Metal-coated hollow glass microspheres can be incorporated into coatings, composites and adhesives to provide these materials with electrical conductivity and shield against electromagnetic interference (EMI).

Due to their hollow glass core, Conductospheres™ have very low particle densities and so provide significant weight reductions over conventional metal fillers.

The Conductospheres™ range includes silver and nickel products with a variety of particle sizes, densities and crush strengths. Conductospheres silver products offer the highest conductivity and stability, and are available with a range of particle sizes and densities.

Typical Surface Resistivities of Coatings Containing Conductospheres™ Silver and Conductospheres™ Nickel

Conductospheres Silver incorporated into a resin at 50% by volume will typically produce a composite with a density of 0.6-0.9 g/cm³ and a volume resistivity of < 0.1 O•cm. The surface resistivity of coatings containing Conductospheres™ Silver is typically about 1 O/sq. The graph shows that the percolation threshold is reached at loadings of 20-30% by volume.

Because the core of Conductospheres™ is hollow glass bead, the physical integrity of the particles may be compromised if they are subjected to severe physical processing techniques, such as ultrasonication, high-shear mixing, grinding or milling. To maintain the free flowing nature of the product and prevent ‘caking’, avoid extended exposure of materials to high humidity and/or conditions susceptible to condensation. Once opened, storage life of the product can be maximized by resealing opened containers immediately after use.

An important application for metalized solid glass microspheres and beads is retroreflectivity. Retroreflective microspheres are based on hemispherically aluminum-coated barium titanate glass beads. The hemispheric aluminum coating creates the mechanism for retro-reflectivity since light passing through the clear half of the glass bead “bounces” off the reflective aluminum-coated back, directing the light back to the source. Pigmented coatings allow expanded applications for hemispherically aluminum coated sphere in particular. Whereas previously their grey color limited the use of metallized spheres to only dark resin systems, pigmented coatings now allow these spheres to be added to most colored paints or plastics—even yellow—with only a slight decrease in the retro reflectivity of the colored sphere, assuring formulations that are attractive by day and brightly visible at night.