Changes

For Pure Gold is besides Platinum the chemically most electrical contact applications gold alloys are usedstable of all precious metals. Depending on the alloying metal the melting In its pure form it is performed either under in not very suitable for use as a reducing atmosphere or contact material in a vacuum. The choice electromechanical devices because of alloying metals depends on the intended use of the resulting its tendency to stick and cold-weld at even low contact materialforces. The binary Au alloys with typically <10 wt% of other precious metals such as Pt, Pd, In addition it is not hard or Ag or non-precious metals like Ni, Co, strong enough to resist mechanical wear and Cu are the more commonly used ones ''exhibits high material losses under electrical arcing loads (Table 2.2<xr id="tab:Contact_and_Switching_Properties_of_Gold_and_Gold_Alloys"/>)''. On one hand these alloy additions improve the mechanical strength and electrical switching properties but on the other hand reduce the electrical conductivity and chemical corrosion resistance ''<!--(FigTab. 2.24)'' to varying degrees-->. This limits its use in form of thin electroplated or vacuum deposited layers.

[[FileFor most electrical contact applications, gold alloys are used. Depending on the alloying metal, the melting is performed either under a reducing atmosphere or in a vacuum. The choice of alloying metals depends on the intended use of the resulting contact material. The binary Au alloys with typically < 10 wt% of other precious metals such as Pt, Pd, Ag or non-precious metals like Ni, Co and Cu are the more commonly used ones (<xr id="tab:Physical Properties of Gold and Gold-Alloys"/>)<!--(Tab. 2.jpg|right|thumb|Physical Properties of Gold and Gold2)-Alloys]][[File:Influence of 1-10 atomic of different>.jpg|right|thumb|Influence of 1-10 atomic% of different alloying metals On one hand these alloy additions improve the mechanical strength and electrical switching properties but on the other hand reduce the electrical resistivity of gold conductivity and chemical corrosion resistance (<xr id="fig:Influence_of_1_10_atomic_of_different"/>)<!--(according to JFig. O2. Linde2)]]--> to varying degrees.

Under the aspect of reducing the gold content , ternary alloys with a gold content of approximately 70 wt% and additions of Ag and Cu or Ag and Ni resp., for example AuAg25Cu5 or AuAg20Cu10 are used , which exhibit for many applications good mechanical stability , while at the same time have sufficientresistance against the formation of corrosion layers ''(<xr id="tab:Mechanical Properties of Gold and Gold-Alloys"/>)<!--(Table 2.3)''-->.

<figtable id="tab:Commonly Used Grades of Gold"><caption>'''Commonly Used Grades of Gold<!--(2.1)-->'''Tab</caption><table class="twocolortable">  <tr><th><p class="s11">Designation</p></th><th><p class="s11">Composition Au</p><p class="s11">(min. content)</p></th><th><p class="s11">Impurites ppm</p></th><th><p class="s12">Remarks on forms and application</p></th></tr><tr><td><p class="s11">Electronic Gold</p><p class="s11">Gold</p></td><td><p class="s11">99.2999</p></td><td><p class="s11">Cu &lt; 3</p><p class="s11">Ag &lt; 3</p><p class="s11">Ca &lt; 1</p><p class="s11">Mg &lt;1</p><p class="s11">Fe &lt; 1</p></td><td><p class="s12">Wires, strips, alloying metal for semiconductors, electronic components</p></td></tr><tr><td><p class="s11">Pure Gold</p></td><td><p class="s11">99.995</p></td><td><p class="s11">Cu &lt; 10</p><p class="s11">Ag &lt; 15</p><p class="s11">Ca &lt; 20</p><p class="s11">Mg &lt; 10</p><p class="s11">Fe &lt; 3</p><p class="s11">Si &lt; 10</p><p class="s11">Pb &lt; 20</p></td><td><p class="s12">Granulate for high purity alloys, strips, tubing, profiles</p></td></tr><tr><td><p class="s11">Ingot Grade-Gold</p></td><td><p class="s11">99.95</p></td><td><p class="s11">Cu &lt; 100</p><p class="s11">Ag &lt; 150</p><p class="s11">Ca &lt; 50</p><p class="s11">Mg &lt; 50</p><p class="s11">Fe &lt; 30</p><p class="s11">Si &lt; 10</p></td><td><p class="s12">Alloys, commonly used grade</p></td></tr></table></figtable><br/><br/> <figtable id="tab: Mechanical Physical Properties of Gold and Gold-Alloys"><caption>'''Physical Properties of Gold and Gold-Alloys'''</caption>

