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Created page with "The platinum group metals include the elements Pt, Pd, Rh, Ru, Ir, and Os ''(Table 2.6)''. For electrical contacts platinum and palladium have practical significance as base a..."
The platinum group metals include the elements Pt, Pd, Rh, Ru, Ir, and Os ''(Table
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.
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 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 ''(Table
2.7)''. 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.
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 ''(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.
Table 2.6: Properties, Production Processes, and Application Forms for Platinum Metals
Table 2.7: Physical Properties of the Platinum Metals and their Alloys
Table 2.8: Mechanical Properties of the Platinum Metals and their Alloys
Fig. 2.25:
Influence of 1-
20 atom% of
different additive
metals on the
electrical
resistivity p of
platinum
(Degussa)
Fig. 2.26:
Influence of 1-22 atom% of different
additive metals on the electrical
resistivity
p of palladium
Fig. 2.27:
Phase diagram of
platinum-iridium
Fig. 2.28:
Phase diagram of
platinum-nickel
Fig. 2.29:
Phase diagram
of platinum-tungsten
Fig. 2.30:
Phase diagram of
palladium-copper
Fig. 2.31:
Strain
hardening
of Pt by cold
working
Fig. 2.32:
Softening of Pt after
annealing for 0.5 hrs
after 80%
cold working
Fig. 2.33:
Strain hardening of PtIr5
by cold working
Fig. 2.34:
Softening of PtIr5 after annealing for 1 hr
after different degrees of cold working
Fig. 2.35:
Strain hardening
of PtNi8 by cold working
Fig. 2.36:
Softening of PtNi8 after
annealing
for 1 hr after
80% cold working
Fig. 2.37:
Strain hardening
of PtW5 by cold working
Fig. 2.38:
Softening
of PtW5 after
annealing for 1hr
after 80% cold
working
Fig. 2.39:
Strain hardening
of Pd 99.99 by cold working
Fig. 2.40:
Strain hardening
of PdCu15 by cold working
Fig. 2.41:
Softening
of PdCu15 after
annealing
for 0.5 hrs
Fig. 2.42:
Strain hardening
of PdCu40 by cold working
Fig. 2.43:
Softening
of PdCu40
after annealing
for 0.5 hrs after 80%
cold working
Fig. 2.44:
Electrical resistivity p
of PdCu alloys with and without an
annealing step for forming an ordered
phase
Table 2.9: Contact and Switching Properties
of the Platinum Metals and their Alloys
Table 2.10: Application Examples and Form
of Supply for Platinum Metals and their Alloys
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.
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 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 ''(Table
2.7)''. 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.
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 ''(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.
Table 2.6: Properties, Production Processes, and Application Forms for Platinum Metals
Table 2.7: Physical Properties of the Platinum Metals and their Alloys
Table 2.8: Mechanical Properties of the Platinum Metals and their Alloys
Fig. 2.25:
Influence of 1-
20 atom% of
different additive
metals on the
electrical
resistivity p of
platinum
(Degussa)
Fig. 2.26:
Influence of 1-22 atom% of different
additive metals on the electrical
resistivity
p of palladium
Fig. 2.27:
Phase diagram of
platinum-iridium
Fig. 2.28:
Phase diagram of
platinum-nickel
Fig. 2.29:
Phase diagram
of platinum-tungsten
Fig. 2.30:
Phase diagram of
palladium-copper
Fig. 2.31:
Strain
hardening
of Pt by cold
working
Fig. 2.32:
Softening of Pt after
annealing for 0.5 hrs
after 80%
cold working
Fig. 2.33:
Strain hardening of PtIr5
by cold working
Fig. 2.34:
Softening of PtIr5 after annealing for 1 hr
after different degrees of cold working
Fig. 2.35:
Strain hardening
of PtNi8 by cold working
Fig. 2.36:
Softening of PtNi8 after
annealing
for 1 hr after
80% cold working
Fig. 2.37:
Strain hardening
of PtW5 by cold working
Fig. 2.38:
Softening
of PtW5 after
annealing for 1hr
after 80% cold
working
Fig. 2.39:
Strain hardening
of Pd 99.99 by cold working
Fig. 2.40:
Strain hardening
of PdCu15 by cold working
Fig. 2.41:
Softening
of PdCu15 after
annealing
for 0.5 hrs
Fig. 2.42:
Strain hardening
of PdCu40 by cold working
Fig. 2.43:
Softening
of PdCu40
after annealing
for 0.5 hrs after 80%
cold working
Fig. 2.44:
Electrical resistivity p
of PdCu alloys with and without an
annealing step for forming an ordered
phase
Table 2.9: Contact and Switching Properties
of the Platinum Metals and their Alloys
Table 2.10: Application Examples and Form
of Supply for Platinum Metals and their Alloys