---
_id: '63720'
abstract:
- lang: eng
text: The aging behavior of closed-cell polyurethane (PUR) foam, a material widely
used in household refrigeration, is studied by examining the variation of cell
gas composition and thermal conductivity over time. Aging is primarily driven
by gas permeation, wherein the initially present cell gases carbon dioxide and
cyclopentane are progressively replaced by nitrogen and oxygen from the ambient,
resulting in an increased thermal conductivity and reduced insulation performance.
The cell gas composition is measured over 1400 days employing gas chromatography,
and the thermal conductivity of the foam is measured over 190 days. Morphological
foam characteristics, such as average cell diameter, are determined via scanning
electron microscopy and barrier measurements are performed to estimate the effective
diffusion coefficient of oxygen. To simulate the aging process, one-dimensional
and three-dimensional models are developed for both diffusive mass transfer as
well as heat transfer. The present model for the thermal conductivity explicitly
accounts for condensation effects, i.e. partial condensation of cyclopentane and
carbon dioxide occurring at around 12°C, which significantly influences the insulation
behavior of the foam. Sensitivity analyses indicate that an initial cell gas pressure
of approximately 0.7 bar yields results that closely coincide with the experimental
measurements, where the three-dimensional model demonstrates better accuracy.
These measurements and simulations provide valuable insights for evaluating and
predicting the long-term degradation of the insulation performance of PUR foams.
article_number: '129850'
article_type: original
author:
- first_name: Daniel
full_name: Schumacher, Daniel
last_name: Schumacher
- first_name: Gabriela
full_name: Guevara-Carrion, Gabriela
last_name: Guevara-Carrion
- first_name: Tina
full_name: Kasper, Tina
id: '94562'
last_name: Kasper
orcid: '0000-0003-3993-5316 '
- first_name: Andreas
full_name: Paul, Andreas
id: '7828'
last_name: Paul
- first_name: Andreas
full_name: Elsner, Andreas
id: '16124'
last_name: Elsner
- first_name: Bettina
full_name: Peters, Bettina
id: '62920'
last_name: Peters
- first_name: Wenke
full_name: Wollny, Wenke
last_name: Wollny
- first_name: Marcus
full_name: Bluemel, Marcus
last_name: Bluemel
- first_name: Heike
full_name: Hoelscher, Heike
last_name: Hoelscher
- first_name: Nicola
full_name: Brzoska-Steinhaus, Nicola
last_name: Brzoska-Steinhaus
- first_name: Klaus
full_name: Heil, Klaus
last_name: Heil
- first_name: Lukas
full_name: Schleelein, Lukas
last_name: Schleelein
- first_name: Wolfgang
full_name: Becker, Wolfgang
last_name: Becker
- first_name: Ulrich
full_name: Gries, Ulrich
last_name: Gries
- first_name: Jadran
full_name: Vrabec, Jadran
last_name: Vrabec
citation:
ama: 'Schumacher D, Guevara-Carrion G, Kasper T, et al. Aging of polyurethane foam:
Experimental analysis and modeling of cell gas composition and thermal conductivity.
Applied Thermal Engineering. 2026;289. doi:10.1016/j.applthermaleng.2026.129850'
apa: 'Schumacher, D., Guevara-Carrion, G., Kasper, T., Paul, A., Elsner, A., Peters,
B., Wollny, W., Bluemel, M., Hoelscher, H., Brzoska-Steinhaus, N., Heil, K., Schleelein,
L., Becker, W., Gries, U., & Vrabec, J. (2026). Aging of polyurethane foam:
Experimental analysis and modeling of cell gas composition and thermal conductivity.
