Changes

Since silver and nickel are not soluble in each other in solid form and in the liquidphase have only very limited solubility silver nickel composite materials withhigher Ni contents can only be produced by powder metallurgy. During extrusionof sintered Ag/Ni billets into wires, strips and rods the Ni particles embedded inthe Ag matrix are stretched and oriented in the microstructure into a pronouncedfiber structure ''(Figs. 2.75. and 2.76)''

The high density produced during hot extrusion aids the arc erosion resistanceof these materials ''(Tables 2.21 and 2.22)''. The typical application of Ag/Nicontact materials is in devices for switching currents of up to 100A ''(Table 2.24)''.In this range they are significantly more erosion resistant than silver or silveralloys. In addition they exhibit with nickel contents <20 wt% a low and over theiroperational lifetime consistent contact resistance and good arc movingproperties. In DC applications Ag/Ni materials exhibit a relatively low tendencyof material transfer distributed evenly over the contact surfaces ''(Table 2.23)''.

Typically Ag/Ni (SINIDUR) materials are usually produced with contents of 10-40wt% Ni. The most widely used materials SINIDUR 10 and SINIDUR 20- and alsoSINIDUR 15, mostly used in north america-, are easily formable and applied bycladding ''(Figs. 2.71-2.74)''. They can be, without any additional welding aids,economically welded and brazed to the commonly used contact carriermaterials.The (SINIDUR) materials with nickel contents of 30 and 40 wt% are used inswitching devices requiring a higher arc erosion resistance and where increases

The most important applications for Ag/Ni contact materials are typically inrelays, wiring devices, appliance switches, thermostatic controls, auxiliary

'''Table 2.21: Physical Properties of Silver-Nickel (SINIDUR) Materials'''

'''Table 2.22: Mechanical Properties of Silver-Nickel (SINIDUR) Materials'''

Fig. 2.71:Strain hardeningof Ag/Ni 90/10 by cold working

Fig. 2.72:Softening of Ag/Ni 90/10after annealingfor 1 hr after 80% cold working

Fig. 2.73:Strain hardeningof Ag/Ni 80/20 by cold working

Fig. 2.74:Softening of Ag/Ni 80/20after annealingfor 1 hr after 80% cold working

Fig. 2.75: Micro structure of Ag/Ni 90/10 a) perpendicular to the extrusion directionb) parallel to the extrusion direction

Fig. 2.76: Micro structure of Ag/Ni 80/20 a) perpendicular to the extrusion directionb) parallel t o the extrusion direction

'''Table 2.23: Contact and Switching Properties of Silver-Nickel (SINIDUR) Materials'''

'''Table 2.24: Application Examples and Forms of Supplyfor Silver-Nickel (SINIDUR) Materials'''