Materials Science & Technology Application of advanced and non - PowerPoint PPT Presentation

Materials Science & Technology Application of advanced and non destructive testing in solid oxide fuel cells Peter Wyss, Erwin Hack Laboratory for Electronics/Metrology/Reliability Artur Braun, Lorenz Holzer, Christian Soltmann, Peter Holtappels Laboratory for High Performance Ceramics Empa, Swiss Federal Laboratories for Materials Testing and Research Überlandstr 129 , CH-8600 Switzerland

metallic components Outline ceramic components Test items and techniques  Non-destructive testing  neutron tomography  Innenringdichtung Innenringdichtung x-ray radiography  thermography  Advanced destructive testing  FIB tomography  Outlook  Radialdichtung Radialdichtung Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 2

Solid Oxide Fuel Cell - Principles - SOFC features&scaling e - Air: O 2 /N 2 N 2 Electrocatalytic activity Nano/atomic scale Cr-, Ni-Cr-Steels Metallic IC Ionic conductivity Nano/atomic scale cathode LSM, LSCF, LSF s e r Electronic conductivity u t c electrolyte „Nano/atomic/micro scale“ O O x YSZ u r t s (Open) porosity D anode Ni/YSZ - 3 Microscale anode support Ni/YSZ SEM/OM/EDX Only 2-D imaging Cr-, Ni-Cr-Steels Metallic IC CO 2 /H 2 O e - Fuel: CH 4 /H 2 O Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 3

Non-destructive Testing (NdT) component state potential problem ndt test method X-ray RT, CT, metallic machined part cracks, bad welds UT for interconn. RT, CT X-rays, assembled in metallic corrosion, contamination stack Neutrons ? green machined porosity + homogenity, RT, µCT local mode, ceramic part shrinkage cracks X-rays, TT assembled and cracks + delaminations RT, µCT local mode, ceramic fired to cell (thermal cycling) X-rays, TT cells mounted fatigue cracks RT, CT, Neutrons + ceramic (thermal cycling) contrast fluid ? in the stack Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 4

1. NdT methods and test items X-ray direction Field of view RT system data (typical) resolution field of view typ. penetrable source beam geometry in µm (FOV) in mm ZrO 2 in mm Neutrons almost parallel 100 300 > 200 X-ray conical 10 400 20 Mini / Micro focus X-ray parallel 1 10 2 Synchrotron Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 5

Neutron tomography ~ 20 cm permits „insight“ into submillimeter porosity of SOFC stack Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 6

2. RT and local µCT to Empa YSZ pellets VISCOM TEP 9225 X-ray flat panel panorama Sample on Hamamatsu tube head low runout 7942 CA-02 or rotation stage TXD 9160 subµ tube head The RT / CT microscopy (macroscopy) system Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 7

RT and local µCT to Empa YSZ pellets The crack detection limit in radiography X-ray direction c α w crack detection is possible if: c > 0.01 w * sin α tube spot size * 0.5 Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 8

RT and local µCT to Empa YSZ pellets Radiographies Visible light microscopy of a hidden coarse grain FOV 5 x 5 mm, pixelsize 2.5 µm Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 9

RT and local µCT to Empa YSZ pellets Radiographies Visible light microscopy of a shrinkage crack FOV 5 x 5 mm, pixelsize 2.5 µm Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 10

RT and local µCT to Empa YSZ pellets Local X-ray µCT of crack in pellet Ø 35 x 1 mm Field of view 5 x 5 mm, voxelsize 5 µm Slices parallel to main surface Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 11

RT and local µCT to Empa YSZ pellets Local X-ray µCT of hidden coarse grain Field of view 5 x 5 mm, voxelsize 5 µm Slices parallel to main surface Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 12

TT, RT and local µCT to HTceramics cells Camera Cedip JADE Camera type Array Resolution 240 x 320 pix Wavelength range 3-5 μ m Frame rate Full: 170 Hz ROI: 9 kHz Lateral resolution 15 x 15 μ m 2 NETD 20 mK Temp. range -20 – 1300 °C Lock-In frequency < 5 kHz The thermography cam, heart of the TT system Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 13

TT, RT and local µCT to HTceramics cells Thermography testing (TT), impulse method flash hits surface lateral resolution ≈ 2 x depth bad bond spot diffusion wave propagates bad bond spot stops time ≈ the heat diffusion wave depth 2 and after some time a thermic contrast appears: positive at the impulse side, negative at the rear side Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 14

TT, RT and local µCT to HTceramics cells Impulse thermography images of a region FOV for RT +µCT containing a spot of high thermal conductivity Istantaneous after flash 20 msec later FOV 180 x 150 pixel or 28 x 25 mm, Pixelsize 167 µm Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 15

TT, RT and local µCT to HTceramics cells The same region (FOV 5 x 5 mm) imaged with: Local tomography, voxel size 5 µm Radiographies, pixel size 2.5 µm Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 16

Focussed Ion Beam (FIB) technique Conventional preparation procedure Advanced preparation procedure Hi2 DLR BekNi 275/3 H 2 Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 17

TEM: Imaging & elemental analysis DLR BekNi 275/3 chemical map: Ni Zr Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 18

FIB-Nanotomography: 3-D structure of a FC Electrolyte stabilised zirconia Air electrode Fuel electrode perovskite Ni-Cermet DLR BekNi 275/3 volume: 40 x 40 x 40  m 3 Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 19

Nanotomography: Informationsgewinn 3D Imaging Particulate und micro structure A 6 µm Distinction Crystallite-Particulate aggregates Use of Information: B Modeling Understanding degradation 6 µm  e.g. sulphur poisoning Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 20

Advanced characterisation access to large scale facilities software sample preparation Source: J.R. Wilson et al., Nature Materials 5 541-544, 2006 micro meter nano meter cm / mm Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 21

NdT methods and diagnostics strategy Visual testing (VT), including Quality assurance   visible light microscopy cell production  will be done in any case stacking   Ultrasonic testing (UT)  requires flat surfaces and low Life time / Durability   damping, 3D possibility comparison of pre and post test  Eddy current testing (ET)  state by NdT possible for electrical conductors only failures affecting mechanical   properties visible by NdT Magnetic testing (MT)  Combination of NdT  for ferritic materials only  advantageous Thermography (TT)  identification of points for  best for close to surface items, 3D  destructive analysis possibility Radiographic testing (RT, CT,  3D imaging  real structures  XTM)  validation of 2D analysis No requirements to surfaces and  damping, 3D possibility (e.g. SEM, OM) Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 22

Acknowledgement Defne Bayraktar, EMPA  Hi2 Ulrich Vogt, EMPA  H 2 Thomas Graule, EMPA  Günter Schiller, DLR  SINQ, PSI  Josef Sfeir, Hexis  HTceramix  Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 23

4. A possible NdT procedure for cells Impulse thermography overview (FOV = 80 x 80 mm) Pixel size 0.33 mm, meas. time per cell ≈ 2 min Impulse thermography close up (FOV = 8 x 8 mm) Pixel size 33 µm , meas. time per cell ≈ 10 min (automated) Radiography overview (FOV = 80 x 80 mm) Pixel size 20 µm , meas. time per cell ≈ 5 min Radiography close up (FOV = 8 x 8 mm) Pixel size 4 µm (OVHM - Movie) , meas. time per item ≈ 10 min (auto) Local tomography (FOV = 8 x 8 mm) , meas. time per item ≈ 60 min voxel size 4 µm or calculation of items depth by evaluating the trajectories from OVHM -Movie Empa, Peter Holtappels, FC Tools, Trondheim, 23.6.2009 24