Production of WCu electrical contact material via conventional powder metallurgy method: Characterization, mechanical and electrical properties

Abstract

    In this study, the effects of increase of sintering temperature and Cu amount on microstructure, mechanical and electrical properties of WCu electrical contact materials fabricated via conventional powder metallurgy (P/M) method were investigated. The powders obtained by adding copper at different ratios into the tungsten powders were cold pressed in a mold under 60 MPa pressure. Samples were sintered at 1000 ^oC and 1100 ^oC using three different compositions (W-%10wtCu, W-%20wtCu- and W-%30wtCu). Microstructures of the samples were investigated by scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD) analysis. Mechanical properties were determined by measuring hardness values and electrical properties were determined by measuring electrical resistivity. When the effect of the copper ratio on the microstructure, mechanical and electrical properties is analyzed, the reduction in the amount of copper has a positive effect on the hardness, while the electrical conductivity is adversely affected. In addition, the application of the sintering temperature above the melting temperature of copper has been effective in increasing the hardness and electrical conductivity values.

Keywords

• Powder metallurgy,tungsten-copper,microstructure,hardness

References

1. [1] Bloor, D., Brook, R.J., Flemings, M.C. and Mahajan, S. The Encyclopedia of Materials, Permagon Pres, Oxford, 1999.
2. [2] Güler, Ö. and Evin, E. The investigation of contact performance of oxide reinforced copper composite via mechanical alloying, Journal of Materials Processing Technology, 209(3), 1286-1290, 2009.
3. [3] Güler, Ö. Investigation of electrical properties of oxide reinforced copper composite produced by mechanical alloying, (Master Thesis), Fırat University, Elazığ, Turkey, 2006.
4. [4] Gök, M.G., Kaplan, M. The production of electrical contact material by means of powder metallurgy and investigation its contact performance, 6th International Advanced Technologies Symposium (IATS’11), 294-298, Elazığ, Turkey, 2011.
5. [5] Kim, D-G, Kim, G-S, Suk, M-J, Oh, S-T, Kim, Y-D. Effect of heating rate on microstructural homogeneity of sintered W-15 wt.% Cu nanocomposite fabricated from W–CuO powder mixture, Scr. Mater., 51, 677–681, 2004. doi:10.1016/j.scriptamat.2004.06.014.
6. [6] Kim, J, Ryu, S, Kim, Y, Moon, I. Densification behavior of mechanically alloyed W–Cu composite powders by the double rearrangement process, Scr. Mater., 39, 669–676, 1998.
7. [7] Liu, B.B., Xie, J.X., Qu, X.H. Fabrication of W–Cu functionally graded materials with high density by particle size adjustment and solid state hot press, Compos. Sci. Technol., 68(6), 1539–1547, 2008. doi:10.1016/j.compscitech.2007.10.023.
8. [8] Chen, P, Shen, Q, Luo, G, Wang, C, Li, M, Zhang, L, Li, X and Zhu, B. Effect of interface modification by Cu-coated W powders on the microstructure evolution and properties improvement for Cu–W composites, Surface & Coatings Technology, 288, 8-14, 2016. doi:10.1016/j.surfcoat.2016.01.014.

9. [9] Bhalla, A.K., Williams, J.D. Comparative assessment of explosive and other methods of compaction in the production of tungsten–copper composite, Powder Metall., 1, 31–37, 1976. doi:10.1179/pom.1976.19.1.31.
10. [10] Li, S.B., Xie, J.X. Processing and microstructure of functionally graded W/Cu composites fabricated by multi-billet extrusion using mechanically alloyed powders, Compos. Sci. Technol., 66(13), 2329-2336, 2006. doi:10.1016/j.compscitech.2005.11.034.
11. [11] Ihn, T.H., Lee, S.W., Joo, S.K. Effect of transition metal addition on liquid phase sintering of W–Cu, Powder Metall., 37(4), 283-288, 1994. doi:10.1179/pom.1994.37.4.283.
12. [12] Luo, S.D., Yi, J.H., Guo, Y.L., Peng, Y.D., Li, L.Y., Ran, J.M. Microwave sintering W-Cu composites: Analyses of densification and microstructural homogenization, Journal of Alloys and Compounds, 473, L5-L9, 2009. doi:10.1016/j.jallcom.2008.05.038.
13. [13] Ardestani, M., Rezaie, H.R., Arabi, H., Razavizadeh, H. The effect of sintering temperature on densification of nanoscale dispersed W-20-40%wt Cu composite powders, Int. Journal of Refractory Metals & Hard Materials, 27, 862-867, 2009. doi:10.1016/j.ijrmhm.2009.04.004.
14. [14] Erçetin A. Manufacturing, characterization and micro machinability of W+Cu+(X) electrode utilized in resistance welding through powder metallurgy method, (Master Thesis), Afyon Kocatepe University, Afyonkarahisar, Turkey, 2015.
15. [15] Findik, F., Uzun, H. Microstructure, hardness and electrical properties of silver-based refractory contact materials, Materials and Design, 24, 489-492, 2003. doi:10.1016/S0261-3069(03)00125-0.
16. [16] Ibrahim, A., Abdallah, M., Mostafa, S.F., Hegazy, A.A. An experimental investigation on the W-Cu composites, Materials and Design, 30, 1398–1403, 2009. doi:10.1016/j.matdes.2008.06.068.
17. [17] Kecskes, L.J., Klotz, B.R., Cho, K.C., Dowding, R.J., Trexler, M.D., Densification and structural change of mechanically alloyed W–Cu composites, Metall. Mater. Trans. A, 32A, 2885–2893, 2001. doi:10.1007/s11661-001-1039-0.
18. [18] Yang, X., Liang, S., Wang, X., Xiao, P., Fan, Z., Effect of WC and CeO2 on microstructure and properties of W–Cu electrical contact material, Int. J. Refract. Met. Hard Mater., 28(2), 305–311, 2010. doi:10.1016/j.ijrmhm.2009.11.009.
19. [19] Chen, P., Luo, G., Li, M., Shen, Q., Zhang, L. Effects of Zn additions on the solid-state sintering of W–Cu composites, Mater. Des., 36, 108–112, 2012. doi:10.1016/j.matdes.2011.10.006.
20. [20] Chen, P., Luo, G., Shen, Q., Li, M., Zhang, L. Thermal and electrical properties of W–Cu composites produced by activated sintering, Mater. Des., 46, 101–105, 2013. doi:10.1016/j.matdes.2012.09.034.
21. [21] Johnson, J.L., German, R.M. Chemically activated liquid phase sintering of tungsten–copper, Int. J. Powder Metall., 30, 91–102, 1994.
22. [22] Johnson, J.L., German, R.M. Phase equilibria effects in enhanced liquid phase sintering of tungsten–copper, Metall. Mater. Trans. A, 24, 2369–2377, 1993. doi:10.1007/BF02646516.
23. [23] Zhou, Z.J., Kwon, Y.S. Fabrication of W–Cu composite by resistance sintering under ultra-high pressure, Journal of Materials Processing Technology, 168(1), 107–111, 2005. doi:10.1016/j.jmatprotec.2004.11.008.