Formation and analysis of particulate carbon in a synthetic lubricant |
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Authors: | R Sabia K Powers J H Adair |
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Institution: | (1) Materials Science and Engineering University of Florida Gainesville, FL 32601, USA, US |
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Abstract: | The formation of discrete carbonaceous particles has been investigated for a conventional synthetic ester-based lubricant
degraded in thermal and thermal–oxidative environments. Experimental factors included oxidative and nonoxidative environments,
high and low humidities, and the presence or lack of a metal catalyst surface, with all samples generated at 250 °C. Characterization
performed for changes in antioxidant content, IR spectroscopy, molecular weight, total acid number, viscosity, and uv/vis
absorbance spectrometry were used to determine the influences of the aforementioned variables on the rates of oil degradation
and formation of high-molecular-weight species. Discrete carbonaceous particle formation was analyzed using Einstein's relationship
for the viscoelastic behavior of particles in Newtonian fluids and by calculating associated radii of gyration. This viscoelastic
behavior of the particles in solution is used to demonstrate how the absorption behavior of the carbonaceous degradation products
tracks the discrete particulate species. The results show the formation of particulate species to be diffusion-limited after
antioxidant depletion, and optical absorption analysis is shown to be a viable technique for monitoring the formation of discrete
carbonaceous particles during lubricant degradation.
Received: 29 February 2000/Accepted: 3 January 2000 |
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Keywords: | Carbonaceous particles Degradation Esters Optical absorption Soot |
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