Changes

===2.1 Introduction===The contact parts are important components in switching devices. They have tomaintain their function from the new state until the end of the functional life of thedevices.

The requirements on contacts are rather broad. Besides typical contact propertiessuch as

they They have to exhibit physical, mechanical, and chemical properties like high electricaland thermal conductivity, high hardness, high corrosion resistance, etc . and besidesthis , should have good mechanical workability, and also be suitable for good weld andbrazing attachment to contact carriers. In addition they must be made fromenvironmentally friendly materials.

Materials suited for use as electrical contacts can be divided into the following groupsbased on their composition and metallurgical structure:

*'''Pure metals''' Within this group, silver has the greatest importance for switching devices in the higher energy technology. Other precious metals such as gold and platinum are only used in applications for the information technology in the form of thin surface layers. As a nonprecious metal, tungsten is used for some special applications such as, for example, automotive horn contacts. In some rarer cases, pure copper is used, but mainly paired to a silver-based contact material. '''Alloys''' Besides these few pure metals, a larger number of alloy materials made by melt technology are available for the use as contacts. An alloy is characterized by the fact, that its components are completely or partially soluble in each other in the solid state. Phase diagrams for multiple metal compositions show the number and type of the crystal structure as a function of the temperature and composition of the alloying components.

Besides these few pure metals a larger number They indicate the boundaries of liquid and solid phases and define the parameters of alloy materials made by meltsolidification.technology are available for Alloying allows to improve the use as contacts. An alloy is characterized by properties of one material at the factthat its components are completely or partially soluble in each other in cost of changing them for the solid statesecond material.Phase diagrams for multiple metal compositions show As an example, the number and type hardness of a base metal may be increased while at thecrystal structure as a function of same time the temperature and composition electrical conductivity decreases with even small additions of the second alloying componentscomponent.

*Composite Materialsmaterials are a material group whose properties are of great importance for electrical contacts that are used in switching devices for higherelectrical currents.

Composite materials are a material group whose properties are of greatimportance for electrical contacts that are used in switching devices for higherelectrical currents.Those used in electrical contacts are heterogeneous materials , composed of twoor more uniformly dispersed components , in which the largest volume portionconsists of a metal.The properties of composite materials are determined mainly independent fromeach other by the properties of their individual components. Therefore it is forexample possible to combine the high melting point and arc erosion resistanceof tungsten with the low melting and good electrical conductivity of copper, orthe high conductivity of silver with the weld resistant metalloid graphite.

Figure 2The properties of composite materials are determined mainly independent from each other by the properties of their individual components.1 Therefore it is, for example, possible to combine the high melting point and arc erosion resistance of tungsten with the low melting and good electrical conductivity of copper or the high conductivity of silver with the weld resistant metalloid graphite. <xr id="fig:Powder metallurgical manufacturing of composite materials (schematic)"/> shows the schematic manufacturing processes from powderblending to contact material. Three basic process variations are typicallyapplied:

During sintering without a liquid phase <figure id="fig:Powder metallurgical manufacturing of composite materials (left side of schematic) the powder mix is">first densified by pressing, then undergoes a heat treatment [[File:Powder metallurgical manufacturing of composite materials (sinteringschematic), andeventually is re-pressed again to further increase the density. The sinteringatmosphere depends on the material components and later application; avacuum is used for example for the low gas content material Cu/Cr. Thisprocess is used for individual contact parts and also termed pressjpg|thumb|<caption>Powder-sinterrepressmetallurgical manufacturing of composite materials (PSRschematic). For materials with high silver content T_s = Melting point of the starting point atpressing is most a larger block (or billetlower melting component) which is then after sintering hotextruded into wire, rod, or strip form. The extrusion further increases the density</caption>]]of these composite materials and contributes to higher arc erosion resistance.Materials such as Ag</Ni, Ag/MeO, and Ag/C are typically produced by thisprocess. Sintering with liquid phase has the advantage of shorter process times due tothe accelerated diffusion and also results in near-theoretical densities of thefigure>

FigDuring ''sintering without a liquid phase'' (left side of schematic), the powder mix is first densified by pressing, then undergoes a heat treatment (sintering) and eventually is re-pressed again to further increase the density. 2The sintering atmosphere depends on the material components and later application; a vacuum is used for example for the low gas content material Cu/Cr.1: PowderThis process is used for individual contact parts and also termed press-metallurgical manufacturing of composite sinter-repress (PSR). For materials with high silver content, the starting point before pressing is mostly a large block (schematicor billet)T = Melting point which is then, after sintering, hot extruded into wire, rod or strip form. The extrusion further increases the density of the lower melting componentthese composite materials and contributes to higher arc erosion resistance. Materials such as Ag/Ni, Ag/MeO and Ag/C are typically produced by this process.

