not in their pure form for electrical contact applications.
Rhodium is not used as a solid contact material but is applied for example as aelectroplated layer in sliding contact systems. Ruthenium is mostly used as an alloyingcomponent in the material PdRu15. The metals osmium and iridium have no practicalapplications in electrical contacts. Since Pd was for the longest time rather stable in price it was looked at as a substitutefor the more expensive gold. This was followed by a steep increase in the Pd pricewhich caused a significant reduction in its use in electrical contacts. Today (2011) thePd price again is lower than that of gold. Alloys of Pt with Ru, Ir, Ni, and W were widely used in electromechanical componentsin the telecommunication industry and in heavy duty automotive breaker points ''(Table2.7)''. Today these components have been replaced in many applications by solidstate technology and the usage of these materials is greatly reduced. Pd alloyshowever have a more significant importance. PdCu15 is widely used for example inautomotive flasher relays. Because of their resistance to sulfide formation PdAg alloysare applied in various relay designs. The ability to thermally precipitation harden somemulti component alloys based on PdAgAuPt they find special usage in wear resistantsliding contact applications. Pd44Ag38Cu15PtAuZn is a standard alloy in this group. Platinum and palladium alloys are mainly used similar to the gold based materials inthe form of welded wire and profile segments but rarely as contact rivets. Because ofthe high precious metal prices joining technologies are used that allow the mosteconomic application of the contact alloy in the area where functionally needed.Because of their resistance to material transfer they are used for DC applications anddue to their higher arc erosion resistance they are applied for medium electrical loadsup to about 30W in relays and switches ''(Table 2.10)''. Multi-component alloys basedon Pd with higher hardness and wear resistance are mainly used as spring arms insliding contact systems and DC miniature motors. Table 2.6: Properties, Production Processes, and Application Forms for Platinum Metals Table 2.7: Physical Properties of the Platinum Metals and their Alloys Table 2.8: Mechanical Properties of the Platinum Metals and their Alloys Fig. 2.25:Influence of 1-20 atom% ofdifferent additivemetals on theelectricalresistivity p ofplatinum(Degussa) Fig. 2.26:Influence of 1-22 atom% of differentadditive metals on the electricalresistivityp of palladium Fig. 2.27:Phase diagram ofplatinum-iridium Fig. 2.28:Phase diagram ofplatinum-nickel Fig. 2.29:Phase diagramof platinum-tungsten Fig. 2.30:Phase diagram ofpalladium-copper Fig. 2.31:Strainhardeningof Pt by coldworking Fig. 2.32:Softening of Pt afterannealing for 0.5 hrsafter 80%cold working Fig. 2.33:Strain hardening of PtIr5by cold working Fig. 2.34:Softening of PtIr5 after annealing for 1 hrafter different degrees of cold working Fig. 2.35:Strain hardeningof PtNi8 by cold working Fig. 2.36:Softening of PtNi8 afterannealingfor 1 hr after80% cold working Fig. 2.37:Strain hardeningof PtW5 by cold working Fig. 2.38:Softeningof PtW5 afterannealing for 1hrafter 80% coldworking Fig. 2.39:Strain hardeningof Pd 99.99 by cold working Fig. 2.40:Strain hardeningof PdCu15 by cold working Fig. 2.41:Softeningof PdCu15 afterannealingfor 0.5 hrs Fig. 2.42Main Articel:Strain hardeningof PdCu40 by cold working Fig. 2.43:Softeningof PdCu40after annealingfor 0.5 hrs after 80%cold working Fig. 2.44:Electrical resistivity pof PdCu alloys with and without anannealing step for forming an orderedphase Table 2.9: Contact and Switching Propertiesof the [[Platinum Metals and their Alloys Table 2.10: Application Examples and Formof Supply for Metal Based Materials| Platinum Metals and their AlloysMetal Based Materials]]
==Silver Based Materials==
