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The platinum group metals include the elements Pt, Pd, Rh, Ru, Ir, and Os ''(Table <xr id="tab:Properties_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:Properties_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"|-!Element !Properties!Processing!Forms of Application|-|Ru<br />Ruthenium|Dull grey to silvery white, very hard and brittle,<br />in the presence of oxygen resistant to acids,<br />oxidizes during heating in air|Vapor deposition, sputtering, powder metallurgy,<br />warm-forming only possible at 1200 – 1500°C|Powder; in sheet form, as coatings,<br />and as wire mostly as alloying component|-|Rh<br />Rhodium |Almost silvery white, very hard and brittle, not soluble in acids,<br />oxidizes in air during red anneal|Electroplating, vapor deposition, sputtering,<br />after warm-forming at 800 – 1000°C cold working is possible|Coatings (electroplated), alloying component,<br />in limited form as sheet and wire|-|Pd<br />Palladium|Dull white, resistant to most acids,<br />oxidizes at red anneal|Electroplating, vapor deposition,<br />sputtering, cold working|Sheet, strip, tubing, wire,<br />rivets, and coatings|-|Os<br />Osmium|Bluish white, hardest platinum metal,<br />very brittle, resistant against non-oxidizing acids,<br />oxidizes easily on air|Powder metallurgy|Powder, alloying component|-|Ir<br />Iridium|Almost silvery white, very hard and brittle,<br />acid resistant, oxidizes at red anneal|Vapor deposition, sputtering, powder metallurgy,<br />warm-forming possible at 1200 – 1500°C|Powder, alloying component,<br />in limited amounts as sheet|-|Pt<br />Platinum|Grey white, ductile, acid resistant except for aqua regia,<br />HBr, and HJ, oxidation resistant at red anneal|Electroplating, vapor deposition,<br />sputtering, cold working|Sheet, strip, tubing, wire, rivets, coatings|}</figtable>
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 around 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 the Platinum Metals an their Alloys/>). <figtable id="tab:Physical Properties of the Platinum Metals an their Alloys"><caption>'''<!--Table 2.7:-->Physical Properties of the Platinum Metals 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/>[10<sup>3</sup>/K]!modulus of gold<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.1800|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|9,3|72|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>
Platinum and palladium alloys are mainly used similar to the gold based materials in the form of welded wire and profile segments but rarely as contact rivets. Because of Due to the high precious metal prices , joining technologies are used , that allow the most economic application of the contact alloy in the area where functionally needed. Because For reason of their resistance to material transfer they are used for DC applications and due to their higher arc erosion resistance , they are applied for medium electrical loads up to about 30W in relays and switches ''(<xr id="fig:Application_Examples_and_Form_of_Supply_for_Platinum_Metals_and_their_Alloys"/><!--(Table 2.10)''-->). Multi-component alloys based on Pd with higher hardness and wear resistance are mainly used as spring arms in sliding contact systems and DC miniature motors.
<figtable id="tab:Mechanical_Properties_of_the_Platinum_Metals_and_their_Alloys"><caption>'''<!--Table 2.68: -->Mechanical Properties, Production Processes, and Application Forms for of the Platinum Metalsand their Alloys'''</caption><table class="twocolortable"><tr><th rowspan="2">Material</th><th colspan="2">Tensile Strength [MPa]</th><th colspan="2">Elongation A [File:Properties production platinum metals.jpg|right|thumb|Properties%]</th><th colspan="2">Vickers Hardness HV 1</th></tr><tr><th>soft</th><th>70% cold worket</th><th>soft</th><th>70% cold worket</th><th>soft</th><th>70% cold worket</th></tr><tr><td>Pt (99, Production