Properties of bulk polycrystalline CVD diamond

Considerable progress has been made in recent years on the synthesis of diamond by chemical vapour deposition (CVD) leading to substantial improvements in material quality and rate of synthesis. As a result it has been possible to manufacture relatively thick plates of free-standing bulk polycrystalline CVD diamond removing many of the limitations of thin-film coatings. This exploit has promoted CVD diamond from experimental novelty to a true engineering material opening a wide range of applications in which the unique properties of diamond can be used. This paper reports on a range of properties of bulk polycrystalline CVD (BPCVD) diamond. The material used in these experiments is synthesized and processed under routine manufacturing conditions rather than as isolated research specimens. Most of the specimens used have been made flat and parallel and have been polished to an optical quality finish. Many of the properties are influenced by surface conditions and it is important to emphasise that after-growth processing is an integral part of what is referred to in this paper as BPCVD diamond specimens. The following properties are reviewed: optical properties; thermal properties; mechanical properties; dielectric properties; and laser induced damage threshold