|R 140<br />R 170<br />R 200<br />R 240|140<br />170<br />200<br />240|30<br />3<br />2<br />1|20<br />50<br />60<br />70

|Copper and copper alloys in plate, sheet, strip, and discs for general applicationsAuAg20|R 190<br />R 250<br />R 320<br />R 390|190<br />250<br />320<br />390|25<br />2<br />1<br />1|38<br />70<br />95<br />115

|DIN EN 1654 AuAg30|Copper and copper alloys for springs and connectorsR 220<br />R 260<br />R 320<br />R 380|220<br />260<br />320<br />380|25<br />3<br />1<br />1|45<br />75<br />95<br />110

|DIN EN 1758 AuAg25Cu5|Copper and copper alloys in strip form for system component carriersR 400<br />R 470<br />R 570<br />R 700|400<br />470<br />570<br />700|25<br />4<br />2<br />2|90<br />120<br />160<br />185

|ASTM B 103AuAg20Cu10|R 480<br />R 560<br />R 720<br /B103M-10 >R 820|480<br />560<br />720<br />820|Spec. for Phosphor Bronce Plate, Sheet, Strip, and Rolled Bar20<br />3<br />1<br />1|125<br />145<br />190<br />230

|ASTM B 36AuAg26Ni3|R 350<br />R 420<br />R 500<br /B36M-95 >R 570|350<br />420<br />500<br />570| Spec. for Brass Plate, Sheet, Strip, and Rolled Bar20<br />2<br />1<br />1|85<br />110<br />135<br />155

|ASTM B 122AuAg25Pt6|R 280<br />R 330<br />R 410<br /B122M-08 >R 480|280<br />330<br />410<br />480| Spec. for CuNiSn-, CuNiZn-, and CuNi-Alloy18<br />2<br />1<br />1|60<br />90<br />105<br />125

|ASTM B 465-09 AuCo5|R 340<br />R 390<br />R 450<br />R 530| Spec. for Copper-Iron-Alloy Plate, Sheet, and Strip340<br />390<br />450<br />530|10<br />2<br />1<br />1|95<br />105<br />120<br />150

|ASTM B 194-08 AuCo5 prec.hardened|heterogeneous|360|3| Standard Spec. for CuBe110-Alloy Plate, Sheet, Strip and Rolled Bar130

|ASTM B 534AuNi5|R 380<br />R 450<br />R 560<br />R 640|380<br />450<br />560<br />640|25<br />3<br />2<br />1|115<br />135<br />160<br />190|-07 |AuPt10| SecR 260<br />R 310<br />R 370<br />R 410|260<br />310<br />370<br />410|20<br />2<br />1<br />1|80<br />90<br />100<br />105|-|AuCu14Pt9Ag4|R 620<br />R 700<br />R 850<br />R 950<br />prec. for CuCoBe-Alloy and CuNiBe-Alloy Plate, Sheet, Strip, and Rolled Barhardened|620<br />700<br />850<br />950<br />900|20<br />3<br />2<br />1<br />3|190<br />225<br />260<br />270<br />280

