New high-performance oxide-based CVD coatings

David Hochauer

Research output: ThesisDoctoral Thesis

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Abstract

The improvement of cutting tool performance is an economic driven process which also adapts tools to their environment, like advanced tooling machines and materials. Since the late 1960-ies, depositing hard coatings several microns thick onto the tool surface offers increased performance, e.g. retarded tool wear or higher cutting speeds. Nowadays, alumina (Al2O3) often is a component of such coating systems, mainly because of its high hot hardness and chemical stability. The goal of this thesis was to investigate the influence of doping and alloying on chemical vapor deposited alumina. Based on a commercial coating architecture, doped alumina coatings were deposited in production-scale plants. Beneficial tribological effects were found for the addition of minor phases to the alumina coating (e.g. titanium oxide), while boron doping slightly increased the coating hardness. The co-deposition of alumina and aluminum borate caused an increased coating growth rate but lower coating hardness. Doped kappa-Al2O3 coatings showed an increased thermal stability and suppressed trans-diffusion of substrate elements more efficiently. New doping elements and precursors were investigated with laboratory experiments, i.e. their volatilization, their gas phase transport and their compatibility with the alumina deposition atmosphere. In general, knowledge about crucial process conditions during alumina deposition was gained.
Translated title of the contributionNeuartige oxidische Hochleistungs-CVD-Schichten
Original languageEnglish
QualificationDr.mont.
Supervisors/Advisors
  • Mitterer, Christian, Assessor A (internal)
  • Dehm, Gerhard, Assessor B (internal)
Publication statusPublished - 2010

Bibliographical note

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Keywords

  • CVD wear-resistant coatings Al2O3 alumina doping alloying cemented carbide cutting tools

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