Advanced Materials Research Vol. 837

Abstract: The industrial engineering experts consider the product early design stage as one of the most important stage of the design process, because it influences all stages of the product life cycle. One of the capital questions for manufacturing or design engineering people is how simple or elaborated work piece to use for a given part, in a specific set of production conditions. The optimization problem consists of the choosing of the right work piece for the current production conditions. In many cases this problem is solved empirically, based on the experience of the manufacturer. This approach leads to results that are situated more or less close to the optimum for the technical and economical point of view. Fuzzy logic is a method that is used in system control and analysis design, because it shortens the time for engineering development and sometimes, in the case of highly complex systems, is the only way to solve the problem. For the parts manufacturing, the main idea of the algorithm is to formalize the knowledge regarding production volume, geometry, loading conditions and other factors, using fuzzy sets and then to take the work piece choosing decision through the inference rules that are specified to fuzzy logic methodology. The described fuzzy logic algorithm allows a rapid, argued choosing of the work piece type in the production. The paper describes the method implementation for the manufacturing of flanges, including the description of the software results.

Abstract: The present paper research performs an overwieved study regarding the engineering activities involved in the industrial design of the edible oil plant units. The objectives of the proposed smart engineering plan were to increase the oil extractability in the condition of process performance analysis of total integrated manufacturing facility, flexible tailor-made production, financial performance analysis and ecological industrial processing. Modern manufacturing operation via mechanical method of oilseeds pre-pressing associated with performant oilseeds preparation (drying, craking, dehulling, flaking) were considered to be analysed in the smart engineering for tailor-made end-product of higher commercial quality.

Abstract: In the specialized literature the cost of the machining process has been analyzed using a number of approaches and varying degrees of simplification to determine the optimum tool life and the tool speed. The accuracy of prediction is dependent on the degree of sophistication of the model. The purpose of this paper is the optimization of the cutting tool life and the cutting speed at the drilling of the stainless steels in terms of the minimum machining cost. A more comprehensive nonlinear programming model to minimize the total cost at the drilling of a stainless steel is developed in this paper. The optimum tool life and the associated tool speed are obtained by solving this model. The results can be taken into consideration in the educational studies and in the theoretical technical research. They can be implemented in the manufacturing activity.

Abstract: The experimental research aim was to analyze the corrosion resistance of superficial layers obtained by electrical sparking on the steel carbon samples. The electrodes used in these processes being made from corrosive resistance materials (coper and nickel). Processing by electric sparking occurs through electrode material erosion (anode) with a transfer by erosion products on the superficial workpiece. Processing of the treated surface begins with approximation of electrode by sample and at critical interval, it triggers electrical discharge through impulses. It is often continuous and ends at the electrodes contact. At the contact surface of the electrodes appear areas strongly heated causing electrical erosion of the electrodes (sample and electrode). The predominant transfer of anode material (electrode) to the cathode (the sample) ensures the formation superficial layer. After it the discharge was complete, at very small time interval, start removal of the Anode by cathode, action which ends with the interruption of electric circuit due to the transfer of material and the thermal changes from discharge area, in the superficial processing of metallic materials with electric sparks, the superficial layer of cathode it changes its structure and chemical composition. The samples being immersed 285 days in static sea water at the environments temperature. Corrosion resistance in seawater of superficial layers obtained with copper and nickel electrodes was determined by gravimetrical method. The samples covered with thin layers immersed in the corrosive agent (sea water) were analyzed through optical microscopy using QX3 Intel Play microscope and through atomic force microscopy. Experimental results were compared for both the surface of the initial sample material (OL 37) and the surface of the samples covered with Cu and Ni layers. One of the conclusions is: the superficial layer obtained by electrical sparking using cooper and nickel electrodes proves a improved corrosion resistance to see water compared to the base steel, specially for long term tries, when the corrosion speed is stabilizing remaining almost constant. The second main conclusion is: the investigations through atomic force microscopy made on the samples tested for long term corrosion, accentuate the compact and homogenous surfaces areas, which had not permitted the corrosive agent to interact with the base material.also, the wave-mode images present the discontinuities of the superficial laid layers, which represent a possible access way in for the corrosive agent to the samples material.

Abstract: The aim of this research is to determine the corrosion resistance on superficial layers laid-down through electrical sparking on the steel carbon OLC 45 samples, the used electrode being made from corrosion resistant material (Aluminum, Copper and Chromium). The superficial treatment through impulse electrical discharges is a procedure through which the proprieties of the metallic materials can be improved. The proprieties of the superficial layers obtained through this procedure are the same as the electrodes material being used or very close to this one, the properties resulting from micro alloying and the diffusion of the electrode material in the sample of steel. The experiments were done, for the superficial treatment through impulse electrical discharges, using Al, Cu and Cr electrodes. The corrosion speed was determinate through electrochemical corrosion. The corrosion potential and marking the polarization curves (linear and cyclic) was determined with an advanced electrochemical system type VOLTALAB 32. The acquisition and processing of experimental data was made with the help of the specialized software VOLTMASTER 2. The corrosion potential was determined by tracing the curves of linear polarization, recorded in sea water, using the Evans coordinates: E = f (log I). The corrosion process analysis was made also based on the cyclic polarization curves. The fine determining of the topography surfaces exposed to the action of the corrosive environment was made using the atomic force microscope (AFM). The support but also the sparking probes, has present the same type of corrosion; a general corrosion, which in the initial moments is represented by the appearance of corrosion dots. The superficial layers laid through Cr, Al and Cu electrodes sparking proves a improved corrosion resistance to see water compared to the base steel. Aluminium has the highest corrosion tendency while copper has the best protection.

