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- Kolbenring (3)
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Organisationseinheit der BAM
The effects of rapid pulse electric current sintering (PECS), substitution of WC by NbC and Co by Ni, and carbide additives (TiC and Mo2C) on the microstructure, elastic modulus, B3B transverse rupture strength (TRS) and high temperature sliding wear on WC-Co, WC-Ni, NbC-Co and NbC-Ni cermets were studied. High temperature sliding wear tests were carried out using a ball-on-disk tribometer, with a 10 N force, at a sliding speed of 1.34 m/s for 0.8 km (10 min) and 2.4 km (30 min), using 100Cr6 (AISI 52100) steel balls at 400 °C and 0% humidity. Additions of TiC and Mo2C to NbC-12Ni improved the sliding wear resistance, with TiC having the greater effect, reducing the sample wear rate by over 30% from 15.1×10−6mm3/N·m to 9.4×10−6mm3/N·m after sliding distance of 2.4 km. Generally, the LPS samples had lower wear volumes than the corresponding SPS samples, due to higher K1c and TRS.
This paper proposes a new test methodology to determine the potential of friction reduction by measuring for the tribosystem piston ring/ cylinder liner outside of the engine Stribeck-type curves involving test pieces prepared from engine components. The frictional work determined in the whole speed ränge of Stribeck-type curves are related to the wettability. The Variation of the friction coefficient with sliding speeddepends on the Chemical structure and Constitution of the base oil, the viscosityIndex, the metallurgy and surface topography of the liner and ring, and the friction modifiers used. Novel organic friction modifiers of low molecular mass not only reduce the friction coefficients under mixed / boundary lubrication, but also in the fluid film (hydrodynamic) regime. In addition, the influence of surface roughness on the wettability of surfaces can be significant for both static and dynamic wetting. For this reason, the interaction of the chemically different lubricants with the surfaces was also investigated to enable a correlation between the surface properties of the liquid and solid phases and the frictional behavior.
Wear tests are often used in engine development in order to characterize the functional profile of surfaces interacting with lubricants. This paper proposes a new test procedure to determine Stribeck-type curves for the tribosystem piston ring/cylinder liner involving test pieces prepared from engine components. The variation of the friction coefficient with sliding speed depends on the structure and constitution of the base oil, the viscosity index, the surface topography of the liner and ring, and the friction modifiers used. Novel organic friction modifiers of low molecular mass not only reduce the friction coefficients under mixed / boundary lubrication, but also in the fluid film regime. In addition, the influence of surface roughness on the wettability of surfaces can be significant for both static and dynamic wetting. For this reason, the interaction of the lubricant with the surfaces was also investigated to enable a correlation between the surface properties of the liquid and solid phases and the tribological behavior.
Wear tests are often used in engine development in order to characterize the functional profile of surfaces interacting with lubricants. This paper proposes a new test procedure to determine Stribeck-type curves for the tribosystem piston ring/cylinder liner involving test pieces prepared from engine components. The Variation of the friction coefficient with sliding speed depends on the structure and Constitution of the base oil, the viscosity index, the surface topography of the liner and ring, and the friction modifiers used. Novel organic friction modifiers of low molecular mass not only reduce the friction coefficients under mixed / boundary lubrication, but also in the fluid film regime. In addition, the influence of surface roughness on the wettability of surfaces can be significant for both static and dynamic wetting. For this reason, the interaction of the lubricant with the surfaces was also investigated to enable a correlation between the surface properties of the liquid and solid phases and the tribological behavior.
Schmieröle können Bestandteile enthalten, welche metallische Gleitlagerwerkstoffe korrosiv angreifen. Dadurch kann die Funktionsfähigkeit von Gleitlagern beeinträchtigt werden. Durch tribologische Beanspruchungen werden chemische Reaktionen und somit wahrscheinlich auch Korrosionsvorgänge in vielen Fällen erheblich beschleunigt. Um dies zu untersuchen, wurden mit dem Stift-Scheibe-Prüfsystem unter Mischreibungsbedingungen tribologische Prüfungen an unterschiedlichen Gleitlagerwerkstoff-Öl-Kombinationen durchgeführt, wobei gehärteter Stahl als Gegenkörperwerkstoff diente. Die Ergebnisse zeigen, daß eine tribochemische Reaktionsschichtbildung schon nach kurzen Beanspruchungszeiten und bei niedrigen Öltemperaturen einsetzt. Die gebildeten Reaktionsschichten wirken aber durchweg verschleißmindernd. Eine für einige Gleitlagerwerkstoff-öl-Kombinationen beobachtete erhöhte Rauheit der Gleitflächen könnte aber das Erreichen von hydrodynamischen Betriebszuständen erschweren.