''Sintering with liquid phase'' has the advantage of shorter process times due to the accelerated diffusion and also results in near-theoretical densities of the composite material. To ensure the shape stability during the sintering process , it

As opposed to the liquid phase sintering , which has limited use for electricalcontact manufacturing, the ''Infiltration process '' as shown on the right side of theschematic , has a broad practical range of applications. In this process thepowder of the higher melting component , sometimes also as a powder mix witha small amount of the second material , is pressed into parts and . Then, right after sintering, the porous skeleton is infiltrated with liquid metal of the second material. Thefilling fill-up process of the pores happens through capillary forces. This process reaches, after the infiltration , near-theoretical density without subsequent pressing and iswidely used for Ag- and Cu-refractory contacts. For Ag/W or Ag/WC contacts,controlling the amount or excess on the bottom side of the contact of theinfiltration metal Ag , results in contact tips that can be easily attached to theircarriers by resistance welding. For larger Cu/W contacts , additional machining isoften used to obtain the final shape of the contact component. ===2.2 Gold Based Materials=== Pure Gold is besides Platinum the chemically most stable of all precious metals.In its pure form it is not very suitable for use as a contact material in electromechanical devices because of its tendency to stick and cold-weld at even low contact forces. In addition it is not hard or strong enough to resistmechanical wear and exhibits high materials losses under electrical arcingloads. This limits its use in form of thin electroplated or vacuum deposited layers. For most electrical contact applications gold alloys are used. Depending on thealloying metal the melting is performed either under in a reducing atmosphere orin a vacuum. The choice of alloying metals depends on the intended use of theresulting contact material. The binary Au alloys with typically <10 wt% of otherprecious metals such as Pt, Pd, or Ag or non-precious metals like Ni, Co, andCu are the more commonly used ones (Table 2.2). On one hand these alloyadditions improve the mechanical strength and electrical switching propertiesbut on the other hand reduce the electrical conductivity and chemical corrosionresistance (Fig. 2.2) to varying degrees. Under the aspect of reducing the gold content ternary alloys with a gold contentof approximately 70 wt% and additions of Ag and Cu or Ag and Ni resp., forexample AuAg25Cu5 or AuAg20Cu10 are used which exhibit for manyapplications good mechanical stability while at the same time have sufficientresistance against the formation of corrosion layers (Table 2.3). Other ternaryalloys based on the AuAg system are AuAg26Ni3 and AuAg25Pt6. These alloysare mechanically similar to the AuAgCu alloys but have significantly higheroxidation resistance at elevated temperatures (Table 2.4). Caused by higher gold prices over the past years the development of alloys withfurther reduced gold content had a high priority. The starting point has been theAuPd system which has continuous solubility of the two components. Besidesthe binary alloy of AuPd40 and the ternary one AuPd35Ag9 other multiplecomponent alloys were developed. These alloys typically have < 50 wt% Au andoften can be solution hardened in order to obtain even higher hardness andtensile strength. They are mostly used in sliding contact applications. Gold alloys are used in the form of welded wire or profile (also called weldtapes),segments, contact rivets, and stampings produced from clad stripmaterials. The selection of the bonding process is based on the cost for thejoining process, and most importantly on the economical aspect of using theleast possible amount of the expensive precious metal component. Besides being used as switching contacts in relays and pushbuttons, goldalloys are also applied in the design of connectors as well as sliding contacts forpotentiometers, sensors, slip rings, and brushes in miniature DC motors(Table 2.5). Table 2.3: Mechanical Properties of Gold and Gold-Alloys Table 2.1: Commonly Used Grades of Gold Table 2.2: Physical Properties of Gold and Gold-Alloys Fig. 2.2:Influence of 1-10 atomic% of differentalloying metals on the electrical resistivity of gold(according to J. O. Linde) Fig. 2.3:Phase diagramof goldplatinum Fig. 2.4:Phase diagramof gold-silver Fig. 2.5:Phase diagramof gold-copper Fig. 2.6: Phase diagram of gold-nickel Fig. 2.7: Phase diagram of gold-cobalt Fig. 2.8:Strain hardeningof Au by cold working Fig. 2.9:Softening of Au after annealingfor 0.5 hrs after 80%cold working Fig. 2.10:Strain hardening ofAuPt10 by cold working Fig. 2.11:Strain hardeningof AuAg20 by cold working Fig. 2.12:Strain hardening ofAuAg30 by cold working Fig. 2.13:Strain hardening of AuNi5by cold working Fig. 2.14:Softeningof AuNi5 after annealingfor 0.5 hrs after 80%cold working Fig. 2.15:Strain hardeningof AuCo5 by cold working Fig. 2.16:Precipitation hardening ofAuCo5 at 400°C hardeningtemperature Fig. 2.17:Strain hardeningof AuAg25Pt6 by cold working Fig. 2.18:Strain hardeningof AuAg26Ni3 by cold working Fig. 2.19:Softeningof AuAg26Ni3 afterannealing for 0.5 hrsafter 80% coldworking Fig. 2.20:Strain hardening ofAuAg25Cu5by cold working Fig. 2.21:Strain hardening ofAuAg20Cu10by cold working Fig. 2.22:Softeningof AuAg20Cu10 afterannealing for 0.5 hrsafter 80% cold working Fig. 2.23:Strain hardening ofAuCu14Pt9Ag4by cold working Fig. 2.24:Precipitationhardening ofAuCu14Pt9Ag4at differenthardeningtemperaturesafter 50%cold working Table 2.4: Contact and Switching Properties of Gold and Gold Alloys Table 2.5: Application Examples and Forms of Gold and Gold Alloys ===2.3 Platinum Metal Based Materials=== The platinum group metals include the elements Pt, Pd, Rh, Ru, Ir, and Os (Table2.6). For electrical contacts platinum and palladium have practical significanceas base alloy materials and ruthenium and iridium are used as alloying components.Pt and Pd have similar corrosion resistance as gold but because of theircatalytical properties they tend to polymerize adsorbed organic vapors on contactsurfaces. During frictional movement between contact surfaces the polymerizedcompounds known as “brown powder” are formed which can lead to significantlyincrease in contact resistance. Therefore Pt and Pd are typically used as alloys andnot 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. 2.42: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 Platinum Metals and their Alloys ===2.4 Silver Based Materials===

