Andrzej Mamala

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.

Research of the Laboratory Wire Drawing Process of Zinc

The paper present results of the research on the laboratory drawing process of zinc obtained in industrial conditions in the CCR by Properzi method. The force drawing, mechanical properties before and after process was measured and formability limit in drawing process was specified. Because the wire drawing process was on hot (above the recrystallization temperature) the material didn’t work hardening as a function of strain which reduces the ductility and breaking just after the die. The microscopic images of microstructure reveal the presence of large twins recrystallization reflecting the dynamic renewal structure.

Effect of Selected Alloying Elements on Aluminium Physical Properties and its Effect on Homogenization after Casting

Modern technology for near net shape aluminium alloy flat rolled products includes twin roll casting, cold rolling and heat treatment. The technology is most common for 1XXX, 3XXX and 8XXX aluminium alloys. In fact, this technology of cold forming is applied to materials with as cast structure which may in some cases limit formability during rolling. As a consequence, the fundamental operation for high quality products is a well chosen homogenization process of material after casting. During the homogenization of 8XXX alloys after twin roll casting, important changes in electrical conductivity of the material have been reported in the literature. Possibly, the observed effects are connected with the migration of alloying element atoms in the microstructure. This study presents the influence of selected alloying elements on the electrical conductivity and mechanical properties of aluminium. On this basis, it is possible to analyse the effect and level of diffusion of alloying elements from particles to matrix and from matrix to particles during homogenization of 8XXX alloys in as cast temper. Additional comparison of experimental results with theoretical considerations via Nordheim’s rule was also analyzed in this study.

A Study of the Influence of Strain Hardening and Precipitation Hardening Sequence on Mechanical Properties of AlMgSi Conductor Alloys

Precipitation-hardenable AlMgSi alloys grade 6101 of 0.5% Mg and 0.5% Si contents, are used for the construction of homogenous wires in overhead power lines. The dominating group of alloys with increased electrical conductivity is the AlMgSi alloy group, these are HC, EHC and EEHC type materials with tensile strength at approximately 300 MPa and electrical conductivity lower than conventional wires (56,5 – 54,3 %IACS). The study presents the results of the research of AlMgSi wires heat treatment in compliance with the PN-EN 50183 standard. The shaping of heat treatable AlMgSi alloy rods and wires properties is possible through an appropriate sequence of a precipitation hardening (during ageing) and strain hardening (during drawing processes). This paper is a comprehensive analysis of the technologies for the production of wires from AlMgSi alloys.

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.

Research of Chemical Composition Influence on the Mechanical and Electrical Properties of Al-Mg-Si Wires

The subject of the work focuses on hardened-precipitation type alloys Al-Mg-Si which constitute the primary component material used to build homogeneous electric wires, type AAAC (All Aluminium Alloy Conductor). The material in consideration is a well-known and well-studied alloy, particularly in terms of the possibilities for using it in thermal treatment processes. However, the subject literature does not present a comprehensive recognition of the effect of heat treatment parameters on the set of mechanical and electrical properties in wires grade 6101. In particular, the study presents the results of experiments that show the possibility of controlling the AlMgSi wire properties by means of selecting the heat treatment parameters for simultaneously obtaining a high tensile strength and high electrical conductivity. Hence, the research described in this paper focuses mostly on determining the impact of the Mg and Si content on the electrical and mechanical properties of wires of Al-Mg-Si wire alloys.

Analysis of the Antimicrobial Copper Alloys Registered by the Environmental Protection Agency

The paper raises the issue of antimicrobial copper and its alloys constituting a promising solution for the constantly increasing problem of dangerous hospital-acquired infections. The major aim of the presented work is a precise analysis of antimicrobial copper alloys approved by The Environmental Protection Agency (EPA) in accordance with the Unified Numbering System, taking into account their European and international equivalent symbols as well – CEN and ISO, respectively. The analysis focuses mostly on the copper alloy types which the EPA list is composed of, their prices as well as materials and technological properties.

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.