http://arthra.ugal.ro/handle/20.500.14043/25333 2026-04-07T17:02:22Z 2026-04-07T17:02:22Z Teletin, Claudiu Crudu, Ion Spânu, Constantin http://arthra.ugal.ro/handle/20.500.14043/25349 2020-09-03T13:24:34Z 2009-01-01T00:00:00Z

Researches on the Presence of Hydrogen During Continuous Casting of Steel Teletin, Claudiu; Crudu, Ion; Spânu, Constantin Due to the negative effects that hydrogen has on steels, its content in steels has lately been given special attention. The paper presents the evolution of hydrogen content in steel during the manufacturing and continuous casting process. The sources that contribute to increasing the content of hydrogen in steel are identified, and are mentioned some measures for its reduction. Some experimental results are presented, obtained both during casting, as the measurements were performed in the charging tundish of the continuous casting machine, and after casting, from the slabs consequential to casting. THE ANNALS OF UNIVERSITY “DUNĂREA DE JOS“ OF GALAŢI FASCICLE VIII, 2009 (XV), ISSN 1221-4590, Issue 1 TRIBOLOGY

2009-01-01T00:00:00Z Ștefănescu, Ioan Șolea, Liviu Zgherea, Gheorghe Chiriță, George Spânu, Constantin http://arthra.ugal.ro/handle/20.500.14043/25348 2020-09-03T13:24:34Z 2009-01-01T00:00:00Z

On Viscosity Variation with Temperature of Rapeseed Oil After Different Processing Stages Ștefănescu, Ioan; Șolea, Liviu; Zgherea, Gheorghe; Chiriță, George; Spânu, Constantin In recent years, vegetal oils are carefully studied as they may constitute a category of basic raw materials for obtaining organic biodegradable lubricants. Rapeseed oil is seen as an alternative of mineral and synthetic oils. This paper presents a study of rapeseed oil concerning the variation of viscosity with temperature. The experimental research used a rotary viscometer type Rheotest 2 to determine the dynamic viscosity, at increasing temperatures, from 40 ° C to 90 ° C. There were analysed rapeseed oils produced in five stages of processing and a hydraulic oil grade H32, as comparison. Following the study, one may notice that generally, the viscosity becomes lower with increasing temperature, at four shear rates at which determinations were done for all the tested oils. Small differences of viscosity variation with temperature of these five types of rapeseed oil and the much reduced price for raw rapeseed oil after pressing, lead to the conclusion that this type of oil can be further studied for its use as a biodegradable lubricant. THE ANNALS OF UNIVERSITY “DUNĂREA DE JOS“ OF GALAŢI FASCICLE VIII, 2009 (XV), ISSN 1221-4590, Issue 1 TRIBOLOGY

2009-01-01T00:00:00Z Poștaru, Gheorghe Ajder, Vasile Crudu, Ion Poștaru, Andrei Ceban, Victor http://arthra.ugal.ro/handle/20.500.14043/25347 2020-09-03T13:24:34Z 2009-01-01T00:00:00Z

Principles and Methodologic Peculiarities in the Research of the Tribosystem with Sliding on Translation Cyclic Movement Poștaru, Gheorghe; Ajder, Vasile; Crudu, Ion; Poștaru, Andrei; Ceban, Victor The work presents methodological aspects of behavior research in the cyclical slip tribosystems regarding the dynamics of contact processes. Taking into account the fact that in the contact, processes of various origins (mechanical, thermal, hydrodynamic, electrical, and chemical) take place and superpose, and these processes influence each other reciprocally, their dynamics may be evaluated only by using dynamic measurement systems. A non-linear mechanical oscillator with an elastic element and dissipation is used as a dynamic system. The evaluation of the tribosystem’s behaviour is made after processing and using methods of non-linear dynamics of data from time series, obtained experimentally and reduced to the coordinates of the oscillator. The suggested method allows correct evaluation and prediction of evolution of the tribosystem THE ANNALS OF UNIVERSITY “DUNĂREA DE JOS“ OF GALAŢI FASCICLE VIII, 2009 (XV), ISSN 1221-4590, Issue 1 TRIBOLOGY

2009-01-01T00:00:00Z Olaru, Dumitru Stamate, Ciprian Dumitrescu, Alina Ianus, Gelu http://arthra.ugal.ro/handle/20.500.14043/25346 2020-09-03T13:24:34Z 2009-01-01T00:00:00Z

Friction in the Microtribosystems.Influence of Condensed Water Olaru, Dumitru; Stamate, Ciprian; Dumitrescu, Alina; Ianus, Gelu To evaluate the influence of condensed water on the rolling friction in the microtribosystems, the authors used a micro tribometer consisting in a driving rotational disc in contact with 3 microballs which sustain an inertially driven rotational disc. The driving disc has a constant rotational speed and the rotational motion is transmitted from the driving disc to the inertially driven disc by friction between the rolling contacts realized by the microballs and the two discs. A camera monitors the angular position of the inertially driven disc, from the start to the synchronism rotation and friction coefficient between the microballs and the inertial disc was determined as a function of the angular acceleration of the inertial disc. Experimental investigations were realized with the microballs having the diameter of 1.588 mm, 2.0 mm and 4.762 mm loaded with normal load of 9.42 mN both in dry conditions and in presence of condensed water on surfaces. The presence of the condensed water on the surfaces leads to the increase on the rolling friction coefficient, depending of the microballs diameter. THE ANNALS OF UNIVERSITY “DUNĂREA DE JOS“ OF GALAŢI FASCICLE VIII, 2009 (XV), ISSN 1221-4590, Issue 1 TRIBOLOGY

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