Other ternary alloys based on the AuAg system are AuAg26Ni3 and AuAg25Pt6. These alloys are mechanically similar to the AuAgCu alloys but have significantly higher oxidation resistance at elevated temperatures ''(Table 2.4)''.[[File:Mechanical Properties of Gold and Gold Alloys.jpg|right|thumb|Mechanical Properties of Gold and Gold Alloys]]'''Table 2.4: Contact and Switching Properties of Gold and Gold Alloys'''<table border="1" cellspacing="0" style="border-collapse:collapse"><tr><td><p class="s11">Material</p></td><td><p class="s12">Properties</p></td></tr><tr><td><p class="s11">Au</p></td><td><p class="s12">Highest corrosion resistance, low</p><p class="s12">hardness</p></td><td><p class="s12">High electr. conductivity,</p><p class="s12">strong tendency to cold welding</p></td></tr><tr><td><p class="s11">AuAg8</p></td><td><p class="s12">High corrosion resistance, low thermo</p><p class="s12">e.m.f.</p></td><td><p class="s12">Low contact resistance</p></td></tr><tr><td><p class="s11">AuPt10</p><p class="s11">AuPd5</p></td><td><p class="s12">Very high corrosion resistance</p></td><td><p class="s12">High hardness</p></td></tr><tr><td><p class="s11">AuAg10 - 30</p></td><td><p class="s12">Mostly corrosion resistant</p></td><td><p class="s12">Higher hardness</p></td></tr><tr><td><p class="s11">AuNi5</p><p class="s11">AuCo5</p></td><td><p class="s12">High corrosion resistance, low</p><p class="s12">tendency to material transfer</p></td><td><p class="s12">High hardness</p></td></tr><tr><td><p class="s11">AuAg25Pt6</p></td><td><p class="s12">High corrosion resistance, low contact resistance</p></td><td><p class="s12">High hardness</p></td></tr><tr><td><p class="s11">AuAg26Ni3</p><p class="s11">AuAg25Cu5</p><p class="s11">AuAg20Cu10</p></td><td><p class="s12">Limited corrosion resistance</p></td><td><p class="s12">High hardness</p></td></tr><tr><td><p class="s11">AuPd40</p><p class="s11">AuPd35Ag10</p><p class="s11">AuCu14Pt9Ag4</p></td><td><p class="s12">High corrosion resistance</p></td><td><p class="s12">High hardness and mechanical</p><p class="s12">wear resistance</p></td></tr></table>Caused by higher gold prices over the past years , the development of alloys with further reduced gold content had a high priority. The starting point has been the AuPd system , which has continuous solubility of the two components. Besides the binary alloy of AuPd40 and the ternary one AuPd35Ag9 , other multiple component alloys were developed. These alloys typically have < 50 wt% Au and often can be solution hardened in order to obtain even higher hardness and tensile 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 the joining 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, gold alloys are also applied in the design of connectors as well as sliding contacts for potentiometers, sensors, slip rings, and brushes in miniature DC motors ''(<xr id="tab:Application Examples and Forms of Gold and Gold Alloys"/>)<!--(Table 2.5)''-->.

'''Table 2.5<figtable id="tab: Application Examples and Forms of Gold and Gold Alloys"><caption>'''<table border="1" cellspacing="0" style="border!--collapseTable 2.5:collapse"><tr><td><p class="s11">Material</p></td><td><p class="s12"-->Application Examples</p></td><td><p class="s12">Form and Forms of Application</p></td></tr><tr><td><p class="s11">Pure Gold</p><p class="s11">(electroplated)</p></td><td><p class="s12">Corrosion protection layer for contact parts, stationary contacts, bonding surfaces</p></td><td><p class="s12">Electroplated coatings, bond surface layers</p></td></tr><tr><td><p class="s11">Hard Gold</p><p class="s11">(sputtered)</p></td><td><p class="s12">Contact parts for connectors and switches, sliding contact tracks, bonding surfaces</p></td><td><p class="s12">Electroplated coatings on contact rivets and stamped parts</p></td></tr><tr><td><p class="s11">Hard GoldAlloys'''</p><p class="s11">(sputtered)</p></td><td><p class="s12">Contacts in switches and relays for low loads, electronic signal relays</p></td><td><p class="s12">Contact surface layer on miniature</p><p class="s12">profiles (weld tapes)</p></td></tr><tr><td><p class="s11">AuAg8</p></td><td><p class="s12">Dry circuit switching contacts, electronic</p><p class="s12">signal relays</p></td><td><p class="s12">Contact rivets, welded contact</p><p class="s12">parts</p></td></tr><tr><td><p class="s11">AuAg20</p></td><td><p class="s12">Switching contacts for low loads, electronic</p><p class="s12">signal relays</p></td><td><p class="s12">Contact rivets, welded contact</p><p class="s12">parts</p></td></tr><tr><td><p class="s11">AuAg25Cu5</p><p class="s11">AuAg25Cu10</p><p class="s11">AuAg26Ni3</p></td><td><p class="s12">Contact parts for connectors, switches and relays</p></td><td><p class="s12">Claddings on Cu alloys, contact rivets, contact layer on micro profiles (weld tapes)</p></td></tr><tr><td><p class="s11">AuNi5</p><p class="s11">AuCo5 (heterogen)</p></td><td><p class="s12">Contacts in switches and relays for low and medium loads, material transfer resistant contacts</p></td><td><p class="s12">Contact rivets, welded contact parts, contact layer on miniature profiles (weld tapes)</p></td></tr><tr><td><p class="s11">AuPt10</p><p class="s11">AuAg25Pt6</p></td><td><p class="s12">Contacts for highest chemical corrosion resistance in switches and relays</p></td><td><p class="s12">Contact rivets, contact layer on micro profiles (weld tapes)</p></td></tr><tr><td><p class="s11">AuCu14Pt9Ag4</p></td><td><p class="s12">Sliding contacts for measurement data transfer</p></td><td><p class="s12">Wire-formed parts</p></td></tr></tablecaption>

