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Recent 31

Vol. 12 (2011), No. 1 (31), March 2011

 

This issue of the RECENT® journal is dedicated to the
7th International Conference on Materials Science & Engineering, BRAMAT 2011

Selection and evaluation of published papers was provided by the BRAMAT Conference Organizing Committee.


CONTENTS


  • Elena Diana APOSTU

Practical Study of the Influence of Load Flow on the Cylindrical and Polygonal Sieves

» Abstract

Experimental research has established conditions under which one sieve can achieve optimum volumetric ranking efficiency. A direct influence in terms of efficiency of these machines has the material load flow in the sieve. The size of this flow may influence the proper functioning of sieve and of course, its operation in the optimal screening condition, that is perpendicular moving of the load to the surface screening. In addition, a great influence for the sieving efficiency it has the grain size of the material that it is to be sorted, the angle of inclination for the rotor axes, the speed of rotation for the rotor, the properties of the screening surface. One of the most important influences is the geometrical form of the rotor section. A series of experimental research was made for a rotor with a cylindrical form, and for a rotor with a hexagonal form. In this article, is presented some of the data that results from the study for the load flow influence, for the cylindrical sieves and for polygonal sieves.

» Keywords

screening, sieve, volumetric ranking

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  • Marius Dan BENŢA, Cosmin AFRENŢOAEI, Eusebiu PAIU, Laurenţiu TODORAN, Octavian DADU

Ways of Working the Data Obtained Through Atomic Force Microscopy Technology

» Abstract

The article presents a series of methods of working the data obtained through Atomic Force Microscopy technology. It shows the way in which the obtained data can be used and read through the Labview programming language. Emphasis is also laid on a series of advantages resulting from scanning by the direct contact or the non-contact method. AFM consists of a sharp microfabricated tip attached to a cantilever, which is scanned across a sample. The deflection of this cantilever is monitored using a laser and photodiode and is used to generate imaging or spectra of the surface. The AFM works in a number of different modes.

» Keywords

technology, Atomic Force Microscopy

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  • Florin CHICHERNEA

Implementing Value Analysis in Designing of Single Roll Crusher

» Abstract

Implementation of Value Analysis in designing of industrial equipment is a demonstrated need for a long time in highly developed industries. Beneficial results of applying this creative, functional and very practical multidisciplinary approach can see at all the products that surround us in everyday life. The paper presents a complete study of Value Analysis applied concretely to a selected part of one single roll crusher. The phases and iterative operation of the Value Analysis method are presented.

» Keywords

value analysis, optimum variant, single roll crusher

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  • Corina COJOCARIU, Adnana MARIN, Camelia GABOR, Daniel MUNTEANU

A General Overview on Performant and Cost-Saving Solutions in Designing Coatings for Fuel Injection Systems

» Abstract

According to C. Treutler, in Europe, more than 40% of all new cars are equipped with Diesel engines, including also the high class cars. High-pressure injection systems with pressure values up to 2000 bar (200 MPa) give the best results for combustion. At the same time, high - hard carbon coatings hold the key to improved performance for these kinds of systems. Regarding this, Diamond-like carbon (DLC) - coatings present crucial advantages in terms of tribological properties (low friction coefficient and low wear for both coated part and counter body). Using a cheaper variant of alloyed steel for manufacturing fuel injection parts and combining it with a DLC deposition, the results could be very performing in terms of quality - cost aspects. Specially designed plasma processes for DLC coatings deposition allow keeping the component temperature below 200 oC, in order to not modify by annealing the structure of steel used and to decrease its hardness. This paper represents a theoretical study of a debutant PhD students group and it aims to present a general overview regarding some advantages of using DLC films; at the same time, there are presented few practical applications of these kinds of films in manufacturing certain parts of Diesel fuel injection systems.

» Keywords

fuel injection system, DLC coatings, tribology, efficient solutions

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  • Dida Georgiana CONSTANTIN, Mihai APREUTESEI, Roxana ARVINTE, Adnana MARIN, Oana Cella ANDREI, Daniel MUNTEANU

Magnetron Sputtering Technique Used for Coatings Deposition: Technologies and Applications

» Abstract

The magnetron sputtering processes allow the deposition of metals, alloys, ceramic, and polymer thin films onto a wide range of substrate materials. Within the frame of this work, the recent developments of reactive magnetron sputtering technique are presented. The development, fundamental principles and applications of the magnetron sputtering process are discussed and commented. At the same time, the paper presents few examples of the use of this technique to develop advanced coatings for industrial applications, including corrosion resistant coatings, hard ceramic coatings, and coatings with novel thermal and chemical properties.

