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Lecture

Manufacturing of functionally graded MMC-materials by segregation

Thursday (29.09.2016)
12:00 - 12:15
Part of:


A new method to create functionally graded MMC (metal matrix composite) materials by means of segregation is presented. By applying vibrations to a granular media consisting of small and large particles, different segregation states can be established. The phenomenon when the larger particles are on the top is called brazil nut effect (BNE). By analogy, when the small ones are on the top the term reverse brazil nut effect (RBNE) is used. Both effects can be reached by varying process-specific parameters like vibration amplitude and frequency as well as material-specific variables like grain size and density ratio. By combining this vibration induced segregation with a rotational motion, the effective force is no longer gravity but a centrifugal force leading to a radial segregation. In this contribution, an experimental setup is presented, which utilizes the described effects. This setup is used to produce a cylindrical MMC-part consisting of silicon carbide (SiC) and aluminum having a radial gradient. More precisely, the outer shell should have the greatest fraction of the hard material SiC, functioning as a wear resistant surface, while the inside should be consisting of light and ductile aluminum. After the desirable segregation state is reached the samples are cold pressed and sintered in order to produce a solid part. Finally, metallographic examinations are carried out by using light microscopy. The first results are found promising which are presented and discussed in this study.

Speaker:
Dieter Bohr
Leibniz Universität Hannover
Additional Authors:
  • Prof. Dr. Bernd-Arno Behrens
    Leibniz Universität Hannover