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→Silver-Nickel (SINIDUR) Materials
Since silver and nickel are not soluble in each other in solid form and in the liquid phase have only very limited solubility silver nickel composite materials with higher Ni contents can only be produced by powder metallurgy. During extrusion of sintered Ag/Ni billets into wires, strips and rods the Ni particles embedded in the Ag matrix are stretched and oriented in the microstructure into a pronounced fiber structure <xr id="fig:Micro structure of AgNi9010"/> (Fig. 2.75) and <xr id="fig:Micro structure of AgNi 8020"/> (Fig. 2.76)
The high density produced during hot extrusion aids the arc erosion resistance of these materials <xr id="tab:Physical Properties of Silver-Nickel (SINIDUR) Materials"/> (Tab 2.21). The typical application of Ag/Ni contact materials is in devices for switching currents of up to 100A <xr id="tab:Application Examples and Forms of Supply for Silver-Nickel (SINIDUR) Materials"/> (Table 2.24). In this range they are significantly more erosion resistant than silver or silver alloys. In addition they exhibit with nickel contents <20 wt% a low and over their operational lifetime consistent contact resistance and good arc moving properties. In DC applications Ag/Ni materials exhibit a relatively low tendency of material transfer distributed evenly over the contact surfaces <xr id="tab:Contact and Switching Properties of Silver-Nickel (SINIDUR) Materials"/> (Table 2.23).
Typically Ag/Ni (SINIDUR) materials are usually produced with contents of 10-40 wt% Ni. The most widely used materials SINIDUR 10 and SINIDUR 20- and also SINIDUR 15, mostly used in north america-, are easily formable and applied by cladding <xr id="fig:Strain hardening of AgNi9010 by cold working"/> (Fig. 2.71) <xr id="fig:Softening of AgNi9010 after annealing"/> (Fig. 2.72) <xr id="fig:Strain hardening of AgNi8020"/> (Fig. 2.73) <xr id="fig:Softening of AgNi8020 after annealing"/> (Fig. 2.74). They can be, without any additional welding aids, economically welded and brazed to the commonly used contact carrier materials.
