Entwicklung einer Methodik zur tribologischen Prüfung von Kolbenhemd und Zylinderlaufbuchse

Translated title of the contribution: Development of a tribological test methodology for piston skirt / cylinder liner systems

Markus Liebenwein

Research output: ThesisMaster's Thesis


This thesis is about the design and development of a model test set-up for the tribological contact between the piston skirt and the cylinder liner surface. The task was to conduct tribological tests on two different test rigs: The tests were to be conducted on the SRV®5 from Optimol Instruments Prüftechnik GmbH and on the TE77 from Phoenix Tribology Ltd. Additionally two different kinds of coatings should be analysed and compared on both test rigs in tribological behaviour. Coating A contains mainly carbon and has a thickness of about 10μm at the valley of the surface waviness of the piston skirt and about 5μm at the wave peaks. Coating B consists of Titanium oxide with a coating thickness of about 15μm. The tests were conducted under different operating conditions on both test rigs to gather further information of both tribological systems. To compare the different wear results of all tests, a method to measure surface wear of the piston skirt specimens was developed. This method consists of measuring the surface geometry using an optical microscope and extracting multiple cross-sectional data lines. From those data lines both the original surface outside of the tested area and the worn surface were approximated. Via calculating the difference in height of those two approximations a single surface wear parameter was calculated for every test specimen. This parameter was used to compare the wear data from all test results. For SRV tests at a stroke of 5mm coating A resulted in high wear rates at the test start, that slowed down after some time had passed. This slowdown in wear rate corresponded to the surface wave peaks being removed and the formation of a surface contact. At this point most of coating A was removed from the specimen surface and a lot of steel ground material was visible at the specimen surface. In comparison to the analysed engine piston coated in Coating A, the wear rate for the 5mm SRV tests was extremely fast and after about 10 Minutes of testing duration the specimen surface showed similar wear amounts as the engine piston. Coating B showed a similar behaviour of extremely fast wear rates during the first period of the model test and a slow down after some time had passed and the surface peaks were removed. But for coating B this slowdown of wear rates occurred a lot faster compared to coating A and almost no ground material was visible after the entire test duration. Wear measurements of coating B showed about half of coating A wear for Coating B. Coating B also showed a lower coefficient of friction for the entire test duration compared to Coating A. The TE77 tests showed, that this behaviour is only observed for small test strokes. Tests with coating A at 25mm and 12, 5mm stroke resulted in about 30 % of wear compared to SRV 5mm tests. This effect was further analysed with the alteration of testing conditions. A reduction of lubrication to 20% of previous tests showed no significant changes in wear results. Doubling the load of the tests also did not result in different wear results. All tests with coating A and a stroke of 12, 5mm or 25mm resulted in about the same amount of wear, no matter the testing conditions used. Further tests on the TE77 at a stroke of 5, 6mm resulted in similar wear results compared to SRV 5mm stroke tests, confirming the theory of a stroke effect for wear of coating A. Coating B did not change in wear behaviour over all performed tests and all wear measurements were approximately in the same range.
Translated title of the contributionDevelopment of a tribological test methodology for piston skirt / cylinder liner systems
Original languageGerman
Awarding Institution
  • Montanuniversität
  • Summer, Florian, Co-Supervisor (internal)
Award date1 Jul 2022
Publication statusPublished - 2022

Bibliographical note

embargoed until 31-05-2027


  • tribology
  • engine piston
  • surface coatings
  • modell test
  • friction
  • wear

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