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Modification of Optical Surfaces Employing CVD Boron Carbide Coatings

Published online by Cambridge University Press:  15 February 2011

Richard A. Lowden
Affiliation:
Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, Tennessee 37831-6063
Laura Riester
Affiliation:
Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, Tennessee 37831-6063
M. Alfred Akerman
Affiliation:
Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, Tennessee 37831-6063
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Abstract

Non-reflective or high emissivity optical surfaces require materials with given roughness or surface characteristics wherein interaction with incident radiation results in the absorption and dissipation of a specific spectrum of radiation. Coatings have been used to alter optical properties, however, extreme service environments, such as experienced by satellite systems and other spacecraft, necessitate the use of materials with unique combinations of physical, chemical, and mechanical properties. Thus, ceramics such as boron carbide are leading candidates for these applications. Boron carbide was examined as a coating for optical baffle surfaces. Boron carbide coatings were deposited on graphite substrates from BCl3, CH4, and H2 gases employing chemical vapor deposition (CVD) techniques. Parameters including temperature, reactant gas compositions and flows, and pressure were explored. The structures of the coatings were characterized using electron microscopy and compositions were determined using x-ray diffraction. The optical properties of the boron carbide coatings were measured, and relationships between processing conditions, deposit morphology, and optical properties were determined.

Type
Research Article
Copyright
Copyright © Materials Research Society 1992

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