Applied Thermal Engineering, 289, Article 129850. https://doi.org/10.1016/j.applthermaleng.2026.129850'
bibtex: '@article{Schumacher_Guevara-Carrion_Kasper_Paul_Elsner_Peters_Wollny_Bluemel_Hoelscher_Brzoska-Steinhaus_et
al._2026, title={Aging of polyurethane foam: Experimental analysis and modeling
of cell gas composition and thermal conductivity}, volume={289}, DOI={10.1016/j.applthermaleng.2026.129850},
number={129850}, journal={Applied Thermal Engineering}, publisher={Elsevier BV},
author={Schumacher, Daniel and Guevara-Carrion, Gabriela and Kasper, Tina and
Paul, Andreas and Elsner, Andreas and Peters, Bettina and Wollny, Wenke and Bluemel,
Marcus and Hoelscher, Heike and Brzoska-Steinhaus, Nicola and et al.}, year={2026}
}'
chicago: 'Schumacher, Daniel, Gabriela Guevara-Carrion, Tina Kasper, Andreas Paul,
Andreas Elsner, Bettina Peters, Wenke Wollny, et al. “Aging of Polyurethane Foam:
Experimental Analysis and Modeling of Cell Gas Composition and Thermal Conductivity.”
Applied Thermal Engineering 289 (2026). https://doi.org/10.1016/j.applthermaleng.2026.129850.'
ieee: 'D. Schumacher et al., “Aging of polyurethane foam: Experimental analysis
and modeling of cell gas composition and thermal conductivity,” Applied Thermal
Engineering, vol. 289, Art. no. 129850, 2026, doi: 10.1016/j.applthermaleng.2026.129850.'
mla: 'Schumacher, Daniel, et al. “Aging of Polyurethane Foam: Experimental Analysis
and Modeling of Cell Gas Composition and Thermal Conductivity.” Applied Thermal
Engineering, vol. 289, 129850, Elsevier BV, 2026, doi:10.1016/j.applthermaleng.2026.129850.'
short: D. Schumacher, G. Guevara-Carrion, T. Kasper, A. Paul, A. Elsner, B. Peters,
W. Wollny, M. Bluemel, H. Hoelscher, N. Brzoska-Steinhaus, K. Heil, L. Schleelein,
W. Becker, U. Gries, J. Vrabec, Applied Thermal Engineering 289 (2026).
date_created: 2026-01-23T12:48:07Z
date_updated: 2026-01-23T12:53:26Z
department:
- _id: '728'
doi: 10.1016/j.applthermaleng.2026.129850
intvolume: ' 289'
keyword:
- Polyurethane
- Foam
- Gas permeation
- Diffusion models
- Thermal conductivity
- Condensation
- Gas chromatography
- Scanning electron microscopy
language:
- iso: eng
publication: Applied Thermal Engineering
publication_identifier:
issn:
- 1359-4311
publication_status: published
publisher: Elsevier BV
quality_controlled: '1'
status: public
title: 'Aging of polyurethane foam: Experimental analysis and modeling of cell gas
composition and thermal conductivity'
type: journal_article
user_id: '7828'
volume: 289
year: '2026'
...
---
_id: '43441'
abstract:
- lang: eng
text: "This paper reveals the 3D character of the intermetallic layer at the aluminum–steel
interface which pops\r\nup above the original sample surface during annealing.
Popping out of the intermetallics was proven using\r\natomic force microscopy.
The phase expands out of the plane due to the exothermic formation of the Al5Fe2\r\nphase
and the feasibility of surface diffusion. Milling by a focused ion beam enabled
the comparison of the\r\nchemical composition of the surface layer with the bulk
interface, showing no difference. The growth direction\r\nis both towards aluminum
and steel — the main diffusion flux is from aluminum towards steel, and the new\r\nintermetallic
phase emerges at the steel side. The shortage of Al atoms causes a shift of the
intermetallic as a\r\nwhole towards aluminum."
