Surfaceplating

Surfaceplating, in materials engineering, denotes the application of a thin metallic layer onto the surface of a substrate to improve performance or appearance. It encompasses several technologies, including electroplating, electroless plating, and vapor-phase coatings such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). The goal is to impart properties such as corrosion resistance, wear resistance, reduced friction, or decorative appeal.

Electroplating uses electrical current to reduce metal ions from an electrolyte onto a conducting substrate. Common finishes include nickel, chromium, copper, and zinc. Substrates typically require pretreatment such as degreasing, etching, and activation to promote adhesion. Bath composition, temperature, and current density influence coating properties and thickness.

Electroless plating deposits metal by chemical reduction without external current, producing uniform coatings even on complex geometries. Nickel-phosphorus and nickel-boron are typical deposits; copper and gold can also be deposited electrolessly. This method is valued for corrosion resistance and coating uniformity.

PVD and CVD create thin, hard coatings with controlled composition. PVD processes (such as sputtering or evaporation) are performed in vacuum and can produce coatings like titanium nitride or carbide. CVD uses reactive gases to form films such as tungsten carbide or aluminum oxide, offering wear resistance and high-temperature stability.

Coating performance depends on surface preparation, adhesion, and thickness. Typical steps include cleaning, degreasing, etching, activation, masking, and post-treatments such as passivation or sealing. Thickness is measured by methods like X-ray fluorescence or profilometry.

Applications span corrosion protection, tooling and wear-critical components, decorative finishes, and electronic contacts. Environmental and safety considerations address waste treatment, handling of toxic baths, and regulatory compliance.