Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
A calorimetric analysis and solid-solubility examination of aluminium alloys containing low-melting-point elements
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
2012 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The formation of liquid films is a widely known problem in aluminium heat exchanger materials. The phenomenon results in decreased brazeability along with severely deteriorated mechanical properties which might cause assembly collapse. In addition, low-melting-point elements like tin, bismuth and lead are thought to promote grain boundary sliding which is the main deformation mechanism during brazing. Their melting characteristics are not adequately reported in literature. It is therefore of great importance to examine the behaviour of these elements.The main objectives with this work is melting range determination of fin heat exchanger materials, melting detection of low-melting-point elements and calculation of tin, bismuth and lead solid-solubility in aluminium. This work does also involve distribution analysis of such elements in aluminium matrix after heat treatment.These investigations require development of a differential scanning calorimetry (DSC) technique that is applicable for analysis of aluminium fin heat exchanger material containing low-melting-point elements on ppm level. Optimization of the technique includes parameter control; like heating rate, sample mass, reproducibility and choice of crucible material. Laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) is additionally used in order to analyse solid solubility and distribution of low-melting-point elements in aluminium after heat treatment.The developed DSC technique shows a sensitivity limit in the range of 260-600 ppm. It means that it is not possible to detect melting of phases within and below that range. Solid solubility of tin was calculated for the three heat treatment temperatures, 400°C, 500°C and 625°C. Same procedure was applied on bismuth and lead. However, calculated values did not agree with Thermo-Calc. The distribution analysis indicate an exudation of trace elements i.e. diffusion toward surface during heat treatment.In conclusion, more knowledge regarding liquid films in aluminium fin heat exchanger material was obtained. Future work should be to further optimize the DSC technique for trace element analysis for concentrations below 100 ppm. The LA-ICP-MS technique is likely to improve experimentally unverified binary phase diagrams like Al-Bi, Al-Pb and Al-Sn phase diagrams. It can also be used to study exudation behaviour of liquid films.

Place, publisher, year, edition, pages
2012.
Keyword [en]
differential scanning calorimetry, calibration, braze clad fin material, heat exchanger, aluminium, heating rate, solid-solubility, trace elements, melting range
National Category
Other Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-103199OAI: oai:DiVA.org:kth-103199DiVA: diva2:558929
Uppsok
Technology
Supervisors
Examiners
Available from: 2012-10-08 Created: 2012-10-05 Last updated: 2013-10-17Bibliographically approved

Open Access in DiVA

fulltext(5203 kB)911 downloads
File information
File name FULLTEXT01.pdfFile size 5203 kBChecksum SHA-512
5d7eecd71435649fe75a735ac2d4a3ccbd0a3c2fb7a658d0c4d744eb727f3855155dd54209db968d3792cf81f9964e2bcf3327b535f48008696a31513406fa94
Type fulltextMimetype application/pdf

By organisation
Materials Science and Engineering
Other Materials Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 911 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

urn-nbn

Altmetric score

urn-nbn
Total: 180 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf