Multifunctional Sol-Gel Coatings for Both Anticorrosion and Electrical Conduction Properties

Area of Science:

• Materials Science
• Surface Engineering
• Electrochemistry

Background:

• Hexavalent chromium (Cr(VI)) and cadmium are toxic heavy metals used in surface treatments.
• Electrical connectors require both corrosion resistance and electrical conductivity, which are often conflicting properties.
• The sol-gel route offers a promising method for developing protective coatings.

Purpose of the Study:

• To develop multifunctional sol-gel coatings as a sustainable alternative to Cr(VI) and cadmium for electrical connectors.
• To achieve a balance between anticorrosion protection and electrical conductivity in coatings for 6061 alloy.
• To ensure the sol-gel process is compatible with health, safety, and environmental (HSE) regulations and ATEX standards.

Main Methods:

• Sol-gel synthesis incorporating carbon fillers into aqueous suspensions.
• Evaluation of experimental parameters: carbon filler type, hydrolysis ratio, and precursor addition order.
• Characterization of coating properties including electrical conductivity and neutral salt spray (NSS) resistance.

Main Results:

• Conductive coatings (200-500 mΩ□) with high anticorrosion properties (500 h NSS resistance) were achieved with coating thickness under 10 microns.
• Incorporation of carbon fillers provided the necessary electrical conductivity.
• Organic additives (poly(2-ethyl-2-oxazoline) or hydroxypropylmethylcellulose) increased the sol's flash point (>60 °C), enhancing process safety.

Conclusions:

• Multifunctional sol-gel coatings containing carbon fillers offer a viable, eco-friendly solution for electrical connector surface treatment.
• The developed coatings successfully combine electrical conductivity and superior anticorrosion performance.
• The enhanced safety profile of the sol-gel process makes it suitable for industrial application and compliance with HSE and ATEX standards.