Paweł Kwaśniewski

Characterization of Nanocarbon Copper Composites Manufactured in Metallurgical Synthesis Process

Currently, there is a worldwide search for new forms of materials with properties that are significantly improved in comparison to materials currently in use. One promising research direction lies in the synthesis of metals containing modern carbon materials (e.g., graphene, nanotubes). In this article, the research results of metallurgical synthesis of a mixture of copper and two different kinds of carbon (activated carbon and multiwall carbon nanotubes) are shown. Samples of copper–carbon nanocomposite were synthesized by simultaneously exposing molten copper to an electrical current while vigorously stirring and adding carbon while under an inert gas atmosphere. The article contains research results of density, hardness, electrical conductivity, structure (TEM), and carbon decomposition (SIMS method) for the obtained materials.

Study of the Structural Properties and Segregation of Alloying Elements in Strips from the TRC Line

Twin roll casting (TRC) technology is becoming increasingly popular because of the opportunity to receive aluminum strips which may serve as input for direct cold rolling processes. Furthermore, these strips have a favourable combination of mechanical and electric properties as well as dimensional tolerances. TRC line strips show segregation of alloying elements and structure providing a combination of casting structure and wrought alloy. As part of this study, the structure of the strips from the TRC line has been analyzed as well as the segregation of the alloying elements.

New Type of Lightweight Railway Overhead Line Carrying Equipment

Traditional carrying equipment that is being still used in polish railway system for dozens of years is based on typical steel profiles with low mechanical strength, low corrosion resistance and also with poor assembly and adjustment possibilities. Major part of other overhead railway equipment like support constructions, trolley wires and current carrying equipment is now modernized leaving the carrying system one of the lasts that needs to be redesigned and optimized to meet nowadays requirements for high speeds of railway travel. For that direct reason a project was started to conduct research works on design and development of the new type of railway overhead carrying equipment with enhanced exploitation properties. Within this articles authors presented a complete set of research results including designing of first concepts, FEM simulation and experimental research results including tests on final geometries in actual railway traffic. Performed studies and design works allowed to obtain an innovative overhead railway carrying system which is based on 6082 aluminum alloy and new geometry of used profiles and connection system. Research results conducted and presented within article are a part of the project co-founded by The National Centre for Research and Development.

Rheological Resistance of CuAg15 Alloy Wires

The paper presents the results of studies on obtaining the alloy and generating a set of very high mechanical and electrical properties of wires. The paper also presents the results of testing the rheological resistance in the form of stress relaxation tests carried out on the wires after various thermomechanical treatment processes. The optimum parameters of the thermo-mechanical treatment of the alloy were determined, enabling obtaining the most favorable mechanical and electrical properties of wires. The relationships of the influence of the material and its deformation on the changes in the mechanical and electrical properties of wires were determined. In addition, a microstructural analysis was carried out of casts and wires using scanning electron microscopy. Cast material was subject to observation and the material at successive stages of heat treatment.

New Aluminum Base Materials for Use on Electrical Purposes

Modern power industry expects new, dedicated aluminum based alloys with non-standard properties, including increased resistance to temperature. Materials exhibiting higher thermal resistance allow to increase operating temperature of electrical conductors, which results in the increase of their current carrying capacity. Commonly known and used in such applications are alloys from the AlZr group. Despite their advantages scientists from around the world are searching for new alternatives. In this paper authors present research results on Al-Mo and Al-Ag alloys with particular interest to the analysis of the molybdenum addition to the aluminum in the amount of 0.05, 0.1, 0.2% and silver addition in the amount of 0.05, 0.1, 0.15% by mass on the mechanical and electrical properties of obtained alloys. Tests were also carried out for reference material which is high-purity aluminum and the AlZr alloy, both in the as cast state temper. Results showed a significant change of temperature coefficient of resistance in Al-Ag alloys compared to Al, which leads to possible increase of the Joule’a heat without the raise of conductors temperature limit. On the other hand, above-average heat resistance of alloys from the Al-Mo group of materials was achieved during the trials. On that basis authors state that Al-Ag alloys may be used for the production of ACSS conductors and Al-Mo alloys for TACSR or TACIR type of conductors.This study was performed under a project financed by NCBiR within the INNOTECH II program.