'''Table 2.1: Commonly Used Grades of Gold'''<table class="twocolortable"><table bordertr><th><p class="1s11" cellspacing>Material</p></th><th><p class="0s12" style>Application Examples</p></th><th><p class="border-collapse:collapses12">Form of Application</p></th></tr><tr><td><p class="s11">DesignationPure Gold</p><p class="s11">(electroplated)</p></td><td><p class="s12">Corrosion protection layer for contact parts, stationary contacts, bonding surfaces</p></td><td><p class="s12">Electroplated coatings, bond surface layers</p></td></tr><tr><td><p class="s11">Composition AuHard Gold</p><p class="s11">(min. contentsputtered)</p></td><td><p class="s11s12">Impurites ppmContact parts for connectors and switches, sliding contact tracks, bonding surfaces</p></td><td><p class="s12">Remarks Electroplated coatings on forms contact rivets and applicationstamped parts</p></td></tr><tr><td><p class="s11">Electronic GlodHard Gold</p><p class="s11">Gold(sputtered)</p></td><td><p class="s11s12">99.999Contacts in switches and relays for low loads, electronic signal relays</p></td><td><p class="s11s12">Cu &lt; 3Contact surface layer on miniature</p><p class="s11s12">Ag &lt; 3profiles (weld tapes)</p></td></tr><tr><td><p class="s11">Ca &lt; 1AuAg8</p></td><td><p class="s11s12">Mg &lt;1Dry circuit switching contacts, electronic</p><p class="s11s12">Fe &lt; 1signal relays</p></td><td><p class="s12">WiresContact rivets, strips, alloying metal for semiconductors, electronic componentswelded contact</p><p class="s12">parts</p></td></tr><tr><td><p class="s11">Pure GoldAuAg20</p></td><td><p class="s11s12">Switching contacts for low loads, electronic</p><p class="s12">99.995signal relays</p></td><td><p class="s11s12">Cu &lt; 10Contact rivets, welded contact</p><p class="s11s12">Ag &lt; 15parts</p><p class="s11"/td>Ca &lt; 20</ptr><tr><td><p class="s11">Mg &lt; 10AuAg25Cu5</p><p class="s11">Fe &lt; 3AuAg25Cu10</p><p class="s11">Si &lt; 10AuAg26Ni3</p></td><td><p class="s11s12">Pb &lt; 20Contact parts for connectors, switches and relays</p></td><td><p class="s12">Granulate for high purity Claddings on Cu alloys, strips, tubingcontact rivets, contact layer on micro profiles(weld tapes)</p></td></tr><tr><td><p class="s11">Ingot Grade-GoldAuNi5</p><p class="s11">AuCo5 (heterogen)</p></td><td><p class="s12">Contacts in switches and relays for low and medium loads, material transfer resistant contacts</p></td><td><p class="s11s12">99.95Contact rivets, welded contact parts, contact layer on miniature profiles (weld tapes)</p></td></tr><tr><td><p class="s11">Cu &lt; 100AuPt10</p><p class="s11">Ag &lt; 150AuAg25Pt6</p></td><td><p class="s11s12">Ca &lt; 50Contacts for highest chemical corrosion resistance in switches and relays</p></td><td><p class="s11s12">Mg &lt; 50Contact rivets, contact layer on micro profiles (weld tapes)</p></td></tr><tr><td><p class="s11">Fe &lt; 30AuCu14Pt9Ag4</p></td><td><p class="s11s12">Si &lt; 10Sliding contacts for measurement data transfer</p></td><td><p class="s12">Alloys, commonly used gradeWire-formed parts</p></td></tr></table></figtable>

