Platinum/Rhodium Wire - Material Information

The Platinum/Rhodium (Pt87/Rh13) alloy is a high-performance material engineered for extreme-temperature applications such as thermocouples, furnaces, and chemical reactors. Its excellent thermal stability, corrosion resistance, and electrical precision make it one of the most reliable materials for temperature measurement up to 1750 °C. This wire composition corresponds to the positive leg of a Type R thermocouple, combining platinum’s inertness with rhodium’s strength and oxidation resistance.

Material Overview

The Pt–Rh alloy system exhibits a continuous solid solution, and at 13 wt% Rh, the material maintains platinum’s fcc crystal structure with improved tensile and creep resistance. The melting point is approximately 1850 °C, and the resistivity at 20 °C is around 10.8 µ?·cm. Rhodium enhances both mechanical durability and oxidation resistance, mitigating platinum grain growth during prolonged exposure at high temperatures. Recent studies by Pearce et al. (2020) demonstrated that dopants like zirconium or yttrium can further increase the long-term stability and reduce drift by forming inert oxide dispersions within the platinum matrix. These oxide particles restrict grain coarsening and preserve the alloy’s electromotive consistency under cyclic heating conditions.

Applications and Advantages

Pt87/Rh13 wire is primarily used as the positive element in Type R thermocouples for precision temperature measurement in glass manufacturing, steel casting, and aerospace testing. The alloy offers reproducible thermoelectric output across repeated thermal cycles and maintains Class 1 IEC tolerance (±1 °C at 1000 °C). According to Wu and Liu (1997), Pt–Rh thermocouples exhibit service lives 1.5–2× longer than conventional platinum wires and greater resistance to contamination. Newer oxide-reinforced Pt–Rh composites (Chen et al., 2019) achieve superior creep strength and electrical homogeneity, extending operational lifetimes in molten metal and high-vacuum environments. These properties make Pt87/Rh13 indispensable in scientific instrumentation, calibration standards, and high-precision thermal monitoring systems.

Goodfellow Availability

Goodfellow provides high-purity Platinum/Rhodium (Pt87/Rh13) wire suitable for thermocouple and high-temperature applications. Custom diameters and research-grade configurations are available. Explore Platinum/Rhodium wire and other noble metal alloys through the Goodfellow product finder.

References

• Pearce, J. V., Tucker, D., Rawal, R., & Hutton, L. (2020). Stability assessment of a new high-strength, high-temperature Type R and S thermocouple. Measurement Science and Technology, 31(1), 015004. https://doi.org/10.1088/1361-6501/ab48bd
• Wu, B., & Liu, G. (1997). Platinum: Platinum-Rhodium Thermocouple Wire. Platinum Metals Review, 41(2), 81–85. https://doi.org/10.1595/003214097x4128185
• Wu, B., et al. (2014). Platinum-rhodium thermocouple fine wire material for measuring temperature of molten steel and preparation method thereof. Patent Publication.
• Chen, S., Xie, M., Wang, S., et al. (2019). Preparation method of oxide-reinforced platinum-rhodium-based composite wire. Patent Publication.