Nanometallurgy of nonferrous metals

Diego Santa Rosa Coradini

Research output: ThesisDoctoral Thesis

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Abstract

Intensive developments have been carried out in the field of nanometallurgy in recent decades. The majority of these developments concern the miniaturization of devices and the improvement of their performance while reducing their volume. In addition, novel applications in environmental preservation and medicine, such as sensors and filters, are also being explored. The main reason for this development lies in the surface properties that can strongly influence the properties of nanoscale materials. For example, the electrical conductivity of nanoscale Cu wires coated with graphene can be increased. However, the resistance in pure nanomaterials, such as Cu NW (nanowire) without coating, increases due to surface effects. Additionally, another classical effect at the nanoscale is the lowering of the melting point. The present work aims to investigate degradation effects at the nanoscale by observing the behavior of Cu NW when exposed to a cold plasma environment, revealing a strong oxidation effect. Nanowires were also heated in a transmission electron microscope (TEM), where an unexpected sublimation effect was observed. In-situ alloying was also tested by heating a binary combination of an Al lamella of nanomaterials with Cu ND and Au nanoparticles (NP). A TEM was used for the characterization of in-situ alloying formation. Techniques such as selected-area electron diffraction (SAED), high-resolution atomic imaging, bright-field TEM (BFTEM), and high-angle annular dark-field TEM (HAADF) are employed for material characterization. The composition analysis was performed using energy-dispersive spectroscopy (EDS) prior to the experiments. In-situ heating was achieved using a microelectromechanical system (MEMS) in the form of a silicon E-chip. Different heating programs were applied depending on the phenomena under investigation. For sublimation experiments, heating ramps were conducted in the temperature range of 600 °C to 850 °C. In the case of nanoalloying experiments, the temperatures used depended on the alloying system. For example, the Al/Cu system was melted at 660 °C and annealed at 440°C for 5 minutes. The melting temperature for the Al/Au system was 660 °C, and the annealing temperature was 250 °C for 2 hours.
Translated title of the contributionNanometallurgie von Nichteisenmetallen
Original languageEnglish
QualificationDr.mont.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Antrekowitsch, Helmut, Co-Supervisor (internal)
  • Kiener, Daniel, Assessor B (internal)
  • Pogatscher, Stefan, Supervisor (internal)
  • Uggowitzer, Peter, Assessor A (internal)
DOIs
Publication statusPublished - 2023

Bibliographical note

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Keywords

  • Nanomaterials
  • Transmission electron microscope
  • Nonferrous
  • Characterization
  • In situ heating
  • Alloying
  • Degradation

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