Use of platinum in glass industries today is very vital as platinum is only metal which is un wetted to glass, so to improve the life of the assemblies which are in direct contact with molten glass platinum is essentially used.
In this paper we will discuss about an alloy of platinum (called hardened platinum) which is specially developed to be used in molten glass temperature measurement with thermocouples
Platinum Thimbles For Thermocouples
Hardened Platinum Material (Grain Stabilized Platinum)
Thimbles made of special platinum alloy containing 10% Rhodium with small% of Zirconium oxide or yttrium oxide (as grain stabilizer), are developed specially for the application in glass industries.
Theses materials offer significantly improved performance over conventional platinum and its alloys.
It is a new class of materials and has optimized it for special applications:
- High strength with good ductility in the high temperature range (up to1700°C).
- Excellent weld ability while the strength is
- Exceptional corrosion resistance and a more stable microstructure over longer service times.
- Less-re-crystallization.
These characteristics allow for longer service lives for the individual components and permit the precious metals to be used more economically, for instance through reduced wall thicknesses. The higher strength of the material also has a stabilizing effect
on the equipment manufactured from it. Strengthening components of e. g. molybdenum, ceramics or refractory metals thus become effectively redundant. The inclusion of finely distributed zirconia as a dispersion impedes grain growth to a temperature just below the melting point. Due to the modified, finer microstructure, it is considerably less sensitive to corrosion processes along the grain boundaries than comparable materials. This ensures better corrosion resistance.
| Material | Density g/cm3 | Melting
Point or solidus Temperature °C |
Vickers hardness | Stress repture strength
(100 h / 1400°C) N/mm2 |
(100h / 1600°C)
N/mm2 |
| Pt | 21.4 | 1772 | 45 | < 1 | – |
| Pt-10Rh | 19.9 | 1840 | 95 | 5 | 2.8 |
| Pt (Hardened) | 21.3 | 1772 | 72 | 25 | – |
| Pt-5Au (Hardened) | 21.3 | 1675 | 115 | 5 | – |
| Pt-10Rh (Hardened) | 19.9 | 1840 | 150 | 40 | 17.0 |