==Gold Based Materials=2.4.1 Pure Silver===Pure silver (also called fine silver) exhibits the highest electrical and thermalconductivity of all metals. It is also resistant against oxidation. Major disadvantagesare its low mechanical wear resistance, the low softening temperature,and especially its strong affinity to sulfur and sulfur compounds. In the presenceof sulfur and sulfur containing compounds brownish to black silver sulfide layerare formed on its surface. These can cause increased contact resistance oreven total failure of a switching device if they are not mechanically, electrically,or thermally destroyed. Other weaknesses of silver contacts are the tendency toweld under the influence of over-currents and the low resistance againstmaterial transfer when switching DC loads. In humid environments and underthe influence of an electrical field silver can creep (silver migration) and causeelectrical shorting between adjacent current paths.

Table 2.11 shows Pure Gold is besides Platinum the typically available quality grades chemically most stable of silverall precious metals. In certaineconomic areas, i.e. Chinaits pure form, there are additional grades with varying amounts ofimpurities available on the market. In powder form silver it is used not very suitable for use as a widevariety of silver based composite contact materials. Different manufacturingprocesses result material in different grades electromechanical devices because of Ag powder as shown in Table 2.12.additional properties of silver powders its tendency to stick and their usage are describedin chapter 8cold-weld at even low contact forces.1.Semi-finished silver materials can easily be warm In addition, it is not hard or cold formed and can beclad strong enough to the usual base materials. For attachment of silver to contact carriermaterials welding of wire or profile cut-offs resist mechanical wear and brazing are most widely appliedexhibits high material losses under electrical arcing loads.Besides these mechanical processes such as wire insertion (wire staking) andthe riveting (staking) This limits its use in form of solid thin electroplated or composite contact rivets are used in themanufacture of contact componentsvacuum deposited layers.

The platinum group metals include the elements Pt, Pd, Rh, Ru, Ir and Os ([[Platinum_Metal_Based_Materials|Table 1]]<!--(Table 2.12: Quality Criteria of Differently Manufactured Silver Powders6)-->). For electrical contacts, platinum and palladium have practical significance as base alloy materials and ruthenium and iridium are used as alloying components. Pt and Pd have similar corrosion resistance as gold but due to their catalytical properties, they tend to polymerize adsorbed organic vapors on contact surfaces. During frictional movement between contact surfaces, the polymerized compounds known as “brown powder” are formed, which can lead to a significant increase in contact resistance. Therefore Pt and Pd are typically used as alloys and are rather not used in their pure form for electrical contact applications.

Fig. 2.45Main Article:Strain hardeningof Ag 99.95 by cold working[[Platinum Metal Based Materials| Platinum Metal Based Materials]]

===2.4.2 Main Article: [[Silver Alloys===To improve the physical and contact properties of fine silver melt-metallurgicalproduced silver alloys are used (Table 2.13). By adding metal components themechanical properties such as hardness and tensile strength as well as typicalcontact properties such as erosion resistance, and resistance against materialtransfer in DC circuits are increased (Table 2.14). On the other hand however,other properties such as electrical conductivity and chemical corrosionresistance can be negatively impacted by alloying (Figs. 2.47 and 2.48).Based Materials| Silver Based Materials]]

===2.4.2.1 Fine-Grain Silver=Tungsten and Molybdenum Based Materials==Fine-Grain Silver (ARGODUR-Spezial) is defined as a silver alloy with an additionof 0.15 wt% of Nickel. Silver and nickel are not soluble in each other in solidform. In liquid silver only a small amount of nickel is soluble as the phase diagram(Fig. 2.51) illustrates. During solidification of the melt this nickel addition getsfinely dispersed in the silver matrix and eliminates the pronounce coarse graingrowth after prolonged influence of elevated temperatures (Figs. 2.49 and 2.50.

Fine-grain silver has almost the same chemical corrosion resistance as finesilver. Compared to pure silver it exhibits a slightly increased hardness Main Article: [[Tungsten andtensile strength (Table 2.14). The electrical conductivity is just slightly decreasedby this low nickel addition. Because of its significantly improved contactproperties fine grain silver has replaced pure silver in many applications.Molybdenum Based Materials| Tungsten and Molybdenum Based Materials]]

==Contact Materials for Vacuum Switches=2.4.2.2 Hard-Silver Alloys===Using copper as an alloying component increases the mechanical stability ofsilver significantly. The most important among the binary AgCu alloys is that ofAgCu3, known in europe also under the name of hard-silver. This material stillhas a chemical corrosion resistance close to that of fine silver. In comparison topure silver and fine-grain silver AgCu3 exhibits increased mechanical strengthas well as higher arc erosion resistance and mechanical wear resistance(Table 2.14).