Fig. 2.4<div class="multiple-images"><figure id="fig: Phase diagram of gold-silvergoldplatinum">[[File:Phase diagram of gold-silvergoldplatinum.jpg|rightleft|thumb|<caption>Phase diagram of gold-silvergoldplatinum</caption>]]</figure>

Fig. 2.5<figure id="fig: Phase diagram of gold-coppersilver">[[File:Phase diagram of gold-coppersilver.jpg|rightleft|thumb|<caption>Phase diagram of gold-coppersilver</caption>]]</figure>

Fig. 2.6<figure id="fig: Phase diagram of gold-nickelcopper">[[File:Phase diagram of gold-nickelcopper.jpg|rightleft|thumb|<caption>Phase diagram of gold-nickelcopper</caption>]]</figure>

Fig. 2.7<figure id="fig: Phase diagram of gold-cobaltnickel">[[File:Phase diagram of gold-cobaltnickel.jpg|rightleft|thumb|<caption>Phase diagram of gold-cobaltnickel</caption>]]</figure>

Fig. 2.8<figure id="fig: Strain hardening Phase diagram of Au by cold workinggold-cobalt">[[File:Strain hardening Phase diagram of Au by cold workinggold-cobalt.jpg|rightleft|thumb|Strain hardening <caption>Phase diagram of Au by cold workinggold-cobalt</caption>]]</figure>

Fig. 2.9<figure id="fig: Softening Strain hardening of Au after annealing for 0.5 hrs after 80% by cold working">[[File:Softening Strain hardening of Au after annealing for 0.5 hrsby cold working.jpg|rightleft|thumb|Softening <caption>Strain hardening of Au after annealing for 0.5 hrs after 80% by cold working</caption>]]</figure>

Fig. 2.10<figure id="fig: Strain hardening Softening of AuPt10 by cold workingAu after annealing for 0.5 hrs">[[File:Strain hardening Softening of AuPt10 by cold workingAu after annealing for 0.5 hrs.jpg|rightleft|thumb|Strain hardening <caption>Softening of AuPt10 by Au after annealing for 0.5 hrs after 80% cold working</caption>]]</figure>

Fig. 2.11<figure id="fig: Strain hardening of AuAg20 AuPt10 by cold working">[[File:Strain hardening of AuAg20 AuPt10 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg20 AuPt10 by cold working</caption>]]</figure>

Fig. 2.12<figure id="fig: Strain hardening of AuAg30 AuAg20 by cold working">[[File:Strain hardening of AuAg30 AuAg20 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg30 AuAg20 by cold working</caption>]]</figure>

Fig. 2.13<figure id="fig: Strain hardening of AuNi5 AuAg30 by cold working">[[File:Strain hardening of AuNi5 AuAg30 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuNi5 AuAg30 by cold working</caption>]]</figure>

Fig. 2.14<figure id="fig: Softening Strain hardening of AuNi5 after annealing for 0.5 hrs after 80% by cold working">[[File:Softening Strain hardening of AuNi5 after annealing for 0.5 hrsby cold working.jpg|rightleft|thumb|Softening <caption>Strain hardening of AuNi5 after annealing for 0.5 hrs after 80% by cold working</caption>]]</figure>

