Modifying the emissivity of non-planar surfaces and objects with complex geometries has proven
to be a difficult task. Optical interference coatings have been successfully used to change the
spectral emissivity of a surface. However, typical deposition processes for these coatings, such
as evaporation, are line-of-sight processes that require complex masking and/or rotation systems
in order to coat non-planar surfaces. Objects with very complex geometries cannot be coated at all
by line-of-sight processes. In addition, evaporative processes often do not provide films with
good resistance to thermal cycling to high temperatures.
Low Pressure Chemical Vapor Deposition (LPCVD) is a non-line-of-sight process that unifonnly
coats all exposed surfaces of objects with complex shapes. DSI has developed an LPCVD
process that is capable of the routine manufacture of optical interference coatings. We have used
this process to deposit high quality, uniform, conformal coatings for the modification of the
emissivity of a variety of materials including ceramics and metals. Coatings of these substrates in
very complex, non-planar forms have been demonstrated. The coatings show excellent durability
and withstand repeated cycling to high temperatures. In this paper we will briefly describe the
coating process, show examples of some of the substrate forms, and describe the spectral and
environmental performance of these emittance control coatings.