Ultrahigh Oxidation Resistance and High Electrical Conductivity in Copper-Silver Powder

Abstract

The electrical conductivity of pure Cu powder is typically deteriorated at elevated temperatures due to the oxidation by forming non-conducting oxides on surface, while enhancing oxidation resistance via alloying is often accompanied by a drastic decline of electrical conductivity. Obtaining Cu powder with both a high electrical conductivity and a high oxidation resistance represents one of the key challenges in developing next-generation electrical transferring powder. Here, we fabricate a Cu-Ag powder with a continuous Ag network along grain boundaries of Cu particles and demonstrate that this new structure can inhibit the preferential oxidation in grain boundaries at elevated temperatures. As a result, the Cu-Ag powder displays considerably high electrical conductivity and high oxidation resistance up to approximately 300 °C, which are markedly higher than that of pure Cu powder. This study paves a new pathway for developing novel Cu powders with much enhanced electrical conductivity and oxidation resistance in service.

Enhanced Property of W–Cu Composites by Minor Addition of Ag

“…39) The WCu composites fabricated by activated sintering process have low electron and conductivity due to that the activated elements go into solution with Cu and decrease electrical conductivity significantly. 40,41) However, the Ag was separated out from the CuAg solid solution and formed a new phase with single Ag element when cooling process in this study, which is coincide with the reports of Li et al 37) The Ag distributed in boundaries and filled the pores in the W-rich area forming a continuous CuAg network along W-boundaries improved the interface and caused densification of the composites, which is the reason that the electrical conductivity of W 18Cu2Ag is higher than W20Ag composite.…”

“…8), Ag is able to dissolve completely into Cu matrix at high temperature while most of Ag will precipitate from Cu matrix during the subsequent cooling, according to CuAg Phase Diagram 36) and our previous research. 37) During liquid sintering process, Ag dissolved in liquid Cu, which is considered to enhance the wettability between liquid Cu and W. The higher capillary force caused by higher wettability and higher wetting speed of liquid CuAg phase to W than liquid Cu resulted in densification of the composites. During cooling process, Ag was preferentially precipitated from the Cu and uniformly distributed in the crystal boundaries and locations of voids with the temperature decreasing, which caused further densification of the composites.…”

Comparison of the effects of microwave and spark plasma sintering on the electrical, thermal, and mechanical properties of Cu-LaB6 nanocomposites

“…The second and third factors result in a reduction in electrical conductivity by causing pores to form in the microstructure. In addition to these factors, elements found in copper metal, such as C and O, may tend to enhance the scattering rate of conducting electrons, resulting in a reduction in the electrical conductivity of the copper (Li et al, 2016;Ayyapadas et al, 2017;Degroh and Balachandran, 2018). Although the amount of Fe, Cr, and Ni contaminants in this study was insufficient to alter the electrical conductivity, C and O may have had a modest effect on the reduction of electrical resistance.…”

Conductive Copper Paste for Crystalline Silicon Solar Cells

“…The invented technique involves copper-containing particles being encapsulated by additional layers of metal and alloys to restrict oxidation and diffusion of copper during the firing. For improving the oxidation resistance of copper, alloying copper with other metals (Ti, Mg, Al, Pd, Ag, Ni, Cr, and Zr) has been researched [37][38][39][40]. The Cu-Ag alloy is estimated as the best materials for improving oxidation resistance with only a slight reduction in electrical conductivity [41].…”