Changes

</div>

<div class="clear"></div>

'''Tab.2.3: Mechanical Properties of Gold and Gold-Alloys'''

<figtable id="tab:tab2.3">

{| class="twocolortable" style="text-align: left; font-size: 12px"

</figtable>

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)''.

'''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.

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 ''(Table 2.5)''.

'''Table 2.5: Application Examples and Forms 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">Application Examples</p></td><td><p class="s12">Form 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 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>

'''Table 2.1: Commonly Used Grades of Gold'''

<table border="1" cellspacing="0" style="border-collapse:collapse"><tr><td><p class="s11">Designation</p></td><td><p class="s11">Composition Au</p><p class="s11">(min. content)</p></td><td><p class="s11">Impurites ppm</p></td><td><p class="s12">Remarks on forms and application</p></td></tr><tr><td><p class="s11">Electronic Glod</p><p class="s11">Gold</p></td><td><p class="s11">99.999</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>