October 12, Pore structure characterization and in-situ diffusion measurement in nanoporous membrane using SANS This research project has been supported by the European Commission under the 6th Framework Programme through the Key Action: Strengthening the European Research Area, Research Infrastructures. Contract n°: RII3-CT (NMI3). 1 Nuclear Physics Institute Řež near Prague, Czech Republic 2 IfW, TU Braunschweig, Germany 3 Helmholtz-Zentrum Berlin, Germany 4 Research Center Řež, CZ Řež near Prague, Czech Republic P. Strunz 1,4, D. Mukherji 2, J. Šaroun 1,4, U. Keiderling 3, J. Rösler 2

October 12, Nuclear Physics Institute Řež near Prague, Czech Republic 2 IfW, TU Braunschweig, Germany 3 Helmholtz-Zentrum Berlin, Germany 4 Research Center Řež, CZ Řež near Prague, Czech Republic P. Strunz 1,4, D. Mukherji 2, J. Šaroun 1,4, U. Keiderling 3, J. Rösler 2

October 12, Pore structure characterization and in-situ diffusion measurement in nanoporous membrane using SANS This research project has been supported by the European Commission under the 6th Framework Programme through the Key Action: Strengthening the European Research Area, Research Infrastructures. Contract n°: RII3-CT (NMI3).

October 12,  A novel process developed at TU Braunschweig to produce nano-porous membrane form metallic alloys  Common Ni-base superalloys can be used for fabrication  Membranes can be produced in varying thicknesses – 100 µm to 1 mm  Very fine open porosity with high degree of regularity  A novel process developed at TU Braunschweig to produce nano-porous membrane form metallic alloys  Common Ni-base superalloys can be used for fabrication  Membranes can be produced in varying thicknesses – 100 µm to 1 mm  Very fine open porosity with high degree of regularity The material: porous membrane from Ni-alloy  Prospective applications:  separation processes  catalytic substrate  miniature heat exchangers  gas permeable membranes  can be functionalized by thin film deposition  Prospective applications:  separation processes  catalytic substrate  miniature heat exchangers  gas permeable membranes  can be functionalized by thin film deposition

October 12,  A) the raft morphology (e.g. finer pores)  B) increase phase dissolution rate (i.e., electrolyte and potential influence the speed and the selectivity)  A) the raft morphology (e.g. finer pores)  B) increase phase dissolution rate (i.e., electrolyte and potential influence the speed and the selectivity) Process optimization Aim of the SANS experiment  Knowledge of microstructural parameters can help to optimize the fabrication of the membrane  The diffusion of liquids and gasses is an important question for the prospective applications of the porous metallic membrane  Knowledge of microstructural parameters can help to optimize the fabrication of the membrane  The diffusion of liquids and gasses is an important question for the prospective applications of the porous metallic membrane

October 12, Basic material properties and process parameters  single-crystal Ni-base superalloy CMSX-4 (average SLD: ρ = 67.27×10 9 cm -2, calculated from the composition)  Heat treatment: 1573K/2.5h K/6h, gas-fan quenched K/6h K/24h  => large volume fraction (over 50%) of cubic γ’- precipitates  uniaxial tensile creep ( 1273K, 170MPa ) - load along [001] direction  single-crystal Ni-base superalloy CMSX-4 (average SLD: ρ = 67.27×10 9 cm -2, calculated from the composition)  Heat treatment: 1573K/2.5h K/6h, gas-fan quenched K/6h K/24h  => large volume fraction (over 50%) of cubic γ’- precipitates  uniaxial tensile creep ( 1273K, 170MPa ) - load along [001] direction

October 12, TU Braunschweig  Step 1: Self-assembly of nano-sized Ni3Al precipitates induced by thermomechanical treatment (rafting)  Step 2: Separating the nano-structure from the bulk by electrochemical selective phase dissolution Nanoporous membrane preparation in 2 steps Thermo- mechanical load => rafts  Result: Porous membrane  Result: Porous membrane

October 12, Experiment First experiments: - MAUD at NPI Řež near Prague - V4 facility at BENSC, HZ Berlin - microstructural characterization - kinetics of the H 2 O and D 2 O diffusion through the membrane D 2 O lowers the scattering contrast as it fills into the pores while H2O increases it => the extent of filling of the pores and thus the diffusion rate could in principle be determined through a time–resolved experiment. First experiments: - MAUD at NPI Řež near Prague - V4 facility at BENSC, HZ Berlin - microstructural characterization - kinetics of the H 2 O and D 2 O diffusion through the membrane D 2 O lowers the scattering contrast as it fills into the pores while H2O increases it => the extent of filling of the pores and thus the diffusion rate could in principle be determined through a time–resolved experiment.

