A research team led by Seil Kim of the Korea Institute of Materials Science (KIMS) Energy & Environmental Materials Research Division has developed an Ag–PTFE composite plating technology that produces silver coatings with greater hardness and wear resistance than conventional silver plating by stably dispersing PTFE nanoparticles in a cyanide-free acidic silver plating bath.
The technology simultaneously achieves high hardness, low friction and excellent wear resistance—properties that have traditionally been difficult to optimize together. It is expected to improve the durability and reliability of components subjected to repeated contact and friction, including electric vehicle connectors, relays and electrical contacts in electronic devices.
The work is published in the journal Surface and Coatings Technology.
Silver's durability problem
Silver plating is widely used on electrical contacts found in electric vehicle connectors, automotive relays and electronic switches because of silver's excellent electrical conductivity. However, silver is relatively soft, making plated surfaces susceptible to scratching and wear during repeated insertion and removal of connectors or continuous operation of relays and switches. Damage to the silver-plated layer can compromise electrical contact reliability, creating a need for more durable coating technologies.
To address this challenge, researchers have investigated incorporating PTFE (polytetrafluorethylene) particles into silver coatings to reduce friction. Commonly known as Teflon, PTFE provides excellent lubricating properties that enable smoother mechanical movement. However, PTFE nanoparticles tend to agglomerate in plating solutions.
Increasing their concentration improves lubrication but weakens the coating, whereas lower concentrations fail to provide sufficient friction reduction. As a result, simultaneously achieving high hardness and low friction has remained a significant technical challenge. Moreover, conventional silver electroplating typically relies on cyanide-based plating baths, raising concerns regarding workplace safety and wastewater treatment.
Keeping PTFE evenly dispersed
To overcome these limitations, the KIMS research team developed a technology that precisely controls the dispersion of PTFE nanoparticles, enabling simultaneous enhancement of hardness, low-friction performance and wear resistance in silver coatings.
Using a cyanide-free acidic silver plating bath containing the fluorinated surfactant FC-4, the researchers optimized the solution's acidity, surfactant concentration and PTFE content to prevent nanoparticle agglomeration and ensure their uniform incorporation into the silver coating.
They further elucidated the stabilization mechanism through experimental analysis and molecular dynamics simulations, demonstrating how the surfactant maintains stable PTFE dispersion.
Uniformly dispersed PTFE particles function as solid lubricants within the silver coating, significantly reducing friction, while the silver grains become finer and denser, resulting in a harder coating. Compared with conventional pure silver plating, the developed Ag–PTFE composite coating exhibited approximately 23% higher hardness, a coefficient of friction below 0.2 and excellent wear resistance.
These results overcome the longstanding trade-off between hardness and friction reduction, producing a coating that is simultaneously harder, smoother and more resistant to wear.
Where the coating could be used
The technology can be applied to components in which metal surfaces repeatedly come into contact and slide against each other, including electric vehicle connectors, relay contacts, switches, lead frames and electronic terminals.
As high-voltage and high-current electrical components become increasingly common in electric vehicles, technologies capable of maintaining reliable electrical contact under vibration and repeated operation are becoming increasingly important.
The developed coating is expected to extend component service life, reduce maintenance and replacement costs and improve the long-term reliability of electric vehicles and electronic products. With the global electroplating market projected to reach approximately $27.2 billion by 2032, the industrial value of high-reliability silver plating technologies is expected to continue growing.
Safety and scale-up prospects
The technology is also significant from an environmental perspective because it employs a cyanide-free acidic silver plating bath, improving workplace safety while reducing the burden associated with wastewater treatment and compliance with increasingly stringent environmental regulations.
Its application to large-area components and mass-production processes could accelerate the commercialization of environmentally friendly, high-performance silver plating while strengthening Korea's technological independence in silver plating materials and processes and enhancing competitiveness in the high-value electrical contact component market.
"This technology is expected to enable high-performance silver coatings that offer significantly improved durability under repeated-contact conditions while eliminating the need for highly toxic cyanide," said Kim, senior researcher at the Korea Institute of Materials Science.
"Our next step is to validate its performance in practical components such as electric vehicle connectors and electrical contacts and to expand the technology to large-area and mass-production processes for industrial applications."
More information
Soojin Lee et al, Simultaneous enhancement of hardness and wear resistance of Ag–PTFE coatings through surfactant-assisted electrodeposition, Surface and Coatings Technology (2026). DOI: 10.1016/j.surfcoat.2026.133671
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Citation: Researchers develop harder, longer-lasting silver plating (2026, July 14) retrieved 14 July 2026 from https://phys.org/news/2026-07-harder-longer-silver-plating.html
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