Papers by Keyword: Metal

Abstract: This paper deals with mechanical properties research of innovative polymer multiphase metal and polymer composite materials consisting of matrix and isotropic or anisotropic oriented deterministic fractal shapes made by 3D printing. By creating of reinforcing internal structure consisting of deterministic fractal connected shapes is possible to gain unlimited mechanical properties directing. These fractal shapes - placed in multiphase system matrix – are significantly influencing whole material system mechanical properties mainly in case of stress on the limit of strength, proportional elongation on the limit of strength or tensile/ flexural modulus. Fractal shapes are also possible to properly locate, orient or shape modify according to potential material using with goal to gain maximal efficiency of fractal shapes occurrence. Producing of this multiphase system is realized by the help of 3D printing technology. Internal fractal shape structure is 3D printed from aluminium. This feature is in the next step over injected by polymer. So is possible to create any fractal shapes placed in polymer matrix which are by another technology unmanufacturable. Mechanical properties analyse is performed with respect to fractal shape type, fractal dimension, and fractal shape orientation.

Abstract: This article explains the physical features of various methods of compaction, primarily for end of life vehicle (ELV) bodies coming from ELV processors. By EU directive 2000/53/EC it is mandatory for all EU members to meet the reuse of 95 % of the old vehicle weight. It means that the vehicles have to be decomposed completely – metal shells freed from all the components like interior trim, rubber sealing, glass, all the liquids, seats tanks and other hard metal components like drive-train, engine etc. It follows that pressing machines used for compressing whole vehicles today, are overpowered, with high energy demand, robust structures and heavy weight. Hence it makes sense to concentrate on comparison of pressing methods and choosing the most energy efficient one and the designing a new device, if necessary. This device is aimed for operation in Slovak Republic but also usable in other countries with same or similar requirements such as optimized system for processing of car bodies, mobile concept and modularity of the whole mobile modular disintegration complex consisting of a pressing machine, shears and shredder. Car body structure

Abstract: Tomatoes (Lycopersicon esculentum), is a fleshy berry regarded as very popular perishable fruit as well as vegetable grown throughout the tropical and temperate regions of the world. This research work investigated the effect of tomato juice on the electrochemical properties of brass, galvanized and stainless steel using potentiostatic polarization method and weight loss technique at room temperature. The samples were cut into sizes, 2 cm by 2 cm for galvanized and stainless steel, while brass a cylindrical shape of 2.5 mm diameter was cut into 5 cm height, the cut metallic samples was weighed using a sensitive weighing balance and recorded. The pH of the tomato juice was measured and the cut metallic samples were immersed into the containers filled with tomato juice and exposed for a period of 30 days. Weight losses of samples and pH of the tomato juice were determined at an interval of 5 days and the corrosion rates were evaluated. The results showed that brass and stainless steel had very low corrosion rates which decreased with time. High corrosion attack was observed on the galvanized steel and this is shown by the high corrosion current density and corrosion rate obtained on the polarization curve showing active corrosion reaction properties. The pH of the tomato progressed to neutrality within five days and to alkalinity at the end of the thirty days test for galvanized steel while the pH of the tomato juice was less acidic at the end of the thirty days test for both brass and stainless steel. Stainless steel was confirmed as best storage material for tomato juice in this study.Keywords: Corrosion, electrochemical, potentiostatic polarization, weight loss, tomato, metal

Abstract: It is well-known that superimposed ultrasonic tool vibrations are capable of decreasing the forming force and the interfacial friction during the deformation of metal. The complex causes of this phenomenon were mainly investigated by focusing on oscillation frequencies above 20 kHz. Due to limitations of the load capacity and the power of the oscillating systems, mostly soft materials, such as aluminium and copper, were analysed. The present study is concerned with the development of a tool system for ultrasonic-assisted compression tests with a 15 kHz oscillation system. The advantages of this type of oscillating system are an increased power and robustness, which allow the testing of high strength materials. In preliminary ultrasonic-assisted compression tests with a S235JR steel a force reduction of up to 63 % was measured. The major challenges identified during the preliminary investigations are a transversal drift of the specimen, a periodic separation between the die and the specimen, a high sound emission and a high demand on the measuring and signal processing technology. Based on the technical challenges and the determined requirements a tool system is introduced.

Abstract: Designing material characteristics by grain refinement using Severe Plastic Deformation (SPD) is an attractive way to create outstanding material properties. This paper presents a unique method which combines SPD and impact extrusion. The extrusion die is designed to create additional material deformation to a defined depth, resulting in a gradient from ultra-fine grained to coarse grained microstructure. Due to the large gradient the method is called gradation extrusion. The paper presents a new analytical calculation method and a numerical evaluation of the strain, showing the relationship between tool design and achievable effects and provides initial experimental results.

Abstract: The exact determination of emissivity and the following determination of the surface temperature of glossy materials can be carried out e. g. after applying a material with a known value of emissivity on the surface (e. g. self-adhesive foil or spray tint). The contribution deals with other possibility of determination of surface temperature and the influence of emissivity of glossy materials using a metal shield that reduces the negative influence of the reflected radiation during the termographical measurement.

Abstract: It is possible to measure the surface temperature of a peripheral wall in a certain point with an advantage when using a technical device for elimination of reflected radiation. Other advantages of the diagnostics of the peripheral wall using the infrared termographic system after removing the mentioned technical device from the wall is, that if we determine (using the technical device) the surface temperature in a determined point, then we are, after inserting it into the termographic systém, able to determine retroactively the real value of the apparent reflected temperature, and this is even done with higher accuracy. Then we use the value for a termographic measuring of all the surface of the peripheral wall, keeping the same angle of scanning.

Abstract: Paper presents necessity of metal plating in the case of highly corosion process acting on metal pieces. By authors researches, the welding plating method has some disadvantages, possible to be eliminated by using the ultrasonic field. The work presents a series of experimental results obtained in the case of metal plating using welding method [10] with or without ultrasonic field. There were analised the main coupled material resulted functional properties and the final microstructure in the distinctive zone: base material, thermal influenced zone, and addition material.

Abstract: The process of hollow conical forming is described for two schemes: crimp-distribution for hollow billets and stretching from sheet billet with subsequent crimping for cylindrical blank. The item thickness varying was investigated for these schemes. Dependency of technological allowance ratio on crimping coefficient and expansion ration for items allowance was investigated. The effectiveness of stretching from sheet billet with subsequent crimping was proven.

Abstract: Biotic ligand model (BLM) is a tool with the consideration of aquatic organism would have interaction with metals in different forms. Water chemical characteristics would also have some influence with bioavailability. In this study, BLM’s theoretical basis and realization process were discussed in detail, followed by the application status of the model. Finally, current challenges and future direction of BLM were pointed out. BLM assumes that the biological effect happens during the chemical equilibrium, which means that the model might only explain the acute toxicity results.