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The effect of embossed surface textures on the friction and wear in boundary lubricated contacts
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences.
2005 In: WearArticle in journal (Refereed) Accepted
Place, publisher, year, edition, pages
URN: urn:nbn:se:uu:diva-93177OAI: oai:DiVA.org:uu-93177DiVA: diva2:166574
Available from: 2005-05-17 Created: 2005-05-17Bibliographically approved
In thesis
1. Surfaces Designed for High and Low Friction
Open this publication in new window or tab >>Surfaces Designed for High and Low Friction
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Ytor utformade för hög och låg friktion
Abstract [en]

This thesis comprises tribological studies of extremely well-defined surfaces of different designs. Both low-friction and high-friction surfaces were manufactured and experimentally evaluated.

In the low-friction studies, lithography and anisotropic etching of silicon was first used as a texturing technique. The textured surfaces were subsequently PVD coated with TiN or DLC to achieve tribologically relevant interfaces. The results showed that under starved lubricated conditions, fine surface textures lowered the coefficient of friction and the wear rate. It was shown that also the orientation of the texture is of major importance for the lubricating function.

Further, a novel embossing technique was developed, permitting texturing of steel and other materials. A micro mechanically designed diamond tool was used to emboss steel surfaces. The roller/piston contact from a hydraulic motor was simulated and introduction of an embossed texture on the piston decreased the level and the fluctuation of the friction. The effect of the texture was here similar to the effect of an additional polish step. However, in general it is not an easy task to substantially improve a boundary lubricated contact by introducing a texture.

Studies of high friction surfaces were performed on micro mechanically designed diamond surfaces equipped with sharp pyramids or ridges. Just as theory predicts, the coefficient of friction was dependent on the shape of the ploughing bodies, but not on the counter material or the load. The tested surfaces resulted in static coefficients of friction between 1.1 and 1.6, depending on surface design and orientation. These are extremely high values, and therefore very interesting for practical applications requiring a high static friction.

Conclusively, the present thesis shows that it is possible to design and produce surfaces both for improved lubrication in sliding contact and for substantially improved high friction performance in static contacts.

Place, publisher, year, edition, pages
Uppsala: Institutionen för teknikvetenskaper, 2005. 43 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 63
Materials science, tribology, friction, surface texture, surface design, low friction, high friction, boundary lubrication, DLC, embossing, Materialvetenskap
National Category
Materials Engineering
urn:nbn:se:uu:diva-5835 (URN)91-554-6278-2 (ISBN)
Public defence
2005-06-07, Siegbahnsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15
Available from: 2005-05-17 Created: 2005-05-17Bibliographically approved

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