Abstract: To obtain SAF we have focused research on Al-Mg alloys with different concentrations of magnesium and silicon carbide (SiC). To obtain these materials has been chosen different gas blowing method (N₂, SO₂ and C₄H₁₀). It was observed that the best results in terms of pore volume gave blowing with C₄H₁₀. The samples obtained were analyzed by optical and electron microscopy.

Abstract: Ti-Nb-Zr-Ta alloys represent a new generation of biomaterials with possible applications in the orthopedic field, being developed in order to eliminate the negative aspects of the current orthopedic biomaterials, which consist mainly in a low biocompatibility with human tissues and high values of modulus of elasticity compared to the human bone. This paper presents a comparative study of new titanium alloys, corresponding to the Ti-Nb-Zr-Ta system: Ti-21Nb-6Zr-15Ta and Ti-25Nb-10Zr-8Ta, which were analyzed by scanning electron microscopy, X-ray diffraction and microindentation. The both alloys are classified as near-β alloys. The addition of alloying elements such as Ta, Nb and Zr represents a good solution for lowering modulus of elasticity, which is an important factor for reducing bone resorption and therefore for preventing implant failure.

Abstract: Concrete is a complex material of construction that enables the high compressive strength of natural stone to be sed in any configuration. In tension, however, concrete can be no stronger than the bond between the cured cement and the surfaces of the aggregate. This is generally much lower than the compressive strength of the concrete. Concrete is therefore frequently reinforced, usually with steel. When a system of steel bars or a steel mesh is incorporated in the concrete structure in such a way that the steel can support most of the tensile stresses and leave the immediately surrounding concrete comparatively free of tensile stress, then the complex is known as reinforced concrete. Corrosion of reinforcing steel in concrete leads to the premature failure of many structures exposed to harsh environments. Rust products form on the bar, expanding its volume and creating stress in the surrounding concrete. This leads to cracking and spalling, both of which can severely reduce the service life and strength of a member. Corrosion of reinforcing steel in concrete structures is one of the most expensive problems facing civil engineers in the world. The structural integrity of many bridges, overpasses, parking garages, and other concrete structures has been impaired by corrosion, and repairs are urgently required to ensure public safety. Corrosion-induced deterioration of reinforced concrete can be modelled in terms of three component steps: (1) time for corrosion initiation; (2) time, subsequent to corrosion initiation, for appearance of a crack on the external concrete surface (crack propagation); and (3) time for surface cracks to progress into further damage and develop into spalls, to the point where the functional service life, is reached. The two most common causes of reinforcement corrosion are: (i) localized breakdown of the passive film on the steel by chloride ions and (ii) general breakdown of passivity by neutralization of the concrete, predominantly by reaction with atmospheric carbon dioxide. Sound concrete is an ideal environment for steel but the increased use of deicing salts and the increased concentration of carbon dioxide in modern environments principally due to industrial pollution, has resulted in corrosion of the rebar becoming the primary cause of failure of this material. The scale of this problem has reached alarming proportions in various parts of the world. Corrosion in reinforced concrete structures is causing deterioration of our infrastructure. Structures in or near marine environments and transportation structures on which deicing salts are used are especially vulnerable. A widely promoted method for repairing damaged structures or for protecting structures in corrosive environments is the application of fiber-reinforced composite wraps over the surface of the structures elements.

Abstract: This work reports hydrotalcite and zinc-substituted hydrotalcite (MeAlLDHs) anionic clays as novel catalytic formulations for some environmental applications regarding specific industrial coloured effluents. In this context, layered double hydroxides, covered or with tailored compositions, were synthesized, characterized using advanced analytical analysis techniques (XRD, FTIR, SEM) and tested in specific environmental applications. More specifically, LDHs samples were tested as catalysts for different treatments of coloured effluents, especially some advanced oxidation processes (i.e. heterogeneous advanced oxidation processes with H₂O₂ of Orange 16 dye-containing effluent). The influence of some operating factors such as catalyst type, concentration of hydrogen peroxide, presence of ferrous ions or UV light, contact time was studied, and the adequate operating values were established. Results show that Orange 16 removal is more than 70%, in specific operating conditions, for two of new tested materials (ZnAlLDH 3:1, and MgAlLDH 3:1). Moreover, the action of UV radiation was found efficient in decomposition of Orange 16 dye in the presence of all four tested catalytic materials, improving with more than 40-50% the color removal.

Abstract: In 1995, Yeh suggested the formation of an alloy made up of at least five metallic elements which have large mixing entropy solutions with many elements forming solide alloys. This alloy appeared because traditional alloys are characteised by high fragility and are difficult to process. High entropy alloys are alloys which have approximately equal concentrations, formed by a group of 5 to 11 elements majority in composition, mole fraction of each major metallic element in the alloy is between 5% and 30%. During the research it has been proved that this alloy has a high hardness and it is also corrosion proof and also resistance and good thermal stability It should be mentioned that High Entropy Alloys are characterized as alloys consisting of roughly equal concentrations of at least five metallic elements and are claimed to favor close-packed, disordered structures due to high configurational entropy. Such crystal structures, e.g. face-centered cubic (FCC), are advantageous in that they should offer multiple active slip systems usually observed in ductile metals and alloys. This opens the door to a large number of rich chemistries which would otherwise contain unacceptable volume fractions of intermetallic compounds to be useful in structural applications That way in this paper will carry out research to one specific high entropy alloy, we analyze the physical, chemical, electrical, magnetic, corrosion resistance of these materials, heat treatments corresponding and plastic deformation. This paper is divided into several chapters which will present application domains, and also a number of conclusions. Key words : high entropy alloys, properties of alloys, application domains, corrosion proof, thermal stability