Increasing the Cu The low gas content further also increases the mechanical strength ofAgCu alloys and improves arc erosion resistance and resistance againstmaterial transfer while at the same time however the tendency to oxide formationbecomes detrimental. This causes during switching under arcing conditions anincrease in contact resistance with rising numbers of operation. In specialapplications where highest mechanical strength is recommended and a reducedchemical resistance can be tolerated, materials are developed for the eutectic AgCu alloy with 28 wt% ofcopper (Fig. 2.52) is used. AgCu10 also known as coin silver has beenreplaced use in many applications by composite silver-based materials while sterlingsilver (AgCu7.5) has never extended its important usage from decorative tablewear and jewelry to industrial applications in electrical contactsvacuum switching devices.

Besides these binary alloys, ternary AgCuNi alloys are used in electrical contactapplications. From this group the material ARGODUR 27, an alloy of 98 wt% Agwith a 2 wt% Cu and nickel addition has found practical importance close to thatof AgCu3. This material is characterized by high resistance to oxidation and lowtendency to re-crystallization during exposure to high temperatures. Besideshigh mechanical stability this AgCuNi alloy also exhibits a strong resistanceagainst arc erosion. Because of its high resistance against material transfer thealloy AgCu24.5Ni0.5 has been used in the automotive industry Main Article: [[Contact Materials for an extendedtime in the North American market. Caused by miniaturization and the relatedreduction in available contact forces in relays and switches this material hasbeen replaced widely because of its tendency to oxide formation.Vacuum Switches| Contact Materials for Vacuum Switches]]

Hard-silver alloys are widely used for switching applications in the informationand energy technology for currents up to 10 AVinaricky, in special cases also for highercurrent ranges E.(Table 2Hrsg.16): Elektrische Kontakte, Werkstoffe und Anwendungen.Springer-Verlag, Berlin, Heidelberg etc.2002

Dispersion hardened alloys of silver with 0Lindmayer, M.5 wt% MgO and NiO (ARGODUR 32)are produced by internal oxidation: Schaltgeräte-Grundlagen, Aufbau, Wirkungsweise. While the melt-metallurgical alloy is easy tocold-work and form the material becomes very hard and brittle after dispersionhardening. Compared to fine silver and hardSpringer-silver this material has a greatlyimproved temperature stability and can be exposed to brazing temperatures upto 800°C without decreasing its hardness and tensile strength.Because of these mechanical properties and its high electrical conductivityVerlag, Berlin, Heidelberg, New York, Tokio, 1987

Table 2Rau, G.13: Physical Properties of Silver and Silver AlloysMetallische Verbundwerkstoffe. WerkstofftechnischeVerlagsgesellschaft, Karlsruhe 1977

ARGODUR 32 is mainly used in the form of contact springs that are exposed toSchreiner, H.: Pulvermetallurgie elektrischer Kontakte. Springer-Verlaghigh thermal and mechanical stresses in relaysBerlin, and contactors for aeronauticapplications.Göttingen, Heidelberg, 1964

FigHansen. 2M.; Anderko, K.47: Constitution of Binary Alloys. New York:Influence of 1Mc Graw-10 atom% of differentalloying metals on the electrical resistivity ofsilverHill, 1958

FigShunk, F. 2A.48:Electrical resistivity pConstitution of AgCu alloys with 0Binary Alloy. 2 Suppl. New York; Mc Graw-20 weight% Cuin the soft annealedand tempered stagea) Annealed and quenchedb) Tempered at 280°CHill, 1969

FigEdelmetall-Taschenbuch. 2( Herausgeber Degussa AG, Frankfurt a.49: Coarse grain micro structureof Ag 99M.97 after 80% cold working),and 1 hr annealing at 600°CHeidelberg, Hüthig-Verlag, 1995

FigRau, G. 2: Elektrische Kontakte-Werkstoffe und Technologie. Eigenverlag G.50: Fine grain microstructureRauof AgNi0GmbH & Co.15 after 80% cold workingand 1 hr annealing at 600°C, Pforzheim, 1984

FigHeraeus, W. 2C.51:Phase diagramof silver-nickelWerkstoffdaten. Eigenverlag W.C. Heraeus, Hanau, 1978

FigLinde, J. 2O.52:Elektrische Widerstandseigenschaften der verdünnten LegierungenPhase diagramof silver-copperdes Kupfers, Silbers und Goldes. Lund: Hakan Ohlsson, 1938

Table 2Großmann, H. Saeger, K. E.; Vinaricky, E.14: Mechanical Properties of Silver Gold and Silver Gold Alloysin ElectricalEngineering. in: Gold, Progress in Chemistry, Biochemistry and Technology. JohnWiley & Sons, Chichester etc, (1999) 199-236

FigGehlert, B. 2: Edelmetall-Legierungen für elektrische Kontakte.54:Strain hardeningof AgCu3by cold workingMetall 61 (2007) H. 6, 374-379

FigAldinger, F. 2; Schnabl, R.55:Edelmetallarme Kontakte für kleine Ströme.Softening of AgCu3after annealing for 1 hrafter 80% cold workingMetall 37 (1983) 23-29

FigBischoff, A. 2; Aldinger, F.56:Einfluss geringer Zusätze auf die mechanischenStrain hardening of AgCu5 by coldworkingEigenschaften von Au-Ag-Pd-Legierungen. Metall 36 (1982) 752-765

FigWise, E. 2M.57: Palladium, Recovery, Properties and Uses. New York, London:Softening of AgCu5 afterannealing for 1 hr after 80% coldworkingAcademic Press 1968

