Ein induktives Messverfahren zur Bestimmung der elektrischen Leitfähigkeit an unterkühlten Metallschmelzen

An apparatus for non-contact maesurements of the electrical resistivity of undercooled metallic melts was developed. It combines containerless positioning by electromagnetic levitation with an inductive technique of conductivity determination. The specimen is inserted in the center of a measurement transformer, the mutual inductance of which is changed by the eddy currents induced. As a condition for the applicability of this method the expression of the mutual inductance change as a function of coil geometry, sample shape and electrical conductivity is derived in perturbation theory for nearly spherical samples as an expansion in bessel functions. Furthermore the technical problem of mutual inductive interactions between levitation and measuring coils is solved by use of compensation transformers and periodic interruption of the levitation current while data reading. High accuracy is attained by homogeneous measurement fields, by optimized levitation coils, by symmetric coil arrangement, precise electronics and digital data recording. First results on copper, nickel and copper-nickel alloys are presented, which are discussed in the framework of the Ziman equation and the fluctuation-scattering-model of Takeuchi and Endo.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2001

Author dc:creator

• Richardsen, Thomas

Contributors dc:contributor

• Egry, Iván

• info:eu-repo/classification/ddc/530
• Physik
• Metallschmelze
• Unterkühlung
• Elektrische Leitfähigkeit
• Berührungslose Messung
• Kupferlegierung
• Nickellegierung

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-118677%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A56585