Brush Electroplating

    Electroplating has been used for hundreds of years to provide objects and mechanical components with additional and desired properties of specific metal.The reasons for plating in metal a component or object, can range from just adding a metallic aesthetic to a decorative object or the essential physical, mechanical and chemical properties of the specific metal or alloy for performance purposes. Improved corrosion resistance, strength, durability, reduced friction, increased solderability and even changes to conductivity might all be factors in selecting a component for the plating process. 

    Electroplating process relies on different components, or electrodes, to achieve the metal coating. The item selected for plating is the cathode – the negatively charged electrode, while the material or metal used makes up the anode – the positively charged electrode. Both components are immersed in an electrolyte bath, that contains metal salts and other ions to allow for proper flow of electricity.

    The Navy, Air force and civilian vessels repair their wear and tear parts and corroded surfaces of the valves, pumps and flanges by building a desire metal by using electroplating. In some cases, metal plating may be required in more localized areas. This process, which is related to electroplating is often referred to as selective plating or brush plating.

    This brush (anode), which is usually made from a plastic, covered with Nickel Alloy 20 or platinum clad niobium mesh wrapped in cotton cloth, holds the plating solution and inhibits the item from making direct contact with the metal mesh. Through the use of low voltage, the anode dipped in the plating solution or pump the solution slowly on it allows for localized plating by an operator. Skilled operators can use this selective electroplating service to apply for spot-plating techniques, making it useful in both repair and refurbishment of parts and components. Unlike full electroplating techniques which requires an immersion in an electrolyte bath, selective plating allows the operator to target a specific area, using a plating solution of electrolyte and anode connected to positive lead by masking the adjacent area.

    ElectroplatingUSA recommends (Carpenter® 20 or Incoloy® 20) Nickel Alloy 20 Wire Mesh anode cover for affordability. Nickel Alloy 20 that is low in carbon (0.07%) , and contain more nickel (35%) and chrome (20%) than 304 and 316, making it more corrosion resistant. Nickel Alloy 20 provides outstanding resistance to stress-corrosion, crevice corrosion, inter-granular attack and pitting. Because of its strong resistance to chlorides and sulfuric, phosphoric and nitric acids. 

     Use of stainless steel anodes for precious metal plating does not meet military specifications.

    Platinum Clad Niobium/Columbium mesh is the best anode cover for the plating of precious metals and for high speed plating of metals such as nickel and copper. But they are 10 times expensive than Alloy 20. They are dimensionally stable, maintain a constant and low cell voltage, and will not contaminate the electrolyte. Platinized anodes are manufactured by bonding platinum to a niobium /columbium base that is better suited for high voltage applications, such as high speed plating. The best type of clad anode is one where the whole surface is coated with platinum.

    In many ways, brush plating may appear similar to welding when compared to other forms of electroplating because it uses a flexible and maneuverable anode attached to a power supply. The cathode is still the component you have selected for plating, but the anode is now connected to a handle and wrapped in an absorbing material, usually cotton cloth. The cloth absorbs the electrolyte during the brush plating process.

    As the operator moves the anode over the cathode, it completes the circuit and supplies the electrolyte continuously. The electrolyte can supply via pump or by dipping.

    One of the greatest advantage that brush electroplating services, offer over a traditional tank plating methods, is flexibility. The equipment for brush plating is mobile and can be done anywhere  from the workshop to on site or on board at customer's location without requiring the transportation or shipment of heavy and delicate components. Some components are welded to the hull of the ship or main engine and can not be separated to carry to workshop and thus it has to be repaired on the spot.

    This is ideal and much faster than traditional electroplating techniques. It allows for the service, repair and refurbishment of parts quickly.