FigSavitskii, E. 2M.; Polyakova, V.P.; Tylina, M.A.58:Palladium Alloys, Primary Sources.Strain hardening of AgCu 10by cold workingNew York: Publishers 1969

FigGehlert, B. 2.59:Lebensdaueruntersuchungen von Edelmetall Kontaktwerkstoff-Softening of AgCu10 afterannealing for 1 hr after 80% coldworkingKombinationen für Schleifringübertrager. VDE-Fachbericht 61, (2005) 95-100

FigHolzapfel,C. 2.60:Verschweiß und elektrische Eigenschaften vonStrain hardening of AgCu28 bycold workingSchleifringübertragern. VDE-Fachbericht 67 (2011) 111-120

FigSchnabl, R. 2; Gehlert, B.61:Lebensdauerprüfungen von Edelmetall-Softening of AgCu28after annealing for 1 hr afterSchleifkontaktwerkstoffen für Gleichstrom Kleinmotoren.80% cold workingFeinwerktechnik & Messtechnik (1984) 8, 389-393

FigKobayashi, T. 2; Koibuchi, K.; Sawa, K.; Endo, K.; Hagino, H.62:A Study of LifetimeStrain hardening of AgNi0Au-plated Slip-Ring and AgPd Brush System for Power Supply.15by cold workingth Proc. 24 Int. Conf. on Electr. Contacts, Saint Malo, France 2008, 537-542

FigHarmsen, U. 2; Saeger K.E.63:Über das Entfestigungsverhalten von SilberSoftening of AgNi0verschiedener Reinheiten.15after annealing for 1 hr after 80%cold workingMetall 28 (1974) 683-686

FigBehrens, V. 2; Michal, R.; Minkenberg, J.N.; Saeger, K.E.64:Abbrand undStrain hardening ofKontaktwiderstandsverhalten von Kontaktwerkstoffen auf Basis von Silber-ARGODUR 27by cold workingNickel. e.& i. 107. Jg. (1990), 2, 72-77

FigBehrens, V. 2.65:Silber/Nickel und Silber/Grafit- zwei Spezialisten auf dem GebietSofteningof ARGODUR 27 after annealingfor 1 hr after 80% cold workingder Kontaktwerkstoffe. Metall 61 (2007) H.6, 380-384

Table 2Rieder, W.15: Contact and Switching Properties of Silver and Silver AlloysSilber / Metalloxyd-Werkstoffe für elektrische Kontakte,VDE - Fachbericht 42 (1991) 65-81

Table 2Harmsen,U.16: Application Examples and Forms of Supply for Silver and Silver AlloysDie innere Oxidation von AgCd-Legierungen unterSauerstoffdruck.Metall 25 (1991), H.2, 133-137

===2Muravjeva, E.4M.2; Povoloskaja, M.3 SilverD.: Verbundwerkstoffe Silber-Palladium Alloys===Zinkoxid undThe addition of 30 wt% Pd increases the mechanical properties as well as theSilber-Zinnoxid, hergestellt durch Oxidationsglühen.resistance of silver against the influence of sulfur and sulfur containingcompounds significantly Elektrotechnika 3 (Tables 2.17 and 2.181965).Alloys with 4037-60 wt% Pd have an even higher resistance against silver sulfideformation. At these percentage ranges however the catalytic properties ofpalladium can influence the contact resistance behavior negatively. Theformability also decreases with increasing Pd contents.39

AgPd alloys are hardBehrens, arc erosion resistantV.; Honig Th.; Kraus, A.; Michal, R.; Saeger, and have a lower tendency towardsmaterial transfer under DC loads (Table 2K.-E.19); Schmidberger, R. On the other hand the electrical;conductivity is decreased at higher Pd contentsStaneff, Th.: Eine neue Generation von AgSnO₂ -Kontaktwerkstoffen. The ternary alloy AgPd30Cu5has an even higher hardness which makes it suitable for use in sliding contactsystems.VDE-Fachbericht 44, (1993) 99-114

AgPd alloys are mostly used in relays for the switching of medium to higher loads(>60VBraumann, >2A) as shown in Table 2P.20; Lang, J. Because of the high palladium price theseformerly solid contacts have been widely replaced by multi: Kontaktverhalten von Ag-layer designs suchMetalloxiden für den Bereichas AgNi0.15 or AgNi10 with a thin Au surface layer. A broader field of applicationfor AgPd alloys remains in the wear resistant sliding contact systemshoher Ströme.VDE-Fachbericht 42, (1991) 89-94

FigHauner, F. ; Jeannot, D.; Mc Neilly, U.; Pinard, J.: Advanced AgSnO Contact 2th Materials for High Current Contactors. Proc. 20 Int.66: Phase diagram of silverConf. on Electr. ContactPhenom., Stockholm 2000, 193-palladium198

FigWintz, J. 2-L.; Hardy, S.; Bourda, C.67:Influence on the Electrical Performances ofStrain hardeningAssembly Process, Supports Materials and Production Means for AgSnO₂ .of AgPd30 by cold workingProc.24_th Int. Conf. on Electr. Contacts, Saint Malo, France 2008, 75-81

