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Proceedings Paper

Preliminary measurements and assessment of strength and fracture toughness in free-standing CVD diamond for high-speed missile domes
Author(s): John M. Trombetta; James T. Hoggins; Paul Klocek; Tom A. McKenna; L. P. Hehn; John J. Mecholsky
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Paper Abstract

While the optical and thermal properties of CVD diamond have been previously addressed, its mechanical properties have received little attention. A preliminary study of strength and fracture toughness in free-standing DC arc-discharge CVD diamond is reported in this paper. The materials studied is characterized by near-randomly oriented grains ranging in size from 3 to 30 microns. Disks ranging from 40 to 800 microns in thickness and from 7 to 16 mm in diameter were tested for flexure strength using a ball-on-ring apparatus. Both polished and unpolished disks were studied resulting in strength values averaging over 100,000 psi. Fracture surface analysis showed that the fracture occurred transgranularly as is generally observed for other brittle polycrystalline materials. The fracture toughness value of 6.5 +/- 1.2 MPa-m1/2 determined by the analysis is enhanced over the previously measured single crystal value of 3.4 MPa-m1/2 reflecting the increased area of the rough fracture surface. The indentation toughness was shown to have a similar value providing additional evidence of this enhancement.

Paper Details

Date Published: 14 December 1992
PDF: 11 pages
Proc. SPIE 1760, Window and Dome Technologies and Materials III, (14 December 1992); doi: 10.1117/12.130796
Show Author Affiliations
John M. Trombetta, Texas Instruments Inc. (United States)
James T. Hoggins, Texas Instruments Inc. (United States)
Paul Klocek, Texas Instruments Inc. (United States)
Tom A. McKenna, Texas Instruments Inc. (United States)
L. P. Hehn, Univ. of Florida (United States)
John J. Mecholsky, Univ. of Florida (United States)

Published in SPIE Proceedings Vol. 1760:
Window and Dome Technologies and Materials III
Paul Klocek, Editor(s)

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