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The platinum group metals include the elements Pt, Pd, Rh, Ru, Ir, and Os (<xr id="tab:tab2.6Properties_Production_Processes_and_Application_Forms_for_Platinum_Metals"/> <!--(Tab. 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 because for the reason of their catalytical properties , they tend to polymerize adsorbed organic vapors on contact surfaces. During frictional movement between contact surfaces , the polymerized compounds known as “brown powder” are formed , which can lead to significantly a significant increase in contact resistance. Therefore Pt and Pd are typically used as alloys and not in their pure form for electrical contact applications.
<figtable id="tab:tab2.6Properties_Production_Processes_and_Application_Forms_for_Platinum_Metals"><caption>'''<!--Table 2.6: -->Properties, Production Processes, and Application Forms for Platinum Metals'''</caption>
{| class="twocolortable" style="text-align: left; font-size: 12px"
Rhodium is not used as a solid contact material but is applied for example as a electroplated layer in sliding contact systems. Ruthenium is mostly used as an alloying component in the material PdRu15. The metals osmium and iridium have no practical applications in electrical contacts.
Since Pd was for the longest time rather stable in price , it was looked at seen as a substitute for the more expensive gold. This was followed by a steep increase in the Pd price , which caused a significant reduction in its use in electrical contacts. Today (2011Dec. 2021) the Pd palladium price again is lower than that of goldaround 2600 Euro/oz.
Alloys of Pt with Ru, Ir, Ni, and W were widely used in electromechanical components in the telecommunication industry and in heavy duty automotive breaker points (<xr id="tab:Physical Properties of platinum metals"the Platinum Metals an their Alloys/> (Tab. 2.7).
<figtable id="tab:Physical Properties of platinum metalsthe Platinum Metals an their Alloys"> <caption>'''<!--Table 2.7: -->Physical Properties of the Platinum Metals and an their Alloys'''</caption> {| class="twocolortable" style="text-align: left; font-size: 12px"|-!Material!Platin/Palladium<br/>Content<br/>[wt.%]!Density<br/>[g/cm<sup>3</sup>]!Melting Point or Range<br/>[°C]!Electrical<br/>Resistivity<br/>[µΩ*cm]!Electrical<br/>Conductivity<br/>[MS/m]!Thermal<br/>Conductivity<br/>[W/m*K]!Temp. Coefficient of the<br/>Electrical Resistance<br/>[File:Physical Properties 10<sup>3</sup>/K]!modulus of platinum metals<br/>Elasticity<br/>[Gpa]|-|Pt (99,95)| >99,95|21,5|1772|10,6|9,5|72|3,9|173|-|PtIr5|95|21,5|1774 - 1776|22,2|4,5|42||190|-|PtIr10|90|21,6|1780 - 1785|17,9|5,6|29|2,0|220|-|PtRu10|90|20,6|ca.jpg1800|33,3|3,0||0,83|235|-|PtNi6|92|19,2|1670 - 1710|30|3,3||1,5|180|-|PtW5|95|21,3|1830 - 1860|43,4|2,3||0,7|185|-|Pd (99,95)| >99,95|12,0|1554|10,8|right9,3|thumb72|Physical Properties of the Platinum Metals and their Alloys]]3,8|124|-|PdCu15|85|11,3|1370 - 1400|38,5|2,6|17|0,49|175|-|PdCu40|60|10,5|1200 - 1230|33,3|3,0|38|0,28|175|-|PdNi5|95|11,8|1455 - 1485|16,9|5,9||2,47|175|-|}
</figtable>
<figtable id="figtab:Mechanical_Properties_of_the_Platinum_Metals_and_their_Alloys"><caption>'''<!--Table 2.8:-->Mechanical Properties of the Platinum Metals and their Alloys'''</caption><table class="twocolortable" border="1" cellspacing="0" style="border-collapse:collapse">
<tr>
<th rowspan="2">Material</th><th colspan="2">Tensile Strength [MPa]</th><th colspan="2">Elongation A [%]</th><th colspan="2">Vickers Hardness HV 1</th></tr>
*maximum hardness
<figtable id="figtab:Contact_and_Switching_Properties_of_the_Platinum_Metals_and_their_Alloys">
<table class="twocolortable">
