The influence of composition and Cr particle size of Cu/Cr contacts on chopping current, contact resistance, and breakdown voltage in vacuum interrupters

Rieder, W.; Schussek, M.; Glatzle, W.; Kny, E.

doi:10.1109/33.31434

Cited by 100 publications

(54 citation statements)

References 5 publications

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“…Furthermore, the impact of Cr-content is also investigated, which was not conclusively reported by authors in the past e.g., in Refs. [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Microstructure Formation and Resistivity Change in CuCr during Rapid Solidification

Hauf

Kauffmann

Kauffmann-Weiss

et al. 2017

Metals

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Abstract:The formation of the surface-near microstructure after a current interruption of CuCr contact materials in a vacuum interrupter is characterized by a fast heating and subsequently rapid solidification process. In the present article, we reveal and analyse the formation of two distinct microstructural regions that result from the heat, which is generated and dissipated during interruption. In the topmost region, local and global texture, as well as the resulting microstructure, indicate that both Cu and Cr were melted during rapid heating and solidification whereas in the region underneath, only Cu was melted and elongated Cu-grains solidified with the <001>-direction perpendicularly aligned to the surface. By analysing the lattice parameter of the Cu solid solution, a supersaturation of the solid solution with about 2.25 at % Cr was found independent if Cu was melted solely or together with the Cr. The according reduction of electrical conductivity in the topmost region subsequent to current interruption and the resulting heat distribution are discussed based on these experimental results.

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“…Furthermore, the impact of Cr-content is also investigated, which was not conclusively reported by authors in the past e.g., in Refs. [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Microstructure Formation and Resistivity Change in CuCr during Rapid Solidification

Hauf

Kauffmann

Kauffmann-Weiss

et al. 2017

Metals

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“…[2] Presently they are used in aircraft, spacecraft and ship structures. [3] The original syntactic foam consists of a epoxy resin which is filled with glass hollow micro spheres (AE < 100 lm).…”

Section: Methodsmentioning

confidence: 99%

Properties of Nanocrystalline CuCr50 Contact Material

et al. 2005

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CuCr alloys are the predominant contact materials for medium-voltage, high-current vacuum interrupters (VIs) due to the unique combination of the properties of the two constituents. [1] With the decreasing of the grain size, the properties of the CuCr materials can be improved significantly. Rieder et al. reported that the maximum chopping current decreased and the breakdown field increased significantly when the size of Cr particles in CuCr contact materials were reduced from about 150 to 36 lm. [2] The microstructure of conventional CuCr materials prepared by powder metallurgy mainly depends on original Cu and Cr powders. CuCr materials, manufactured by arc melting with a grain size of 15±30 lm, have better performance than that of conventional CuCr materials with a grain size 74±150 lm. [3] Because of the limitation of cooling rate, the grain size of the CuCr contact materials manufactured by arc melting technique cannot be fine further. Mechanical milling/alloying, which was first developed by Benjamin for the production of complex oxide dispersion strengthened alloys, is found to be particularly suitable for yielding relatively large quantities of the powders with nanocrystalline grains. [4] In this paper, nanocrystalline CuCr50(nc-CuCr50) contact material were prepared by mechanical alloying and hot press sintering techniques(HPS). The properties and microstructure as well as surface morphology of nc-CuCr50 prepared by HPS after arcing were investigated.Results: Figure 1 shows the XRD patterns of the original and milled Cu, Cr powders and the nc-CuCr50 sample. The diffraction peaks of Cu and Cr powders were broadened and lowered significantly after high energy milling, indicating a decreasing of the grain size. For the nc-CuCr50 specimen, the intensity of diffraction peaks is similar to that of milled powder, the broadened and lowered peaks show that the grain size is small. Based on TEM results, as shown in Figure 2, the grain size was less than 50 nm, which is in good agreement with the results of XRD. COMMUNICATIONS

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“…[1,2] It was indicated that the smaller the Cr-rich phase in Cu-Cr alloys was, the better the electric properties could achieve. [2][3][4] Powder sintering is widely used to produce Cu-Cr contacts in industry, because finer Cr particles can be obtained in comparison with traditional melting and casting, where the microstructures consist of some coarse Cr-rich dendrites and Cu-rich matrix. The diameters of Cr particles in sintered products are in the range of 30 to 100 lm.…”

Section: Introductionmentioning

confidence: 99%

Effects of Ti Addition on the Liquid-Phase Separation of Cu71Cr29 Alloy during Rapid Cooling

Sun

Guo

et al. 2008

Metall Mater Trans A

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The effects of Ti addition on the liquid-phase separation of Cu 71 Cr 29 alloy have been investigated. It is revealed that Ti addition can partly suppress the liquid-phase separation of the alloy melts, resulting in refining of Cr-rich particles formed after liquid-phase separation during rapid cooling. Nanoscaled Cr 2 Ti and Cu 4 Ti phases precipitate in the annealed Cu-Cr-Ti ribbons when Ti content attains 2.5 pct. The thermodynamic analyses indicate that the large positive mixing heat between Cu and Cr is reduced by the addition of Ti, leading to the liquid-phase separation occurring at a lower temperature and being driven by a smaller force. However, more Cr and Ti dissolve in Cu solid solution when Ti content is more than 3 pct, and as a result, the electrical resistivity of the ribbons is increased sharply.

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The influence of composition and Cr particle size of Cu/Cr contacts on chopping current, contact resistance, and breakdown voltage in vacuum interrupters

Cited by 100 publications

References 5 publications

Microstructure Formation and Resistivity Change in CuCr during Rapid Solidification

Microstructure Formation and Resistivity Change in CuCr during Rapid Solidification

Properties of Nanocrystalline CuCr50 Contact Material

Effects of Ti Addition on the Liquid-Phase Separation of Cu71Cr29 Alloy during Rapid Cooling

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