article_number: '112043'
article_type: original
author:
- first_name: Michaela
full_name: Šlapáková, Michaela
last_name: Šlapáková
- first_name: Barbora
full_name: Kihoulou, Barbora
last_name: Kihoulou
- first_name: Jozef
full_name: Veselý, Jozef
last_name: Veselý
- first_name: Peter
full_name: Minárik, Peter
last_name: Minárik
- first_name: Klaudia
full_name: Fekete, Klaudia
last_name: Fekete
- first_name: Michal
full_name: Knapek, Michal
last_name: Knapek
- first_name: Rostislav
full_name: Králík, Rostislav
last_name: Králík
- first_name: Olexandr
full_name: Grydin, Olexandr
id: '43822'
last_name: Grydin
- first_name: Mykhailo
full_name: Stolbchenko, Mykhailo
last_name: Stolbchenko
- first_name: Mirko
full_name: Schaper, Mirko
id: '43720'
last_name: Schaper
citation:
ama: Šlapáková M, Kihoulou B, Veselý J, et al. 3D-structure of intermetallic interface
layer in Al–steel clad material. Vacuum. 2023;212. doi:10.1016/j.vacuum.2023.112043
apa: Šlapáková, M., Kihoulou, B., Veselý, J., Minárik, P., Fekete, K., Knapek, M.,
Králík, R., Grydin, O., Stolbchenko, M., & Schaper, M. (2023). 3D-structure
of intermetallic interface layer in Al–steel clad material. Vacuum, 212,
Article 112043. https://doi.org/10.1016/j.vacuum.2023.112043
bibtex: '@article{Šlapáková_Kihoulou_Veselý_Minárik_Fekete_Knapek_Králík_Grydin_Stolbchenko_Schaper_2023,
title={3D-structure of intermetallic interface layer in Al–steel clad material},
volume={212}, DOI={10.1016/j.vacuum.2023.112043},
number={112043}, journal={Vacuum}, publisher={Elsevier BV}, author={Šlapáková,
Michaela and Kihoulou, Barbora and Veselý, Jozef and Minárik, Peter and Fekete,
Klaudia and Knapek, Michal and Králík, Rostislav and Grydin, Olexandr and Stolbchenko,
Mykhailo and Schaper, Mirko}, year={2023} }'
chicago: Šlapáková, Michaela, Barbora Kihoulou, Jozef Veselý, Peter Minárik, Klaudia
Fekete, Michal Knapek, Rostislav Králík, Olexandr Grydin, Mykhailo Stolbchenko,
and Mirko Schaper. “3D-Structure of Intermetallic Interface Layer in Al–Steel
Clad Material.” Vacuum 212 (2023). https://doi.org/10.1016/j.vacuum.2023.112043.
ieee: 'M. Šlapáková et al., “3D-structure of intermetallic interface layer
in Al–steel clad material,” Vacuum, vol. 212, Art. no. 112043, 2023, doi:
10.1016/j.vacuum.2023.112043.'
mla: Šlapáková, Michaela, et al. “3D-Structure of Intermetallic Interface Layer
in Al–Steel Clad Material.” Vacuum, vol. 212, 112043, Elsevier BV, 2023,
doi:10.1016/j.vacuum.2023.112043.
short: M. Šlapáková, B. Kihoulou, J. Veselý, P. Minárik, K. Fekete, M. Knapek, R.
Králík, O. Grydin, M. Stolbchenko, M. Schaper, Vacuum 212 (2023).
date_created: 2023-04-08T17:24:40Z
date_updated: 2023-06-01T14:22:15Z
department:
- _id: '158'
doi: 10.1016/j.vacuum.2023.112043
intvolume: ' 212'
keyword:
- Al-steel clad
- twin-roll casting
- 3D characterization
- atomic force microscopy
- diffusion direction
- surface growth
language:
- iso: eng
publication: Vacuum
publication_identifier:
issn:
- 0042-207X
publication_status: published
publisher: Elsevier BV
quality_controlled: '1'
status: public
title: 3D-structure of intermetallic interface layer in Al–steel clad material
type: journal_article
user_id: '43720'
volume: 212
year: '2023'
...
