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.figure>

Sintering with During ''sintering without a liquid phase has '' (left side of schematic), the advantage of shorter process times due powder mix is first densified by pressing, then undergoes a heat treatment (sintering) and eventually is re-pressed again tofurther increase the accelerated diffusion density. The sintering atmosphere depends on the material components and later application; a vacuum is used for example for the low gas content material Cu/Cr. This process is used for individual contact parts and also results in neartermed press-theoretical densities sinter-repress (PSR). For materials with high silver content, the starting point before pressing is mostly a large block (or billet) which is then, after sintering, hot extruded into wire, rod or strip form. The extrusion further increases the density of thethese 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.

Fig. 2.1: Powder''Sintering with liquid phase'' has the advantage of shorter process times due to the accelerated diffusion and also results in near-metallurgical manufacturing of composite materials (schematic)T = Melting point theoretical densities of the lower melting component 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=== ===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 the typically available quality grades of silver. In certaineconomic areas, i.e. China, there are additional grades with varying amounts ofimpurities available on the market. In powder form silver is used for a widevariety of silver based composite contact materials. Different manufacturingprocesses result in different grades of Ag powder as shown in Table 2.12.additional properties of silver powders and their usage are describedin chapter 8.1.Semi-finished silver materials can easily be warm or cold formed and can beclad to the usual base materials. For attachment of silver to contact carriermaterials welding of wire or profile cut-offs and brazing are most widely applied.Besides these mechanical processes such as wire insertion (wire staking) andthe riveting (staking) of solid or composite contact rivets are used in themanufacture of contact components. Contacts made from fine silver are applied in various electrical switchingdevices such as relays, pushbuttons, appliance and control switches forcurrents < 2 A (Table 2.16). Electroplated silver coatings are widely used toreduce the contact resistance and improve the brazing behavior of other contactmaterials and components. Table 2.11: Overview of the Most Widely Used Silver Grades Table 2.12: Quality Criteria of Differently Manufactured Silver Powders Fig. 2.45:Strain hardeningof Ag 99.95 by cold working Fig. 2.46:Softening of Ag 99.95after annealing for 1 hr after differentdegrees of strain hardening ===2.4.2 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). ===2.4.2.1 Fine-Grain Silver===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 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. ===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 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, the eutectic AgCu alloy with 28 wt% ofcopper (Fig. 2.52) is used. AgCu10 also known as coin silver has beenreplaced 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 contacts. 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 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. The attachment methods used for the hard silver materials are mostly close tothose applied for fine silver and fine grain silver. Hard-silver alloys are widely used for switching applications in the informationand energy technology for currents up to 10 A, in special cases also for highercurrent ranges (Table 2.16). Dispersion hardened alloys of silver with 0.5 wt% MgO and NiO (ARGODUR 32)are produced by internal oxidation. 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 hard-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 conductivity Table 2.13: Physical Properties of Silver and Silver Alloys ARGODUR 32 is mainly used in the form of contact springs that are exposed tohigh thermal and mechanical stresses in relays, and contactors for aeronauticapplications. Fig. 2.47:Influence of 1-10 atom% of differentalloying metals on the electrical resistivity ofsilver Fig. 2.48:Electrical resistivity pof AgCu alloys with 0-20 weight% Cuin the soft annealedand tempered stagea) Annealed and quenchedb) Tempered at 280°C Fig. 2.49: Coarse grain micro structureof Ag 99.97 after 80% cold workingand 1 hr annealing at 600°C Fig. 2.50: Fine grain microstructureof AgNi0.15 after 80% cold workingand 1 hr annealing at 600°C Fig. 2.51:Phase diagramof silver-nickel Fig. 2.52:Phase diagramof silver-copper Fig. 2.53:Phase diagram ofsilver-cadmium Table 2.14: Mechanical Properties of Silver and Silver Alloys Fig. 2.54:Strain hardeningof AgCu3by cold working Fig. 2.55:Softening of AgCu3after annealing for 1 hrafter 80% cold working Fig. 2.56:Strain hardening of AgCu5 by coldworking

FigPure 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. 2In addition, it is not hard or strong enough to resist mechanical wear and exhibits high material losses under electrical arcing loads.58:Strain hardening This limits its use in form of AgCu 10by cold workingthin electroplated or vacuum deposited layers.

