TY - THES

T1 - Development of a Tribological Model Test for Evaluating the Scuffing Resistance of Coated Piston Ring/Cylinder Liner Systems

AU - Wuketich, Daniel

N1 - embargoed until 21-09-2025

PY - 2020

Y1 - 2020

N2 - The increasing efficiency of engines makes operating conditions more demanding. Due to this, the necessity for novel coatings, which can withstand these harsher operating conditions, also increases. There are a vast number of different material combinations available, but in regards to real life scuffing performance, very little is known about most of them. To effectively assess the scuffing performance of such systems model testing is employed. This requires an appropriate methodology, which has to be representative of the operating conditions in the engine and has to be versatile enough to determine the scuffing resistance of various tribosystems. In this thesis the process of developing a methodology, with which the scuffing resistance of a number of different tribosystems can be realistically determined, is thoroughly explained. The test specimens were machined out of real engine components that are based on a gas engine. The analysis of scuffed engine parts served as a guide on which damage mechanisms can occur in the engines. A linear tribometer, that received a few special modifications to better accommodate for these tests, served as a test rig. The sensors on the test rig allowed a close observation of the tribosystem during test procedures. Through variation of parameters such as load, time and lubrication the scuffing limits were determined for two different ring-on-liner tribosystems. The challenges of developing a methodology were ensuring the damages on the test specimens were comparable to the damages found on engine parts and that the parameters of the methodology remained realistic. A total of four methodology tests were created, all of which proved to deliver the desired results. The damages, such as crack formations, material transfer and material fatigue, which were found on scuffed engine parts, were successfully reproduced. The last test methodology, for which the lubrication was reduced, proved to have the most potential as the scatter of the results was minimized and the scuffing limit of the standard system was lowered to an acceptable level. It was also demonstrated that with this methodology the differences in performance of the two tribosystems based on engine tests can be reproduced.

AB - The increasing efficiency of engines makes operating conditions more demanding. Due to this, the necessity for novel coatings, which can withstand these harsher operating conditions, also increases. There are a vast number of different material combinations available, but in regards to real life scuffing performance, very little is known about most of them. To effectively assess the scuffing performance of such systems model testing is employed. This requires an appropriate methodology, which has to be representative of the operating conditions in the engine and has to be versatile enough to determine the scuffing resistance of various tribosystems. In this thesis the process of developing a methodology, with which the scuffing resistance of a number of different tribosystems can be realistically determined, is thoroughly explained. The test specimens were machined out of real engine components that are based on a gas engine. The analysis of scuffed engine parts served as a guide on which damage mechanisms can occur in the engines. A linear tribometer, that received a few special modifications to better accommodate for these tests, served as a test rig. The sensors on the test rig allowed a close observation of the tribosystem during test procedures. Through variation of parameters such as load, time and lubrication the scuffing limits were determined for two different ring-on-liner tribosystems. The challenges of developing a methodology were ensuring the damages on the test specimens were comparable to the damages found on engine parts and that the parameters of the methodology remained realistic. A total of four methodology tests were created, all of which proved to deliver the desired results. The damages, such as crack formations, material transfer and material fatigue, which were found on scuffed engine parts, were successfully reproduced. The last test methodology, for which the lubrication was reduced, proved to have the most potential as the scatter of the results was minimized and the scuffing limit of the standard system was lowered to an acceptable level. It was also demonstrated that with this methodology the differences in performance of the two tribosystems based on engine tests can be reproduced.

KW - Ring-on-Liner

KW - Beschichtungen

KW - Kolbenring-Zylinderwand-Tribosystem

KW - Fressen

KW - Tribologie

KW - Gasmotor

KW - Ring-on-Liner

KW - Coatings

KW - Piston ring-Cylinder liner-tribosystem

KW - Scuffing

KW - Tribology

KW - Gas engine

M3 - Master's Thesis

ER -