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Selective electrolysis

Selective electrolysis is an electrolytic coating process conducted without immersing the part in a bath. The bath is brought to the part by a special anode device (also called pad) impregnated with electrolyte and adapted to the shape and size of the part to be coated.

Pad electrolysis is applicable not only in the case of industrial maintenance but also on new parts in small or medium series.

The advantages of selective electrolysis

  • Allowing selective coatings, particularly interesting when depositing precious metals
  • Easy to set up on-site intervention thanks to our portable, compact and lightweight equipment
  • No risk of part distortion as the treatment is carried out at room temperature
  • Lower risk of hydrogen embrittlement, particularly for aeronautical parts, as the friction of the anode on the part facilitates degassing
  • Treatment of very limited areas on untransportable or unremovable assemblies
  • Coatings directly to size without final re-machining
  • Possibility of working on large parts and/or with large surfaces to be treated

The principles of selective electrolysis

The pad or selective electrolysis process makes it possible to obtain a metal deposit under the action of electric current.

Specific ranges allow coatings to be produced on all types of electrically conductive substrate: steel, cast iron, stainless steel, aluminum alloy, titanium alloy, copper alloy, etc.

By means of a generator, a voltage of about ten volts is imposed on the anode (or pad) which is applied to the area to be treated by moving the anode device on the part or by moving the part when possible. This achieves a transfer of the electrons contained in the electrolyte onto the part. The thicknesses deposited range from microns to millimeters and sometimes even more.

This cold process allows the deposition of many common metals but also binary and ternary alloys:

  • Nickel
  • Copper
  • Chromium
  • Silver
  • Tin
  • Zinc
  • Silver
  • Gold
  • Zinc-Nickel
  • Nickel-Cobalt
  • Tin-Nickel-Lead

It allows conversion treatments such as the oxidation of aluminum and titanium.

 

Adhesion is achieved at the microscopic level by the combination of 2 actions:

  • An electrical action due to the passage of current. The positively charged filler metal is attracted to the negatively charged base metal. At the atomic level there is interpenetration of the 2 metallic networks.
  • An electrolytic stripping action that cleans grain boundaries and creates an anchoring network for the deposit.

Possible features

Pad electrolysis is applicable not only in the case of industrial maintenance but also on new parts in small or medium series by providing solutions for:

  • Mechanical reloading or height adjustment
  • Repair of shocks, scratches and impacts
  • Anti-corrosion and anti-fretting protection (contact corrosion)
  • Electromagnetic shielding
  • Electrical Insulation
Icône réparation

Refilling - Repairing

Icône résistance chimique

Chemical anti-corrosion

Icône frottement

Friction resistance

Icône anti-corrosion atmosphérique

Atmospheric anti-corrosion

Icône anti-abrasion

Abrasion resistance

Icône conduction isolation électrique

Electrical Insulation/conductivity