April 19, 2023 1

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-2003-505925 (NMI3).

1 Nuclear Physics Institute Řež near Prague, Czech Republic2 IfW, TU Braunschweig, Germany3 Helmholtz-Zentrum Berlin, Germany4 Research Center Řež, CZ-25068 Řež near Prague, Czech Republic

P. Strunz1,4, D. Mukherji2, J. Šaroun1,4, U. Keiderling3, J. Rösler2

April 19, 2023 2

1 Nuclear Physics Institute Řež near Prague, Czech Republic (email:strunz@ujf.cas.cz)

2 IfW, TU Braunschweig, Germany3 Helmholtz-Zentrum Berlin, Germany4 Research Center Řež, CZ-25068 Řež near Prague, Czech

Republic

P. Strunz1,4, D. Mukherji2, J. Šaroun1,4, U. Keiderling3, J. Rösler2

April 19, 2023 3

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-2003-505925 (NMI3).

April 19, 2023 4

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-alloyThe 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

April 19, 2023 5

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 optimizationProcess optimization

Aim of the SANS experimentAim 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

April 19, 2023 6

Basic material properties and process parameters

Basic material properties and process parameters

single-crystal Ni-base superalloy CMSX-4 (average SLD: ρ = 67.27×109 cm-2, calculated from the composition)

Heat treatment: 1573K/2.5h + 1583K/6h, gas-fan quenched + 1413K/6h + 1123K/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 = 67.27×109 cm-2, calculated from the composition)

Heat treatment: 1573K/2.5h + 1583K/6h, gas-fan quenched + 1413K/6h + 1123K/24h

=> large volume fraction (over 50%) of cubic γ’-precipitates

uniaxial tensile creep (1273K, 170MPa) - load along [001] direction

April 19, 2023 7

TU BraunschweigTU Braunschweig

Step 1: Self-assembly of nano-sized Ni3Al precipitates induced by thermomechanical treatment (rafting)

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

Step 2: Separating the nano-structure from the bulk by electrochemical selective phase dissolution

Nanoporous membrane preparation in 2 steps Nanoporous membrane preparation in 2 steps

Thermo-mechanical load

Thermo-mechanical load

=> rafts => rafts

Result: Porous membrane

Result: Porous membrane

April 19, 2023 8

Experiment

First experiments: - MAUD at NPI Řež near Prague - V4 facility at BENSC, HZ Berlin

- microstructural characterization- kinetics of the H2O and D2O

diffusion through the membrane

D2O 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 H2O and D2O

diffusion through the membrane

D2O 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.

beam shutter

position sensitivedetector

beam tube w ith collimator

sam ples

bent S i 220

bent S i 111 analyzer(asym metric cut) PE + B

Pb

bent S i 111

diffraction planes 111

steel rods

D q Dqx R LD A D S = ( s in(2 ) + )

DqS

DxD

L D

April 19, 2023 9

Double-Bent-Crystal SANS data

•=> interparticle interference maximum

•=> interparticle interference maximum

0.0004 0.0008 0.0012 0.0016 0.0020

2000

4000

6000

8000

10000

12000

Porous membrane from CMSX4, measured at MAUD, NPI Rez

empty pores

measured data fitS

x(Q

x) (

cm-1ra

d-1)

Q (Å-1)

•facility MAUD (NPI Řež)

•facility MAUD (NPI Řež)

•Bragg-like scattering on the ordered rafts =>

•Bragg-like scattering on the ordered rafts =>

Sx(Qx) is the cross-section dΣ/dΩ(Qx,Qy) integrated over the vertical angular component

Sx(Qx) is the cross-section dΣ/dΩ(Qx,Qy) integrated over the vertical angular component

April 19, 2023 10

Double-Bent-Crystal SANS data

• allow determining the average distance between the longitudinal pores (4800 Å)

• allow determining the average distance between the longitudinal pores (4800 Å)

0.0000 0.0004 0.0008 0.0012 0.0016 0.00200

100

200

300

400

500

600

700

800Porous membrane from CMSX4, measured at MAUD, NPI Rez

D2O filled

measured data fit

Sx(

Qx)

(c

m-1ra

d-1)

Q (Å-1)

μm

April 19, 2023 11

Determined microstructural parametersDetermined 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: 49000

cm2/cm3.SLD of the γ' rafts: 73.0×109 cm-2. back-calculated SLD of the γ matrix: 57.3×109 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: 49000

cm2/cm3.SLD of the γ' rafts: 73.0×109 cm-2. back-calculated SLD of the γ matrix: 57.3×109 cm-2.

April 19, 2023 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

April 19, 2023 13

pinhole SANS, V4, BENSC, HZ Berlin

• V4 SANS data for D2O (left) and H2O filled (right) membrane. 2D cross-section dΣ/dΩ(Qx,Qy) is shown.

• V4 SANS data for D2O (left) and H2O filled (right) membrane. 2D cross-section dΣ/dΩ(Qx,Qy) is shown.

April 19, 2023 14

D2O, H2O 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.

D2O, H2O 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 experimentKinetics experiment

the pores are occupied by D2O or H2O 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 D2O 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 D2O or H2O 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 D2O 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

ResultsResults

April 19, 2023 15

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 D2O, H2O 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 D2O, H2O 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

SummarySummary

April 19, 2023 16

J. Rösler, O. Näth, F. Schmitz, D. Mukherji: Acta Mater. 53 (2005) 1397-1406.

D. Mukherji, G. Pigozzi, F. Schmitz, O. Näth, J. Rösler and G. Kostorz (2005): Nanotechnology 16, 2176-87.

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) 277-284

J. Rösler, O. Näth, F. Schmitz, D. Mukherji: Acta Mater. 53 (2005) 1397-1406.

D. Mukherji, G. Pigozzi, F. Schmitz, O. Näth, J. Rösler and G. Kostorz (2005): Nanotechnology 16, 2176-87.

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) 277-284

ReferencesReferences