Factorial study of diesel engine oil contamination effects on steel and ceramic sliding contacts

Abstract

The present work investigates the effects of diesel contaminants and their interaction on tribological properties for bearing steel (En31) and ceramic (Si 3 N 4) sliding contacts using a factorial study. The contaminants are soot, sulphuric acid, moisture and oxidation, and each contaminant has three different level of concentration (low, medium and high) in the test matrix. The factorial test matrix consisted of 20 tests, constructed from a quarter fractional factorial test matrix with four points at the medium values for the contaminants. Results from this matrix required six further tests to elucidate aliased pairs of interactions using Bayesian model selection. A pin-on-disc tribometer was used to carry out all the experiments. All tests were carried out under ambient conditions at 5 m/s sliding speed and contact stress of 1.5-2.05 GPa to simulate a valve-train in a diesel engine with fully formulated heavy-duty diesel engine oil used as lubricant. Four different tribological properties were studied. The factorial study showed that charge was influenced by tribocouple material; the silicon nitride discs produced higher charge than steel discs. However, it was opposite for friction; the silicon nitride disc gave lower friction and the pins showed higher friction than their steel counterparts. For wear scar and temperature, soot contaminant was found to be important. The two important interactions were found for the charge response, with the interaction between sulphuric acid and pin material being more important than sulphuric acidoxidation interaction. Similarly to charge, an interaction between sulphuric acid and pin material interaction was found for friction.

Transient Wear FEA Modelling Using Extrapolation Technique for Steel-on-Steel Dry Sliding Contact

“…6. Corresponding wear depth of the worn-out pin is calculated using spherical cap geometry Equation [21,22] given by,…”

A study on the tribological behavior of hybrid and all-steel rough sliding contacts

“…[6][7][8][9] Muthunilavan et al 10 compared the rolling friction process of different ceramic and steel hybrid friction pairs under the dry friction and lubricant conditions. Ramkumar et al 11 studied the wear characteristics and lubrication state of the ceramic ball and steel ball on the surface of the steel disc and confirmed that the wear resistance of the silicon nitride ball was better than that of the bearing steel ball through sliding wear test experiments. In addition, Lu et al 12 studied the influence of diesel pollutants and their interaction on the tribological characteristics of the sliding contact point between the steel and ceramics (silicon nitride) through a pin-on-disc (POD) friction meter.…”

Tribological Properties of ZrO2 Coating on the Ball Joint of an Axial Piston Pump in High Water-Based Emulsion Medium

“…e test results show that this method achieves good results and reduces pollution from the working parts. Ramkumar et al [30] used a factorial study to investigate the effects of diesel contaminants and their interaction with tribological properties for the building of steel and ceramic sliding contacts. Vasanth et al [31,32] used the uniaxial compaction method to fabricate ceramic disk type microfiltration membranes, with chemical stability tests indicating that these membranes are stable in both acidic and basic media.…”