Platinum & Palladium Alloys
| The platinum family (platinum, palladium, ruthenium, iridium, osmium and rhodium) is one of the most important to the contact user. These materials and their alloys display exceptional qualities as they have high corrosion resistance, high resistance to arc erosion and a high melting point. The alloys of this family are very hard. Hence, they have good mechanical wear ability. When used in the proper applications, the platinum metals provide years of successful operation, but they have their limits. Due to fairly low conductivity, these materials are limited to light current applications, usually under five amperes. Another consideration is their cost which is relatively high in comparison with silver base materials. To secure a reasonable cost relationship, these materials are normally furnished as composite contacts with a nickel-plated backing. Some platinum materials, because of their lack of ductility, must be supplied as composites.
DMC-202 (99.9% minimum platinum) has excellent properties and is one of the most noble contact materials. It is used in high reliability, low force, low current level applications. It can be supplied in all conventional contact shapes. Platinum is relatively soft. Dramatic gains in hardness can be achieved by the addition of iridium. Deringer materials DMC-213 (95% platinum, 5% iridium), DMC-205 (90% platinum, 10% iridium), DMC-214 (85% platinum, 15% iridium) and DMC-260 (80% platinum, 20% iridium) clearly demonstrate this gain. In addition to the gain in hardness, other benefits include higher melting temperature and greater resistance to transfer. DMC-213 and DMC-205 are headable, but DMC-214 and DMC-260 must be used as composites. Again, these alloys are used in low current applications where the contact user desires greater mechanical wearability. Another platinum alloy group is arrived at by the addition of ruthenium. DMC-201 (95% platinum, 5% ruthenium) and DMC-227 (89% platinum, 11% ruthenium) are typical. Here, too there is a great increase in material hardness. Ruthenium achieves the same increase in hardness at twice the rate of iridium and, being a less expensive material, this group of materials will be somewhat more economical. The characteristics of the platinum ruthenium materials are the same as platinum iridium, and the end uses are also the same. DMC-201 is headable; DMC-227 is not. DMC-100 (99.9% minimum palladium) can, in certain applications, replace DMC-202 (99.9%) minimum platinum). Since at the present time palladium costs much less than platinum, it finds wide application in low current level operations. Typical of these are telephone relays and sensitive gages. DMC-100 is ductile, and is available in all the contact forms. There are several palladium ruthenium alloys. DMC-208 (95% palladium, 5% ruthenium) and DMC-102 (90% palladium, 10% ruthenium) are typical of these. As with the platinum alloys, the addition of ruthenium increases the hardness of palladium. These alloys are resistant to tarnishing, and, of course, are much less costly than platinum ruthenium materials. Palladium ruthenium alloys are often used instead of DMC-100 when the application requires more resistance to wear. DMC-262 (72% palladium, 26% silver, 2% nickel) exhibits excellent hardness, is more economical than most palladium alloys, and still retains the ability to resist sulphide tarnishing. This material is used in low current A.C. and D.C. applications. It is headable within a reasonable design range.* DMC-30 (60% palladium, 40% silver) is an alloy containing the maximum amount of silver that will retain protection from silver sulphide tarnish. It is used in low current applications, and provides a cost saving over the higher percentage platinums and palladiums. As with DMC-262, it is headable within a limited range. Properties Of Platinum, Palladium and Their Alloys 
* Refer to Engineering Data, |