Lubricating Oil Degradation Research Articles

Experimental Investigation of the Effect of Exhaust Gas Recirculation on Lubricating Oil Degradation and Wear of a Compression Ignition Engine

This experimental investigation was aimed to investigate the effect of exhaust gas recirculation (EGR) on wear of in-cylinder engine parts. EGR setup was prepared for a two-cylinder, air-cooled, constant-speed direct-injection compression-ignition engine. Test setup was run for 96hr under predetermined loading cycles in two phases; normally, operating condition (i.e., without EGR) and with a fixed EGR rate of 25%. Addition of metallic wear debris in the lubricating oil samples drawn after regular interval from both engine operating phases was investigated. Relatively higher concentrations of all wear metals were found in the lubricating oil of the EGR-operated engine, which indicates higher wear of various engine parts. Weight loss of piston rings used in both phases was compared to quantify the amount of wear of piston rings. To quantify the amount of cylinder wear surface roughness parameters of cylinder liners were measured at three positions (top dead center, mid-stroke, and bottom dead center) on thrust and anti-thrust side. A qualitative analysis was also carried out by taking surface profiles and Scanning Electron Micrographs at same locations.

NMR relaxometry analysis of lubricant oils degradation

The present work was undertaken in order to investigate lubricant oil degradation at the molecular level. Ageing effects, as reflected on the proton spin-lattice relaxation rate dispersion, were studied in two different lubricant engine oils. The proton field cycling technique was used to scan relaxation of new and aged samples of monograde and multigrade oils. Relaxation dispersions were interpreted in terms of self-diffusion and molecular rotations. Our study shows that proton could be very sensitive to degradation processes, especially at low Larmor frequencies. The analysis reveals a noticeable sensitivity of the involved correlation times. The pros and cons of the technique are also discussed.

Effect of mechanical factors on tribological properties of palm oil methyl ester blended lubricant

The effects of mechanical factors viz. applied load and temperature on the tribological performance of 5% palm oil methyl ester (POME) blended lubricant were studied using a steel–cast iron pair. Wear and frictional measurements were made using a stationary steel ball and a reciprocating cast iron plate in a modified universal wear and friction testing machine. The test conditions were contact pressure, 400 MPa; mean contact velocity, 0.34 m/s; reciprocating stroke, 80 mm; loads, 100–1100 N (fixed temperature); and temperature, 40–140°C (fixed load). Wear scar surfaces were investigated using scanning electron microscopy (SEM) to understand the wear mechanisms involved. Analysis of post bench test lubricating oils was performed using an ISL viscometer and TAN/TBN analyzers to investigate the lubricating oil degradation properties. Results showed that at lower loads (up to 500 N) and temperatures (up to 100°C), the wear rates under 5% POME lubricant are lower, whereas at higher loads and temperatures, the wear rates are higher. The friction behavior of POME as an additive in commercial lubricant indicates the prevalence of the boundary lubrication regime. The viscosity test results showed that 5% POME can improve the viscosity index (VI) properties of mineral-based lubricant up to 500 N load. However, in this investigation, corrosive wear and pits on the damaged surface are the dominant wear mode at higher temperature.

Experimental and Modeling Study of Kinetics and Selectivity in the Oxidation of a Poly(.alpha.-olefin) Lubricant

A major means of lubricant oil degradation is by oxidation in the presence of metal surfaces that can have catalytic activity. An experimental and modeling study has been carried out on the oxidation kinetics and selectivity of a typical poly(α-olefin) (PAO) lubricant in the presence of both inert (glass) and active (brass, steel) surfaces in the temperature range 170-240°C. Inhibition of the reaction by zinc dialkyl dithiophosphate (ZDP) has been investigated. A batch recycling trickle-bed reactor system has been developed which provides reliable data on intrinsic chemical kinetics. Reaction rates are a strong function of temperature, with products appearing in the order of water, carbon dioxide, aldehydes, ketones, acids, and alcohols in both gas and liquid phases. Significant changes in viscosity and molecular weight were observed for T>200°C. A four-lump (PAO, carbonyl-containing compounds in the liquid phase, gaseous products, and deposits) kinetic model has been developed that gives good agreement with experimental results, including oxidation rate promotion by metals and inhibition by ZDP