» Keywords

magnetron sputtering, coatings, technological parameters, control, applications

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  • Emilian ENE, Nicoleta TORODOC, Adriana ZARA

The Influence of Vacuum Heat Treatment on High Speed Steel Characteristics

» Abstract

This paper intends to highlight the advantages of technical and economic vacuum heat treatment compared with classical methods. Thus were subjected to final heat treatment of high speed steel samples both by heating in molten salts bath and quenching in oil, and also vacuum heating and cooling in nitrogen recycled. On samples so treated were made measurements of hardness, resilience and metallographic studies. Samples treated in vacuum have revealed near uniform and finer structure and better mechanical features 10...15%. Also, an advantage that can not be neglected is the better quality of surfaces, which require further processing insignificant.

» Keywords

vacuum, high pressure quenching, optimization, vacuum quenching

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  • Florin Constantin GÂDEA, Alexandru VAS, Angela VAS, Teodor MACHEDON-PISU

Aspects Regarding Mechanized Thermal Plasma Cutting of Metallic Materials - Carbon Steel

» Abstract

The purpose of this paper is to present an up to date analysis concerning the status of mechanized thermal cutting procedures, which have to be taken into account when settling the manufacturing technology in industrial usage. In particular, this paper refers to the plasma thermal cutting procedures, which tend to be chosen by a large number of manufacturers that take into account very carefully the fragile balance between manufacturing costs and final product selling price. Thermal cutting definition refers to melting or burning cutting procedures applied on the base material by using the help of a thermal source. Among these classes of procedures, there are oxy-fuel cutting, electric arc, plasma and laser cutting. When classifying thermal cutting procedures, there were taken into account the achievements regarding quality levels specified inside SR EN ISO 9013:2003 Norm that refer to the mechanized cutting conditions. Prior to economical issues, quality conditions stipulated into standards or manufacturing norms have to be taken into consideration. Cutting accuracy, chamfer angle, surface roughness cutting width and thermally influenced area size are just some of the factors that determine the future working procedure. It is certain that the achievement of the quality. The mechanized cutting procedures are characterized by advantages and disadvantages that conditions stipulated into standards or manufacturing norms can be done only by using CNC automatic cutting machines have to be taken into consideration when settling the manufacturing technology.

» Keywords

mechanized thermal plasma cutting, CNC cutting machines, quality criteria

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  • Adnana MARIN, Corina COJOCARIU, Dida Georgiana CONSTANTIN, Oana Cella ANDREI

Biosensors Based on Surface Plasmon Resonance Phenomenon: A Theoretical Review

» Abstract

Surface Plasmon’s are waves that propagate along the surface on a conductor, and have been studied intensively. The phenomenon has been utilized in studies of the properties of surfaces and thin films devices and, in particular, to recent developments in biosensor devices. Surface Plasmon resonance (SPR) biosensors gained an important place in detection, point- of- care diagnostics, and even as potential therapeutic agents. In this way the SPR biosensors have becomes central tool for characterizing and quantifying biomolecular interaction. Not all the materials can be utilized as surface active media; gold (Au) and silver (Ag) are the best examples of materials which can support surface Plasmon’s. The optical properties of metallic nanostructures are particularly important for the field of Nano science and technology. This paper attempts to review the major developments in SPR technology. Main application areas are outlined and examples of applications of SPR sensor technology are presented.

» Keywords

surface Plasmon resonance, Plasmon’s, biosensors

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  • Ioan MILOŞAN

Study About the Influence of Cryogenic Treatment on the Impact Strength Properties of C45 Steel

» Abstract

The paper presents the influence of the subzero treatment on the impact strength properties of case steel C45. The modern processes employed to produce durable components include cryogenic treatment as well as conventional heat treatment. Metallic materials in various applications are subject to exploitation negative temperature of -10°C…-200°C. Limits of elasticity and flow resistance to plastic deformation, that in some cases and increase hardness and fatigue strength, with decreasing temperature. At low temperatures, however, the mechanical characteristics of particular importance, has tenacity, sensitivity decreased and the tendency of brittle fracture. Steels, cast iron and ferrous alloys for the cryogenic should not show (except in the smallest possible) the latter trend. The C45, behaviour of low temperature is one of the most important studies when we want to determinate the phase transformation in solid state and the results of impact strength properties of this material and this paper present some aspects of this.

