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Power Connectors
Published in Paul G. Slade, Electrical Contacts, 2017
Copper is a soft, malleable and ductile metal with high conductivity and excellent weld-ability and solderability. By rolling and drawing, a variety of electrical products such as wires, sheets, tubes, shaped bars, and flat busbars can be manufactured. The high-conductivity copper useful for electrical applications must be brought about by careful refining treatments such as electrolytic refining which removes Ag, Au, As, Sb and other impurities. The most common copper used in the power industry is electrolytically tough pitch copper ETP or C11000 made by electrolytic refining of copper. The main shortcoming of ETP copper is the embrittlement to which it is subject when heated in hydrogen to temperatures of 370°C or more. This results from the presence of oxygen in the metal which reacts with the hydrogen, making steam and leading to internal cracking. The solution to this problem is to use copper of substantially lower oxygen content. While phosphorus is an effective deoxidizer for copper, it degrades the conductivity too much to give a product suited for electrical applications. Instead, electrolytic slabs are melted and refined in a special process using oxygen-free inert gas and no metallic oxidizers. The result, a 99.98% pure copper with essentially no oxygen and <0.005% of any one impurity, is known as oxygen-free high-conductivity copper (OFHC). The conductivity of copper is frequently referred to in terms of the international annealed copper standard (IACS), thus % IACS equals 100 (resistivity IACS/resistivity of sample). In absolute terms, the IACS has resistivity of 1.7241 μΩ cm. A common criterion for defining the purity of metals is the ratio of their resistivity at 273 and 5.2 K. This ratio varies between 150 and 400 for OFHC copper but can reach 1000–5000 and higher for zone-refined materials.
Contact Materials
Published in Milenko Braunovic, Valery V. Konchits, Nikolai K. Myshkin, Electrical Contacts, 2017
Milenko Braunovic, Valery V. Konchits, Nikolai K. Myshkin
The conductivity of copper is frequently referred to in terms of the International Annealed Copper Standard (IACS). Thus, percent IACS equals 100 (resistivity IACS/resistivity of sample). In absolute terms, the IACS has a resistivity of 1.7241 Σ cm. A common criterion for defining the purity of metals is the ratio of their resistivities at 273 and 4.2 K. This ratio varies between 150 and 400 for OFHC copper but can reach 1000–5000 and higher for zone-refined materials.
Microstructure and properties of Cu-Fe alloys fabricated via powder metallurgy and rolling
Published in Powder Metallurgy, 2021
Chenzeng Zhang, Cunguang Chen, Lina Huang, Tianxing Lu, Pei Li, Wenwen Wang, Fang Yang, Alex A. Volinsky, Zhimeng Guo
The density was measured according to Archimedes’ principle. Phase identification was evaluated by X-ray diffraction (XRD, TTRIII) with Cu Kα radiation at a scanning rate of 5° min−1, 40 kV and 30 mA. The microstructure and composition of CFAs were analysed by field emission scanning electron microscope (FESEM, Zeiss Supra 55), energy dispersive spectra (EDS) and transmission electron microscopy (TEM, FEI Tecnai G2-F20). Room temperature tensile tests were conducted using a YHS-216W-200N electronic universal testing machine, according to the ASTM E8. Electrical conductivity was measured by using a four-point probe at room temperature. The results were expressed in units of ‘% IACS’ calculated by comparison with the electrical conductivity of an International Annealed Copper Standard. The magnetic performance test was carried out by the Lakeshore-7400s vibration sample magnetometer with a maximum applied magnetic field of 15,000 Oe. The measurement accuracy of the magnetic saturation strength (Ms) was 5 × 10−7 emu, and the coercivity (Hc) was measured by a dc BH circuit tracer with an accuracy of 10−2 Oe. After testing, the samples were weighed using a precision balance with an accuracy of 0.0001 g.
Parameters effect on electrical conductivity of copper fabricated by rapid manufacturing
Published in Materials and Manufacturing Processes, 2020
Gurminder Singh, Sunpreet Singh, Jagtar Singh, Pulak M Pandey
The electrical conductivity has been measured on the cylindrical specimens of size 10 × 15 mm, prepared from the fabricated Cu specimens. The ASTM E1004-17 standard has been adopted for understanding the implication of the phase-sensitive eddy current methods, for the electrical conductivity measurement. A contact probe having the current carrying coil has been used for the generation of the eddy currents and primary magnetic field was produced. Figure 2(a) shows the schematic representation of the phase-sensitive eddy current method. The primary field flew the eddy current inside the fabricated Cu specimen; therefore, another magnetic field (secondary) has been obtained in the opposite direction. A contact probe method has been used to convert the observed amplitude and voltage values into electrical conductivity. The test apparatus was based on Sigmascope SMP350 (Fischer Technology Inc. USA, refer Fig. 2(b)). The electrical conductivity data were captured in MS/m and converted into IACS % (100% International Annealed Copper Standard = 58 MS/m).
Accelerating heterogeneous nucleation to increase hardness and electrical conductivity by deformation prior to ageing for Cu-4 at.% Ti alloy
Published in Philosophical Magazine Letters, 2019
Seung Zeon Han, Satoshi Semboshi, Jee Hyuk Ahn, Eun-Ae Choi, Minah Cho, Yusuke Kadoi, Kwangho Kim, Jehyun Lee
Cu (99.99% pure) and Ti (99.9% pure) were used to fabricate a Cu-4 at.% Ti alloy ingot using a vacuum induction melting process. The ingot was then machined to a 2 cm diameter rod. The rod specimens were solution-heat-treated at 900°C for 1 h and immediately water quenched. The solution-treated rod specimens were grooved to 10 mm diameter at room temperature, which corresponds to a 75% area reduction. After the grooving deformation, the specimens were aged at 400°C, 450°C and 500°C for various periods. For comparison, the datum for the Cu-4 at.% Ti alloy that was solid-solution treated and then aged (i.e. without deformation prior to ageing) was used from reference [6]. The detailed ageing procedure of the specimens without cold working is described in reference [6]. The samples were mechanically polished and etched with a solution containing 5 g FeCl3·6H2O, 12.5 ml HCl and 100 ml H2O. The microstructure was observed using an optical microscope (Olympus Model GX51) and a scanning electron microscope (SEM) (JEOL Model JSM-6610LV). The characterisation of the specimens was carried out using a 200 kV field-emission transmission electron microscope (FE-TEM) (JEOL Model 2100F) equipped with an energy-dispersive X-ray spectroscopy (EDS) detector, along with a scanning TEM probe. Disk-type TEM samples (3 mm in diameter and 100 μm thick) were prepared by mechanically polishing the samples with a digitally enhanced precision sample grinder (Total Solution Model DEPS-101). The samples were subsequently dimpled using a dimple grinder (Gatan Model 656). Microhardness was measured using a Vickers hardness tester (Matsuzawa Model MXT70) with a load of 100 gf. The electrical resistivity was measured by a portable double-bridge apparatus (2769, Yokogawa M&C) at room temperature (27 ± 1°C) on a 300 mm-long specimen, and was then converted to conductivity by taking the inverse of the resistivity. The conductivity was expressed in % of the international annealed copper standard (IACS), which gives the ratio of the conductivity compared with annealed pure copper. (IACS = International Annealed Copper Standard. 100% IACS is defined as the conductivity corresponding to a volume resistivity at 20°C of 17.241 nΩ.