Beurteilung der Einflussgrößen auf die Verdüsbarkeit von Metallschmelzen

Translated title of the contribution: Evaluation of the determining factors on the atomisability of metallic melts

Michael Hirtler

Research output: ThesisMaster's Thesis

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Abstract

The successful atomization of a metallic material depends to a large extent on the properties of the melt (viscosity, overheating, etc.) and their behaviour towards the material of the nozzle. The present work investigates the formation of metallic accretions at the bottom of the atomizing nozzle, the so-called "nozzle bear", as well as the properties of one good and one bad pair of material that can be atomized. The Böhler brands W360 and L326 were chosen as the good disintegrating materials. The counterparts that represent a poor atomization are Böhler W722 and L334. The optical examination of the used nozzles showed that the growth of these steel bears is initiated on cracks trigger due thermal shock. It was possible to investigate the interface of Böhler W722 and Böhler L334 bear through a REM examination of an embedded bear/nozzle combination. It was found, that titanium oxide (in the W722) and aluminum oxide (in the L334) were formed at the interface. FactSage calculations confirmed the formation of titanium oxide. Furthermore, it was possible to determine the contact angle in the system W360/Z95 and W722/Z95 by experiments in the tube furnace. Moreover, the melting behaviour of all four materials was determined by a DSC measurement. The final step was a rheometric examination of the materials Böhler W360, W722 and L334. This confirmed that the viscosity of the best atomized W360 is lowest at all shear rates and temperatures. Thus, it has a significant influence on the atomization behaviour.
Translated title of the contributionEvaluation of the determining factors on the atomisability of metallic melts
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Bernhard, Christian, Supervisor (internal)
Award date14 Dec 2018
DOIs
Publication statusPublished - 2018

Bibliographical note

embargoed until 01-11-2023

Keywords

  • atomization
  • clogging
  • viscosity
  • metal powder

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