Electrodeposited Ag–TiB₂ nanocomposite coatings for electrical contact applications: influence of TiB₂ content and current type on arc erosion resistance and mechanical properties

This study investigates the influence of titanium diboride (TiB₂) nanoparticle content on the microstructure, mechanical properties, corrosion behavior, and electrical contact performance of electrodeposited silver (Ag) nanocomposite coatings applied to copper contact buttons. Ag–TiB₂ nanocomposite coatings were fabricated via direct current (DC) electrodeposition using electrolytes containing 0.5, 1.0, 2.0, and 4.0 g/L TiB₂. The coatings were systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), Vickers microhardness testing, corrosion measurements, and electrical contact testing. The incorporation of TiB₂ nanoparticles refined the grain structure, increased hardness, enhanced corrosion resistance, and improved arc erosion behavior. Among the coatings, the one with 1.0 g/L TiB₂ exhibited the most favorable combination of surface compactness, hardness, corrosion protection, and thermal stability under high cycle contact testing. Electrical contact tests conducted up to 10,000 cycles showed reduced erosion and lower surface temperatures compared to unreinforced Ag coatings. However, TiB₂ concentrations beyond 1.0 g/L led to nanoparticle agglomeration, increased surface roughness, and reduced long-term performance in both contact and corrosion environments. These findings demonstrate that the controlled incorporation of TiB₂ nanoparticles into Ag matrices via DC electrodeposition significantly enhances the multifunctional performance of contact coatings, offering a promising cadmium-free solution for high-reliability electrical switching components. Among the investigated compositions, the Ag–TiB₂ coating containing 1.0 g/L TiB₂ exhibited the optimum balance of mechanical, electrical, and corrosion performance, highlighting its suitability as an effective cadmium-free electrical contact coating.