INFLUENCE OF THE RHEOMETER GEOMETRY ON THE RHEOLOGICAL PROPERTIES OF INDUSTRIAL LUBRICANTS

Alexandru V. RADULESCU¹
varrav2000@yahoo.com

Irina RADULESCU²
irena_sandu@yahoo.com


¹ Department of Machine Elements and Tribology, University POLITEHNICA Bucharest, ROMANIA
² Mechanical Engineering and Research Institute S. C. ICTCM S.A. Bucharest, ROMANIA

Abstract.  The rheological properties of two transmission lubricants (75W90 and 75W140), in fresh and used state, were investigated using shear viscosity rheological measurements. It was found that the lubricants do not exhibit a yield stress and that, above a critical shear rate, they exhibit shear-thinning behavior, well described by the Cross model.
The rheological measurements were performed on a Brookfield viscometer CAP2000+ equipped with four cone-and-plate geometry, for a range of temperature between 20 … 70°C, using the viscometer Peltier system. The experiments have shown that only two geometries are appropriate for testing the transmission lubricants. Another important conclusion refers to the influence of the wear degree of the lubricant on the rheological parameter of the model.
 

Keywords:  viscosity, lubricants, shear-thinning, wear

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