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.jpg|right|thumb| Tab 2.2 Physical Properties of Gold and Gold)--Alloys]]>.[[FileOn 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 (<xr id="fig:Influence of 1Influence_of_1_10_atomic_of_different"/>)<!--10 atomic of different(Fig.jpg|right|thumb|Fig 2.2 Influence of 1)--10 atomic% of different alloying metals on the electrical resistivity of gold (according > to J. Ovarying degrees. Linde)]]

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>'''Tab.Commonly Used Grades of Gold<!--(2.3: Mechanical Properties of Gold and Gold1)--Alloys>'''</caption><table class="twocolortable">

Other ternary Caused by higher gold prices over the past years, the development of alloys based on with further reduced gold content had a high priority. The starting point has been the AuAg AuPd system are AuAg26Ni3 , which has continuous solubility of the two components. Besides the binary alloy of AuPd40 and AuAg25Pt6the ternary one AuPd35Ag9, other multiple component alloys were developed. These alloys are mechanically similar typically have < 50 wt% Au and often can be solution hardened in order to the AuAgCu alloys but have significantly obtain even higher oxidation resistance at elevated temperatures ''(Table 2hardness and tensile strength.4)''They are mostly used in sliding contact applications.

'''Table 2.4: Contact and Switching Properties Gold alloys are used in the form 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. conductivitywelded wire or profile (also called weldtapes),</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 resistancesegments, 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 rivets and mechanical</p><p class="s12">wear resistance</p></td></tr></table>stampings produced from clad stripCaused by higher gold prices over materials. The selection of the past years bonding process is based on the development of alloys with further reduced gold content had a high priority. The starting point has been cost for the joining process and most importantly on the AuPd system which has continuous solubility economical aspect of using the two components. Besides the binary alloy least possible amount of AuPd40 and the ternary one AuPd35Ag9 other multiple expensive precious metal 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 Besides being used as switching contacts in relays and pushbuttons, gold alloys are used also applied in the form design of welded wire or profile (also called weldtapes)connectors as well as sliding contacts for potentiometers, segments, contact rivetssensors, slip rings and brushes in miniature DC motors (<xr id="tab:Application Examples and stampings produced from clad stripmaterials. The selection Forms of the bonding process is based on the cost for the joining process, Gold and most importantly on the economical aspect of using theleast possible amount of the expensive precious metal componentGold Alloys"/>)<!--(Table 2.5)-->.

Besides being used as switching contacts in relays <figtable id="tab:Application Examples and pushbuttons, gold alloys are also applied in the design Forms of connectors as well as sliding contacts for potentiometers, sensors, slip rings, Gold and brushes in miniature DC motors Gold Alloys"><caption>''('<!--Table 2.5):-->Application Examples and Forms of Gold and Gold Alloys''.'</caption>

'''Table 2.5: Application Examples and Forms of Gold and Gold Alloys'''<table borderclass="1" cellspacing="0" style="border-collapse:collapsetwocolortable"><tr><tdth><p class="s11">Material</p></tdth><tdth><p class="s12">Application Examples</p></tdth><tdth><p class="s12">Form of Application</p></tdth></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 Gold</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></table></figtable>

Fig. 2.3<div class="multiple-images"><figure id="fig: Phase diagram of goldplatinum">[[File:Phase diagram of goldplatinum.jpg|rightleft|thumb|<caption>Phase diagram of goldplatinum</caption>]]</figure>

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

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

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

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

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

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

Fig. 2.10<figure id="fig: Strain hardening of AuPt10 by cold working">[[File:Strain hardening of AuPt10 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuPt10 by cold working</caption>]]</figure>

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

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

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

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

Fig. 2.15<figure id="fig: Strain hardening of AuCo5 by cold working">[[File:Strain hardening of AuCo5 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuCo5 by cold working</caption>]]</figure>

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

Fig. 2.17<figure id="fig: Strain hardening of AuAg25Pt6 by cold working">[[File:Strain hardening of AuAg25Pt6 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg25Pt6 by cold working</caption>]]</figure>

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

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

Fig. 2.20<figure id="fig: Strain hardening of AuAg25Cu5 by cold working">[[File:Strain hardening of AuAg25Cu5 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuAg25Cu5 by cold working</caption>]]</figure>

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

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

Fig. 2.23<figure id="fig: Strain hardening of AuCu14Pt9Ag4 by cold working">[[File:Strain hardening of AuCu14Pt9Ag4 by cold working.jpg|rightleft|thumb|<caption>Strain hardening of AuCu14Pt9Ag4 by cold working</caption>]]</figure>

Fig. 2.24<figure id="fig: Precipitation hardening of AuCu14Pt9Ag4 at different hardening temperatures after 50% cold working">[[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>