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Radulescu A.V.,Polytechnic University of Bucharest | Radulescu I.,Science ICTCM SA
Journal of the Balkan Tribological Association | Year: 2012

The present paper presents 2 comparative methods for measuring the rheological properties of oils, with different wear degrees. The 1st method is based on an experimental stand, which uses the squeeze film process between 2 circular parallel surfaces, in order to measure the viscosity of oils. The results of these measurements are compared with those obtained using the 2nd method, based on a Brookfield rheometer, equipped with a cone and plate geometry. Finally, the results are numerically treated, in order to obtain the correlation between the 2 methods. Source


Radulescu A.V.,Polytechnic University of Bucharest | Radulescu I.,Science ICTCM SA
BALTTRIB 2011 - 6th International Scientific Conference, Dedicated to 65th Anniversary of Faculty of Agricultural Engineering, Proceedings | Year: 2011

Lubricants degradation process is quantified by the changes in physical characteristics and chemical composition of oils, which are caused by internal and external factors and the severity of operating conditions. Experimental methods for determining the degree of lubricants wear and their durability led to the development of a methodology for the assessment and the quantification of lubricants life cycle. The paper proposes the achievement of the lubricants global performance passport, which is a complete characterization of the lubricants behavior during their life, in terms of rheological, tribological and microscopically properties. Finally, the achievement of the lubricants global performance passport should be correlated with the determination of the economic profitability threshold for the investment made by a potential user. Source


Radulescu I.,Science ICTCM SA | Radulescu A.V.,Polytechnic University of Bucharest | Petrescu F.,University of Bucharest
17th International Colloquium Tribology 2010 - Solving Friction and Wear Problems | Year: 2010

The paper presents the accomplished researches using laboratory tests for lubricants performances, in different state, from fresh one (before utilization) to the used state (after a certain period of working time). Main evaluation criteria of lubricants durability was the modification of their tribological properties. Considerations about lubricants performances and their durability were made using specific quantity indicators. The obtained data are useful to evaluate the friction coefficient due to the charge. Source


Pirvu C.,Polytechnic University of Bucharest | Demetrescu I.,Polytechnic University of Bucharest | Drob P.,Institute of Physical Chemistry | Vasilescu E.,Institute of Physical Chemistry | And 3 more authors.
Progress in Organic Coatings | Year: 2010

This paper presents the results regarding the electrochemical stability and surface analysis of a new alkyd paint with low content of volatile organic compounds in comparison with a conventional alkyd paint. The alkyd films were realized on carbon steel substrate. Dry films thickness in 30-35 μm range was obtained. The experimental tests were carried out in 3% NaCl solution at the 25 °C temperature. The electrochemical techniques (electrochemical impedance spectroscopy (EIS), potentiodynamic and Tafel polarization) and surface analysis techniques (AFM, SEM, EDX) were used to evaluate protective properties of the tested paint films. The correlation of all experimental results established that the new alkyd paint with low content of volatile organic compounds presents better protective performances and lower permeability than conventional alkyd paint. AFM, SEM and EDX indicated a compact, homogenous, non-porous and adherent coating. © 2010 Elsevier B.V. All rights reserved. Source


Radulescu A.V.,Polytechnic University of Bucharest | Balan C.,Polytechnic University of Bucharest | Radulescu I.,Science ICTCM SA
17th International Colloquium Tribology 2010 - Solving Friction and Wear Problems | Year: 2010

The present theoretical analysis is carried out to determine the analytical approximate formulation of the squeeze film process between circular tilted surfaces. This paper focuses on an approximate mathematical model for the one-dimensional lubrication equation, taking into account the "narrow bearing theory". The theoretical results are validated on an experimental stand, based on a modified Weissenberg rheogoniometer. Source

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