With the strongly acidic alloy electrolyte PLATUNA®-Alloy RH, smooth, bright and crack-free platinum-rhodium coatings can be deposited up to a layer thickness of 0.5 μm. The...
Abrasion-resistant platinum-rhodium layers for sparkling jewelry
With the strongly acidic alloy electrolyte PLATUNA®-Alloy RH, smooth, bright and crack-free platinum-rhodium coatings can be deposited up to a layer thickness of 0.5 μm. The deposited coatings are characterized by a brilliant luster and, in contrast to conventional platinum coatings, do not exhibit a yellow tint.
An important advantage of the coating is the high hardness due to the rhodium content. Furthermore, the electrolyte has a low sulfuric acid content and is therefore less aggressive to the coating substrate. The deposition rate is independent of the current density, which leads to an optimum layer thickness distribution. No precipitation occurs and the platinum concentrate does not have to be stored in the refrigerator.
Electrolytes Characteristics
| Electrolyte type | Strongly acidic |
| Metal content | 1.2 (0.8 - 1.6) g/l Pt, 0.3 (0.2 - 0.4) g/l Rh |
| pH value | < 1 |
| Operating temperature | 60 (55 - 65) °C |
| Current density range | 5 (0.5 - 10) A/dm² |
| Plating speed | approx. 0.12 μm/min at 5 A/dm² |
| Deposition rate | approx. 4.7 mg/Amin at 5 A/dm² |
Coating Characteristics
| Coating | Platinum rhodium |
| Alloy composition | approx. 80 % Pt, approx. 20 % Rh |
| Colour of deposit | White |
| Brightness | Bright, brilliant |
| Hardness | not measurable, approx. 600 HV |
| Max. coating thickness | approx. 0.5 μm |
| Density of the coating | approx. 18.7 g/cm³ |
Advantages
- Excellent brillance without yellow tint
- Longer durability
- High abrasion resistance
- Current density independent
- Easy handling - no cold storage and no precipitation
Applications
- Jewelry
- Watches
- Writing implements
- Spectacles frames
- Bathroom fittings
