Selective or brush plating is an application method for electrodeposition which can be used for coating an array of pure metals, alloys, and composite materials. The 'brush' in brush plating describes a porous, non-conductive, flexible material which wraps the anode to keep it separated from the part to be plated. The plating solution is applied by rubbing the anode, covered with the brush material and saturated by the plating solution, against the area to be plated. This is done in lieu of dipping the entire part in a large tank of plating solution. Brush plating has seen its most advantageous use in plating smaller areas of larger parts because the amount of masking used can be reduced, and smaller volumes of solution can be utilized compared to traditional tank plating methods. Brush plating is portable and repair plating can be performed in the field, sometimes without even disassembling equipment. Brush plating is currently used for numerous specialty applications in the fields of aerospace, oil and gas, marine environments, manufacturing, and many others.
The process of brush plating will be presented in terms common to all electroplating processes. The effects of parameters particular to brush plating shall be clarified in terms of their contributions to the molecular level and to the properties of the resulting deposit. Applying solution by brushing it onto a part allows for higher metal concentrations in the plating solution, higher current densities, and higher plating rates compared to other plating methods. The application method (brushing) promotes fast solution replenishment on the electrode surface and dissipation of species generated by side reactions at the work surface. The type of brush material used on the anode will affect the type of surface finish or even the structure of the deposited material.
The paper will include a summary of a brush plating process for depositing nickel pre-plate on titanium with strong adhesion, highlighting advancements made to the plating process for a classic sulfamate nickel plating solution formulation, the application of copper onto threaded connections and evaluating differences in solution composition focusing on particle loading.