» Keywords

materials science, steel, heat treatment, cryogenic treatment, phase transformation, impact strength

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  • Aurelia Magdalena PISOSCHI, Gheorghe P. NEGULESCU

Comparison between the Performances of Platinum and Carbon Paste Electrodes for Voltammetric Vitamin C Determination

» Abstract

Voltammetric and amperometric methods allow fast, sensitive and selective ascorbic acid determination, requiring little or no sample preparation. Voltammetry at various electrodes was used to assess the ascorbic acid content in different media. For differential pulse voltammetry, the oxidation peak of ascorbic acid occurs at about 470 mV on a carbon paste working electrode and at about 530 mV (vs. SCE) on a Pt strip working electrode. A linear dependence between the current intensity measured for the peak height and ascorbic acid concentration was obtained between 0.31 and 20 mM on a Pt working electrode and between 0.07 and 20 mM on a carbon paste electrode. Lower detection limits were obtained with a carbon paste working electrode.

» Keywords

voltammetry, ascorbic acid, Pt electrode, carbon paste electrode

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  • Robert ROSCA, Lucian FERARU, Florin SAPARIUC, Iacob-Nicolae TRIF

Metallographic Researches on Welded Construction of the Telecommunication Antennae

» Abstract

Modern telecommunications antennas are made in welded steel pipes. Constructive complexity, functional, parametric and resistance require special materials and a blend of modern technology. The paper presents a welded construction made of telecom antennas welded pipes using welding manual process and "very short arc spray” process. Two welding processes of metallographic samples taken are presented: welding with a metal coated electrodes made by MAG and by "very short arc spray”. The structures were compared using microscopic examination, resulting in the conclusion of the joining process.

» Keywords

metallographic samples, welded construction, telecommunication antennae

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  • Adrian STAICU, Bogdan ANDREESCU, Radu IOVĂNAŞ

The Macroscopic Analysis of Samples Cut With a CO2 Laser Type TC L4003

» Abstract

In industrial practice, metal materials such as steel, tool steel, stainless steel, aluminium and aluminium alloys are cut using laser (considered an allied welding process). But laser can also cut materials such as titanium, silicon steels and titanium alloys. Laser radiation is used also for cutting non-metallic materials such as wood, leather, glass, ceramics and plastics (polyethylene, polyamide). Compared with other methods of cutting (plasma, oxyacetylene, erosion), laser cutting process has the advantage that the material processing is possible without contact or forces. To observe the thermal influence of the laser beam on the material there were carried out nine tests at different processing speed and laser powers. The tests were performed on different sheet thicknesses.

» Keywords

macroscopic analysis, samples, laser

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  • Cornel TANCO, Maria HERAŞCU (ROŞCA), Camelia RADU (HANEA), Iacob-Nicolae TRIF

Research on Reconditioning Agricultural Plough by Applying Welding Hardfacing

» Abstract

The paper shows the components of agricultural utilities: plough and knives of the cultivators who suffer the wear processes during operation. These components are studied by the degree of wear and are fixed by welding technology. Article presents experimental researches on welding hardfacing, materials, technological parameters and qualitative study of hardfacing surfaces.

» Keywords

plough, wear, refurbishment, welding hardfacing

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  • Mircea Horia TIEREAN

Evaluation of Stresses in the Air Conditioning Tower in Cement Industry

» Abstract

The paper presents the simulation of air conditioning tower loading in order to determinate the stresses. The 3D model of air conditioning tower was done using Autodesk Inventor. The stresses were obtained using Ansys and Design Star software. The reason of this calculus was to propose a reconditioning/replacement solution for the air conditioning tower. In the final there are presented the upgrading measures.

» Keywords

FEA, stress, simulation

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  • Violeta VASILACHE, Catalin POPA, Constantin FILOTE, Monica Anca CRETU, Marius BENTA

Nanoparticles Applications for Improving the Food Safety and Food Processing

» Abstract

In the last years, nanoparticles are studied for a number of industrial applications, such as electronics, environmental, synthetic textiles, packaging, pharmaceutical industry, medical care, as well as construction and decoration. They can be classified into two types, organic and inorganic. Organic antibacterial materials are less stable, especially at high temperatures and/or pressures comparing with inorganic antibacterial agents. This fact could be an obstacle for the production necessities. Consequently, inorganic materials such as metal and metal oxides have attracted lots of attention due to their ability to withstand harsh process conditions. From the inorganic materials class, metal oxides such as TiO2, ZnO, MgO and CaO present special interest, as they are not only stable under harsh process conditions but also generally regarded as safe materials to human beings and animals. Furthermore, the antimicrobial activity of ZnO draws our attention for its possible application in food industry. We resume and we underlined the actual knowledge about ZnO in order to support the researches for obtaining new materials for food industry.

» Keywords

antibacterial activity, antifungal activity, nanoparticles, zinc oxide, food safety, hygiene, energy efficiency

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