Preparation and Characterization Cu-Cr Contact Material and Study their Hardness and Conductivity


Article Preview

Cu-Cr contact material is used in medium voltage, high current vacuum interrupters. Vacuum interrupter is the heart of Vacuum Circuit breaker. Contact tips are usually made using powder metallurgical techniques in disk shape. These disks are machined to required dimensions and then hermitically sealed by vacuum brazing. The properties of the final contact tips are thus usually rarely studied. In the present study the properties before and after the vacuum sealing are compared in order to establish a correlation between them. The Cu-Cr contact tips were made under different compaction pressures, sintering temperatures and soaking time periods. Cu-Cr contacts were prepared by powder processing route and sintering in vacuum furnace at the temperatures of 1050°C for different soaking time period of 4, 6 and 8 Hrs. The samples were then subjected to simulated sealing cycle at temperatures (870 and 960°C). The electrical conductivity, hardness, microstructure and grain morphology of all the samples were studied. Properties of as-sintered and after sealing were analyzed and compared. The results of quantitative microscopy shows the better result on sintered sample soaked for 4 Hrs. The hardness and conductivity of the sample without brazing, varies between 79.9 - 83.8 HRF and 37.9 - 43.1% IACS respectively. The hardness and conductivity of the brazed sample varies between 52.5 - 63.42 HRF and 48.32 - 51.33 %IACS respectively.



Edited by:

B.S.S. Daniel and G.P. Chaudhari




K. Maiti et al., "Preparation and Characterization Cu-Cr Contact Material and Study their Hardness and Conductivity", Advanced Materials Research, Vol. 585, pp. 250-254, 2012

Online since:

November 2012




[1] P. G. Slade, Advances in Material development for high power, vacuum interrupter contacts, IEEE Trans. on CPMT. 17A (1994) 96 -106.

[2] B. Miao, Y. Zhang and G. Liu, Current status and developing trends, of Cu-Cr manufacturing technique contact materials for VCB, IEEE, (2004) 311-314.

[3] W. J. Boettinger, S. R. Coriell et al., Solidification microstructures: Recent developments, future directions, Acta mater., 48 (2000) 43-70.


[4] W. Li, Robert L. Thomas, and R. K. Smith, Effects of Cr content on the interruption ability of CuCr contact materials, IEEE Transactions on plasma science, 29 (2001) 744 – 748.


[5] W. F. Rieder, , M. Schussek, W. Glatzle, and K. Erich, The influence of composition and Cr particle size of Cu/Cr Contacts on chopping current, contact resistance, and breakdown voltage in vacuum interrupters, IEEE Trans. comp., Hybrids and manuf. Tec., 12 (1989).


[6] X.C. Dong, T.B. Hong, L. Ping, F. Zhang, Current research status on CuCr alloy for contact material, J. Today's Foundry, 28 (2007) 139-140.

[7] K. R. Anderson and J.R. Groza, Microstructural size effects in high-strength high-conductivity Cu-Cr-Nb Alloys, Metal. Matter. Trans. A, 32A (2001) 1211- 1224.


[8] X.S. Xin, Y. Ren, X. Jun, W.J. Xing, Properties of vacuum cast CuCr25 and CuCr25Te contact material, Trans. Nonferrous Met. Soc. China, 19 (2009) 444 - 447.