---
_id: '9899'
abstract:
- lang: eng
text: Bainite is a steel microstructure consisting of three phases, bainitic ferrite,
austenite and carbides. It forms in two different morphologies, upper and lower
bainite, where different diffusion mechanisms are dominant. The aim of this work
is to simulate both transformations within a unified model. To this end, we extend
an own previously published model for lower bainite with diffusion across the
phase interface. As a central idea we introduce weighted Helmholtz energy functions
and a weighted mobility tensor, respectively. The individual Helmholtz energy
functions and mobility terms are related to the different diffusion mechanisms
which are responsible for the formation of both morphologies. Two representative
examples illustrate the capability of the coupled phase field/diffusion model
and show the expected behaviour.
author:
- first_name: M.
full_name: Düsing, M.
last_name: Düsing
- first_name: R.
full_name: Mahnken, R.
last_name: Mahnken
citation:
ama: Düsing M, Mahnken R. „A coupled phase field/diffusion model for upper and lower
bainitic transformation”. International Journal of Solids and Structures.
2018;135:172-183.
apa: Düsing, M., & Mahnken, R. (2018). „A coupled phase field/diffusion model
for upper and lower bainitic transformation”. International Journal of Solids
and Structures, 135, 172–183.
bibtex: '@article{Düsing_Mahnken_2018, title={„A coupled phase field/diffusion model
for upper and lower bainitic transformation”}, volume={135}, journal={International
Journal of Solids and Structures}, publisher={Elsevier}, author={Düsing, M. and
Mahnken, R.}, year={2018}, pages={172–183} }'
chicago: 'Düsing, M., and R. Mahnken. “„A Coupled Phase Field/Diffusion Model for
Upper and Lower Bainitic Transformation”.” International Journal of Solids
and Structures 135 (2018): 172–83.'
ieee: M. Düsing and R. Mahnken, “„A coupled phase field/diffusion model for upper
and lower bainitic transformation”,” International Journal of Solids and Structures,
vol. 135, pp. 172–183, 2018.
mla: Düsing, M., and R. Mahnken. “„A Coupled Phase Field/Diffusion Model for Upper
and Lower Bainitic Transformation”.” International Journal of Solids and Structures,
vol. 135, Elsevier, 2018, pp. 172–83.
short: M. Düsing, R. Mahnken, International Journal of Solids and Structures 135
(2018) 172–183.
date_created: 2019-05-21T13:03:05Z
date_updated: 2019-05-21T13:12:27Z
department:
- _id: '154'
intvolume: ' 135'
keyword:
- Coupled phase field/diffusion model
- Bainite
- Multiphase field method
- Cahn–Hilliard diffusion
- Diffusion across the interface
- Lower bainitic transformation
- Upper bainitic transformation
- Thermodynamic framework
- Microforce balance
language:
- iso: eng
page: 172-183
publication: International Journal of Solids and Structures
publication_identifier:
issn:
- 0020-7683
publication_status: published
publisher: Elsevier
status: public
title: „A coupled phase field/diffusion model for upper and lower bainitic transformation”
type: journal_article
user_id: '78813'
volume: 135
year: '2018'
...
---
_id: '9868'
abstract:
- lang: eng
text: In order to increase mechanical strength, heat dissipation and ampacity and
to decrease failure through fatigue fracture, wedge copper wire bonding is being
introduced as a standard interconnection method for mass production. To achieve
the same process stability when using copper wire instead of aluminum wire a profound
understanding of the bonding process is needed. Due to the higher hardness of
copper compared to aluminum wire it is more difficult to approach the surfaces
of wire and substrate to a level where van der Waals forces are able to arise
between atoms. Also, enough friction energy referred to the total contact area
has to be generated to activate the surfaces. Therefore, a friction model is used
to simulate the joining process. This model calculates the resulting energy of
partial areas in the contact surface and provides information about the adhesion
process of each area. The focus here is on the arising of micro joints in the
contact area depending on the location in the contact and time. To validate the
model, different touchdown forces are used to vary the initial contact areas of
wire and substrate. Additionally, a piezoelectric tri-axial force sensor is built
up to identify the known phases of pre-deforming, cleaning, adhering and diffusing
for the real bonding process to map with the model. Test substrates as DBC and
copper plate are used to show the different formations of a wedge bond connection
due to hardness and reaction propensity. The experiments were done by using 500
$\mu$m copper wire and a standard V-groove tool.
