210
edits
Changes
no edit summary
The platinum group metals include the elements Pt, Pd, Rh, Ru, Ir, and Os <xr id="tab:Properties, Production Processes, and Application Forms for Platinum MetalsProperties_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 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 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 MetalsProperties_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"
Since Pd was for the longest time rather stable in price it was looked at 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 (2011) the Pd price again is lower than that of gold.
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"/> <!--(Tab. 2.7)-->.
<figtable id="tab:Physical Properties of platinum metals">
[[File:Physical Properties of platinum metals.jpg|right|thumb|Physical Properties of the Platinum Metals and their Alloys]]
</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. 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:Mechanical_Properties_of_the_Platinum_Metals_and_their_Alloys"/> <!--(Tab 2.8) --> und <xr id="figtab:Contact_and_Switching_Properties_of_the_Platinum_Metals_and_their_Alloys"/> <!--(Tab. 2.9)-->
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 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 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 2.8: -->Mechanical Properties of the Platinum Metals and their Alloys''' <figtable id="fig:Mechanical_Properties_of_the_Platinum_Metals_and_their_Alloys"/caption>
<table class="twocolortable">
<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]]
