Analysis of the Interaction of NH<sub>4</sub>Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings

André Langohr; Sarah Groß-Bölting; Ulrich Holländer; Kai Möhwald

doi:doi:10.11648/j.ijmsa.20180703.12

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Analysis of the Interaction of NH₄Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings

André Langohr, Sarah Groß-Bölting, Ulrich Holländer, Kai Möhwald

Published in International Journal of Materials Science and Applications (Volume 7, Issue 3)

Received: 14 December 2017 Accepted: 26 January 2018 Published: 23 April 2018

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Abstract

This paper reports on the development of a braze metal coating and a brazing process for joining aluminum alloys at temperatures < 570°C without applying a flux before brazing. This is achieved using a duplex braze metal coating made of an aluminum-silicon alloy and zinc as top layer in combination with the use of hydrogen chloride doped nitrogen as process gas. Here hydrogen chloride deoxidate the surface of the zinc coating and form zinc chloride flux in-situ. Defined hydrogen chloride partial pressures between 100 vpm (volume parts per million) and 300 vpm in nitrogen were produced by thermal decomposition of solid ammonium chloride. Reaction kinetics of hydrogen chloride with the zinc coating was investigated by detecting the generation of reaction heat at different hydrogen chloride concentrations and temperatures. An activation energy of was determined, a value that matches the values stated in the literature. The order of reaction n was found to be significantly lower than 1, which is consistent with gas solid reactions at microscopically fissured interfaces. An in-situ zinc chloride formation rate of 3 µg/(min cm²) at 400°C and 200 vpm hydrogen chloride concentration was obtained from the measured data, which may be sufficient for triggering the flow of braze metal. Experimental brazing tests showed, that when the reaction time was long enough to permit the formation of zinc chloride and this is followed than by a brazing process at 560°C to 570°C in subsequently hydrogen chloride-free nitrogen atmosphere, a liquid ternary AlSiZn braze metal is formed from the dublex coating enabling a wetting and brazing of the contacting join partner.

Published in	International Journal of Materials Science and Applications (Volume 7, Issue 3)
DOI	10.11648/j.ijmsa.20180703.12
Page(s)	75-84
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2018. Published by Science Publishing Group

Keywords

Aluminum Brazing, In-Situ Fluxing Agent, Reaction Kinetics

References

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[2]	Wielage, B.: Entwicklung eines Controlled Atmosphere Brazing (CAB) Verfahrens zum Fügen von Aluminiumguss- und Aluminiumknetlegierungen, research report for the project of the same name, AiF Project No. 13.788 N.
[3]	Belt, H.-J.; Swidersky, H.-W., Wielage, B., Martinez, L.: Aluminium brazing at 500°C – characteristics of ZnAl-joints, conference transcript of “Löt 2001”, 6th International Conference on Brazing, High Temperature Brazing and Diffusion Bonding, 8-10 May, Aachen, DVS-Reports, Vol. 212, pp. 214–217.
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André Langohr, Sarah Groß-Bölting, Ulrich Holländer, Kai Möhwald. (2018). Analysis of the Interaction of NH4Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings. International Journal of Materials Science and Applications, 7(3), 75-84. https://doi.org/10.11648/j.ijmsa.20180703.12

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André Langohr; Sarah Groß-Bölting; Ulrich Holländer; Kai Möhwald. Analysis of the Interaction of NH4Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings. Int. J. Mater. Sci. Appl. 2018, 7(3), 75-84. doi: 10.11648/j.ijmsa.20180703.12

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AMA Style

André Langohr, Sarah Groß-Bölting, Ulrich Holländer, Kai Möhwald. Analysis of the Interaction of NH4Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings. Int J Mater Sci Appl. 2018;7(3):75-84. doi: 10.11648/j.ijmsa.20180703.12

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@article{10.11648/j.ijmsa.20180703.12,
  author = {André Langohr and Sarah Groß-Bölting and Ulrich Holländer and Kai Möhwald},
  title = {Analysis of the Interaction of NH4Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings},
  journal = {International Journal of Materials Science and Applications},
  volume = {7},
  number = {3},
  pages = {75-84},
  doi = {10.11648/j.ijmsa.20180703.12},
  url = {https://doi.org/10.11648/j.ijmsa.20180703.12},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijmsa.20180703.12},
  abstract = {This paper reports on the development of a braze metal coating and a brazing process for joining aluminum alloys at temperatures  was determined, a value that matches the values stated in the literature. The order of reaction n was found to be significantly lower than 1, which is consistent with gas solid reactions at microscopically fissured interfaces. An in-situ zinc chloride formation rate of 3 µg/(min cm2) at 400°C and 200 vpm hydrogen chloride concentration was obtained from the measured data, which may be sufficient for triggering the flow of braze metal. Experimental brazing tests showed, that when the reaction time was long enough to permit the formation of zinc chloride and this is followed than by a brazing process at 560°C to 570°C in subsequently hydrogen chloride-free nitrogen atmosphere, a liquid ternary AlSiZn braze metal is formed from the dublex coating enabling a wetting and brazing of the contacting join partner.},
 year = {2018}
}

