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==Silver Based Materials==
Pure silver (also called fine silver) exhibits the highest electrical and thermal
conductivity of all metals. It is also resistant against oxidation. Major disadvantages
degrees of strain hardening
To improve the physical and contact properties of fine silver melt-metallurgical
produced silver alloys are used ''(Table 2.13)''. By adding metal components the
resistance can be negatively impacted by alloying ''(Figs. 2.47 and 2.48)''.
Fine-Grain Silver (ARGODUR-Spezial) is defined as a silver alloy with an addition
of 0.15 wt% of Nickel. Silver and nickel are not soluble in each other in solid
properties fine grain silver has replaced pure silver in many applications.
Using copper as an alloying component increases the mechanical stability of
silver significantly. The most important among the binary AgCu alloys is that of
Table 2.16: Application Examples and Forms of Supply for Silver and Silver Alloys
The addition of 30 wt% Pd increases the mechanical properties as well as the
resistance of silver against the influence of sulfur and sulfur containing
Table 2.20: Application Examples and Forms of Suppl for Silver-Palladium Alloys
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
for Silver-Nickel (SINIDUR) Materials
The family of silver-metal oxide contact materials includes the material groups:
silver-cadmium oxide (DODURIT CdO), silver-tin oxide (SISTADOX), and silverzinc
Table 2.31: Application Examples of Silver–Metal Oxide Materials
Ag/C (GRAPHOR) contact materials are usually produced by powder metallurgy
with graphite contents of 2 – 5 wt% ''(Table 2.32)''. The earlier typical
(Bild)
Tungsten is characterized by its advantageous properties of high melting and
boiling points, sufficient electrical and thermal conductivity and high hardness
Table 2.35: Mechanical Properties of Tungsten and Molybdenum
Ag/W (SIWODUR) contact materials combine the high electrical and thermal
conductivity of silver with the high arc erosion resistance of the high melting
distribution.
This group of contact materials contains the typically 40-65 wt-% of the very
hard and erosion wear resistant tungsten carbide and the high conductivity silver
The applications of Ag/WC contacts are similar to those for Ag/W ''(Table 2.38)''.
Ag/Mo materials with typically 50-70 wt% molybdenum are usually produced by
the powder metallurgical infiltration process ''(Fig. 2.137) (Table 2.36)''. Their
Copper (CUWODUR) Contact Materials
The trade name VAKURIT is assigned to a family of low gas content contact
materials developed for the use in vacuum switching devices ''(Table 2.42)''.
Contact materials of W/Cu, W/Ag, WC/Ag, or Mo/Cu can be used in vacuum
switches if their total gas content does not exceed approximately 150 ppm. In
their contact carriers ''(Table 2.44)''.
As contact materials in vacuum interupters in medium voltage devices low gas
materials based on Cu/Cr have gained broad acceptance. The typical chromium