Fig. 2.59Main Article:Softening of AgCu10 afterannealing for 1 hr after 80% coldworking[[Gold Based Materials| Gold Based Materials]]

FigThe platinum group metals include the elements Pt, Pd, Rh, Ru, Ir and Os ([[Platinum_Metal_Based_Materials|Table 1]]<!--(Table 2.6)-->). 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. 2During frictional movement between contact surfaces, the polymerized compounds known as “brown powder” are formed, which can lead to a significant increase in contact resistance.61:Softening of AgCu28after annealing Therefore Pt and Pd are typically used as alloys and are rather not used in their pure form for 1 hr after80% cold workingelectrical contact applications.

Fig. 2.62Main Article:Strain hardening of AgNi0.15by cold working[[Platinum Metal Based Materials| Platinum Metal Based Materials]]

Fig. 2.64Main Article:Strain hardening ofARGODUR 27by cold working[[Silver Based Materials| Silver Based Materials]]

Table 2.15Main Article: Contact [[Tungsten and Switching Properties of Silver Molybdenum Based Materials| Tungsten and Silver AlloysMolybdenum Based Materials]]

Table 2.16: Application Examples and Forms of Supply ==Contact Materials for Silver and Silver AlloysVacuum Switches==

===2.4.2.3 Silver-Palladium Alloys===The addition of 30 wt% Pd increases the mechanical properties as well as theresistance of silver against low gas content contact materials are developed for the influence of sulfur and sulfur containingcompounds significantly (Tables 2.17 and 2.18).Alloys with 40-60 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 contentsuse in vacuum switching devices.

AgPd alloys are hard, arc erosion resistant, and have a lower tendency towardsmaterial transfer under DC loads (Table 2.19). On the other hand the electricalconductivity is decreased at higher Pd contents. The ternary alloy AgPd30Cu5has an even higher hardness which makes it suitable Main Article: [[Contact Materials for use in sliding contactsystems.Vacuum Switches| Contact Materials for Vacuum Switches]]

FigVinaricky, E. 2(Hrsg.66): Phase diagram of silverElektrische Kontakte, Werkstoffe und Anwendungen.Springer-palladiumVerlag, Berlin, Heidelberg etc. 2002

FigLindmayer, M. 2: Schaltgeräte-Grundlagen, Aufbau, Wirkungsweise.67:Strain hardeningof AgPd30 by cold workingSpringer-Verlag, Berlin, Heidelberg, New York, Tokio, 1987

FigRau, G. 2: Metallische Verbundwerkstoffe.68:Strain hardeningWerkstofftechnischeof AgPd50 by cold workingVerlagsgesellschaft, Karlsruhe 1977

FigSchreiner, H. 2: Pulvermetallurgie elektrischer Kontakte.69:Strain hardeningof AgPd30Cu5Springer-Verlagby cold workingBerlin, Göttingen, Heidelberg, 1964

FigHansen. 2M.70; Anderko, K.: Constitution of Binary Alloys. New York:Softening of AgPd30Mc Graw-Hill, AgPd50,and AgPd30Cu5 after annealing of 1 hrafter 80% cold working1958

Table 2Shunk, F.A.17: Physical Properties Constitution of SilverBinary Alloy. 2 Suppl. New York; Mc Graw-Palladium AlloysHill, 1969

Table 2Edelmetall-Taschenbuch. ( Herausgeber Degussa AG, Frankfurt a. M.18: Mechanical Properties of Silver),Heidelberg, Hüthig-Palladium AlloysVerlag, 1995

Table 2Rau, G.19: Contact and Switching Properties of SilverElektrische Kontakte-Palladium AlloysWerkstoffe und Technologie. Eigenverlag G. RauGmbH & Co., Pforzheim, 1984

Table 2Heraeus, W. C.20: Application Examples and Forms of Suppl for Silver-Palladium AlloysWerkstoffdaten. Eigenverlag W.C. Heraeus, Hanau, 1978

