TY - THES

T1 - Assessment of contact pressure and sliding velocity on the Tribological Performance of TPU Seal Materials for the Establishment of a Rating System

AU - Jölly, Ines

N1 - embargoed until 24-05-2016

PY - 2011

Y1 - 2011

N2 - Over the last years, Thermoplastic Polyurethanes (TPU) have firmly established themselves as high performance engineering materials based on their excellent mechanical and processing properties . Accordingly, TPUs have now been utilized as seal materials for quite some time. Mechanical seal performance is critically dependant on the tribology of the seal material, hence a reliable testing procedure to determine and compare the friction and wear related properties is of outermost importance. The aim of this thesis is to develop a tribological benchmark testing methodology for TPU seal materials, using a precise rotary tribometer. The testing procedure based on the standard ASTM D3702 (ASTM International Standard D 3702-94, 1999), in the Ring on Disc (RoD) mode is adapted to polymeric materials. The test specimen is a polymer disc, which slides on a ring shaped steel counterpart at dry contact at room temperature. During our former research the present test configuration was used for the tribological characterization of seal materials. The methodology has to investigate the influence of the main performance parameters, the sliding velocity v and the normal pressure p (in short: PV-parameters) on the materials tribological behaviour. Therefore, a procedure was set up by progressively varying p at constant values of v and reversed varying v at constant values of p. The results demonstrate a strong dependency between friction related parameters and variations in PV-parameters. Additionally, friction and wear mechanisms of the tested materials can be further investigated by optical investigation of the worn surfaces along with an analysis of thermo-mechanical material parameters. Conclusively, a significant tribological performance rating can be achieved via PV-step tests in correlation with contact surface formations, deterioration mechanisms and thermo-mechanical bulk characteristics. A relative PV-limiting value can be deflected and the accumulation of damage mechanisms as well as the initiation of tribological failure can be analyzed.

AB - Over the last years, Thermoplastic Polyurethanes (TPU) have firmly established themselves as high performance engineering materials based on their excellent mechanical and processing properties . Accordingly, TPUs have now been utilized as seal materials for quite some time. Mechanical seal performance is critically dependant on the tribology of the seal material, hence a reliable testing procedure to determine and compare the friction and wear related properties is of outermost importance. The aim of this thesis is to develop a tribological benchmark testing methodology for TPU seal materials, using a precise rotary tribometer. The testing procedure based on the standard ASTM D3702 (ASTM International Standard D 3702-94, 1999), in the Ring on Disc (RoD) mode is adapted to polymeric materials. The test specimen is a polymer disc, which slides on a ring shaped steel counterpart at dry contact at room temperature. During our former research the present test configuration was used for the tribological characterization of seal materials. The methodology has to investigate the influence of the main performance parameters, the sliding velocity v and the normal pressure p (in short: PV-parameters) on the materials tribological behaviour. Therefore, a procedure was set up by progressively varying p at constant values of v and reversed varying v at constant values of p. The results demonstrate a strong dependency between friction related parameters and variations in PV-parameters. Additionally, friction and wear mechanisms of the tested materials can be further investigated by optical investigation of the worn surfaces along with an analysis of thermo-mechanical material parameters. Conclusively, a significant tribological performance rating can be achieved via PV-step tests in correlation with contact surface formations, deterioration mechanisms and thermo-mechanical bulk characteristics. A relative PV-limiting value can be deflected and the accumulation of damage mechanisms as well as the initiation of tribological failure can be analyzed.

KW - Thermoplastische Polyurethane

KW - tribologische Charakterisierung

KW - Ring-on-Disc

KW - PV-Parameter

KW - Thermoplastic Polyurethanes

KW - tribological characterization

KW - Ring-on-Disc

KW - PV-parameters

M3 - Master's Thesis

ER -