Main Articel: [[Tungsten and Molybdenum Based Materials| Tungsten and Molybdenum Based Materials]]
=== Silver–Tungsten Carbide (SIWODUR C) Materials===
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
''(Fig. 2.135) (Table 2.36)''. Compared to Ag/W the Ag/WC (SIWODUR C)
materials exhibit a higher resistance against contact welding ''(Table 2.37)''. The
rise in contact resistance experienced with Ag/W is less pronounced in Ag/WC
because during arcing a protective gas layer of CO is formed which limits the
reaction of oxygen on the contact surface and therefore the formation of metal
oxides.
Higher requirements on low temperature rise can be fulfilled by adding a small
amount of graphite which however increases the arc erosion. Silver–tungsten
carbide–graphite materials with for example 27 wt% WC and
3 wt% graphite or 16 wt% WC and 2 wt% graphite are manufactured using the
single tip press-sinter-repress (PSR) process ''(Fig. 2.136)''.
The applications of Ag/WC contacts are similar to those for Ag/W ''(Table 2.38)''.
=== Silver–Molybdenum (SILMODUR) Materials===
