témavezető: Kaptay György
társ-témavezető: Tóth László
helyszín (magyar oldal): University of Miskolc helyszín rövidítés: UM
A kutatási téma leírása:
Severe plastic deformation (SPD) of metals is a suitable process to obtain nano-structuration of a metal composed initially from large grains. The grain size can be readily decreased by a factor of 100, leading to high mechanical resistance and improvement of several mechanical, physical and chemical properties. Recent studies demonstrate that SPD is suitable for bonding metal surfaces to each other from similar or dissimilar metals. Because of the simplicity of an SPD process, it is technologically very promising to implement new SPD processes for metal bonding. The most widely known process is Accumulative Roll Bonding (ARB), which consist in repeating several times a sequence of rolling, cutting, and surface cleaning steps, so it is quite time taking and complicated. A recently developed SPD process, named Friction Assisted Lateral Extrusion (FALEP) seems very suitable for metal bonding, in which lower number of steps are needed compared to ARB, due to the much larger plastic strain imposed to the metal in FALEP. While several experimental results obtained on the SPD platform of the LEM3 laboratory in Metz (France) show that the process is highly effective, there is no any publication yet on it, and many questions are arising on the process, which could be called ASB (Accumulative Shear Bonding). The main questions are: What technical parameters of the ASB process are the most effective? What kind of metals can be joined by ASB? What are the chemical composition characteristics that mostly influence the bonding? What is the role of the oxide layer on the bonding surfaces? Is there a dependence on initial grain size? If yes, what is the mechanism behind? What is the effect of processing temperature? Is there an effect of the crystallographic texture on bonding? What are the conditions to obtain multilayered metals with layer thickness in nanometer range? Etc.
The response to these questions can be elaborated by experimental investigations, that are helped with modeling in the field of mechanics, crystal plasticity, surface chemistry. There is a new FALEP equipment in the University of Miskolc suitable for metal bonding experiments, together with a testing attachment on an Instron machine for characterizing the strength of the bonded surfaces.
előírt nyelvtudás: B2 felvehető hallgatók száma: 1
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