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Nucleation and growth of CVD α-Al2O3 on TixOy template
Högskolan Dalarna, materialvetenskap. (Tribomaterial)
(English)Article in journal (Other academic) Submitted
Abstract [en]

The microstructure, phase and chemical composition of TixOy templates used to  nucleate α-Al2O3 on Ti(C,N) coated cemented carbide have been elucidated using scanning electron microscopy, X-ray diffraction, Auger electron spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry. Further, the adhesive strength of the α-Al2O3-TixOy-Ti(C,N) interfaces was investigated using scratch adhesion testing.


The present study confirmed that the as-deposited template consisted of a Ti4O7 phase which during subsequent deposition of the Al2O3 layer transformed to a Ti3O5 phase and that the grown Al2O3 layer consisted of 100% α-Al2O3. Furthermore, the results showed that the lowest interfacial strength within the multilayer structure was exhibited by the Ti(C,N)-TixOy interface and that the transformation of Ti4O7 to Ti3O5 in the template resulted in formation of pores in the Ti(C,N)-template interface lowering the interfacial strength even more. The use of surface analysis techniques such as Auger electron spectroscopy and especially Time-of-Flight Secondary Ion Mass Spectrometry enabled trace element analyses using depth profiling to characterise the thin interfacial layers in detail.

Keyword [en]
CVD, α-Al2O3, nucleation, template, adhesion
National Category
Materials Engineering
Research subject
Materials Science
URN: urn:nbn:se:uu:diva-172446OAI: oai:DiVA.org:uu-172446DiVA: diva2:514691
Available from: 2012-04-10 Created: 2012-04-10 Last updated: 2012-08-01
In thesis
1. Microstructural, Mechanical and Tribological Characterisation of CVD and PVD Coatings for Metal Cutting Applications
Open this publication in new window or tab >>Microstructural, Mechanical and Tribological Characterisation of CVD and PVD Coatings for Metal Cutting Applications
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present thesis focuses on characterisation of microstructure and the resulting mechanical and tribological properties of CVD and PVD coatings used in metal cutting applications. These thin and hard coatings are designed to improve the tribological performance of cutting tools which in metal cutting operations may result in improved cutting performance, lower energy consumption, lower production costs and lower impact on the environment.  In order to increase the understanding of the tribological behaviour of the coating systems a number of friction and wear tests have been performed and evaluated by post-test microscopy and surface analysis. Much of the work has focused on coating cohesive and adhesive strength, surface fatigue resistance, abrasive wear resistance and friction and wear behaviour under sliding contact and metal cutting conditions.

The results show that the CVD deposition of accurate crystallographic phases, e.g. α-Al2O3 rather than κ-Al2O3, textures and multilayer structures can increase the wear resistance of Al2O3. However, the characteristics of the interfaces, e.g. topography as well as interfacial porosity, have a strong impact on coating adhesion and consequently on the resulting properties.  Through the deposition of well designed bonding and template layer structures the above problems may be eliminated.

Also, the presence of macro-particles in PVD coatings may have a significant impact on the interfacial adhesive strength, increasing the tendency to coating spalling and lowering the surface fatigue resistance, as well as increasing the friction in sliding contacts.

Finally, the CVD-Al2O3 coating topography influences the contact conditions in sliding as well as in metal cutting.

In summary, the work illuminates the importance of understanding the relationships between deposition process parameters, composition and microstructure, resulting properties and tribological performance of CVD and PVD coatings and how this knowledge can be used to develop the coating materials of tomorrow.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 83 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 934
Tribology, Friction, Wear, Coatings, CVD, PVD, Alumina, Metal cutting
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Tribo Materials
urn:nbn:se:uu:diva-172364 (URN)978-91-554-8371-5 (ISBN)
Public defence
2012-06-08, Claes Ohlsson-salen, Skomakargatan 1, Borlänge, 10:00 (Swedish)
Available from: 2012-05-15 Created: 2012-04-05 Last updated: 2012-08-01Bibliographically approved

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Fallqvist, Mikael
Materials Engineering

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