Completed Projects of Brazing Technology
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Fe-amorph – Simulation-aided material design of iron-based amorphous brazing foils
Short description:
In order to meet the increasing requirements of different areas in mechanical engineering, new alloying concepts for brazing have to satisfy constantly growing requirements in terms of mechanical properties and corrosion resistance. The use of amorphous brazing foils for the brazing of steel offers several advantages over conventional alloys. On the one hand, the foils, produced by Melt Spinning, are flexible and can be better adapted to the component geometry that has to be brazed, and on the other hand, the environmental impact is lower, since no organic binders are required compared to brazing pastes and powders. Ni-based alloys are frequently used for amorphous brazing foils. Due to the high raw material prices for nickel, an Fe-based brazing material is preferable. For the alloy development, it is important to aim for amorphous solidification of the brazing foils, as this counteracts embrittlement. The GFA (glass forming ability) is an important empirical parameter representing the tendency of a metallic melt to solidify amorphously.The experimental determination of the GFA and the alloy optimization based on it, is extremely costly and time-consuming. The reason for this is that the investigated alloys are multicomponent systems. A simulation-based material design using the CALPHAD method (calculation of phase diagrams) should help to indentify promising alloy compositions with respect to the GFA tendency. Subsequently, the results of the simulation will be validated experimentally. The alloy design can thus be supported by numerical calculations in the future.
| Funding: | Deutsche Forschungsgemeinschaft (DFG) |
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| Porject number: | BO 1979/80-1 |
| Duration: | August 01, 2021 to July 3, 2023 |
Surface pretreatment of steel sheets for die casting of gap-free and low-distortion cast aluminum/steel sheet metal hybrids
Short description:
The aim of the research project is to produce gap-free and low-distortion hybrid Al/steel-components by high pressure die casting. For this purpose, coatings are applied on steel insert by means of thermal spraying and deposition brazing, which enable a metallurgical bonding or solid form closure connection to the steel sheet and Al-cast during the casting process. The second phase of the project focuses on the „WING“ high pressure die casing tool as a geometrically more complex hybrid tool. This allows the scientific investigation of relevant parameters and mechanisms of the individual process steps and their interactions at the required level of complexity. Therefore, the overall goal of the planned project is on the one hand the exp. Development of the relevant mechanisms and their dependencies on process and material parameters along the production chain. With the help of developed criterion functions in combination with thermophysical simulations, areas of the substrate that are suitable for structuring and/or those areas in which a coating is more likely to enable the optimum bond between aluminium casting and steel are to be determined.
| Funding: | German Research Foundation (DFG) |
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| Porject number: | BO 1979/39-2 |
| Duration: | July 1, 2020 to March 31, 2023 |
Adamant - Immunize of Ni and Fe based filler metals to improve bonding properties
Short description:
The manufacture of high-strength joints using a wide variety of brazing technologies is state of the art in a wide range of industrial sectors. The classes of Ni- and Fe-based filler metal alloys have proved particularly suitable for applications at high temperatures and simultaneous corrosive stress, such as in the exhaust tract of motor vehicles or for the repair of turbine blades. The alloying concepts of the Ni and Fe filler metals most commonly used in industry are very similar and are based on the respective main alloying element, i.e. Ni or Fe, Cr to improve corrosion resistance and mechanical properties, and elements which lower the melting point. Typically, the metalloids silicon, boron and phosphorus are used for this purpose. However, these elements favour the formation of hard and brittle phosphides, borides and silicides. The brittle phases are not only metallurgical notches, the phase bands formed from them also fail brittle due to their low toughness, so that spontaneous component failure occurs in case of overload. Previous concepts for avoiding these brittle phases are associated with very high technical effort and economic costs. One possibility, which has not been considered so far, is the improvement of the mechanical properties by interrupting the hard phase bands by means of targeted precipitation formation. The addition of even small amounts of Ti can significantly improve the strength of these brazed joints. The aim of the project is to investigate this approach and make it usable for industrial application.
