Platinised Titanium Anodes
Platinised titanium anodes are recommended for use in the following
- Precious metal electroplating - e.g. Au, Pt, Pd, Rh and Ru baths
- Non-ferrous metal electroplating - e.g. Ni, Cu, Sn, Zn and non-fluoride
Platinised titanium anodes consist of a titanium base, in the form of either expanded metal, sheet, rod, wire or tube with a thin coating of platinum between 2 to 5 microns thick. They posses the electrochemical properties of platinum. The titanium used is 99.5% pure titanium as established by ASTM (American Society of Metal).
Platinum coatings in the range of 2 to 5 microns are not completely impervious, whatever the process by which they are applied. This is particularly the case with expanded metals where acute angles of the diamond mesh result in minimum coverage.
Schloetter recommend 2.5 micron coating as this gives longer life and minimises any porosity pinholes. We try to avoid 1 to 1.5 microns coating as this can cause problems with pinholes, etc. If you use 7 to 10 microns coating they are much more expensive but give a much greater life.
Platinised titanium anodes can only be used successfully in electrolytes which do not attack the titanium base. This excludes use at very low and very high pH values and also Chromium baths containing fluorides.
The service time of the platinised titanium anodes depends on the chemical resistivity of the base metal, the dissolution rate of the deposited platinum in the electrolyte, which in turn depends upon layer morphology, and adhesive qualities, pH, current density and current ripple.
For most applications the dissolution rate is low and the advantages of platinised titanium anodes are far greater than any metal loss. For fluoride-free chromium baths, the platinum consumption will be approximately 1 to 4 g of platinum per million Ah. No reliable values exist for other baths.
- Long operating life; maintenance-free.
- Economical due to low platinum requirements.
- High dimensional stability and load resistance.
- Good current distribution.
- High corrosion resistance.
- Low weight.
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Specification subject to change without prior notice