Influence of Continuous Casting Conditions on Segregation of Additions in EN AW 1350 Aluminum Alloy

Integrated continuous casting processes are an important element of the production process in modern industry. Requirements for quality and exploitation properties of products obtained using continuous casting processes necessitate a revision of the role of impurities distribution in the material. This paper concerns on the influence of the casting process on the distribution of alloy additions. Spectroscopy studies were performed for the most sensitive elements, from the segregation, (i.e. : iron and silicon) point of view. Next obtained research results were correlated with the parameters of chemical composition such as casting speed, the presence of a modifier and the processing of metal crystallization zone. Analysis of the results clearly shows the presence of iron and silicon normal macrosegregation. It was observed that the concentration of these elements is highest in the casting axis and, in the case of iron, is 50% higher in the axis than in the circumference of casts.

Researches on the Production of Conductive Aluminium-Graphene Composites

All over the world, intensive research is being conducted on the development of new conductive materials to be used in power engineering. The objective of this research is to increase electrical conductivity in wire and cable materials, and consequently, to increase line current-carrying capacities and reduce losses in electric energy transfer. Today, the expectations in the power engineering sector concentrates on conductive materials with electrical conductivity higher than conductivity of base materials, i.e. aluminum. The scientific discovery of the recent years, graphene, one of carbon allotropic variants with a very high electrical and thermal conductivity and mechanical strength, creates great possibilities to design and manufacture new materials, with super-standard functional properties. Graphene, can be a new kind of “alloy additive” to aluminum, which can significantly change their electric and another properties.This article focuses attention on the possibilities of graphene and aluminum synthesis. The researches was made over the different methods of producing these materials, in particular: chemical synthesis consisting in the combination of liquid metal with graphene into a form suitable for further processing in the processes of forming into wires. The article presents the results of mechanical properties and structural studies of aluminum-graphene composites.

Studies on Copper – Activated Carbon (CWZ14) Metallurgical Synthesis with the Use of Continuous Casting Method

Various allotropic forms of carbon like carbon nanotubes (CNT’s) can have high mechanical, thermal and electrical properties. Because of this phenomena research results are being conducted worldwide on their possible use in electro-technical and electrical industry, for heat removal applications and in the fields of widely understood mechanical industry. Development method of high quality CNT’s is complex and can be long lasting. Because of those difficulties the production cost is very high and price of obtained CNT’s can reach thousands of euros. High cost of pure CNT’s and graphene is a direct reason for numbers of studies, also conducted in this article, on the synthesis of copper and other forms of carbon like i.e. activated carbon. Authors of this article state that also with the use of activated carbon one can achieve increase of copper mechanical, electrical, and technological properties. In this paper research results on copper and activated carbon (CWZ14) synthesis method are presented along with the research results of electrical, mechanical, rheological and micro-structural properties for obtained composites.

An Analytical Model for the High Temperature Low Sag Conductor Knee Point Determination

The modern high voltage power overhead lines operate with high temperature low sag (HTLS) conductors due to possibility of the current capacity increase. HTLS conductors are material and technological advanced solutions. The main advantage of HTLS conductors is a special designed operation conditions which cause the transformation of tensile stresses from the external aluminium base layers to the core. The conditions of this transformation are called “knee point” because a rapid change of the conductor sag - temperature relationship is observed. Prediction of conditions of the “knee point” temperature (KPT) is a key problem during overhead line design. The KPT is a function of different factors like conductor materials properties, conductor design, span parameters, sagging procedures and overhead line exploitation conditions. The paper presents an original theoretical model for HTLS conductors KPT calculations and shows some examples and comparisons of the different conductor designs and parameters.

Analysis of Properties of Selected Aluminium Alloys, Obtained by Twin Roll Casting Method and Subjected to Cold Rolling Process

Modern manufacturing technologies of flat cold-rolled products made of aluminium and its alloys are based on raw materials produced with the use of continuous casting technology. One of the most frequently used integrated production processes, based on continuous casting of metal, is twin roll casting method (TRC). In TRC method liquid metal flows into the area formed by two water-cooled rolls, solidifies and next is deformed (rolled) which allows to obtain strip with several millimetres thickness. Thanks to this, it is possible to eliminate hot rolling stage from the typical production technology, and directly subject obtained sheets to cold rolling process.This paper presents results of cold rolling strain dependency on the mechanical properties of tested aluminium alloys from 1XXX, 3XXX and 8XXX series, produced in the laboratory conditions with the use of TRC method. Furthermore the rolling loads and basic mechanical properties, determined in an uniaxial tensile, were examined.