1 / 20

Synthesis of porous metals

Synthesis of porous metals. Keiji Nagai ILE Osaka. Contents. Sphere temple method ----- Established synthetic method to prepare porous material. Design of porous tungsten for the wall material. We will discuss about the merits and demerits of porous tungsten.

joycelyn
Download Presentation

Synthesis of porous metals

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Synthesis of porous metals Keiji Nagai ILE Osaka

  2. Contents • Sphere temple method ----- Established synthetic method to prepare porous material. • Design of porous tungsten for the wall material. • We will discuss about the merits and demerits of porous tungsten. 1) Controllability of the synthesis. 2) high surface area (>100m2/g). 3) conductivity. • Future plan as a summary

  3. Sphere temple method is powerful tool to prepare porous material. Liquid metal source I0 um Removal of template I um Pore size and density were well controlled by the template spheres. K. Nagai et al., Trans. Mater. Res. Soc. Jpn., 29 (3) 943 (2004)

  4. Surfactant-free emulsion polymerizationto prepare mono-dispersed sized nanoparticles Water suspension Nanoparticle film 100m Styrene/water~1/9 80 oC, 24 hours

  5. 2 mm Thickness: 10 µm, Density: 20% of b-Sn Porous metal tin (Sn) was prepared electrochemically. Porous Sn film PS template Electrode SnSO4 electrochemical plating -> Sn metal Removal of PS using toluene 1 mm Nagai et al., Fusion Sci. Technol. 2006

  6. Lithium can be filled into the voids of porous Sn. Electrode 1 mm Sn deposition of Li Li Nagai et al., Laser Partcl. Beams 2008

  7. Porous metal gold (Au) was also prepared electrochemically. Electrode [Au(CN)2]- electrochemical plating -> Au metal Thickness: 2 µm, Density: 4.3g/cm3 (23% of Au) 1 mm • Nagai et al., Fusion Sci. Technol., 49 (4), 686-690, (2006).

  8. *After TJ Renk B - boiling M - melting C - cracking R - roughening Helium implantation & thermal conduction (100 MW m-2 s0.5)* are the erosion mechanisms. Performance of Tungsten under short transient thermal loads RHEPP-1 Heat Flux Parameter P x sqrt (t) / MW m-2 s0.5 B M M M M C C R J. Linke et al, JNM 367-370 (2007) 1422-1431 pulse duration / s Thermal conduction is a dominant mechanism

  9. Pulsed Power Sciences, Sandia National Laboratories TJR 9/27/2008 After TJ Renk Polycrystalline Tungsten He exposure behavior - 1600 pulses All samples initially Room Temperature (RT) All images 1000X magnification Ave 0.6 J/cm2 /pulse Ave 1.4 J/cm2 /pulse Ave 0.8 J/cm2/pulse Ave 0.85 J/cm2 /pulse ~600°C Average MaxTemp ~1000°C Average MaxTemp ~1500°C Average MaxTemp ~1050°C Average MaxTemp 350 GW/m2/pulse (50 µm) 1200 pulses 800 pulses 400 pulses 1600 pulses Ra ~ 1.5 µm • Average maximum surface temperature < 1500°C • No effect 1st 400 pulses: below threshold • Using √t scaling: 0.8 J/cm2 equivalent of 0.4 MJ/m2. Consistent with QSPA plasma exposure of tungsten PFCs (ref: A. Zhitukhin et al, JNM 363-365 (2007) 301-307 • Final 400 pulses @ 0.85 J/cm2: probable cumulative mass loss (Est) total He implantation ~ 1.8e16 /cm2

  10. Design of porous tungsten • Porous tungsten has merits of 1) small and controllable distance of nanowall. 2) high surface area (~100m2/g) for high radiation cooling. • Porous tungsten has demerits of 3) poorer conductivity than the metal bulk. 4) mechanical fragility.

  11. n=10 Surface template -> Open cell 1) The template technique gives small and controllable distance of nanowall. SEM images before removal of template Volume template vs. Surface template n=2 Volume template n=2 n=4 -> Closed cell n=6 n=10 n = EtOHmol/ SnCl4 mol More EtOH (n), lower contact angle (higher affinity for PS) Q.C.Gu et al., Chem. Mater., 17 (5), 1115-1122, (2005).

  12. 2) The template technique gives high surface area (~100m2/g) which would effective for radiation cooling. • An example of surface area of 60 m2/g BET isotherm 1 m The porous SnO2 shows a hierarchical pore system at three different scale length, 1) mesopore, the interparticle space (<10 nm), 2) small macropore-window ( ∼102 nm), and 3) large macropore-cell ( ∼103 nm). Q.C.Gu et al., Chem. Mater., 17 (5), 1115-1122, (2005).

  13. 3) Estimation of conductivity of the porous metal. • Current during the electroplating is an indicator of the conductivity of the porous metal. A V Working electrode Counter electrode pf platinum supplies the current (A). Reference electrode gives relative potential (V) from Ag+/Ag0

  14. Estimation of conductivity of the porous metal. -1.08 V vs Ag/AgCl -1.10 V vs Ag/AgCl -0.39 V vs Ag/AgCl -0.45 V vs Ag/AgCl Although the over potentials for porous metal plating mean the larger resistance than the bulk, the time independent currents indicate that that is due to the interfaces.

  15. We did not find a large difference of conductivity between the bulk and porous metals. coulomb efficiency of the electrochemical plating ________________________________________________________ material thickness weight density electric coulomb charge efficiency [m/cm2] [g/cm2] [g/cm3] [C/cm2] ________________________________________________________ bulk Sn 8.29 6.03 7.23 7.31 0.67 porous Sn 5.20 0.756 1.45 0.95 0.65 bulk Au 2.00 3.86 19.3 2.86 0.66 porous Au 6.39 2.99 4.28 2.24 0.65 ________________________________________________________ coulomb efficiency = Faraday const. x (mole of metal)/charge

  16. Needle like millimeter-sized structure is effective to decrease the threshold per cross section area. HAPL Pulsed Power Sciences, Sandia National Laboratories TJR 9/25/2008 After TJ Renk Two arrayed needle geometries investigated • Left: ‘Array’ - Sewing needles and dressmaker pins on Al-6061 substrate, mylar strip in center. Hole diameter 0.029in, 175 drilled into 1/8 in substrate 0.060in apart. • Needle Composition; high carbon steel with Nickel plating • Bottom Left: ‘Bundle’ - sewing needles tied together by wires • Below: Arrays mounted before 400 shot He series Cost ~ $5

  17. Control of pore in micro~milli-meter • Millimeter sized pore tungsten would be a candidate material as seen in the tungsten needle. Liquid metal source Removal of template We can prepare millimeter pore by changing millimeter templates

  18. Millimeter sized templates can be prepared using droplet generator and emulsion technique. W1 W2 O W1: inner water O: oil W2: outer water Compound emulsion O W1 W2

  19. Future plans • Ion beam irradiation using RHEPP-1 at SNL. • Estimation of the resistivity depending on the thickness (~50 nm) • Re-design of the porous tungsten. • PISCES irradiation

More Related