===2Linde, J.4O.3 Silver Composite Materials===: Elektrische Widerstandseigenschaften der verdünnten Legierungendes Kupfers, Silbers und Goldes. Lund: Hakan Ohlsson, 1938

===2.4.3.1 Silver-Nickel (SINIDUR) Materials===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 wiresEngineers Relay Handbook, 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)RSIA, 2006

The high density produced during hot extrusion aids the arc erosion resistanceof these materials (Tables 2Großmann, H. Saeger, K.21 and 2E.22); Vinaricky, E. The typical application of Ag/Nicontact materials is : Gold and Gold Alloys in devices for switching currents of up to 100A (Table 2.24).ElectricalIn this range they are significantly more erosion resistant than silver or silveralloysEngineering. In addition they exhibit with nickel contents <20 wt% a low in: Gold, Progress in Chemistry, Biochemistry and over theiroperational lifetime consistent contact resistance and good arc movingpropertiesTechnology. In DC applications Ag/Ni materials exhibit a relatively low tendencyJohnof material transfer distributed evenly over the contact surfaces Wiley & Sons, Chichester etc, (Table 2.231999).199-236

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-Gehlert, are easily formable and applied bycladding (FigsB. 2.71: Edelmetall-2Legierungen für elektrische Kontakte.74). They can be, without any additional welding aids,economically welded and brazed to the commonly used contact carriermaterials.The Metall 61 (SINIDUR2007) 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 forcesH.6, 374-379

The most important applications for Ag/Ni contact materials are typically inrelaysAldinger, wiring devicesF.; Schnabl, appliance switches, thermostatic controls, auxiliaryR.: Edelmetallarme Kontakte für kleine Ströme.switches, and small contactors with nominal currents >20A Metall 37 (Table 2.241983).23-29

Table 2Bischoff, A.; Aldinger, F.21: Physical Properties of SilverEinfluss geringer Zusätze auf die mechanischenEigenschaften von Au-Nickel Ag-Pd-Legierungen. Metall 36 (SINIDUR1982) Materials752-765

Table 2Wise, E.M.22: Mechanical Palladium, Recovery, Properties of Silver-Nickel (SINIDUR) Materialsand Uses. New York, London:Academic Press 1968

FigSavitskii, E. 2M.; Polyakova, V.P.; Tylina, M.A.71:Palladium Alloys, Primary Sources.Strain hardeningof Ag/Ni 90/10 by cold workingNew York: Publishers 1969

FigGehlert, B. 2.72:Lebensdaueruntersuchungen von Edelmetall Kontaktwerkstoff-Softening of Ag/Ni 90/10after annealingfor 1 hr after 80% cold workingKombinationen für Schleifringübertrager. VDE-Fachbericht 61, (2005) 95-100

FigHolzapfel,C. 2.73:Verschweiß und elektrische Eigenschaften vonStrain hardeningof Ag/Ni 80/20 by cold workingSchleifringübertragern. VDE-Fachbericht 67 (2011) 111-120

FigSchnabl, R. 2; Gehlert, B.74:Lebensdauerprüfungen von Edelmetall-Softening of Ag/Ni 80/20after annealingSchleifkontaktwerkstoffen für Gleichstrom Kleinmotoren.for 1 hr after 80% cold workingFeinwerktechnik & Messtechnik (1984) 8, 389-393

FigKobayashi, T. 2; Koibuchi, K.; Sawa, K.; Endo, K.; Hagino, H.75: Micro structure A Study of Lifetimeof Ag/Ni 90/10 a) perpendicular to the extrusion directionAu-plated Slip-Ring and AgPd Brush System for Power Supply.b) parallel to the extrusion directionth Proc. 24 Int. Conf. on Electr. Contacts, Saint Malo, France 2008, 537-542

FigHarmsen, U. 2; Saeger K.E.76: Micro structure of Ag/Ni 80/20 a) perpendicular to the extrusion directionÜber das Entfestigungsverhalten von Silberbverschiedener Reinheiten. Metall 28 (1974) parallel t o the extrusion direction683-686

