Reformulating lubricating oils for the internal combustion engine could result in an improvement in the life of the oil and engine itself, according to a recent article by Dr. Pranesh Aswath.
Dr. Aswath and colleagues from the Department of Materials Science and Engineering at the University of Texas focuses specifically on the effect soot has on the stability of engine oil as well as engine wear. Conducted at the Canadian Light Source (CLS) at the University of Saskatchewan the researchers studied the effect elemental additives such as calcium, sulphur and phosphorous in lubricating oils have on dealing with soot issues.
The CLS is a national synchrotron light source research facility located in the province of Saskatchewan in Canada. Scientists from around the world gather to use the 15 operating beamlines (a beamline is the trajectory of the beam of accelerated particles) and three commissioning beamlines available. This particular study utilized three beamlines: High Resolution Spherical Grating Monochromator (SGM), Variable Line Spacing Plane Grating Monochromator (VLS-PGM), and Soft X-Ray Microcharacterization Beamline (SXRMB). The SGM uses long-wavelength (soft) X-rays, the VLS-PGM uses long wavelengths (both soft X-ray and ultraviolet) while the SXRMB uses light wavelengths between soft and hard X-rays.
This study specifically looked at possibilities to decrease the negative effects of soot in the internal combustion engine. Soot is a fine dark powder formed through the process of incomplete combustion. It is a slightly sticky material that clings to various surfaces. The soot in this case is a result of the incomplete combustion in the internal combustion engine. From there additives in the crankcase oil trap the soot. However, the result is reduced engine efficiency and a breakdown of the lubricating oil.
Calcium is a commonly used dispersant in oil due to its low cost and high availability, used to keep any debris collected by the oil from forming a sludge. However, when calcium mixes with the soot calcium phosphate forms, resulting in abrasive particles of soot. This abrasiveness rubs against the engine parts, causing wear and deterioration in effectiveness.
While current additives are often chosen for their low cost, that low cost comes at price, especially in terms of a reduced life span of engine parts and the oil itself. Replacing vehicle parts is costly. While oil itself is not extremely pricey, the need to replace it more frequently adds up to a large price tag over the years.
Dr. Aswath feels that it is time to look at alternative additives to decrease soot issues in internal combustion engines and increase the efficiency and lifespan of both engine parts and the oil itself.
Kimaya Vyavhare et al. Impact of Diesel Engine Oil Additives–Soot Interactions on Physiochemical, Oxidation, and Wear Characteristics of Soot, Energy & Fuels (2019). DOI: 10.1021/acs.energyfuels.8b03841