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→Silver-Nickel (SINIDUR) Materials
====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:fig2.75Micro structure of AgNi9010"/> (Fig. 2.75) and <xr id="fig:fig2.76Micro 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:tab2.24"/> (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:tab2.23"/> (Table 2.23).
<xr id="fig:Softening of AgNi8020 after annealing"/> Fig. 2.74: Softening of Ag/Ni 80/20 after annealing for 1 hr after 80% cold working
<xr id="fig:fig2.75Micro structure of AgNi9010"/> Fig. 2.75: Micro structure of Ag/Ni 90/10 a) perpendicular to the extrusion direction b) parallel to the extrusion direction
<xr id="fig:fig2.76Micro structure of AgNi 8020"/> Fig. 2.76: Micro structure of Ag/Ni 80/20 a) perpendicular to the extrusion direction b) parallel t o the extrusion direction
</figure>
<figure id="fig:fig2.75Micro structure of AgNi9010">
[[File:Micro structure of AgNi9010.jpg|right|thumb|<caption>Micro structure of Ag/Ni 90/10 a) perpendicular to the extrusion direction b) parallel to the extrusion direction</caption>]]
</figure>
<figure id="fig:fig2.76Micro structure of AgNi 8020">
[[File:Micro structure of AgNi 8020.jpg|right|thumb|<caption>Micro structure of Ag/Ni 80/20 a) perpendicular to the extrusion direction b) parallel to the extrusion direction</caption>]]
</figure>
