Preliminary measurements and assessment of strength and fracture toughness in free-standing CVD diamond for high-speed missile domes

John M. Trombetta; James T. Hoggins; Paul Klocek; Tom A. McKenna; L. P. Hehn; John J. Mecholsky Jr.

doi:10.1117/12.130796

14 December 1992 Preliminary measurements and assessment of strength and fracture toughness in free-standing CVD diamond for high-speed missile domes

John M. Trombetta, James T. Hoggins, Paul Klocek, Tom A. McKenna, L. P. Hehn, John J. Mecholsky Jr.

Author Affiliations +

Proceedings Volume 1760, Window and Dome Technologies and Materials III; (1992) https://doi.org/10.1117/12.130796
Event: San Diego '92, 1992, San Diego, CA, United States

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-m^1/2 determined by the analysis is enhanced over the previously measured single crystal value of 3.4 MPa-m^1/2 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.

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John M. Trombetta, James T. Hoggins, Paul Klocek, Tom A. McKenna, L. P. Hehn, and John J. Mecholsky Jr. "Preliminary measurements and assessment of strength and fracture toughness in free-standing CVD diamond for high-speed missile domes", Proc. SPIE 1760, Window and Dome Technologies and Materials III, (14 December 1992); https://doi.org/10.1117/12.130796

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