu-23Ni, Cu2O is dispersed in NiO because the maximum solubility of Cu in NiO is exceeded, whereas in Cu-65Ni-2Fe, a Cu2O shell is present between CuO and NiO layers. Chemical etching removed the unoxidized metallic core and Cu2O with formation of porous oxide microtubes. Porosity increases with Cu content because of the larger amount of Cu2O in the partially oxidized wire. After reduction, the transversal sections of the metallic porous microtubes show a series of f.c.c.-(Cu,Ni) solid solutions with different compositions, due to the segregation of CuO and NiO during oxidation caused by the different diffusion coefficients of Ni and Cu in the respective oxides. Pore formation occurs at each step of the process because of the Kirkendall effect, selective phase removal and volume contraction. |
| first_indexed | 2024-12-16T18:58:56Z |
| format | Article |
| id | doaj.art-c4b31bf22b634e3797930532fdf49100 |
| institution | Directory Open Access Journal |
| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-12-16T18:58:56Z |
| publishDate | 2017-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Metals |
| spelling | doaj.art-c4b31bf22b634e3797930532fdf491002022-12-21T22:20:26ZengMDPI AGMetals2075-47012017-02-01724610.3390/met7020046met7020046Nanoporous Microtubes via Oxidation and Reduction of Cu–Ni Commercial WiresEmanuele Francesco Marano0Alberto Castellero1Marcello Baricco2Department of Chemistry and NIS, University of Turin, I-10125 Turin, ItalyDepartment of Chemistry and NIS, University of Turin, I-10125 Turin, ItalyDepartment of Chemistry and NIS, University of Turin, I-10125 Turin, ItalyMetallic porous microtubes were obtained from commercial wires (200–250 µm diameter) of Cu-65Ni-2Fe, Cu-44Ni-1Mn and Cu-23Ni, alloys (wt. %) by surface oxidation at 1173 K in air, removal of the unoxidized core by chemical etching, and reduction in annealing in the hydrogen atmosphere. Transversal sections of the partially oxidized wires show a porous layered structure, with an external shell of CuO (about 10 μm thick) and an inner layer of NiO (70–80 μm thick). In partially oxidized Cu-44Ni-1Mn and Cu-23Ni, Cu2O is dispersed in NiO because the maximum solubility of Cu in NiO is exceeded, whereas in Cu-65Ni-2Fe, a Cu2O shell is present between CuO and NiO layers. Chemical etching removed the unoxidized metallic core and Cu2O with formation of porous oxide microtubes. Porosity increases with Cu content because of the larger amount of Cu2O in the partially oxidized wire. After reduction, the transversal sections of the metallic porous microtubes show a series of f.c.c.-(Cu,Ni) solid solutions with different compositions, due to the segregation of CuO and NiO during oxidation caused by the different diffusion coefficients of Ni and Cu in the respective oxides. Pore formation occurs at each step of the process because of the Kirkendall effect, selective phase removal and volume contraction.http://www.mdpi.com/2075-4701/7/2/46Cu-Ni alloyoxidationetchingreductionporous materialmicrotube |
| spellingShingle | Emanuele Francesco Marano Alberto Castellero Marcello Baricco Nanoporous Microtubes via Oxidation and Reduction of Cu–Ni Commercial Wires Metals Cu-Ni alloy oxidation etching reduction porous material microtube |
| title | Nanoporous Microtubes via Oxidation and Reduction of Cu–Ni Commercial Wires |
| title_full | Nanoporous Microtubes via Oxidation and Reduction of Cu–Ni Commercial Wires |
| title_fullStr | Nanoporous Microtubes via Oxidation and Reduction of Cu–Ni Commercial Wires |
| title_full_unstemmed | Nanoporous Microtubes via Oxidation and Reduction of Cu–Ni Commercial Wires |
| title_short | Nanoporous Microtubes via Oxidation and Reduction of Cu–Ni Commercial Wires |
| title_sort | nanoporous microtubes via oxidation and reduction of cu ni commercial wires |
| topic | Cu-Ni alloy oxidation etching reduction porous material microtube |
| url | http://www.mdpi.com/2075-4701/7/2/46 |
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