Mpb Communications Inc.

Institut National De La Recherche Scientifique

Emile Haddad

Mohamed Chaker

Roman Kruzelecky

Brian Wong

Wes R Jamroz

Ali Hendaoui

There is described a passive variable emittance device comprising: a substrate having a receiving surface adapted to reflect radiations having a given wavelength; an intermediary layer deposited on the receiving surface of the substrate and being substantially transparent to the radiations having the given wavelength; and a thermochromic layer deposited on top of the intermediary layer, the thermochromic layer being substantially transparent to the radiations having the given wavelength for a first temperature below a given transition temperature, and presenting both reflection and absorption for the radiations for a second temperature above the given transition temperature, a total optical thickness for the intermediary and thermochromic layers being substantially equal to one quarter of the given wavelength so that radiations reflected by the thermochromic layer at the second temperature destructively interfere with radiations transmitted by the thermochromic and intermediary layers and reflected by the substrate in order to obtain a first emittance for the passive variable emittance device at the second temperature being greater than a second emittance for the passive variable emittance device at the first temperature.

Passively variable emittance device and method for making the same

The emittance value is a measure of an amount of energy expelled from a given surface area relative to a black-body reference. Depending on the specific coating a change in the emittance value is actively or passively effected. There are known active variable emittance thermal control coatings. However, such coatings are actually panels housing a mixture of both high and low emissivity materials that are electrically manipulated to control the emittance value of the panel. These 'coatings' are classified as either electrochromic or electrophorectic. Both electrochromic and electrophorectic coatings require an applied voltage to cause a change in the emittance value of the coating. By contrast, aspects of the present invention do not include active variable emittance thermal control coatings. Aspects of the present invention do include passive variable emittance thermal control coatings and materials. In accordance with aspects of the present invention 'passive' means that the variable emittance value changes in response to changes in the environment without active control (e.g. neither a voltage nor a current is applied). More specifically, in accordance with one aspect of the invention a passive variable emittance thermochromic material is provided that has a relatively low emittance value at low temperatures and a relatively high emittance value at high temperatures.

Variable emittance thermochromic material and satellite system

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Montreal, Canada

Emile Haddad