Table 2Behrens, V.; Michal, R.; Minkenberg, J.N.; Saeger, K.E.23: Contact and Switching Properties of SilverAbbrand undKontaktwiderstandsverhalten von Kontaktwerkstoffen auf Basis von Silber-Nickel . e.& i. 107. Jg. (SINIDUR1990) Materials, 2, 72-77

Table 2Behrens, V.24: Application Examples and Forms of SupplySilber/Nickel und Silber/Grafit- zwei Spezialisten auf dem Gebietfor Silver-Nickel der Kontaktwerkstoffe. Metall 61 (SINIDUR2007) MaterialsH.6, 380-384

===2Rieder, W.4.3.2: SilverSilber / Metalloxyd-Metal Oxide Materials Ag/CdO, Ag/SnO Werkstoffe für elektrische Kontakte, Ag/ZnO===The family of silverVDE -metal oxide contact materials includes the material groups:silver-cadmium oxide (DODURIT CdO), silver-tin oxide (SISTADOX), and silverzincoxide Fachbericht 42 (DODURIT ZnO1991). Because of their very good contact and switchingproperties like high resistance against welding, low contact resistance, and higharc erosion resistance, silver65-metal oxides have gained an outstanding positionin a broad field of applications. They mainly are used in low voltage electricalswitching devices like relays, installation and distribution switches, appliances,industrial controls, motor controls, and protective devices (Table 2.13).81

*SilverHarmsen,U.: Die innere Oxidation von AgCd-cadmium oxide Legierungen unterSauerstoffdruck.Metall 25 (DODURIT CdO1991) materials, H.2, 133-137

SilverMuravjeva, E.M.; Povoloskaja, M.D.: Verbundwerkstoffe Silber-cadmium oxide (DODURIT CdO) materials with 10Zinkoxid undSilber-15 wt% are producedZinnoxid, hergestellt durch Oxidationsglühen.by both, internal oxidation and powder metallurgical methods Elektrotechnika 3 (Table 2.251965).37-39

The manufacturing of strips and wires by internal oxidation starts with a moltenalloy of silver and cadmiumBehrens, V.; Honig Th.; Kraus, A.; Michal, R.; Saeger, K.-E. During a heat treatment below it's melting point in aoxygen rich atmosphere in such a homogeneous alloy the oxygen diffuses fromthe surface into the bulk of the material and oxidizes the Cd to CdO in a more orless fine particle precipitation inside the Ag matrix; Schmidberger, R. The CdO particles are ratherfine in the surface area and are becoming larger further away towards the center;of the material (FigStaneff, Th. : Eine neue Generation von AgSnO₂ -Kontaktwerkstoffen.83VDE-Fachbericht 44, (1993).99-114

During the manufacturing of Ag/CdO contact material by internal oxidation theprocesses vary depending on the type of semi-finished materialBraumann, P.For Ag/CdO wires a complete oxidation of the AgCd wire is performed; Lang, followedby wire-drawing to the required diameter (FigsJ. 2.77 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 Kontaktverhalten von Ag backing suitable for-Metalloxiden für den Bereicheasy attachment by brazing (sometimes called “Conventional Ag/CdO”)hoher Ströme. Usinga technology that allows the partial oxidation of a dualVDE-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 Fachbericht 42, (Fig. 2.851991). These materials (DODURIT CdO ZH) are mainlyused as the basis for contact profiles and contact tips.89-94

During powder metallurgical production the powder mixed made by differentprocesses are typically converted by pressingHauner, F.; Jeannot, D.; Mc Neilly, U.; Pinard, sintering and extrusion to wiresand stripsJ. The high degree of deformation during hot extrusion produces a: Advanced AgSnO Contact 2uniform and fine dispersion of CdO particles in the Ag matrix while at the sametime achieving a high density which is advantageous th Materials for good contact properties(FigHigh Current Contactors. 2Proc.84)20 Int. To obtain a backing suitable for brazing, a fine silver layer is appliedby either com-pound extrusion or hot cladding prior to or right after the extrusion(FigConf. 2on Electr.86)ContactPhenom., Stockholm 2000, 193-198