October 12, Double-Bent-Crystal SANS data => interparticle interference maximum facility MAUD (NPI Řež) Bragg-like scattering on the ordered rafts => S x (Q x ) is the cross-section dΣ/dΩ(Q x,Q y ) integrated over the vertical angular component

October 12, Double-Bent-Crystal SANS data allow determining the average distance between the longitudinal pores (4800 Å) μmμm

October 12, Determined microstructural parameters By combining data from both facilities:  the average distance between the longitudinal pores: 4800 Å  the average thickness of the rafts 2700 Å  volume fraction of the rafts: 64%  volume fraction of pores around: 36%  the specific interface between γ' phase and the pores: cm 2 /cm 3.  SLD of the γ' rafts: 73.0×10 9 cm -2.  back-calculated SLD of the γ matrix: 57.3×10 9 cm -2. By combining data from both facilities:  the average distance between the longitudinal pores: 4800 Å  the average thickness of the rafts 2700 Å  volume fraction of the rafts: 64%  volume fraction of pores around: 36%  the specific interface between γ' phase and the pores: cm 2 /cm 3.  SLD of the γ' rafts: 73.0×10 9 cm -2.  back-calculated SLD of the γ matrix: 57.3×10 9 cm -2.

October 12, pinhole SANS, V4, BENSC, HZ Berlin Left: V4 data for unfilled pores [ the grey scale map shows measured 2D data and the white equi-intensity lines depict the fitted curve ] Right: section through the optimum model Left: V4 data for unfilled pores [ the grey scale map shows measured 2D data and the white equi-intensity lines depict the fitted curve ] Right: section through the optimum model

October 12, pinhole SANS, V4, BENSC, HZ Berlin V4 SANS data for D 2 O (left) and H 2 O filled (right) membrane. 2D cross-section dΣ/dΩ(Q x,Q y ) is shown.

October 12,  D 2 O, H 2 O was filled in the reservoir of a specially constructed cell: - fluid was filled on one side of the porous membrane and allowed to flow through the pores under ambient pressure.  D 2 O, H 2 O was filled in the reservoir of a specially constructed cell: - fluid was filled on one side of the porous membrane and allowed to flow through the pores under ambient pressure. Kinetics experiment  the pores are occupied by D 2 O or H 2 O very quickly, already during the time between the reservoir filling and the measurement start, i.e. in the time span of less than 20s.  A similar test done with silicon oil with same result.  After removal of D 2 O from the reservoir (i.e. both surfaces are on air), the evaporation of liquid from the pores occurs.  Huge scattering from the freed pores => scattering intensity increase with time. 0.5μm depth emptied each minute  the pores are occupied by D 2 O or H 2 O very quickly, already during the time between the reservoir filling and the measurement start, i.e. in the time span of less than 20s.  A similar test done with silicon oil with same result.  After removal of D 2 O from the reservoir (i.e. both surfaces are on air), the evaporation of liquid from the pores occurs.  Huge scattering from the freed pores => scattering intensity increase with time. 0.5μm depth emptied each minute Results

October 12,  Combined SANS results from pinhole and double-bent- crystal facility enabled us to determine microstructural parameters of the nanoporous membrane (SLD, pore-to- pore distance, raft thickness, pore volume fraction, specific interface)  Kinetics experiment showed that the pores are filled instantly (less than 20s) by D 2 O, H 2 O or silicon oil (strong capillary effects)  Empting of pores by evaporation (a much slower process) throw some light on the diffusion process through the pores  Combined SANS results from pinhole and double-bent- crystal facility enabled us to determine microstructural parameters of the nanoporous membrane (SLD, pore-to- pore distance, raft thickness, pore volume fraction, specific interface)  Kinetics experiment showed that the pores are filled instantly (less than 20s) by D 2 O, H 2 O or silicon oil (strong capillary effects)  Empting of pores by evaporation (a much slower process) throw some light on the diffusion process through the pores Summary

October 12,  J. Rösler, O. Näth, F. Schmitz, D. Mukherji: Acta Mater. 53 (2005)  D. Mukherji, G. Pigozzi, F. Schmitz, O. Näth, J. Rösler and G. Kostorz (2005): Nanotechnology 16,  P. Strunz, D. Mukherji, O. Naeth, R. Gilles, J. Roesler: Characterization of nanoporous superalloy by SANS. Physica B 385– 386 (2006) 626–629.  P. Strunz, D. Mukherji, G. Pigozzi, R. Gilles, T. Geue, K. Pranzas: Appl. Phys. A 88 [Materials Science & Processing], (2007)  J. Rösler, O. Näth, F. Schmitz, D. Mukherji: Acta Mater. 53 (2005)  D. Mukherji, G. Pigozzi, F. Schmitz, O. Näth, J. Rösler and G. Kostorz (2005): Nanotechnology 16,  P. Strunz, D. Mukherji, O. Naeth, R. Gilles, J. Roesler: Characterization of nanoporous superalloy by SANS. Physica B 385– 386 (2006) 626–629.  P. Strunz, D. Mukherji, G. Pigozzi, R. Gilles, T. Geue, K. Pranzas: Appl. Phys. A 88 [Materials Science & Processing], (2007) References