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.

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<figtable id="tab:Properties_Production_Processes_and_Application_Forms_for_Platinum_Metals"><caption>'''<!--Table 2. The metals osmium 6:-->Properties, Production Processes, and iridium have no practical applications in electrical contacts.Application Forms for Platinum Metals'''</caption>

Since Pd was for {| 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 longest time rather stable presence of oxygen resistant to acids,<br />oxidizes during heating in price it was looked air|Vapor deposition, sputtering, powder metallurgy,<br />warm-forming only possible at 1200 – 1500°C|Powder; in sheet form, as a substitute for the more expensive gold. This was followed by a steep increase coatings,<br />and as wire mostly as alloying component|-|Rh<br />Rhodium |Almost silvery white, very hard and brittle, not soluble in the Pd price which caused a significant reduction acids,<br />oxidizes in its use in electrical contacts. Today air during red anneal|Electroplating, vapor deposition, sputtering,<br />after warm-forming at 800 – 1000°C cold working is possible|Coatings (2011electroplated) the , alloying component,<br />in limited form as sheet and wire|-|Pd price again is lower than that of gold.<br />Palladium|Dull white, resistant to most acids,<br />oxidizes at red anneal|Electroplating, vapor deposition,<br />sputtering, cold workingAlloys of Pt with Ru|Sheet, strip, tubing, Irwire, Ni<br />rivets, and W were widely used in electromechanical components in the telecommunication industry 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 in heavy duty automotive breaker points brittle,<br />acid resistant, oxidizes at red anneal|Vapor deposition, sputtering, powder metallurgy,<xr id="tab:tab2.7"br />(Table 2.7).warm-forming possible at 1200 – 1500°C|Powder, alloying component,<figtable id="fig:Physical_Properties_of_the_Platinum_Metals_and_their_Alloys"br />in limited amounts as sheetTable 2.7: Physical Properties of the |-|Pt<br />Platinum Metals |Grey white, ductile, acid resistant except for aqua regia,<br />HBr, and their AlloysHJ, oxidation resistant at red anneal|Electroplating, vapor deposition,<br />sputtering, cold working|Sheet, strip, tubing, wire, rivets, coatings|}

Platinum and palladium alloys are mainly Rhodium is not used similar to the gold based materials in the form of welded wire and profile segments as a solid contact material but rarely is applied for example as a electroplated layer in sliding contact rivetssystems. Because of the high precious metal prices joining technologies are Ruthenium is mostly used that allow the most economic application of the contact alloy as an alloying component in the area where functionally needed. Because 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 (Table 2PdRu15.10). Multi-component alloys based on Pd with higher hardness The metals osmium and wear resistance are mainly used as spring arms iridium have no practical applications in sliding contact systems and DC miniature motorselectrical contacts.

<xr id="fig:Properties_Production_ProcessesSince Pd was for the longest time rather stable in price, it was seen as a substitute for the more expensive gold. This was followed by a steep increase in the Pd price,_and_Application_Forms_for_Platinum Metals"which caused a significant reduction in its use in electrical contacts. Today (Dec. 2021) the palladium price is around 2600 Euro/> Properties, Production Processes, and Application Forms for Platinum Metals 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="figtab:Physical_Properties_of_the_Platinum_Metals_and_their_Alloys"/> Physical Properties of the Platinum Metals and an their Alloys/>).

<xr figtable id="figtab:Mechanical_Properties_of_the_Platinum_Metals_and_their_AlloysPhysical Properties of the Platinum Metals an their Alloys"/><caption>'''<!--Table 2.87: Mechanical -->Physical Properties of the Platinum Metals and an their Alloys'''</caption>

<xr id{| class="twocolortable" style="figtext-align:Influence_of_1left; font-20_atom%_of_different_additive_metals_on_the_electrical_resistivit_ p_of_platinum_(Degussa)size: 12px"|-!Material!Platin/Palladium<br/>Content<br/>Influence of 1-20 atom[wt.% ]!Density<br/>[g/cm³]!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 different additive metals on the electrical resistivity p <br/>Electrical Resistance<br/>[10³/K]!modulus of platinum <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 (Degussa99,95)| >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>

Today these components have been replaced in many applications by solid state technology and the usage of these materials is greatly reduced. Pd alloys however have a more significant importance. PdCu15 is widely used, for example in automotive flasher relays. Because of their resistance to sulfide formation PdAg alloys are applied in various relay designs. With the ability to thermally precipitation harden some multi component alloys based on PdAgAuPt, they find special usage in wear resistant sliding contact applications. Pd44Ag38Cu15PtAuZn is a standard alloy in this group (<xr id="figtab:Phase_diagram_of_platinumMechanical_Properties_of_the_Platinum_Metals_and_their_Alloys"/><!--(Tab 2.8)-iridium-> and <xr id="tab:Contact_and_Switching_Properties_of_the_Platinum_Metals_and_their_Alloys"/>Fig<!--(Tab. 2.27: Phase diagram of platinum9)--iridium>).