For larger contact tipsWintz, and especially those with a rounded shapeJ.-L.; Hardy, the single tipPress-Sinter-Repress process (PSR) offers economical advantagesS. Thepowder mix is pressed in a die close to the final desired shape; Bourda, C.: Influence on the “green” tipsElectrical Performances ofare sinteredAssembly Process, Supports Materials and in most cases the repress process forms the final exact shapeProduction Means for AgSnO₂ .while at the same time increasing the contact density and hardnessProc.24_th Int. Conf. on Electr.Contacts, Saint Malo, France 2008, 75-81

FigSchöpf, Th. 2.77:Silber/Zinnoxid und andere Silber-Metalloxidwerkstoffe inStrain hardening of internally oxidizedAg/CdO 90/10 by cold workingNetzrelais. VDE-Fachbericht 51 (1997) 41-50

FigSchöpf, Th. 2; Behrens, V.; Honig, Th.; Kraus, A.78:Softening Development of internally oxidizedSilver ZincAg/CdO 90/10 after annealingth Oxide for General-Purpose Relays. Proc. 20 Int. Conf. on Electr. Contacts,for 1 hr after 40% cold workingStockholm 2000, 187-192

Table 2Braumann, P.; Koffler, A.25: Physical and Mechanical Properties as well as Manufacturing Processes andEinfluss von Herstellverfahren, Metalloxidgehalt undForms of Supply of Extruded Silver Cadmium OxideWirkzusätzen auf das Schaltverhalten von Ag/SnO in Relais. 2VDE-Fachbericht 59, (DODURIT CdO2003) Contact Materials133-142

FigKempf, B. 2; Braumann, P.; Böhm, C.; Fischer-Bühner, J.79:Silber-Zinnoxid-Strain hardening ofAg/CdO 90/10 P by cold workingWerkstoffe: Herstellverfahren und Eigenschaften. Metall 61(2007) H. 6, 404-408

FigLutz, O. 2; Behrens, V.; Finkbeiner, M.; Honig, T.; Späth, D.80: Softeningof Ag/CdO 90/10 P after annealing-Ersatz infor 1 hr after 40% cold workingLichtschaltern. VDE-Fachbericht 61, (2005) 165-173

FigLutz, O. 2; Behrens, V.; Wasserbäch, W.; Franz, S.; Honig, Th.; Späth,D.; Heinrich, J.81:Improved Silver/Tin Oxide Contact Materials for AutomotiveStrain hardeningth Applications. Proc.24 Int. Conf. on Electr. Contacts, Saint Malo, France 2008,of Ag/CdO 88/12 WP-93

FigLeung, C. 2; Behrens, V.82:Softening A Review of Ag/CdO 88/12WP after annealingSnO Contact Materials and Arc Erosion. 2for 1 hr after different degrees ofcold workingth Proc.24 Int. Conf. on Electr. Contacts, Saint Malo, France 2008, 82-87

FigChen, Z. 2K.; Witter, G.J.83: Micro structure of Ag/CdO 90/10 iComparison in Performance for Silver–Tin–IndiumOxide Materials Made by Internal Oxidation and Powder Metallurgy.th Proc.o55 IEEE Holm Conf. a) close to surfaceon Electrical Contacts, Vancouver, BC, Canada,b(2009) in center area167 – 176

FigRoehberg, J. 2; Honig, Th.; Witulski, N.; Finkbeiner, M.; Behrens, V.84: Micro structure Performanceof Ag/CdO 90Different Silver/10 P:Tin Oxide Contact Materials for Applications in Low Voltagea) perpendicular to extrusion directionth Circuit Breakers. Proc. 55 IEEE Holm Conf. on Electrical Contacts, Vancouver,bBC, Canada, (2009) parallel to extrusion direction187 – 194

FigMuetzel, T. 2; Braumann, P.; Niederreuther, R.85:Micro structure Temperature Rise Behavior of Ag/CdO 90/10 ZH:1) th Ag/CdO layerSnO Contact Materials for Contactor Applications. Proc. 55 IEEE Holm 22Conf. on Electrical Contacts, Vancouver, BC, Canada, (2009) AgCd backing layer200 – 205

