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Wollaston Platinum/Rhodium Alloy Spooled Wire (Pt90/Rh10)
Available Configurations
Properties common to all products in this list
| Core Diameter | Outside Diameter | Cladding | Length | Thermocouple Compatibility |
|---|---|---|---|---|
| 0.0025 mm to 0.006 mm | 0.025 mm to 0.1 mm | Silver | 0.05 m to 7.62 m | Type S (+) |
Need custom configurations? Please contact us.
Key Features
Wollaston Platinum/Rhodium Alloy Spooled Wire (Pt90/Rh10) is a composite wire in which an ultra-fine Pt-10%Rh alloy core is encased in silver cladding, enabling alloy sensing elements at diameters unreachable by conventional drawing:
Ultra-Fine Alloy Core Enabled by Silver Cladding
The silver cladding provides mechanical support during drawing, allowing the Pt-10%Rh core to reach diameters finer than conventional alloy drawing permits. The cladding is selectively etched away with dilute nitric acid over the active sensing length, releasing the alloy core as a dimensionally precize, free-standing element.
Type S Thermocouple Positive Leg Compatibility
The Pt-10%Rh composition carries Type S (+) thermocouple compatibility, making this wire the positive-leg counterpart to Wollaston pure platinum wire for fabricating ultra-miniaturized Type S thermocouple junctions.
Greater Strength and Creep Resistance Than Pure Platinum
The rhodium addition gives the alloy core greater mechanical strength and creep resistance than pure platinum at elevated temperatures. Under repeated thermal cycling, the alloy core maintains its dimensional stability more reliably than a pure platinum element of equivalent fineness.
Retained Noble Metal Stability and Chemical Inertness
Chemical inertness, oxidation resistance, and consistent electrical properties are retained across the alloy’s application range. The Pt-Rh composition provides catalytic activity in oxidation and combustion reactions alongside its sensing and thermometry roles.
Well-Characterized Electrical Properties at Sub-Millimeter Scale
The alloy core retains well-characterized electrical and thermal properties at the scales achievable through the Wollaston process, supporting its use in high-temperature resistance elements and miniaturized electrode structures where conventional drawing cannot reach the required dimensions.
Industrial Applications
Wollaston Platinum/Rhodium Alloy Spooled Wire (Pt90/Rh10) is used wherever the mechanical advantages of the Pt-Rh alloy are needed at sensing element dimensions unreachable by conventional wire drawing:
- ✦ Ultra-Miniaturized Type S Thermocouple Positive Leg Fabrication
- Used to fabricate the Pt-10%Rh positive leg of ultra-miniaturized Type S thermocouple junctions for surface temperature measurement, thin-film thermometry, and precision sensing in constrained geometries. Paired with Wollaston pure platinum wire as the negative leg.
- ✦ Hot-Wire Anemometry Probes Requiring Enhanced Durability
- Applied in hot-wire anemometry probes where dimensional stability of the sensing element under repeated thermal cycling is a priority. The rhodium content provides greater creep resistance than pure platinum at elevated operating temperatures, extending probe service life compared with Wollaston pure platinum wire.
- ✦ High-Temperature Resistance Elements at Miniature Scale
- Used as miniaturized high-temperature resistance elements in instrumentation where the alloy’s elevated mechanical strength and stable electrical properties support accurate, long-term measurement at temperatures beyond the range suitable for pure platinum elements of equivalent fineness.
- ✦ Catalytic Wire Substrates at Micro-Scale
- Applied as catalytic wire substrates in gas-phase reaction studies and combustion research at the micro-scale, where the Pt-Rh composition provides catalytic activity and the mechanical integrity to survive repeated high-temperature thermal cycling.
- ✦ Miniaturized Electrode Structures in Analytical Instrumentation
- Used in miniaturized electrode structures for analytical and research instrumentation where noble metal stability, chemical inertness, and consistent electrical properties are required at dimensions incompatible with conventionally drawn alloy wire.
Material Properties
| Element | Value |
|---|---|
| Hardness - Brinell | 90-165 |
| Elongation at break( % ) | 35 |
| Tensile strength( MPa ) | 320-620 |
| Element | Value |
|---|---|
| Electrical resistivity( µOhmcm ) | 18.4-19.2 |
| Temperature coefficient( K⁻¹ ) | 0.0017 |
| Element | Value |
|---|---|
| Melting point( C ) | 1830-1855 |
| Thermal conductivity( W m⁻¹ K⁻¹ ) | 38@23°C |
| Element | Value |
|---|---|
| Density( gcm⁻³ ) | 19.97 |
Tolerances
| Diameter | ±10% | |
|---|---|---|
| Length | +5% / -1% |