| Funding: | Arbeitsgemeinschaft industrieller Forschungsvereinigungen „Otto von Guericke“ (AiF) |
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| Porject number: | 21.231 N |
| Duration: | June 1, 2020 to November 30, 2022 |
2BeSafe2 - Development of design concepts for the assessment of the fatigue strength of brazed joints under consideration of process-related brazing seam conditions
Short description:
As a result of efforts to further increase engine performance and environmental policy objectives, the demands on dynamically stressed components in the automotive sector are constantly increasing. In order to use the fuel more and more efficiently, engines with gasoline direct injection operate with ever higher injection pressures in the common rail systems of p > 350 bar with simultaneous reduction of wall thicknesses. An economical design of these highly dynamically loaded brazed joints is of great importance. The few currently available approaches for evaluating the fatigue strength of brazed joints do not take into account the real, microscopic condition of the brazed seam, but refer to idealized fillets. In addition, various damage mechanisms occur that have not been considered in the design concepts so far. This results in a relatively large dispersion, which makes it necessary to design components much more conservatively than necessary.This problem, which is particularly relevant in the automotive industry, is to be solved in this project by deriving reliable design concepts for brazed joints with realistic brazing seam conditions. Different influencing variables such as type and duration of the brazing process, but also geometrical deviations of the component geometries are recorded and used to derive holistic design concepts.
| Funding: | Arbeitsgemeinschaft industrieller Forschungsvereinigungen „Otto von Guericke“ (AiF) |
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| Porject number: | 20.370 N |
| Duration: | January 1, 2019 to June 30, 2022 |
Network for the development and qualification of efficiency-maintaining protective coatings against erosion and corrosion of turbine blades in steam/gas turbines and compressors - Coat4Turbine.NRW
Short description:
The aim of the research project is the development of erosion and corrosion protective coatings, which results in preservation of the efficiency-optimized contours and the increase of the service life of rotating steam turbine and compressor blades. Innovative coating concepts are developed, manufactured, tested and applied on industry-oriented components. In the field of brazing technology, the sub-goal is to evaluate Ni- and Fe-based coatings with different contents of chromium or tungsten carbides for steam turbine blades made of X12CrNiMo12 steel as protection against water droplet erosion and corrosion. The use of these protective coatings results in permanently high efficiency, increased life cycle efficiency and, above all, enormous CO2 savings. Poster EFRE-0801003
| Funding: | European Regional Development Fund (ERDF) |
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| Porject number: | EFRE-0801003 |
| Duration: | March 23, 2018 to March 22, 2021 |
Development of innovative tapes, presintered preforms and process parameters for repair brazing of gas turbine components
Short description:
The aim of the research project is to develop pore-free and low-shrinkage green tapes and presintered preforms made of Ni- and Co-based materials. Additionally, an adapted process for repair brazing of turbine components is designed. This process should cover the application method for the tapes and preforms as well as novel approaches for the brazing process parameters. Starting point is the analysis of the influence of the grain size distribution of braze metal and additive powders used to produce the tapes and preforms. Poster EFRE-0801003
| Funding: | Zentrales Innovationsprogramm Mittelstand (ZIM) |
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| Porject number: | ZF 4059004TA7 |
| Duration: | June 1, 2017 to December 31, 2019 |
Optimization of carbide-steel brazed joints regarding strength, performance and reliability by improving process control in induction brazing
Short description:
The aim of the research project is to improve the temperature control during induction brazing and thus to increase the reproducibility and quality of the brazed joints. As a result of the liquefaction of the filler metal and the sinking of the upper substrate, geometry and force changes occur in the brazing process on the component. By using high-resolution force and displacement sensors, the sinking of the substrate during melting of the filler metal can be detected. As a result of the improved sensor technology, it is possible to develop a controller which takes account of the filler metal state in addition to the conventional surface temperature. Thus, it is possible to neglect many disturbance variables, such as the influence of the component geometry, the heating rate or the heat conduction and to produce high quality brazed components with reproducible strength. Poster 19.201 N