FigLutz, O. 2et al.86: Micro structure of AgCdO 88Silber/12 WP: a) perpendicular to extrusion directionZinnoxid – Kontaktwerkstoffe auf Basis der InnerenOxidation fuer AC – und DC – Anwendungen.bVDE Fachbericht 65 (2009) parallel to extrusion direction167 – 176

*Silver–tin oxide(SISTADOX)materialsOver the past yearsHarmsen, many Ag/CdO contact materials have been replaced byAg/SnO based materials with 2-14 wt% SnO 2 2 because of the toxicity ofCadmiumU. This changeover was further favored by the fact that Ag/SnO2contacts quite often show improved contact and switching properties such aslower arc erosion; Meyer, higher weld resistance, and a significant lower tendencytowards material transfer in DC switching circuits (Table 2C.30)L. Ag/SnO2: Mechanische Eigenschaften stranggepresster Silber-materials have been optimized for a broad range of applications by other metaloxide additives and modification in the manufacturing processes that result indifferent metallurgical, physical and electrical properties Graphit-Verbundwerkstoffe. Metall 21 (Table 2.291967)., 731-733

Manufacturing of Ag/SnO2 by ''internal oxidation'' is possible in principleBehrens, butduring heat treatment of alloys containing > 5 wt% of tin in oxygenV.: Mahle, dense oxidelayers formed on the surface of the material prohibit the further diffusion ofoxygen into the bulk of the materialE. By adding Indium or Bismuth to the alloy theinternal oxidation is possible and results in materials that typically are rather hardand brittle and may show somewhat elevated contact resistance and is limitedto applications in relays; Michal, R. To make a ductile material with fine oxide dispersion(SISTADOX TOS F) (Fig; Saeger, K. 2E.114) it is necessary to use special process variations: An Advanced Silver/Graphitein oxidation and extrusion which lead to materials with improved properties inrelaysth Contact Material Based on Graphite Fibre. Proc. Adding a brazable fine silver layer to such materials results in a semifinishedmaterial suitable for the manufacture as smaller weld profiles(SISTADOX WTOS F) (Fig16 Int. 2Conf.116)on Electr. Because of their resistance to materialtransfer and low arc erosion these materials find for example a broaderapplication in automotive relays (Table 2.31).Contacts, Loghborough 1992, 185-189

''Powder metallurgy'' plays a significant role in the manufacturing of Ag/SnO2contact materialsSchröder, K.-H. Besides SnO2 a smaller amount (<1 wt%) of one or moreother metal oxides such as WO3; Schulz, MoO3, CuO and/or Bi2O3 are addedE.-D. These: Über den Einfluss des Herstellungsverfahrensadditives improve the wettability of the oxide particles and increase the viscosityof the Ag meltth auf das Schaltverhalten von Kontaktwerkstoffen der Energietechnik. Proc. 7 Int. They also provide additional benefits to the mechanical andarcing contact properties of materials in this group ''(Table 2Conf.26)''on Electr.Contacts, Paris 1974, 38-45

In the manufacture the initial powder mixes different processes are appliedwhich provide specific advantages of the resulting materials in respect to theircontact properties ''(FigsMützel, T. 2: Niederreuther, R.87 – 2: Kontaktwerkstoffe für Hochleistungsanwendungen.119)''. Some of them are described here asfollows::'''aVDE-Bericht 67 (2011) Powder blending from single component powders''' <br> In this common process all components including additives that are part of the powder mix are blended as single powders. The blending is usually performed in the dry stage in blenders of different design.103-110

Lambert, C.; Cambon, G.:'''b) Powder blending The Influence of Manufacturing Conditions andMetalurgical Characteristics on the basis of doped powders''' <br> For incorporation Electrical Behaviour of additive oxides in the SnO2 powder the reactive spray process (RSV) has shown advantagesSilver-Graphiteth Contact Materials. This process starts with a waterbased solution of the tin and other metal compoundsProc. This solution is nebulized under high pressure and temperature in a reactor chamber9 Int. Through the rapid evaporation of the water each small droplet is converted into a salt crystal and from there by oxidation into a tin oxide particle in which the additive metals are distributed evenly as oxidesConf. The so created doped AgSnO2 powder is then mechanically mixed with silver powderon Electr.Contacts,Chicago 1978, 401-406