Processes95)</td><td>150</td><td>360</td><td>40</td><td>3</td><td>40</td><td>120</td></tr><tr><td>PtIr5</td><td>260</td><td>550</td><td>25</td><td>2</td><td>85</td><td>160</td></tr><tr><td>PtIr10</td><td>340</td><td>570</td><td>24</td><td>2</td><td>105</td><td>210</td></tr><tr><td>PtRu10</td><td>650</td><td>1000</td><td>24</td><td>2</td><td>195</td><td>320</td></tr><tr><td>PtNi8</td><td>640</td><td>950</td><td>22</td><td>2</td><td>200</td><td>320</td></tr><tr><td>PtW5</td><td>530</td><td>860</td><td>21</td><td>2</td><td>150</td><td>270</td></tr><tr><td>Pd (99, and Application Forms for Platinum Metals]]95)</td><td>200</td><td>420</td><td>42</td><td>2</td><td>40</td><td>90</td></tr><tr><td>PdCu15</td><td>400</td><td>780</td><td>38</td><td>2</td><td>90</td><td>220</td></tr><tr><td>PdCu40</td><td>550</td><td>950</td><td>35</td><td>2</td><td>120</td><td>260</td></tr>Table <tr><td>PdNi5</td><td>340</td><td>700</td><td>25</td><td>2.7: Physical Properties of the Platinum Metals and their Alloys</td><td>95</td><td>200</td></tr><tr><td>Pd35AuAgPt</td><td></td><td></td><td></td><td></td><td></td><td>420*</td></tr><tr><td>Pd44Ag38Cu15 PtAuZn</td><td/><td/><td/><td/><td/><td>405*</td></tr><tr><td>Pd40Co40W20</td><td/><td/><td/><td/><td/><td>680*</td></tr></table></figtable>
<table borderfigtable id="1" cellspacing="0" style="border-collapsetab:collapseContact_and_Switching_Properties_of_the_Platinum_Metals_and_their_Alloys"><tr><td/><td><p table class="s11twocolortable">soft</pcaption>'''</td><td><p class="s11"!--Table 2.9:-->70% cold worketContact and Switching Properties of the Platinum Metals and their Alloys'''</pcaption></tdtr><tdth><p class="s11">softMaterial</p></tdth><tdth><p class="s11s12">70% cold</p>Properties<p classth colspan="s11">worket</p></td><td><p class="s11">soft</p></td><td><p class="s11">70% cold</p><p class="s112">worket</p></tdth></tr><tr><td><p class="s11">Pt (99,95)</p></td><td><p class="s11">150</p></td><td><p class="s11">360</p></td><td><p class="s11">40</p></td><td><p class="s11">3</p></td><td><p class="s11s12">40Very high corrosion resistance</p></td><td><p class="s11">120</p></td></tr><tr><td><p class="s11">PtIr5- 10</p></td><td><p class="s11s12">260Very high corrosion resistance, low contact resistance</p></td><td><p class="s11s12">550</p></td><td><p class="s11">25</p></td><td><p class="s11">2</p></td><td><p class="s11">85</p></td><td><p class="s11">160</p></td></tr><tr><td><p class="s11">PtIr10</p></td><td><p class="s11">340</p></td><td><p class="s11">570</p></td><td><p class="s11">24</p></td><td><p class="s11">2</p></td><td><p class="s11">105</p></td><td><p class="s11">210High arc erosion resistance, high hardness</p></td></tr><tr><td><p class="s11">PtRu10</p></td><td><p class="s11s12">650Very high corrosion resistance, low welding tendency</p></td><td><p class="s11s12">1000Low contact resistance, very</p></td><td><p class="s11s12">24</p></td><td><p class="s11">2</p></td><td><p class="s11">195</p></td><td><p class="s11">320high hardness</p></td></tr><tr><td><p class="s11">PtNi8</p></td><td><p class="s11s12">640Low material transfer tendency</p></td><td><p class="s11s12">950</p></td><td><p class="s11">22</p></td><td><p class="s11">2</p></td><td><p class="s11">200</p></td><td><p class="s11">320Very high hardness</p></td></tr><tr><td><p class="s11">PtW5</p></td><td><p class="s11s12">530Low material transfer tendency</p></td><td><p class="s11s12">860</p></td><td><p class="s11">21</p></td><td><p class="s11">2</p></td><td><p class="s11">150</p></td><td><p class="s11">270High hardness</p></td></tr><tr><td><p class="s11">Pd (99,95)</p></td><td><p class="s11s12">200Strong tendency to “Brown Powder” formation</p></td><td><p class="s11s12">420</p></td><td><p class="s11">42</p></td><td><p class="s11">2</p></td><td><p class="s11">40</p></td><td><p class="s11">90Less arc erosion resistant than Pt</p></td></tr><tr><td><p class="s11">PdCu15</p></td><td><p class="s11">400</p></td><td><p class="s11">780</p></td><td><p class="s11">38</p></td><td><p class="s11">2</p></td><td><p class="s11">90</p></td><td><p