Fig. 2.15<figure id="fig: Strain hardening Softening of AuCo5 by cold workingAuNi5 after annealing for 0.5 hrs">[[File:Strain hardening Softening of AuCo5 by cold workingAuNi5 after annealing for 0.5 hrs.jpg|rightleft|thumb|Strain hardening <caption>Softening of AuCo5 by AuNi5 after annealing for 0.5 hrs after 80% cold working</caption>]]</figure>

Fig. 2.16<figure id="fig: Precipitation Strain hardening of AuCo5 at 400°C hardening temperatureby cold working">[[File:Precipitation Strain hardening of AuCo5 atby cold working.jpg|rightleft|thumb|Precipitation <caption>Strain hardening of AuCo5 at 400°C hardening temperatureby cold working</caption>]]</figure>

Fig. 2.17<figure id="fig: Strain Precipitation hardening of AuAg25Pt6 by cold workingAuCo5 at">[[File:Strain Precipitation hardening of AuAg25Pt6 by cold workingAuCo5 at.jpg|rightleft|thumb|Strain <caption>Precipitation hardening of AuAg25Pt6 by cold workingAuCo5 at 400°C hardening temperature</caption>]]</figure>

Fig. 2.18<figure id="fig: Strain hardening of AuAg26Ni3 AuAg25Pt6 by cold working">[[File:Strain hardening of AuAg26Ni3 AuAg25Pt6 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg26Ni3 AuAg25Pt6 by cold working</caption>]]</figure>

Fig. 2.19<figure id="fig: Softening Strain hardening of AuAg26Ni3 after annealing for 0.5 hrs after 80% by cold working">[[File:Softening Strain hardening of AuAg26Ni3 after annealing for 0.5-hrsby cold working.jpg|rightleft|thumb|Softening <caption>Strain hardening of AuAg26Ni3 after annealing for 0.5 hrs after 80% by cold working</caption>]]</figure>

Fig. 2.20<figure id="fig: Strain hardening Softening of AuAg25Cu5 by cold workingAuAg26Ni3 after annealing for 0.5-hrs">[[File:Strain hardening Softening of AuAg25Cu5 by cold workingAuAg26Ni3 after annealing for 0.5-hrs.jpg|rightleft|thumb|Strain hardening <caption>Softening of AuAg25Cu5 by AuAg26Ni3 after annealing for 0.5 hrs after 80% cold working</caption>]]</figure>

Fig. 2.21<figure id="fig: Strain hardening of AuAg20Cu10 AuAg25Cu5 by cold working">[[File:Strain hardening of AuAg20Cu10 AuAg25Cu5 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg20Cu10 AuAg25Cu5 by cold working</caption>]]</figure>

Fig. 2.22<figure id="fig: Softening Strain hardening of AuAg20Cu10 after annealing for 0.5 hrs after 80% by cold working">[[File:Softening Strain hardening of AuAg20Cu10 after annealing for 0.5 hrsby cold working.jpg|rightleft|thumb|Softening <caption>Strain hardening of AuAg20Cu10 after annealing for 0.5 hrs after 80% by cold working</caption>]]</figure>

Fig. 2.23<figure id="fig: Strain hardening Softening of AuCu14Pt9Ag4 by cold workingAuAg20Cu10 after annealing for 0.5 hrs">[[File:Strain hardening Softening of AuCu14Pt9Ag4 by cold workingAuAg20Cu10 after annealing for 0.5 hrs.jpg|rightleft|thumb|Strain hardening <caption>Softening of AuCu14Pt9Ag4 by AuAg20Cu10 after annealing for 0.5 hrs after 80% cold working</caption>]]</figure>

Fig. 2.24<figure id="fig:Strain hardening of AuCu14Pt9Ag4 by cold working">[[File: Precipitation Strain hardening of AuCu14Pt9Ag4 at different by cold working.jpg|left|thumb|<caption>Strain hardening temperatures after 50% of AuCu14Pt9Ag4 by cold working</caption>]]</figure> <figure id="fig:Precipitation hardening of AuCu14Pt9Ag4">[[File:Precipitation hardening of AuCu14Pt9Ag4.jpg|rightleft|thumb|<caption>Precipitation hardening of AuCu14Pt9Ag4 at different hardening temperatures after 50% cold working</caption>]]</figure></div><div class="clear"></div>