FigBehrens, V. 2; Honig, Th.; Kraus, A.; Michal, R.68:Schalteigenschaften vonStrain hardeningverschiedenen Silber-Zinnoxidwerkstoffen in Kfz-Relais. VDE-Fachbericht 51of AgPd50 by cold working(1997) 51-57

FigSchöpf, Th. 2.69:Silber/Zinnoxid und andere Silber-Metalloxidwerkstoffe inStrain hardeningof AgPd30Cu5by cold workingNetzrelais. VDE-Fachbericht 51 (1997) 41-50

FigSchöpf, Th. 2; Behrens, V.; Honig, Th.; Kraus, A.70:Development of Silver ZincSoftening of AgPd30th Oxide for General-Purpose Relays. Proc. 20 Int. Conf. on Electr. Contacts, AgPd50Stockholm 2000,and AgPd30Cu5 after annealing of 1 hrafter 80% cold working187-192

Table 2Braumann, P.; Koffler, A.17: Physical Properties of SilverEinfluss von Herstellverfahren, Metalloxidgehalt undWirkzusätzen auf das Schaltverhalten von Ag/SnO in Relais. 2VDE-Fachbericht 59, (2003) 133-Palladium Alloys142

Table 2Kempf, B.; Braumann, P.; Böhm, C.; Fischer-Bühner, J.18: Mechanical Properties of SilverSilber-Zinnoxid-Werkstoffe: Herstellverfahren und Eigenschaften. Metall 61(2007) H. 6, 404-Palladium Alloys408

Table 2Lutz, O.; Behrens, V.; Finkbeiner, M.; Honig, T.; Späth, D.19: Contact and Switching Properties of SilverAg/CdO-Ersatz inLichtschaltern. VDE-Fachbericht 61, (2005) 165-Palladium Alloys173

Table 2Lutz, O.; Behrens, V.; Wasserbäch, W.; Franz, S.; Honig, Th.; Späth,D.; Heinrich, J.20: Application Examples and Forms of Suppl Improved Silver/Tin Oxide Contact Materials for SilverAutomotiveth Applications. Proc.24 Int. Conf. on Electr. Contacts, Saint Malo, France 2008,88-Palladium Alloys93

===Leung, C.; Behrens, V.: A Review of Ag/SnO Contact Materials and Arc Erosion. 2th Proc.424 Int.3 Silver Composite Materials===Conf. on Electr. Contacts, Saint Malo, France 2008, 82-87

===2Chen, Z.K.4; Witter, G.3J.1 Silver-Nickel (SINIDUR) Materials===Since silver and nickel are not soluble : Comparison in each other in solid form and in the liquidPerformance for Silver–Tin–Indiumphase have only very limited solubility silver nickel composite materials withhigher Ni contents can only be produced Oxide Materials Made by powder metallurgyInternal Oxidation and Powder Metallurgy. During extrusionof sintered Ag/Ni billets into wiresth Proc. 55 IEEE Holm Conf. on Electrical Contacts, Vancouver, BC, Canada, 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 2.762009)167 – 176

The high density produced during hot extrusion aids the arc erosion resistanceof these materials (Tables 2Roehberg, J.; Honig, Th.; Witulski, N.21 and 2; Finkbeiner, M.22); Behrens, V. The typical application : Performanceof AgDifferent Silver/NiTin Oxide Contact Materials for Applications in Low Voltagecontact materials is in devices for switching currents of up to 100A (Table 2th Circuit Breakers.24)Proc.In this range they are significantly more erosion resistant than silver or silveralloys55 IEEE Holm Conf. In addition they exhibit with nickel contents <20 wt% a low and over theiron Electrical Contacts, Vancouver,operational 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 BC, Canada, (Table 2.232009).187 – 194

Typically Ag/Ni (SINIDUR) materials are usually produced with contents of 10-40wt% NiMuetzel, T. The most widely used materials SINIDUR 10 and SINIDUR 20- and alsoSINIDUR 15; Braumann, mostly used in north america-P.; Niederreuther, are easily formable and applied byR.: Temperature Rise Behavior ofcladding (Figsth Ag/SnO Contact Materials for Contactor Applications. 2Proc.71-55 IEEE Holm 2Conf.74). They can beon Electrical Contacts, Vancouver, BC, without any additional welding aidsCanada,economically welded and brazed to the commonly used contact carriermaterials.The (SINIDUR2009) materials with nickel contents of 30 and 40 wt% are used inswitching devices requiring a higher arc erosion resistance and where increasesin contact resistance can be compensated through higher contact forces.200 – 205

The most important applications for AgLutz, O. et al.: Silber/Ni contact materials are typically inZinnoxid – Kontaktwerkstoffe auf Basis der Innerenrelays, wiring devices, appliance switches, thermostatic controls, auxiliaryOxidation fuer AC – und DC – Anwendungen.switches, and small contactors with nominal currents >20A VDE Fachbericht 65 (Table 2.242009).167 – 176

Table 2Harmsen, U.; Meyer, C.L.21: Physical Properties of SilverMechanische Eigenschaften stranggepresster Silber-Nickel Graphit-Verbundwerkstoffe. Metall 21 (SINIDUR1967) Materials, 731-733

Table 2Behrens, V.22: Mechanical Properties of Mahle, E.; Michal, R.; Saeger, K.E.: An Advanced Silver/Graphiteth Contact Material Based on Graphite Fibre. Proc. 16 Int. Conf. on Electr.Contacts, Loghborough 1992, 185-Nickel (SINIDUR) Materials189