Vinaricky, E.:'''cGrundsätzliche Untersuchungen zum Abbrand- undSchweißverhalten von Ag/C-Kontaktwerkstoffen. VDE-Fachbericht 47 (1995) Powder blending based on coated oxide powders''' <br> In this process tin oxide powder is blended with lower meting additive oxides such as for example Ag2 MoO4 and then heat treated. The SnO2 particles are coated in this step with a thin layer of the additive oxide.159-169

Agte, C.; Vacek, J.:'''d) Powder blending based on internally oxidized alloy powders''' <br> A combination of powder metallurgy and internal oxidation this process starts with atomized Ag alloy powder which is subsequently oxidized in pure oxygen. During this process the Sn and other metal components are transformed to metal oxide and precipitated inside the silver matrix of each powder particleWolfram und Molybdän.Berlin: Akademie-Verlag 1959

:'''e) Powder blending based on chemically precipitated compound powders''' <br> Keil, A silver salt solution is added to a suspension of for example SnO2 together with a precipitation agent. In a chemical reaction silver and silver oxide respectively are precipitated around the additive metal oxide particles who act as crystallization sites; Meyer, C. Further chemical treatment then reduces the silver oxide with the resulting precipitated powder being a mix of Ag and SnO2-L.: Der Einfluß des Faserverlaufes auf die elektrischeVerschleißfestigkeit von Wolfram-Kontakten. ETZ 72, (1951) 343-346

Further processing of these differently produced powders follows theconventional processes of pressingSlade, sintering and hot extrusion to wires andstripsP. From these contact parts such as contact rivets and tips aremanufacturedG. To obtain a brazable backing the same processes as used : Electric Contacts forPower Interruption. A Review. Proc. 19 Int.Ag/CdO are appliedConf. As for Ag/CdOon Electric Contact Phenom. Nuremberg (Germany) 1998, larger contact tips can also bemanufactured more economically using the press239-sinter-repress (PSR) process''(Table 2.27).''245

FigSlade, P. 2G.87:Variations in Contact Resistance Resulting from Oxide FormationStrain hardening ofand Decomposition in AgW and Ag-WC-C Contacts Passing Steady CurrentsAg/SnO 92/8 PE by cold workingfor Long Time Periods. IEEE Trans. Components, Hybrids and Manuf. Technol.CHMT-9,1 (1986) 3-16

FigSlade, P. 2G.88:Effect of the Electric Arc and the Ambient Air on the ContactSoftening Resistance ofSilver, Tungsten and Silver-Tungsten Contacts.Ag/SnO 92/J.Appl.Phys. 47, 8 PE after annealingfor 1 hr after 40% cold working(1976) 3438-3443

Table 2Lindmayer, M.; Roth, M.26: Physical Contact Resistance and Mechanical Properties as well as Manufacturing Processes Arc-Erosion of W-Ag andForms of Supply of Extruded SilverWC-Ag. IEEE Trans components, Hybrids and Manuf. Technol.CHMT-Tin Oxide 2, 1 (SISTADOX1979) Contact Materials70-75

FigLeung, C. 2-H.; Kim, H.J.89:Strain hardening A Comparison ofAg/SnO 88W, Ag/WC and Ag/12 PE by cold workingMo ElectricalContacts. IEEE Trans. Components, Hybrids, Manuf. Technol.,Vol. CHMT-7, 1 (1984) 69-75

FigAllen, S. 2E.; Streicher, E.90:The Effect of Microstructure on the ElectricalSoftening th Performance of Ag/SnO 88/12 PEafter annealing for-WC-C Contact Materials. Proc. 44 IEEE Holm Conf. on Electr.1 hr after 40% cold workingContacts, Arlington, VA, USA (1998), 276-285

FigHaufe, W. 2; Reichel, W.; Schreiner H.91:Abbrand verschiedener W/Cu-Sinter-Strain hardening of oxidizedAg/SnO 88/12 PW4 by cold workingTränkwerkstoffe an Luft bei hohen Strömen. Z. Metallkd. 63 (1972) 651-654