class="s11">220</p></td></tr><tr><td><p class="s11">PdCu40</p></td><td><p class="s11s12">550Tendency to “Brown Powder” formation</p></td><td><p class="s11s12">950Mostly resistant to material</p></td><td><p class="s11s12">35</p></td><td><p class="s11">2</p></td><td><p class="s11">120</p></td><td><p class="s11">260transfer, high hardness</p></td></tr><tr><td><p class="s11">PdNi5</p><p class="s11">Pd35AuAgPt</p></td><td><p class="s11">340</p></td><td><p class="s11">700</p></td><td><p class="s11s12">25Strong tendency to “Brown Powder” formation</p></td><td><p class="s11s12">2</p></td><td><p class="s11">95</p></td><td><p class="s11">200</p><p class="s11">420*Low welding tendency</p></td></tr><tr><td><p class="s11">Pd44Ag38Cu15</p></td><td/><td/><td/><td/><td/><td><p class="s11">405*PtAuZn</p></td></tr><tr><td><p class="s11s12">PtAuZnHigh mechanical wear resistance</p><p class="s11">Pd40Co40W20</p></td><td/><td/><td/><td/><td/><td><p class="s11s12">680*Standard material for sliding</p></td></tr><tr><td><p class="s31s12">*maximum hardnesscontact brushes</p></td><td/tr><td/table><td/><td/><td/><td/></tr></tablefigtable>
<figure id="fig:Phase_diagram_of_platinum-iridium">[[File:Phase diagram of platinum iridium.jpg|left|thumb|<caption>Fig. 2.3427: Softening of PtIr5 after annealing for 1 hr after different degrees Phase diagram of cold workingplatinum-iridium</caption>]]</figure>
<figure id="fig:Phase_diagram_of_platinum-nickel">[[File:Phase diagram of platinum nickel.jpg|left|thumb|<caption>Fig. 2.3528: Strain hardening Phase diagram of PtNi8 by cold workingplatinum-nickel</caption>]]</figure>
<figure id="fig:Phase_diagram_of_platinum-tungsten">[[File:Phase diagram of palladium copper.jpg|left|thumb|<caption>Fig. 2.3629: Softening Phase diagram of PtNi8 after annealing for 1 hr after 80% cold workingplatinum-tungsten</caption>]]</figure>
<figure id="fig:Phase_diagram_of_platinum-copper">[[File:Phase diagram of palladium copper2.jpg|left|thumb|<caption>Fig. 2.3730: Strain hardening Phase diagram of PtW5 by cold workingpalladium-copper</caption>]]</figure>
<figure id="fig:Strain_hardening_of_Pt_by_cold_working">[[File:Strain hardening of Pt by cold working.jpg|left|thumb|<caption>Fig. 2.3831: Softening Strain hardening of PtW5 after annealing for 1hr after 80% Pt by cold working</caption>]]</figure>
<figure id="fig:Softening_of_Pt_after_annealing_for_0.5_hrs_after_80%_cold_working">[[File:Softening of Pt after annealing.jpg|left|thumb|<caption>Fig. 2.3932: Strain hardening Softening of Pd 99Pt after annealing for 0.99 by 5 hrs after 80% cold working</caption>]]</figure>
<figure id="fig:Strain_hardening_of_PtIr5_by_cold_working">[[File:Strain hardening of PtIr5 by cold working.jpg|left|thumb|<caption>Fig. 2.4033: Strain hardening of PdCu15 PtIr5 by cold working</caption>]]</figure>
<figure id="fig:Softening_of_PtIr5_after_annealing_for_1_hr_after_different degrees_of_cold_working">[[File:Softening of PtIr5 after annealing.jpg|left|thumb|<caption>Fig. 2.4134: Softening of PdCu15 PtIr5 after annealing for 0.5 hrs1 hr after different degrees of cold working</caption>]]</figure>
<figure id="fig:Strain_hardening_of_PtNi8_by_cold_working">[[File:Strain hardening of PtNi8 by cold working.jpg|left|thumb|<caption>Fig. 2.4235: Strain hardening of PdCu40 PtNi8 by cold working</caption>]]</figure>
<figure id="fig:Softening_of_PtNi8_after_annealing_for_1_hr_after_80%_cold_working">[[File:Softening of PtNi8 after annealing.jpg|left|thumb|<caption>Fig. 2.4336: Softening of PdCu40 PtNi8 after annealing for 0.5 hrs 1 hr after 80% cold working</caption>]]</figure>
<figure id="fig:Strain_hardening_of_PtW5_by_cold_working">[[File:Strain hardening of PtW5 by cold working.jpg|left|thumb|<caption>Fig. 2.4437: Electrical resistivity p Strain hardening of PdCu alloys with and without an annealing step for forming an ordered phasePtW5 by cold working</caption>]]</figure>
==References==
[[Contact Materials for Electrical Engineering#References|References]]
[[de:Werkstoffe_aus_Platin-Metallen]]