Nanoporous microtubes obtained from a Cu-Ni metallic wire
Nanoporous microtubes of a nickel-copper alloy were obtained from a Cu-44Ni-1Mn (wt%) commercial wire (200 μm diameter). A new synthesis method was established through three steps: 1) partial oxidation of the wire at 1173 K in air, 2) removal of the inner unoxidized core by chemical etching, 3) reduction in 10 bar hydrogen atmosphere. During oxidation, the segregation of Cu and Ni occurred because of their different diffusion coefficients in the corresponding oxides. As a consequence, pores were formed by Kirkendall effect and due to selective chemical etching of the different oxides. Additional porosity formed because of volume contraction during reduction with hydrogen. After reduction, the microtube shows a composition gradient from the inner wall (almost pure nickel) to the outer wall (almost pure copper). The process allowed to obtain microtubes with tuneable wall thickness and inner pores around 180 ± 80 nm. The morphological features developed suggest improved capillarity properties for applications in MEMS.
Keywordsmicrotube porous materials annealing oxidation X-ray diffraction
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- 1.W. P. Hoffman and P. G. Waper, Microscopic Tube Devices and Method of Manufacture, pp.1–16, patent US6113722A (2000).Google Scholar
- 20.wwwthermocalccom (accessed May 27, 2015).Google Scholar
- 21.http://wwwingunitnit/~maud/indexhtml (accessed May 27, 2015).Google Scholar
- 22.Z.-Q. Cao, Y. Niu, and F. Gesmundo, Trans. Nonferrous Met. Soc. China 11, 499 (2001).Google Scholar
- 23.J. A. Sartell and C. H. Li, Trans. Am. Soc. Met. 55, 158 (1962).Google Scholar
- 28.A. D. Smigelskas and E. O. Kirkendall, Trans. AIME 171, 130 (1947).Google Scholar
- 29.H. Hokamoto, Phase Diagrams for Binary Alloys, p.303, ASM International, Metals Park (2000).Google Scholar
- 30.B. D. Cullity, Elements of X-ray diffraction, 2nd ed., p.376, Addison Wesley, Reading (1978).Google Scholar
- 34.R. Souchet, M. Lenglet, P. Miche, S. Weber, and S. Scherrer, Analusis 21, 173 (1993).Google Scholar