| Funding: | Arbeitsgemeinschaft industrieller Forschungsvereinigungen „Otto von Guericke“ (AiF) |
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| Porject number: | 19.201 N |
| Duration: | 01.01.2017 bis 30.06.2019 |
Surface pretreatment of steel sheets for die casting of gap-free and low-distortion cast aluminum/steel sheet metal hybrids
Short description:
The aim of the research project is to produce gap-free and low-distortion hybrid Al/steel-components by high pressure die casting. For this purpose, coatings are applied on steel insert by means of thermal spraying and deposition brazing, which enable a metallurgical bonding or solid form closure connection to the steel sheet and Al-cast during the casting process. Partial melting of the coating during casting facilitates the cracking of the oxide scales present on the coating surface, supporting the metallurgical bonding. The influence of the different coating deposition processes on the wetting behavior of the coatings, the formation of the intermetallic phases at the Al/steel interface as well as the melting and oxidation behavior of the coatings is investigated. Poster BO 1979/39-1
| Funding: | German Research Foundation (DFG) |
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| Porject number: | BO 1979/39-1 |
| Duration: | January 1, 2015 to June 30, 2018 |
Prevention of binder-related defects due to reliable processing of brazing pastes in for large-area joints
Short description:
Brazing pastes consist of a filler metal and organic binders. In practice, the organic binder leads to defects such as pores, inclusions or wetting defects, especially in large-area joints. The aim of the project was to extend the usability of brazing pastes to large-area and complex component geometries and to avoid the formation of defects. In the first step, a comprehensive process understanding of defect formation in the brazing process was developed. This included a thorough investigation of binder-related residues and the investigation of the decomposition and degassing behaviour of organic binders using various thermoanalytical methods. Subsequently, it was possible to significantly reduce the formation of defects by means of various process engineering and material technology approaches. In the case of Ni-based filler metals, the controlled removal of the resulting vaporous decomposition products of the binder by structuring the brazing paste, and the addition of a carbide-forming element for binding of organic residues, have proven to be successful to achieve pore free joints. Poster 17.907 N
| Funding: | Arbeitsgemeinschaft industrieller Forschungsvereinigungen „Otto von Guericke“ (AiF) |
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| Porject number: | 17.907 N |
| Duration: | 01.11.2014 bis 31.08.2017 |
Systematic analysis of the influence of surface conditions on brazed joints with application-oriented methods III
Short description:
The aim of the research project is to increase the brazing process reliability by avoiding brazing defects induced by surface contaminations. For this purpose, the influence of different surface conditions on the joint quality was analysed systematically. Defined surface conditions were produced by a variation of machining processes, contamination by cooling lubricants and subsequent cleaning processes. The quality of the brazed joints was determined by non-destructive and destructive testing methods. Poster IGF-Nr. 18.387 N
| Funding: | German Federation of Industrial Research Associations (AiF) |
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| Porject number: | IGF-Nr. 18.387 N |
| Duration: | January 1, 2014 to July 31, 2017 |
Evaluation of the fatigue strength of safety-related brazed components
Short description:
The aim of the research project is to develop evaluation strategies for the fatigue strength of brazed joints in safety-related components such as rails for direct fuel injection. Additionally to the analysis of the joining process and of the influence of the macroscopic fillet, numerous characteristic geometric values of the brazed joints were determined for a detailed quality assurance. The influence of these geometric values on the fatigue strength was evaluated. Subsequently, the results were transferred to a more complex, component-like pipe joint. Poster IGF-Nr. 17.766 N
| Funding: | German Federation of Industrial Research Associations (AiF) |
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| Porject number: | IGF-Nr. 17.766 N |
| Duration: | August 1, 2013 to December 31, 2016 |