FigAlthaus, B. 2; Vinaricky, E.92:Das Abbrandverhalten verschieden hergestellterSoftening of Ag/SnO 88/12 PW4 afterannealing for 1 hrWolfram-Kupfer-Verbundwerkstoffe im Hochstromlichtbogen.after 30% cold workingMetall 22 (1968) 697-701

FigGessinger, G. 2H.; Melton, K.N.93:Strain hardening Burn-off Behaviour ofWCu Contact Materials in anAg/SnO 98/2 PXby cold workingElectric Arc. Powder Metall. Int. 9 (1977) 67-72

FigMagnusson, M. 2.94:Abbrandverhalten und Rißbildung bei WCu-TränkwerkstoffenSoftening ofAg/SnO unterschiedlicher Wolframteilchengröße. ETZ-A 98/2 PXafter annealingfor 1 hr after 80%cold working(1977) 681-683

Fig 2Heitzinger, F.; Kippenberg, H.; Saeger, K.E.; Schröder, K.H.95:Contact Materials forStrain hardeningof Ag/SnO 92/8 PXby cold workingVacuum Switching Devices. Proc. XVth ISDEIV, Darmstadt 1992, 273-278

FigGrill, R. 2; Müller, F.96:Verbundwerkstoffe auf Wolframbasis fürSoftening ofAg/SnO 92/8 PXafter annealing for 1 hrafter 40% cold workingHochspannungsschaltgeräte. Metall 61 (2007) H. 6, 390-393

FigSlade, P. 2: G.97:The Vacuum Interrupter- Theory; Design; and Application. CRCStrain hardening of internallyoxidizedAg/SnO 88/12 TOS Fby cold workingPress, Boca Raton, FL (USA), 2008

FigFrey, P. 2; Klink, N.; Saeger, K.E.98:Untersuchungen zum Abreißstromverhalten vonSoftening ofAg/SnO 88/12 TOS F afterannealing for 1 hr after 30%cold workingKontaktwerkstoffen für Vakuumschütze. Metall 38 (1984) 647-651

FigFrey, P. 2; Klink, N.; Michal, R.; Saeger, K.E.99:Strain hardening Metallurgical Aspects ofContactinternally oxidizedAg/SnO 88/12PMaterials for Vacuum Switching Devices. IEEE Trans. Plasma Sc. 17, (1989) 743-by cold working740

FigSlade, P. 2.100:Advances in Material Development for High Power Vacuum InterrupterSoftening ofth Contacts. Proc.16 Int. Conf. on Electr. Contact Phenom.,Ag/SnO 88/12Pafter annealing for Loughborough 1992,1 hr after40% cold working-10

FigBehrens, V. 2; Honig, Th.; Kraus, A.; Allen, S.101:Strain hardening Comparison ofDifferent ContactAg/SnO 88/12 WPCth Materials for Low Voltage Vacuum Applications. Proc.19 Int. Conf. on Electr.by cold workingContact Phenom., Nuremberg 1998, 247-251

FigRolle, S. 2; Lietz, A.; Amft, D.; Hauner, F.102:CuCr Contact Material for Low VoltageSoftening of Ag/SnO 88/12 WPC after annealingth Vacuum Contactors. Proc. 20 int. Conf. on Electr. Contact. Phenom. Stockholmfor 1 hr after different degrees of cold working2000, 179-186

FigKippenberg, H. 2: CrCu as a Contact Material for Vacuum Interrupters.103:Strain hardening ofAg/SnO 86/14 WPCby cold workingth Proc.13 Int. Conf. on Electr. Contact Phenom. Lausanne 1986, 140-144

FigHauner, F. 2; Müller, R.; Tiefel, R.104:CuCr für Vakuumschaltgeräte-Softening of Ag/SnO 86/14 WPC after annealingHerstellungsverfahren, Eigenschaften und Anwendung.for 1 hr after different degrees of cold workingMetall 61 (2007) H. 6, 385-389

Fig. 2.106[[de:Softening of Ag/SnO 88/12 WPD afterannealing for 1 hr after different degreesof cold workingKontaktwerkstoffe_für_die_Elektrotechnik]]