Materials and Technologies

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Authors: Cornel Ciupan, A. Pop, Liviu Morar
Abstract: The paper presents the mathematical model of abrasive waterjet milling process. Based on analysis of existing models the authors realize a new mathematical model, considering some simplifying hypothesis. This model uses output data from model [1] and determines the advance speed, the consumption of the abrasive and the productivity of the process. To establish the productivity of the process and the advance speed we’ll use the “energy preservation” model. This model takes in account the material characteristics. The mathematical model has been solved numerical and the results have been interpreted.
Authors: Huseyin Gürbüz, Adem Kurt, I. Korkut, Ulvi Şeker
Abstract: The objective of this paper is experimentally investigation of the effects of different chip breaker forms on the cutting forces according to various cutting parameters. AISI 1050 workpiece material, most used material in the manufacturing industry, and SNMG 120408R inserts and PSBNR 2525M12 tool holder have 75° approaching angle according to ISO 3685 are used in the experiments. Seven groups chip breaker form were used in the tests. The chip breaker forms are the coated inserts MA, SA, MS, GH and standard, and the uncoated inserts MS and standard. These inserts are Mitsubishi UC 6010 and UTI20T grade; correspond to ISO P30 and P15 grade, respectively. Machining tests were carried out by using five levels of cutting speeds (150, 200, 250, 300, 350 m/min), three levels of feed rate (0.15, 0.25, 0.35 mm/rev) and two levels of depth of cut (1.6, 2.5 mm). Cutting forces were measured using Kistler dynamometer. The test results show that the highest cutting force values were measured on SA, GH, MA forms, respectively. Complex chip breaker forms cause the increase of the cutting forces. Although the cutting forces on the uncoated inserts were partly small in light cutting conditions, it has increased on the uncoated inserts in heavy cutting conditions compared to coated inserts.
Authors: G. Strnad, D. Biro, I. Vida-Simiti
Abstract: Recently a great deal of attention has been devoted to sputtering technology for nanostructured coatings. Wear resistant nanocomposite coatings are very promising materials, which can be easily scaled up for industrial production. Therefore, reactive magnetron sputtering of alloy targets or co-sputtering of elemental metal targets are now intensively investigated. Present paper presents some results of our research work for optimization of tribological properties by definition of selected parameters for reactive sputtering process conditions of self-lubricated carbon doped TiAlN coating. Tailored nanocomposite thin films of multicomponent and multiphase materials have been performed by DC reactive UM magnetron co-sputtering of TiAl and TiC target materials in Ar–N2 respectively C2H2 and CH4 as carbon precursor gases.
Authors: Maria Stoicănescu, I. Giacomelli, Maria Simona Pantelimon
Abstract: It is well known that the aluminum alloys containing Cu and/or Mg lead to soluble compounds which themselves allow the hardening during the process of strengthening and ageing. At the same time, the hardening process during ageing takes a relatively long period of time, and the registered rises are generally not too high. There are presented studies regarding to alloy AlCu4Mg1,5Mn which was tested in several heat treatment conditions. These alloy, after final heat treatment of hardness by and ageing, suffers a sensitive hardening – the ageing is recommended for pieces used under medium and intense mechanical stresses Using the alternative electromagnetic fields is more efficient by 10 to 12% than stationary one, not only regarding to the period of ageing, but also regarding to the highest values of hardness; Also other specific results are given in the paper.
Authors: Ion Mitelea, G. Gavanescu, B. Radu
Abstract: In this paper is analyzed the effect of normalizing post-weld heat treatment for SAW TWIN-ARC on grain size and aging of the Widmannstätten structure. Tests of elongation and toughness made with welded joints from S355J0 justify heat treatment opportunity and also the structural modification developed in deposited metal and in heat-affected zone.
Authors: O. Uzlov, A. Malchere, V.I. Bolshakov, Claude Esnouf
Abstract: Low carbon-manganese wrought steels with addition of Ti-Al-N have been treated in order to obtain acicular ferrite structure. The microstructure of fine acicular ferrite nucleated intragranularly on Ti(C,N)+AlN and Ti(C,N)+AlN+MeS inclusions has showed high strength and toughness at low temperatures.
Authors: P. Motoiu, Gabriela Popescu, Horia Binchiciu, D. Dumitrescu, S. Ivanescu, C. Fratila, F. Stoiciu
Abstract: Thermal spraying technologies are an effective way to ensure surface protection against destructive effects of wear, corrosion and oxidizing phenomena which can be applied in majority industrial sectors for improving properties of new parts or for reconditioning worn out parts technology. The powders used in this study are mainly used in the repair of cast iron parts (e.g. engine blocks) and in build - up of press tools for car bodies, threads, turbine-guided vanes, rotating valves and shafts in eccentric presses. Three types of tubular composites based on WC powders were studied which demonstrated that this technology improved their properties.
Authors: Iulia Mirela Britchi, Mircea Olteanu, Niculae Ene
Abstract: In order to manufacture ceramic coatings on metallic substrates with medical applicability, a compromise has to be made between adherence, mechanical resistance and bioactivity. Biovitroceramic layers to satisfy all these requirements are extremely difficulty to develop. The goal of this contribution is to employ a simple technique like enamelling for making biocompatible and bioactive coatings with improved mechanical properties and very good adherence onto metallic substrates made of titanium samples. One important factor for a good adherence is the value of the thermal expansion coefficient of the ceramic coating to be closed to that of the metallic substrate. Once this achieved by establishing an adequate ceramic composition, there remain other factors that contribute to a good adherence such as metallic surface pretreatment. The surface was processed by Al2O3 powder (125 'm) blasting, degreased with acetone in an ultrasonic device and immersion in phosphoric acid. The (Na2O-K2O-Li2O-CaO-MgO-SiO2- B2O3-TiO2-P2O5) biovitroceramic coating – titanium interface was examined by means of optical microscopy and electronic microscopy. The coating adherence to the metallic substrate was evaluated qualitatively by Vickers microhardness tests at the interface.
Authors: Cosmin Codrean, Ion Mitelea, Viorel Aurel Şerban
Abstract: Tapes of stainless steels were brazed inside a vacuum oven using amorphous or quasi amorphous alloy based on Ni-Cr. By means of different investigation methods (optical microscopy, X ray diffraction) there were emphasized the structural morphology transformations inside brazed joints, revealing the role of process parameters on obtained structure.
Authors: Ion Mitelea, A. Mosila, B. Radu
Abstract: In this paper is revealed the structural transformations and diffusion processes that take place as a result of the local thermo-mechanical treatment regimes specific to friction welding of nitrided and not nitrided quenched and tempered steels. To obtain welded joints with good mechanical properties it is necessary to remove the nitrided layer from the contact surfaces.

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