Platinum-Rhodium Thermocouple
A temperature-sensing device built by pairing a pure platinum wire with a platinum-rhodium alloy wire. The pairing can measure furnace and kiln temperatures up to about 1,800 degrees Celsius (3,270 degrees Fahrenheit).
Covered in 1 MetalsCost.com News Intelligence article, most recently on August 25, 2026.
Overview
A platinum-rhodium thermocouple pairs a pure platinum wire with a platinum-rhodium alloy wire (or two different rhodium-content alloys, for Type B), generating a small voltage proportional to temperature at the junction. The three standard types — S, R and B — differ mainly in rhodium content and usable range, with Type B's higher rhodium loading giving it the highest ceiling, up to roughly 1800°C, while all three read at only about 10 microvolts per degree, far less sensitive than base-metal types but far more stable at extreme heat.
Industrial Uses
These thermocouples are the standard choice wherever base-metal types would melt or degrade: steel and glass furnaces, cement kilns, ceramics firing, and other processes running above roughly 1200°C. Their precious-metal construction makes them costly compared with base-metal alternatives, so they're generally reserved for applications that genuinely need the extended range rather than used as a default industrial sensor.