<caption> '''<!--Table 2.9: -->Contact and Switching Properties of the Platinum Metals and their Alloys'''</caption>
<tr><th><p class="s11">Material</p></th><th><p class="s12">Properties<th colspan="2"></p></th></tr><tr><td><p class="s11">Pt</p></td><td><p class="s12">Very high corrosion resistance</p></td><td/></tr><tr><td><p class="s11">PtIr5 - 10</p></td><td><p class="s12">Very high corrosion resistance, low contact resistance</p></td><td><p class="s12">High arc erosion resistance, high hardness</p></td></tr><tr><td><p class="s11">PtRu10</p></td><td><p class="s12">Very high corrosion resistance, low welding tendency</p></td><td><p class="s12">Low contact resistance, very</p><p class="s12">high hardness</p></td></tr><tr><td><p class="s11">PtNi8</p></td><td><p class="s12">Low material transfer tendency</p></td><td><p class="s12">Very high hardness</p></td></tr><tr><td><p class="s11">PtW5</p></td><td><p class="s12">Low material transfer tendency</p></td><td><p class="s12">High hardness</p></td></tr><tr><td><p class="s11">Pd</p></td><td><p class="s12">Strong tendency to “Brown Powder” formation</p></td><td><p class="s12">Less arc erosion resistant than Pt</p></td></tr><tr><td><p class="s11">PdCu15</p><p class="s11">PdCu40</p></td><td><p class="s12">Tendency to “Brown Powder” formation</p></td><td><p class="s12">Mostly resistant to material</p><p class="s12">transfer, high hardness</p></td></tr><tr><td><p class="s11">PdNi5</p></td><td><p class="s12">Strong tendency to “Brown Powder” formation</p></td><td><p class="s12">Low welding tendency</p></td></tr><tr><td><p class="s11">Pd44Ag38Cu15</p><p class="s11">PtAuZn</p></td><td><p class="s12">High mechanical wear resistance</p></td><td><p class="s12">Standard material for sliding</p><p class="s12">contact brushes</p></td></tr></table>
</figtable>
<figtable id="fig:Application_Examples_and_Form_of_Supply_for_Platinum_Metals_and_their_Alloys">
<table class="twocolortable">
<caption>'''<!--Table 2.10: -->Application Examples and Form of Supply for Platinum Metals and their Alloys'''</caption><tr><th><p class="s11">Material</p></th><th><p class="s12">Application Examples</p></th><th><p class="s12">Forms of Supply</p></th></tr><tr><td><p class="s11">Pt (99,95)</p></td><td><p class="s12">Relays</p></td><td><p class="s12">Contact rivets, welded contact parts</p></td></tr><tr><td><p class="s11">PtIr5</p><p class="s11">PtIr10</p><p class="s11">PtRu10</p><p class="s11">PtNi8</p><p class="s11">PtW5</p></td><td><p class="s12">Relays, sliding contact systems,</p><p class="s12">automotive ignition breaker points</p></td><td><p class="s12">'''Semi-finished Contact Materials''':</p><p class="s12">Wire, seam-welded contact profiles</p><p class="s12">'''Contact Parts:'''</p><p class="s12">Tips, wire-formed parts, solid and composite contact rivets, welded contact parts</p></td></tr><tr><td><p class="s11">Pd (99,95)</p><p class="s11">PdNi5</p></td><td><p class="s12">Relays</p></td><td><p class="s12">Micro-profiles (weld tapes), contact rivets, welded contact parts</p></td></tr><tr><td><p class="s11">PdCu15</p><p class="s11">PdCu40</p></td><td><p class="s12">Automotive flasher relays</p></td><td><p class="s12">Micro-profiles, composite contact rivets</p></td></tr><tr><td><p class="s11">Pd35AuAgPt</p><p class="s11">Pd44Ag38Cu15</p><p class="s11">PtAuZn</p><p class="s11">Pd40Co40W20</p></td><td><p class="s12">Potentiometers, slip rings, miniature</p><p class="s12">DC motors</p></td><td><p class="s12">Wire-formed parts, welded wire segments, multi-arm sliding contact brushes</p></td></tr></table>
</figtable>
==References==
[[Contact Materials for Electrical Engineering#References|References]]
[[de:Werkstoffe_aus_Platin-Metallen]]