FigSchröder, K. 2-H.; Schulz, E.-D.71:Über den Einfluss des HerstellungsverfahrensStrain hardeningth auf das Schaltverhalten von Kontaktwerkstoffen der Energietechnik. Proc. 7 Int.of Ag/Ni 90/10 by cold workingConf. on Electr. Contacts, Paris 1974, 38-45

FigMützel, T. 2: Niederreuther, R.72:Kontaktwerkstoffe für Hochleistungsanwendungen.Softening of Ag/Ni 90/10after annealingfor 1 hr after 80% cold workingVDE-Bericht 67 (2011) 103-110

FigLambert, C. 2; Cambon, G.73:The Influence of Manufacturing Conditions andStrain hardeningMetalurgical Characteristics on the Electrical Behaviour of Silver-Graphiteof Ag/Ni 80/20 by cold workingth Contact Materials. Proc. 9 Int. Conf.on Electr. Contacts,Chicago 1978, 401-406

FigVinaricky, E. 2.74:Grundsätzliche Untersuchungen zum Abbrand- undSoftening of Schweißverhalten von Ag/Ni 80/20after annealingC-Kontaktwerkstoffen. VDE-Fachbericht 47 (1995)for 1 hr after 80% cold working159-169

FigAgte, C. 2; Vacek, J.75: Micro structure of Ag/Ni 90/10 a) perpendicular to the extrusion directionb) parallel to the extrusion directionWolfram und Molybdän. Berlin: Akademie-Verlag 1959

FigKeil, A. 2; Meyer, C.-L.76: Micro structure of Ag/Ni 80/20 a) perpendicular to the extrusion directionDer Einfluß des Faserverlaufes auf die elektrischebVerschleißfestigkeit von Wolfram-Kontakten. ETZ 72, (1951) parallel t o the extrusion direction343-346

Table 2Slade, P. G.23: Electric Contacts for Power Interruption. A Review. Proc. 19 Int.Conf. on Electric Contact and Switching Properties of Silver-Nickel Phenom. Nuremberg (SINIDURGermany) Materials1998, 239-245

Table 2Slade, P. G.24: Application Examples Variations in Contact Resistance Resulting from Oxide Formationand Decomposition in AgW and Forms of SupplyAg-WC-C Contacts Passing Steady Currentsfor SilverLong Time Periods. IEEE Trans. Components, Hybrids and Manuf. Technol.CHMT-Nickel 9,1 (SINIDUR1986) Materials3-16

===2Slade, P.4G.3.2: Silver-Metal Oxide Materials Ag/CdO, Ag/SnO , Ag/ZnO===The family Effect of silver-metal oxide contact materials includes the material groups:silver-cadmium oxide (DODURIT CdO), silver-tin oxide (SISTADOX), Electric Arc and silverzincthe Ambient Air on the Contactoxide (DODURIT ZnO). Because Resistance of their very good contact and switchingproperties like high resistance against welding, low contact resistanceSilver, Tungsten and higharc erosion resistance, silverSilver-metal oxides have gained an outstanding positionTungsten Contacts.in a broad field of applicationsJ.Appl.Phys. They mainly are used in low voltage electricalswitching devices like relays, installation and distribution switches, appliances47,industrial controls, motor controls, and protective devices 8 (Table 2.131976).3438-3443

*===SilverLindmayer, M.; Roth, M.: Contact Resistance and Arc-cadmium oxide Erosion of W-Ag andWC-Ag. IEEE Trans components, Hybrids and Manuf. Technol.CHMT-2, 1 (DODURIT CdO1979) materials===70-75

SilverLeung, C.-cadmium oxide (DODURIT CdO) materials with 10H.; Kim, H.J.: A Comparison of Ag/W, Ag/WC and Ag/Mo ElectricalContacts. IEEE Trans. Components, Hybrids, Manuf. Technol.,Vol. CHMT-15 wt% are producedby both7, internal oxidation and powder metallurgical methods 1 (Table 2.251984).69-75

Allen, S.E.; Streicher, E.: The manufacturing Effect of strips and wires by internal oxidation starts with a moltenalloy of silver and cadmium. During a heat treatment below it's melting point in aoxygen rich atmosphere in such a homogeneous alloy Microstructure on the oxygen diffuses fromElectricalthe surface into the bulk th Performance of the material and oxidizes the Cd to CdO in a more orless fine particle precipitation inside the Ag matrix-WC-C Contact Materials. Proc. 44 IEEE Holm Conf. on Electr. The CdO particles are ratherfine in the surface area and are becoming larger further away towards the centerof the material Contacts, Arlington, VA, USA (Fig. 2.831998)., 276-285

During the manufacturing of Ag/CdO contact material by internal oxidation theprocesses vary depending on the type of semi-finished materialHaufe, W.For Ag/CdO wires a complete oxidation of the AgCd wire is performed; Reichel, followedby wire-drawing to the required diameter (FigsW. 2; Schreiner H.77 and 2.78). The resultingmaterial is used for example in the production of contact rivets. For Ag/CdO stripmaterials two processes are commonly used: Cladding of an AgCd alloy stripwith fine silver followed by complete oxidation results in a strip material with asmall depletion area in the center of it's thickness and a Ag backing suitable foreasy attachment by brazing (sometimes called “Conventional AgAbbrand verschiedener W/CdO”). Usinga technology that allows the partial oxidation of a dualCu-Sinter-strip AgCd alloy materialin a higher pressure pure oxygen atmosphere yields a composite Ag/CdO stripmaterial that has besides a relatively fine CdO precipitation also a easily brazableAgCd alloy backing (FigTränkwerkstoffe an Luft bei hohen Strömen. 2Z.85)Metallkd. These materials 63 (DODURIT CdO ZH1972) are mainlyused as the basis for contact profiles and contact tips.651-654

