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Services | Platinum Plating 

 

 

NMT® Electrodes PTY LTD and NMT® Electrodes Australia PTY LTD are the only companies in Southern Africa and Australia that produce Platinised Titanium Anodes.

 

Our Platinised Titanium Anodes have a proven track record in applications such as:

  • Cathodic Protection
  • Sodium Hypochlorite
  • Electroplating
  • Electrosynthesis
  • Electrodialysis

NMT® Electrodes PTY LTD has the technology to platinum plate titanium substrates in the form of wire, rod, tube, plate and mesh. Furthermore, we have the ability to manufacture complex fabricated anodes.

 

Due to our proven plating technology, NMT® Electrodes' Platinised Titanium Anodes have become the anodes of choice.

 

The ZA technology employed by NMT® Electrodes results in coatings which provide the following attributes:

  • Higher levels of adhesion of the precious metal coating
  • Better uniformity of coating
  • Greatly improved resistance to acid attack
  • Resistance to interface degradation by deposits

 

The external surface of all platinised titanium anodes is essentially pure platinum which exhibits all the normal characteristics of the wrought metal as far as corrosion behaviour is concerned. The secret of the quality of a platinised anode lies in the nature of the interface between the platinum and the titanium. It is well known that normal untreated titanium presents a very inert and intractable surface when it comes to applying precious metal coatings. That this problem was overcome to an adequate extent is demonstrated by the wide acceptance of platinised titanium anodes in different industries throughout the world. Although there are still many platinum electroplated anodes produced without an adequate interlayer, they are used for less demanding applications.

 

The shortcomings of such anodes are that the coating has pores and cracks which allow access of the surrounding electrolyte to the titanium substrate. This porosity increases during the life of the anode as the platinum coating wears away, thus allowing increased exposure of the substrate, formation of internal crevices under the coating and progressive loss of points of mechanical attachment between the coating and the substrate.

 

Under mild conditions of operation this degradation is not serious, but it may be aggravated by adverse factors. It must be remembered that all operating anode surfaces generate acidity, the level of which is related to current density and the external environment.

 

If the acid generated at the surface is not removed quickly enough (particularly from the internal crevices mentioned above) then the interface between platinum and titanium can be attacked, leading to rapid and progressive coating loss by undermining.

 

This situation can arise under conditions of stagnation or more quickly where deposits are allowed to form on anodes (e.g. manganese dioxide in sea water). An extreme case is where an anode is inadvertently buried or allowed to become silted. Although not allowed for at the design stage these conditions can occur accidentally in many Cathodic Protection situations.

 

Conditions are sometimes met in metal plating (e.g. gold plating of electronic components) where the composition of the electrolyte will activate the normally passive surface of the titanium and allow deposition of foreign metals within the pores of the coating and at the coating/titanium interface.

 

 

Type ZA Coatings

 

In this improved coating the interface between the platinum and titanium is radically altered. Extra processing confers almost complete freedom from interface degradation and premature coating loss by undermining mechanisms. Only in circumstances of continuous operation in strong acids or where solutions are chemically incompatible with titanium (e.g. acid fluorides) will the Type ZA coating be liable to premature failure. Even in these circumstances the life will exceed that of a platinised anode without an interlayer, sometimes by a considerable margin.

 

The improved process also confers other benefits on the composite, notably significant improvements in the adhesion strength of the coating, the uniformity of coating thickness and the intrinsic level of coating porosity.

 

Type ZA platinum coated anodes are available in the following forms:

  • Titanium Wire 3mm diameter - lengths up to 200 metres (2.5 micron plating thickness)
  • Titanium Rod Greater than 3mm diameter – lengths up to 4 metres
  • Titanium Mesh 1000mm x 500mm x 1 meter max.
  • Titanium Plate 1000mm x 500mm x 3 metres max.
  • Platinum plating thickness up to 8.5 microns can be supplied.
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