Pigments with potential for adaptable optical properties

The main objective for the project, Pigments with Potential for Adaptable Optical Properties, is to produce material in which the electromagnetic properties can be controlled thereby enabling the object to adapt its signature to its background. This property is desirable within both the visible wavelength range as well as in the microwave and infrared ranges. Paint consists of pigment and binders. For signature management applications, highly reflective paint in the infrared area of between 3-5 µm and 8-12 µm but low reflectance in the visible area, is usually desired. We have investigated how, through varying pigment particle composition and size, pigment can be designed with the desired reflectance properties. Particles of conducting (silver) as well as semi conducting (silicon) and isolating (aluminum oxide) materials have been investigated. Particle sizes varied from 0,5 µm to 80 µm. The powders were studied in a scanning electron microscope and their reflectance measured in both the visible and infrared areas. The results show that pigment material, particle size and shape of the particles are important for reflectance. The next step will be to produce paint by mixing pigment particles with a suitable binder. If this combination of pigment/binder is successful, we will be able to produce paint with potentially adaptable optical properties.