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Proceedings Paper

High Modulus Layers As Protective Coatings For 'Window' Materials
Author(s): R. J. Hand; J. E. Field; S. van der Zwaag
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Paper Abstract

Theoretical and experimental studies have been made on the effect of thin hard coatings on the stress fields generated by indentation and impact onto a flat half space. The theoretical work uses finite element techniques and shows that a thin hard coating can have a significant effect on the maximum tensile stress generated in the substrate providing there is a good bond at the coating/substrate interface. As it is technically difficult to deposit layers of thickness greater than a few microns without residual stresses causing debonding and peeling; double layer and multilayer systems have also been examined. Hertzian indentation on hard carbon coated germanium has shown that such coatings do offer protection against indentation damage. High speed liquid impact on coated germanium and zinc sulphide has shown, however, that although the quasi-static performance of the material may be improved the impact resistance of the coated material is not significantly affected. Reasons for this are discussed. In conclusion, although it is still to be hope that coatings that do improve the impact performance of materials can be manufactured, current coatings offer better protection against handling damage rather than against impact.

Paper Details

Date Published: 11 September 1989
PDF: 9 pages
Proc. SPIE 1112, Window and Dome Technologies and Materials, (11 September 1989); doi: 10.1117/12.960771
Show Author Affiliations
R. J. Hand, University of Cambridge (U.K.)
J. E. Field, University of Cambridge (U.K.)
S. van der Zwaag, University of Cambridge (U.K.)

Published in SPIE Proceedings Vol. 1112:
Window and Dome Technologies and Materials
Paul Klocek, Editor(s)

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