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Vasile Bratu  - - - 
Top co-authors
Elena Valentina Stoian

20 shared publications

Valahia University of Targoviste, Faculty of Materials Engineering and Mechanics, Department of Materials Engineering, Mechatronics and Robotics 13 Aleea Sinaia Steet, Targoviste, Romania

Ileana Nicoleta Popescu

18 shared publications

Valahia University of Targoviste, Faculty of Materials Engineering and Mechanics, 13 Aleea Sinaia Street, Targoviste, Romania

Aurel Gaba

3 shared publications

23
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Publication Record
Distribution of Articles published per year 
(2011 - 2018)
Total number of journals
published in
 
7
 
Publications See all
Article 0 Reads 0 Citations Researches Regarding the Influence of Alloying Elements on the Mechanical Properties of Lamellar Graphite Cast Iron Elena Valentina Stoian, Vasile Bratu, Cristiana Maria Enescu... Published: 01 October 2018
Scientific Bulletin of Valahia University - Materials and Mechanics, doi: 10.1515/bsmm-2018-0012
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Aim of the study is to present the technological process of obtaining cast iron with lamellar graphite for use in the manufacture of cylinder liners, and to identify the main alloying elements and track their influence on the mechanical properties of cast iron with lamellar graphite. Also paper presents analysis of 20 batches of cast iron with lamellar graphite, which are made of cylinder liners, in terms of chemical composition and the mechanical properties. After the analysis of the 20 castings of cast iron Fc 250 it is observed that: the increase in the carbon content shows a decrease of the tensile strength and hardness of the gray cast iron; the increase in silicon content shows a decrease in hardness and tensile strength. Decreasing the amount of graphite and especially the alloy of silicon iron lead to hardness increase 1% Si increases hardness by 50 HB). A statistical analysis has been performed on the data obtained that accounts for changes in alloying additions. A modeling and optimization of mechanical properties (tensile strength and hardness) was performed according to the percentages of carbon, silicon and manganese. Mathematical modeling found that the hardness and traction resistance of the cast iron decreased with the increase in carbon, silicon and manganese content.
Article 0 Reads 0 Citations Analysis of Internal Defects Appeared in the Continuous Casting Elena Valentina Stoian, Vasile Bratu, Cristiana Maria Enescu... Published: 01 April 2018
Scientific Bulletin of Valahia University - Materials and Mechanics, doi: 10.1515/bsmm-2018-0005
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The paper presents the study of internal defects resulting from the continuous casting of steels. The 50 samples were taken from a total of 20 continuously cast bits of different steel grades. The investigation of the causes of internal defects, shown on the analyzed samples, started from the assumption that the secondary metallurgy was performed correctly. The following internal defects have been evident: internal cracks (axial cracks, section cracks), central porosity and marginal punctuation impurities.
Article 0 Reads 0 Citations Dental Cements Nicolae Angelescu, Vasile Bratu, Elena Valentina Stoian, Dan... Published: 01 October 2017
Scientific Bulletin of Valahia University - Materials and Mechanics, doi: 10.1515/bsmm-2017-0014
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Calcium-phosphate cements is one of the most popular types of biomaterials, both due to their specific properties of self - setting and of their superior biocompatibility. Although in general the phosphocalcic cements, which are the subject of the present paper, have somewhat lower mechanical properties than other biomaterials based on calcium and phosphorus, or even other dental cements of the same nature. The ceramic compositions presented in the present paper constitute a special category of biomaterials due to other notable advantages that characterize them. Thus, this category of materials is defined by a near-perfect adaptation to the surface of the biological tissue, as well as by a convenient resorption rate, processes followed by the generation of optimal bone formation. In this paper are presented principles of realization of the calcium-phosphate cements (raw materials and conditions of production), as well as the properties of these biomaterials, insisting, in particular, on the chemistry of the setting reactions. At the same time, informations regarding the possibilities of clinical use, such as implants are presented.
Article 0 Reads 0 Citations Study on Influence of Microstructure and Thermal Treatment on Magnetic Losses from Non-Oriented Silicon Electrical Steel Elena Valentina Stoian, Maria Cristiana Enescu, Vasile Bratu... Published: 01 October 2017
Scientific Bulletin of Valahia University - Materials and Mechanics, doi: 10.1515/bsmm-2017-0012
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Non/oriented electrical sheets are sheets tailored to produce specific properties and are produced from Fe-Si or Fe-Si-Al alloys. Non-oriented electrical steel sheets are incorporated into a wide range of equipment, from the simplest domestic appliances to hybrid and pure electric vehicles. In studying about the magnetic, there have a lot of method can be used for the different experiment requirement such as measuring magnetic flux, nominal loss and other objectives. During electrical steel processing, there are usually small variations in both chemical composition and thickness in the hot-rolled material that may lead to different magnetic properties for the same steel grade. Therefore, it is of great importance to know the effects of such variations on the final microstructure and magnetic properties of these steels. The purpose of this work was to study microstructural changes of the bands investigated during processing occurring siliceous strips with non-oriented grains. The second aim was to study the influence of grain size on the total magnetic losses at 1.0 T and 1.5 T. Materials 10 rolls intended to be processed into quality electrical steel M400-50A (according to EN 100027-1) were analyzed with metallographic microscope Neophet 32 and the magnetic characteristics was made with Epstein frame according IEC 6040/4-2, with an exiting current frequency of 50Hz at 1.5T and 1.0T induction after aging treatment of 225°C for 24 hours. Sample for light microscopy observation were prepared by polishing and etching in 5% Nital.
Article 0 Reads 0 Citations Porous Metallic Biomaterials Processing (Review) Part 1: Compaction, Sintering Behavior, Properties and Medical Applicat... Ileana Nicoleta Popescu, Ruxandra Vidu, Vasile Bratu Published: 01 October 2017
Scientific Bulletin of Valahia University - Materials and Mechanics, doi: 10.1515/bsmm-2017-0015
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Over the last few decades, researchers has been focused on the study of processing using different methods of new biocompatible and/or biodegradable materials such as permanent or temporary medical implants in reconstructive surgery. The advantages of obtaining biomedical implants by Powder Metallurgy (P/M) techniques are (i) obtaining the near-net-shaped with complex forms, (ii) making materials with controlled porosity or (iii) making mechanically resistant sintered metallic materials used as reinforcing elements for ceramic/polymeric biocompatible materials. In this first part of the 2-part review, the most used and newest metallic biomaterials obtained by P/M methods are presented, along with their compaction and sintering behavior and the properties of the porous biomaterials studied in correlation with the biomedical domain of application.
Article 3 Reads 0 Citations Cold End Corrosion Avoiding by Using a New Type of Air Combustion Pre-Heater Maria Cristiana Enescu, C. Marius Vlădulescu, Aurel Gaba, Va... Published: 01 September 2017
Materials Science Forum, doi: 10.4028/www.scientific.net/msf.907.157
DOI See at publisher website
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