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. 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. 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:Phase_diagram_of_platinum-nickelApplication_Examples_and_Form_of_Supply_for_Platinum_Metals_and_their_Alloys"/>Fig<!--(Table 2. 210)-->).28: Phase diagram of platinumMulti-nickelcomponent alloys based on Pd with higher hardness and wear resistance are mainly used as spring arms in sliding contact systems and DC miniature motors.

<xr figtable id="figtab:Phase_diagram_of_platinum-tungstenMechanical_Properties_of_the_Platinum_Metals_and_their_Alloys"/>Fig. <caption>'''<!--Table 2.298: Phase diagram -->Mechanical Properties of platinum-tungstenthe Platinum Metals and their Alloys'''</caption><table class="twocolortable"><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><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 (99,95)</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 (99,95)</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><tr><td>PdNi5</td><td>340</td><td>700</td><td>25</td><td>2</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>

<xr figtable id="figtab:Strain_hardening_of_Pt_by_cold_workingContact_and_Switching_Properties_of_the_Platinum_Metals_and_their_Alloys"><table class="twocolortable"/>Fig. <caption> '''<!--Table 2.319: Strain hardening -->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 by cold working</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>

<xr figtable id="fig:Softening_of_PtIr5_after_annealing_for_1_hr_after_different degrees_of_cold_workingApplication_Examples_and_Form_of_Supply_for_Platinum_Metals_and_their_Alloys"><table class="twocolortable"/>Fig. <caption>'''<!--Table 2.3410: Softening -->Application Examples and Form of PtIr5 after annealing Supply for 1 hr after different degrees of cold workingPlatinum Metals and their Alloys'''</caption><xr idtr><th><p class="fig:Strain_hardening_of_PtNi8_by_cold_workings11">Material</p></th><th>Fig. 2.35: Strain hardening of PtNi8 by cold working <xr idp class="fig:Softening_of_PtNi8_after_annealing_for_1_hr_after_80%_cold_workings12">Application Examples</p>Fig. 2.36: Softening </th><th><p class="s12">Forms of PtNi8 after annealing for 1 hr after 80% cold working Supply</p></th></tr><tr><td><xr idp class="fig:Strain_hardening_of_PtW5_by_cold_workings11">Pt (99,95)</p></td><td>Fig. 2.37: Strain hardening of PtW5 by cold working <xr idp class="fig:Softening_of_PtW5_after_annealing_for_1_hr_after_80%_cold_workings12">Relays</p></td><td>Fig. 2.38: Softening of PtW5 after annealing for 1hr after 80% cold working <xr idp class="fig:Strain_hardening_of_Pd_99.99_by_cold_workings12">Contact rivets, welded contact parts</p></td></tr><tr><td>Fig. 2.39: Strain hardening of Pd 99.99 by cold working <xr idp class="fig:Strain_hardening_of_PdCu15_by_cold_workings11">PtIr5</p>Fig. 2.40: Strain hardening of PdCu15 by cold working <xr idp class="fig:Softening_of_PdCu15_after_annealing_for_0.5_hrss11">PtIr10</p>Fig. 2.41: Softening of PdCu15 after annealing for 0.5 hrs <xr idp class="fig:Strain_hardening_of_PdCu40_by_cold_workings11">PtRu10</p>Fig. 2.42: Strain hardening of PdCu40 by cold working <xr idp class="fig:Softening_of_PdCu40_after_annealing_for_0.5_hrs_after_80%_cold_workings11">PtNi8</p>Fig. 2.43: Softening of PdCu40 after annealing for 0.5 hrs after 80% cold working <xr idp class="fig:Electrical_resistivity_p_of_PdCu_alloyss11">PtW5</p>Fig. 2.44: Electrical resistivity </td><td><p class="s12">Relays, sliding contact systems,</p of PdCu alloys with and without an annealing step for forming an ordered phase ><xr idp class="fig:Contact_and_Switching_Properties_of_the_Platinum_Metals_and_their_Alloyss12">automotive ignition breaker points</p></td><td><p class="s12">'''Table 2.9: Semi-finished Contact and Switching Properties of the Platinum Metals and their AlloysMaterials''' :</p><xr idp class="fig:Application_Examples_and_Form_of_Supply_for_Platinum_Metals_and_their_Alloyss12">Wire, seam-welded contact profiles</p><p class="s12">'''Table 2.10Contact Parts: Application Examples and Form of Supply for Platinum Metals and their Alloys'''</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>