During powder metallurgical production the powder mixed made by differentprocesses are typically converted by pressingAlthaus, sintering and extrusion to wiresand stripsB. The high degree of deformation during hot extrusion produces auniform and fine dispersion of CdO particles in the Ag matrix while at the sametime achieving a high density which is advantageous for good contact properties(Fig. 2; Vinaricky, E.84). To obtain a backing suitable for brazing, a fine silver layer is applied: Das Abbrandverhalten verschieden hergestellterby either comWolfram-Kupfer-pound extrusion or hot cladding prior to or right after the extrusionVerbundwerkstoffe im Hochstromlichtbogen.Metall 22 (Fig. 2.861968).697-701

For larger contact tipsGessinger, and especially those with a rounded shapeG.H.; Melton, the single tipPress-SinterK.N.: Burn-Repress process (PSR) offers economical advantages. Thepowder mix is pressed off Behaviour of WCu Contact Materials in a die close to the final desired shape, the “green” tipsanare sintered, and in most cases the repress process forms the final exact shapewhile at the same time increasing the contact density and hardnessElectric Arc. Powder Metall. Int.9 (1977) 67-72

Using different silver powders and minor additives for the basic Ag and CdOstarting materials can help influence certain contact properties for specializedMagnusson, M.: Abbrandverhalten und Rißbildung bei WCu-Tränkwerkstoffenapplicationsunterschiedlicher Wolframteilchengröße.ETZ-A 98 (1977) 681-683

FigHeitzinger, F. 2; Kippenberg, H.; Saeger, K.E.; Schröder, K.H.77:Contact Materials forStrain hardening of internally oxidizedAg/CdO 90/10 by cold workingVacuum Switching Devices. Proc. XVth ISDEIV, Darmstadt 1992, 273-278

FigGrill, R. 2; Müller, F.78:Verbundwerkstoffe auf Wolframbasis fürSoftening of internally oxidizedAg/CdO 90/10 after annealingfor 1 hr after 40% cold workingHochspannungsschaltgeräte. Metall 61 (2007) H. 6, 390-393

Table 2Slade, P.25: Physical G.: The Vacuum Interrupter- Theory; Design; and Mechanical Properties as well as Manufacturing Processes andForms of Supply of Extruded Silver Cadmium OxideApplication. CRCPress, Boca Raton, FL (DODURIT CdOUSA) Contact Materials, 2008

FigFrey, P.; Klink, N.; Saeger, K. 2E.79:Untersuchungen zum Abreißstromverhalten vonStrain hardening ofAg/CdO 90/10 P by cold workingKontaktwerkstoffen für Vakuumschütze. Metall 38 (1984) 647-651

FigFrey, P. 2; Klink, N.; Michal, R.; Saeger, K.E.80: SofteningMetallurgical Aspects of Ag/CdO 90/10 P after annealingContactMaterials for 1 hr after 40% cold workingVacuum Switching Devices. IEEE Trans. Plasma Sc. 17, (1989) 743-740

FigSlade, P. 2.81:Advances in Material Development for High Power Vacuum InterrupterStrain hardeningth Contacts. Proc.16 Int. Conf. on Electr. Contact Phenom.,of Ag/CdO 88/12 WPLoughborough 1992,1-10

FigBehrens, V. 2; Honig, Th.; Kraus, A.; Allen, S.82:Softening Comparison of Ag/CdO 88/12WP after annealingDifferent Contactth Materials for 1 hr after different degrees ofLow Voltage Vacuum Applications. Proc.19 Int. Conf. on Electr.cold workingContact Phenom., Nuremberg 1998, 247-251

FigRolle, S. 2; Lietz, A.; Amft, D.; Hauner, F.83: Micro structure of Ag/CdO 90/10 iCuCr Contact Material for Low Voltageth Vacuum Contactors. Proc. 20 int. Conf. on Electr. Contact.oPhenom. a) close to surfaceStockholmb) in center area2000, 179-186

FigKippenberg, H. 2.84: Micro structure of Ag/CdO 90/10 P:CrCu as a) perpendicular to extrusion directionContact Material for Vacuum Interrupters.b) parallel to extrusion directionth Proc.13 Int. Conf. on Electr. Contact Phenom. Lausanne 1986, 140-144

FigHauner, F. 2; Müller, R.; Tiefel, R.85:CuCr für Vakuumschaltgeräte-Micro structure of Ag/CdO 90/10 ZH:Herstellungsverfahren, Eigenschaften und Anwendung.1Metall 61 (2007) Ag/CdO layer2) AgCd backing layerH. 6, 385-389

Fig. 2.86: Micro structure of AgCdO 88/12 WP: a) perpendicular to extrusion directionManufacturing Equipment for Semi-Finished Materialsb(Bild) parallel to extrusion direction