author:
- first_name: Simon
full_name: Althoff, Simon
last_name: Althoff
- first_name: Jan
full_name: Neuhaus, Jan
last_name: Neuhaus
- first_name: Tobias
full_name: Hemsel, Tobias
id: '210'
last_name: Hemsel
- first_name: Walter
full_name: Sextro, Walter
id: '21220'
last_name: Sextro
citation:
ama: 'Althoff S, Neuhaus J, Hemsel T, Sextro W. Improving the bond quality of copper
wire bonds using a friction model approach. In: Electronic Components and Technology
Conference (ECTC), 2014 IEEE 64th. ; 2014:1549-1555. doi:10.1109/ECTC.2014.6897500'
apa: Althoff, S., Neuhaus, J., Hemsel, T., & Sextro, W. (2014). Improving the
bond quality of copper wire bonds using a friction model approach. In Electronic
Components and Technology Conference (ECTC), 2014 IEEE 64th (pp. 1549–1555).
https://doi.org/10.1109/ECTC.2014.6897500
bibtex: '@inproceedings{Althoff_Neuhaus_Hemsel_Sextro_2014, title={Improving the
bond quality of copper wire bonds using a friction model approach}, DOI={10.1109/ECTC.2014.6897500},
booktitle={Electronic Components and Technology Conference (ECTC), 2014 IEEE 64th},
author={Althoff, Simon and Neuhaus, Jan and Hemsel, Tobias and Sextro, Walter},
year={2014}, pages={1549–1555} }'
chicago: Althoff, Simon, Jan Neuhaus, Tobias Hemsel, and Walter Sextro. “Improving
the Bond Quality of Copper Wire Bonds Using a Friction Model Approach.” In Electronic
Components and Technology Conference (ECTC), 2014 IEEE 64th, 1549–55, 2014.
https://doi.org/10.1109/ECTC.2014.6897500.
ieee: S. Althoff, J. Neuhaus, T. Hemsel, and W. Sextro, “Improving the bond quality
of copper wire bonds using a friction model approach,” in Electronic Components
and Technology Conference (ECTC), 2014 IEEE 64th, 2014, pp. 1549–1555.
mla: Althoff, Simon, et al. “Improving the Bond Quality of Copper Wire Bonds Using
a Friction Model Approach.” Electronic Components and Technology Conference
(ECTC), 2014 IEEE 64th, 2014, pp. 1549–55, doi:10.1109/ECTC.2014.6897500.
short: 'S. Althoff, J. Neuhaus, T. Hemsel, W. Sextro, in: Electronic Components
and Technology Conference (ECTC), 2014 IEEE 64th, 2014, pp. 1549–1555.'
date_created: 2019-05-20T12:11:44Z
date_updated: 2019-09-16T10:57:58Z
department:
- _id: '151'
doi: 10.1109/ECTC.2014.6897500
keyword:
- adhesion
- circuit reliability
- deformation
- diffusion
- fatigue cracks
- friction
- interconnections
- lead bonding
- van der Waals forces
- Cu
- adhering process
- adhesion process
- ampacity improvement
- bond quality improvement
- cleaning process
- diffusing process
- fatigue fracture failure
- friction energy
- friction model
- heat dissipation
- mechanical strength
- piezoelectric triaxial force sensor
- predeforming process
- size 500 mum
- total contact area
- van der Waals forces
- wedge copper wire bonding
- Bonding
- Copper
- Finite element analysis
- Force
- Friction
- Substrates
- Wires
language:
- iso: eng
page: 1549-1555
publication: Electronic Components and Technology Conference (ECTC), 2014 IEEE 64th
quality_controlled: '1'
status: public
title: Improving the bond quality of copper wire bonds using a friction model approach
type: conference
user_id: '55222'
year: '2014'
...