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TY  - JOUR
T1  - Analysis of the Interaction of NH4Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings
AU  - André Langohr
AU  - Sarah Groß-Bölting
AU  - Ulrich Holländer
AU  - Kai Möhwald
Y1  - 2018/04/23
PY  - 2018
N1  - https://doi.org/10.11648/j.ijmsa.20180703.12
DO  - 10.11648/j.ijmsa.20180703.12
T2  - International Journal of Materials Science and Applications
JF  - International Journal of Materials Science and Applications
JO  - International Journal of Materials Science and Applications
SP  - 75
EP  - 84
PB  - Science Publishing Group
SN  - 2327-2643
UR  - https://doi.org/10.11648/j.ijmsa.20180703.12
AB  - This paper reports on the development of a braze metal coating and a brazing process for joining aluminum alloys at temperatures  was determined, a value that matches the values stated in the literature. The order of reaction n was found to be significantly lower than 1, which is consistent with gas solid reactions at microscopically fissured interfaces. An in-situ zinc chloride formation rate of 3 µg/(min cm2) at 400°C and 200 vpm hydrogen chloride concentration was obtained from the measured data, which may be sufficient for triggering the flow of braze metal. Experimental brazing tests showed, that when the reaction time was long enough to permit the formation of zinc chloride and this is followed than by a brazing process at 560°C to 570°C in subsequently hydrogen chloride-free nitrogen atmosphere, a liquid ternary AlSiZn braze metal is formed from the dublex coating enabling a wetting and brazing of the contacting join partner.
VL  - 7
IS  - 3
ER  -

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Author Information

André Langohr

Institute of Materials Science, Gottfried Wilhelm Leibniz Universit?t Hannover, Hannover, Germany
Sarah Groß-Bölting
Ulrich Holländer
Kai Möhwald

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APA Style

André Langohr, Sarah Groß-Bölting, Ulrich Holländer, Kai Möhwald. (2018). Analysis of the Interaction of NH4Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings. International Journal of Materials Science and Applications, 7(3), 75-84. https://doi.org/10.11648/j.ijmsa.20180703.12

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ACS Style

André Langohr; Sarah Groß-Bölting; Ulrich Holländer; Kai Möhwald. Analysis of the Interaction of NH4Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings. Int. J. Mater. Sci. Appl. 2018, 7(3), 75-84. doi: 10.11648/j.ijmsa.20180703.12

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AMA Style

André Langohr, Sarah Groß-Bölting, Ulrich Holländer, Kai Möhwald. Analysis of the Interaction of NH4Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings. Int J Mater Sci Appl. 2018;7(3):75-84. doi: 10.11648/j.ijmsa.20180703.12

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@article{10.11648/j.ijmsa.20180703.12,
  author = {André Langohr and Sarah Groß-Bölting and Ulrich Holländer and Kai Möhwald},
  title = {Analysis of the Interaction of NH4Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings},
  journal = {International Journal of Materials Science and Applications},
  volume = {7},
  number = {3},
  pages = {75-84},
  doi = {10.11648/j.ijmsa.20180703.12},
  url = {https://doi.org/10.11648/j.ijmsa.20180703.12},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijmsa.20180703.12},
  abstract = {This paper reports on the development of a braze metal coating and a brazing process for joining aluminum alloys at temperatures  was determined, a value that matches the values stated in the literature. The order of reaction n was found to be significantly lower than 1, which is consistent with gas solid reactions at microscopically fissured interfaces. An in-situ zinc chloride formation rate of 3 µg/(min cm2) at 400°C and 200 vpm hydrogen chloride concentration was obtained from the measured data, which may be sufficient for triggering the flow of braze metal. Experimental brazing tests showed, that when the reaction time was long enough to permit the formation of zinc chloride and this is followed than by a brazing process at 560°C to 570°C in subsequently hydrogen chloride-free nitrogen atmosphere, a liquid ternary AlSiZn braze metal is formed from the dublex coating enabling a wetting and brazing of the contacting join partner.},
 year = {2018}
}

Copy | Download

TY  - JOUR
T1  - Analysis of the Interaction of NH4Cl-Doped Process Gases with Zinc-Coated Surfaces with Regard to Aluminum Brazing with Zn-AlSi Duplex Braze Metal Coatings
AU  - André Langohr
AU  - Sarah Groß-Bölting
AU  - Ulrich Holländer
AU  - Kai Möhwald
Y1  - 2018/04/23
PY  - 2018
N1  - https://doi.org/10.11648/j.ijmsa.20180703.12
DO  - 10.11648/j.ijmsa.20180703.12
T2  - International Journal of Materials Science and Applications
JF  - International Journal of Materials Science and Applications
JO  - International Journal of Materials Science and Applications
SP  - 75
EP  - 84
PB  - Science Publishing Group
SN  - 2327-2643
UR  - https://doi.org/10.11648/j.ijmsa.20180703.12
AB  - This paper reports on the development of a braze metal coating and a brazing process for joining aluminum alloys at temperatures  was determined, a value that matches the values stated in the literature. The order of reaction n was found to be significantly lower than 1, which is consistent with gas solid reactions at microscopically fissured interfaces. An in-situ zinc chloride formation rate of 3 µg/(min cm2) at 400°C and 200 vpm hydrogen chloride concentration was obtained from the measured data, which may be sufficient for triggering the flow of braze metal. Experimental brazing tests showed, that when the reaction time was long enough to permit the formation of zinc chloride and this is followed than by a brazing process at 560°C to 570°C in subsequently hydrogen chloride-free nitrogen atmosphere, a liquid ternary AlSiZn braze metal is formed from the dublex coating enabling a wetting and brazing of the contacting join partner.
VL  - 7
IS  - 3
ER  -

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