Platinum-Rhodium Pt80/Rh20 wire, composed of 80% platinum and 20% rhodium, represents the premium thermocouple and high-temperature catalyst material combining exceptional thermal stability, chemical inertness, and precise thermoelectric properties. This noble metal alloy serves as the industry standard for Type R thermocouples and finds critical applications in glass manufacturing, aerospace, and catalytic processes requiring reliable performance above 1400°C.
Material Overview
Pt80/Rh20 exhibits melting point of approximately 1825°C, significantly higher than pure platinum (1768°C), with rhodium additions enhancing mechanical strength and oxidation resistance [1]. The alloy demonstrates exceptional chemical inertness to most molten metals, glasses, and corrosive atmospheres, enabling long-term service in harsh environments. When paired with pure platinum in Type R thermocouples, Pt80/Rh20 provides thermoelectric output of approximately 6 μV/°C at 100°C, with stable, reproducible performance across the temperature range of 0-1600°C [2]. Electrical resistivity is approximately 19 μΩ·cm at room temperature, while thermal conductivity reaches 47 W/(m·K). The material exhibits excellent high-temperature mechanical strength with minimal creep at operating temperatures [3]. Density is 19.9 g/cm3, with thermal expansion coefficient of 9.1 × 10−6/°C. The alloy resists contamination and maintains calibration accuracy over extended periods, critical for precision temperature measurement [1].
Applications and Advantages
Platinum-rhodium wire serves as the positive leg in Type R and Type S thermocouples, providing accurate temperature measurement in steel manufacturing, glass production, ceramic firing, and heat treatment processes [2]. The material functions as catalyst wire in ammonia oxidation for nitric acid production, where its selectivity and durability surpass alternative catalysts. High-temperature furnace windings and heating elements utilize Pt-Rh alloys for contamination-free heating in semiconductor processing and materials research [4]. Aerospace applications include turbine temperature sensors and combustion monitoring systems requiring reliable performance under extreme conditions. Laboratory crucibles and sample holders fabricated from Pt-Rh wire resist chemical attack during high-temperature analytical procedures. The alloy serves in spark plug electrodes for specialized engines and ignition systems demanding long service life [3]. Glass fiber production employs Pt-Rh bushings and spinnerets that maintain dimensional stability while resisting molten glass corrosion. Its biocompatibility enables use in medical implants and electrodes for neural stimulation and cardiac pacing applications.
Goodfellow Availability
Goodfellow supplies Platinum-Rhodium Pt80/Rh20 wire in various diameters to meet thermocouple, catalyst, and high-temperature application requirements. Custom dimensions are available to support specialized research and industrial needs.
Explore Platinum-Rhodium wire and other advanced materials in Goodfellow's online catalogue: Goodfellow product finder.
References
- [1] Darling, A. S. (1961). Platinum-rhodium alloys. Platinum Metals Review, 5(2), 58-64.
- [2] Burns, G. W., Scroger, M. G., Strouse, G. F., et al. (1993). Temperature-Electromotive Force Reference Functions and Tables for the Letter-Designated Thermocouple Types Based on the ITS-90. NIST Monograph 175. https://doi.org/10.6028/NIST.MONO.175
- [3] Chaston, J. C. (1964). The oxidation of the platinum metals. Platinum Metals Review, 8(2), 50-54.
- [4] Weast, R. C. (Ed.). (1984). CRC Handbook of Chemistry and Physics (64th ed.). CRC Press.