Transfer of titanium in sliding contacts: new discoveries and insights revealed by in situ studies in the SEM
2014 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 315, no 1-2, p. 87-94Article in journal, Editorial material (Refereed) Published
Abstract [en]
Titanium and its alloys generally display poor tribological properties in sliding contacts due to their high chemical activity and strong adhesion to the counter surface. The strong adhesion causes a high tendency to transfer and ultimately galling or build-up edge formation, resulting in severe surface damage. As a result, forming and machining of titanium and its alloys are generally associated with significant problems such as high friction, rapid tool wear and poor surface finish of the formed/machined surface.
In the present study, in situ tests in a scanning electron microscope have been performed to increase the understanding of the mechanisms controlling the initial transfer of titanium (Grade 2) in sliding contact with tool surfaces. Tool materials included cover cold work tool steel, cemented carbide, CVD deposited Al2O3and PVD deposited DLC. In these tests, a relatively sharp tip, representing the titanium work material, slides against a flat surface, representing the tool. The contact conditions result in plastic deformation of the work material against the tool surface, thereby simulating forming or machining. The limited and well-defined contact, along with the possibility to study the sliding in the SEM, makes it possible to correlate local surface variations to transfer of work material and frictional response. Post-test characterization of the contact surfaces was performed by high-resolution SEM, TEM, EDS and EELS.
The initial friction was low and stable against all tested materials, but then gradually escalated against all surfaces except the DLC. The friction escalation was associated to increasing levels of transfer, while the DLC stayed virtually free from transfer. From these very initial sliding tests DLC is a promising tool coating in forming and machining of titanium.
Place, publisher, year, edition, pages
Elsevier, 2014. Vol. 315, no 1-2, p. 87-94
Keywords [en]
Sliding contact, Material transfer, Titanium, SEM
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Research Profiles 2009-2020, Steel Forming and Surface Engineering
Identifiers
URN: urn:nbn:se:du-14738DOI: 10.1016/j.wear.2014.04.006ISI: 000337877700012Scopus ID: 2-s2.0-84899812600OAI: oai:DiVA.org:du-14738DiVA, id: diva2:736629
2014-08-072014-08-072021-11-12Bibliographically approved