Spectroscopic analysis of structural and chemical properties of solid thin film lubricants

Thomann, Carl Arne

Spectroscopic analysis of structural and chemical properties of solid thin film lubricants

dc.contributor.advisor	Debus, Jörg
dc.contributor.author	Thomann, Carl Arne
dc.contributor.referee	Westphal, Carsten
dc.date.accepted	2023-12-12
dc.date.accessioned	2024-03-28T06:23:51Z
dc.date.available	2024-03-28T06:23:51Z
dc.date.issued	2023
dc.description.abstract	Upon tribological loading, especially at elevated temperatures or in humidity, chemical transitions and structural processes are known to take place in solid thin film lubricants like amorphous carbons (a-C) and molybdenum disulphide (MoS2) and to critically limit their performance. To accommodate those restrictions, a selection of element-modifications is applied on a regular basis. General aim is to analyse structural and chemical properties in a-C and MoS2 thin films. The understanding of those is a prerequisite for the scientific conception around tribo-film formation, which is identified as critical part of the tribological system. For this, Raman microscopy is augmented by a setup for optical temperature tuning via a pulsed laser. This work summarises the Raman-accessible film properties and the changes after element-modification and thermal impact. In a-C studies of optical temperature tuning, two ordering mechanisms are found, which are affected by element-modification. As initial reaction upon heating, graphitic clusters within an amorphous matrix increase in number and, subsequently, in size upon further heating. A Five Stage-model of structural relaxation in a-C is proposed. For MoS2, it is found that the formation of tribo-films is strongly dependent on the working environment, the tribo-film gains temperature resistance over untouched thin film material, and tribo-film formation is affected by element-modification. In studies of optical temperature tuning, an initial ordering process of amorphous MoS2 and subsequent chemical reaction to distinct oxides were found. The results are useful for identification of defect mechanisms and possibly for gauging the status of wear in a-C and MoS2 thin films. Element-modification in a-C with previously unknown effects may now be interpreted within a found Five Stage-model; similarly, the behaviour of MoS2 spectra upon heating can now be evaluated.	de
dc.identifier.uri	http://hdl.handle.net/2003/42409
dc.identifier.uri	http://dx.doi.org/10.17877/DE290R-24245
dc.language.iso	en	de
dc.subject	Optical spectroscopy	de
dc.subject	Vibrational spectroscopy	de
dc.subject	Raman spectroscopy analysis	de
dc.subject	Tribology	de
dc.subject	Tribo-films	de
dc.subject	Amorphous carbon	de
dc.subject	Molybdenum Disulfide	de
dc.subject	Optical temperature tuning	de
dc.subject	Chemical modification	de
dc.subject.ddc	530
dc.subject.rswk	Optische Spektroskopie	de
dc.subject.rswk	Festschmierstoff	de
dc.title	Spectroscopic analysis of structural and chemical properties of solid thin film lubricants	de
dc.type	Text	de
dc.type.publicationtype	PhDThesis	de
dcterms.accessRights	open access
eldorado.secondarypublication	false	de

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Experimentelle Physik II