Konzepte zur Optimierung des Hartmetallrecyclings

Translated title of the contribution: Concepts for optimisation of cemented carbides recycling

Tamara Ebner

Research output: ThesisDoctoral Thesis

Abstract

The hardness of tungsten carbide combined with the ductility of the metallic binder result in outstanding properties of high wear resistance and compressive strength, which turned cemented carbides into an indispensable instrument of high-tech machining industries. Tungsten and cobalt represent the basic components of machining tools applied in metal cutting and furthermore belong to the group of critical raw materials. Consequently, the processing of cemented carbides at the end of their product life cycle needs to be focused with particular importance. The objective of this thesis comprises the development of an integrated recycling concept for coated carbide cutting tools, which enables ecological, economical as well as strategical process optimisations. The zinc technology represents a relatively simple and environmentally friendly procedure and therefore constitutes an ideal starting point for pursuing enhancements. A wet chemical removal of hard coatings from the metal surface enables the application of such scraps in this sustainable treatment and additionally improves the quality of the produced powder. The development of a processing route for used stripping solutions from the decoating process ensures a comprehensive approach for recycling of cemented carbides. Conditioning the applied etchants reduces the amount of dissolved components and leads to an accumulation in a solid residue. Since the exact mechanism for the progress of disintegration during the zinc process is not yet fully known, this thesis additionally puts a specific objective on generating fundamental knowledge regarding the first stage of this recycling technique. A simplified system of the two main components zinc and cobalt served for the investigations regarding the growth of intermetallic phases. Furthermore, the impact of an additional alloying element on the formation of compound layers has been examined. Providing basic information relating the first stage of the zinc process, this research constitutes the background for a wider use of this sustainable method. Improving the processing of cemented carbide scrap leads to an increase of resource efficiency and consequently counteracts future supply shortfalls. This in turn plays a decisive role in regards to the critical raw materials tungsten and cobalt. The stated strategies for the optimisation of the cemented carbide recycling route represent the fundament for an improvement concerning the treatment of W and Co containing secondary raw materials, which contributes to a careful and sustainable use of natural resources.
Translated title of the contributionConcepts for optimisation of cemented carbides recycling
Original languageGerman
QualificationDr.mont.
Supervisors/Advisors
  • Luidold, Stefan, Supervisor (internal)
  • Antrekowitsch, Helmut, Assessor A (internal)
  • Lehner, Markus, Assessor B (internal)
Publication statusPublished - 2016

Bibliographical note

embargoed until null

Keywords

  • cemented carbides
  • recycling
  • process optimisation

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