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1
Content available remote A new approach to flux deposition for brazing aluminium by low pressure cold spraying
Wojdat Tomasz, Winnicki Marcin, Pabian Jarosław
Materials Science Poland
|
2022
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Vol. 40, No. 4
114--124
EN
This paper presents the results of study on the possibility of Nocolok flux deposition to aluminium substrates using the low-pressure cold gas spraying (LPCS) method. An innovative method of applying flux in the form of a powder without organic adhesive additives was proposed, allowing strict control of the deposited material. The influence of the flux powder feeding rate (PFR – 4.5 g/min, 6.3 g/min and 8.5 g/min) on the efficiency of the brazing process of AA3003 aluminium alloy plates was investigated. The results of energy dispersive spectrometry (EDS) analysis of the deposited flux coatings are presented for various process parameters. The wettability tested by spreading the B-AlSi12 filler metal on flux-covered aluminium substrates increased significantly with increasing PFR – the contact angle decreased from 21.0° to 4.6°. Microstructure analysis confirmed the high quality of the brazed joints, which were devoid of braze incompatibilities.
2
Content available The Influence of Copper Powder Morphology on Mechanical Properties of Low-Pressure Cold Sprayed Coatings
Grygier Dominika, Rutkowska-Gorczyca Małgorzata, Winnicki Marcin G., Wojdat Tomasz
Archives of Metallurgy and Materials
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2021
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Vol. 66, iss. 2
573--580
EN
Thermal spraying methods are commonly used to regenerate damaged surface or change materials surface properties. One of the newest methods is cold spraying, where coating is deposited of material in the solid state. Therefore shape and size of the powder particles are very important parameters. The article presents the influence of copper powder morphology on mechanical properties of the coatings (adhesion, hardness, Young’s modulus) deposited with the Low Pressure Cold spraying method on the AA1350 aluminium alloy substrate. The coatings were deposited using two commercially available copper powders with spherical and dendritic morphology and granulation of -40+10 μm. The bond strength of coatings was determined with the pull off method, the hardness with the Vickers method at load of 2.94 N, while the Young’s modulus through measurement of nanoindentation. Microstructure of the coatings was analysed using the light and scanning electron microscopy (SEM). Shape of the powder influences mechanical properties of the coating significantly. The coatings deposited with dendritic powder had low mechanical properties, hardness of the 81 HV0.3 order and adhesion of about 4 MPa. However changing powder morphology to spherical increased hardness of the coating to 180 HV0.3 and adhesion to 38.5 MPa.
3
Content available Dissolution and Erosion Phenomena in the Brazing of Aluminum Heat Exchangers
Mirski Zbigniew, Pabian Jarosław, Wojdat Tomasz
Archives of Metallurgy and Materials
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2021
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Vol. 66, iss. 4
1131--1140
EN
On the basis of research, the mechanisms of dissolution and erosion during brazing of aluminium alloys and the influence of these phenomena on brazed joints of heat exchangers are presented. A number of factors have been identified that affect the formation of these phenomena during brazing aluminium alloys, these include: the maximum temperature and holding time at brazing temperature, and the type and amount of filler metal. The research was supported by examples of dissolution and erosion phenomena during series production of aluminium heat exchangers using three brazing profiles (normal, hot and very hot). It has been found that the dissolution of the engine radiator components during brazing, is from 18 to 68%, depending on the brazing profile used. For a very hot profile, erosion in part of the brazed exchanger, even destroys (removes) thin elements of the cooling fins.
4
Content available Significance of the brazing gap in the brazing of aluminium heat exchangers for automotive industry
Mirski Zbigniew, Pabian Jarosław, Wojdat Tomasz, Hejna Jan
Welding Technology Review
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2020
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R. 92, nr 4
7--14
EN
The paper presents the influence of the brazing gap width on the structure of bonded joints during the production of aluminum heat exchangers, using brazing technology, in tunnel furnaces with controlled atmosphere. Based on the wedge test, an analysis and qualitative assessment of brazed joints was made for the changing width of the brazing gap and the filler metal used. For the received brazed joints, metallographic tests were carried out using light (LM) and electron microscopy (SEM) and microhardness measurements in the characteristic areas of brazed joints. Based on the results obtained, the recommended width of the brazing gap was determined.
PL
W pracy przedstawiono wpływ szerokości szczeliny lutowniczej na strukturę złączy spajanych, podczas produkcji aluminiowych wymienników ciepła przy zastosowaniu technologii lutowania twardego, w przelotowych piecach tunelowych z atmosferą kontrolowaną. Na podstawie próby klinowej, dokonano analizy i oceny jakościowej połączeń lutowanych dla zmieniającej się szerokości szczeliny lutowniczej i zastosowanego spoiwa. Dla otrzymanych złączy lutowanych przeprowadzono badania metalograficzne przy użyciu mikroskopii świetlnej i elektronowej (SEM) oraz pomiary mikrotwardości w charakterystycznych obszarach połączeń lutowanych. Na podstawie otrzymanych wyników określono zalecaną szerokość szczeliny lutowniczej.
5
Content available remote Assessment of structure and selected mechanical properties of braze welded joints of copper‑lined steel tubes
Mirski Zbigniew, Wojdat Tomasz, Hejna Jan
Archives of Civil and Mechanical Engineering
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2020
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Vol. 20, no. 1
157--167
EN
In the paper, results of a research on braze welded joints of copper-lined 10CrMo9-10 (10H2M) steel tubes made by CMT arc braze welding are presented. As a filler metal, silicon bronze was applied. Results of metallographic examinations with the use of light microscopy, electron scanning microscopy and X-ray microanalysis are presented. Mechanical properties of the joints were assessed on the grounds of static tensile test, technological bending test, as well as hardness measurements. Quality of the obtained joints was good. No cracks were observed in the brazed joints and the obtained mechanical properties were satisfactory.
6
Content available An innovative method of applying fluxes using the low-pressure cold gas spraying method
Wojdat Tomasz, Winnicki Marcin, Mirski Zbigniew, Żuk Agata
Welding Technology Review
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2019
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R. 91, nr 10
17--24
EN
In the paper, the results of tests of flux application for aluminum brazing processes using the low-presure cold gas spraying method, are presented. It was pointed out that this method could be used as an alternative to current methods of flux application, among others in the production of aluminum heat exchangers. The results of wettability tests made with braze spreading method on fluxed substrates and metallographic investigations of brazed joints are presented. Good quality of brazed joints without incompatibilities and good mechanical properties have been demonstrated.
PL
W artykule przedstawiono wyniki badań nanoszenia topnika do procesów lutowania aluminium metodą niskociśnieniowego natryskiwania zimnym gazem. Wskazano na możliwość zastosowania niniejszej metody, jako alternatywnej dla obecnie stosowanych metod aplikacji topników m.in. w produkcji aluminiowych wymienników ciepła. Przedstawiono wyniki badań zwilżalności wykonane metodą rozpływności lutów na topnikowanych podłożach oraz badania metalograficzne złączy lutowanych. Wykazano dobrą jakość połączeń lutowanych, bez niezgodności lutowniczych oraz dobre właściwości mechaniczne.
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