Fracture Toughness of Chemically Vapor‐Deposited Diamond

The fracture toughness of chemically vapor‐deposited diamond is estimated by a Vickers indentation method. Freestanding diamond films of 400‐μm thickness are produced with plasma‐enhanced chemical vapor deposition and highly polished for indentation testing. Indentation testing was performed with a microhardness tester using a load range of 5 to 8 N. The average fracture toughness is estimated as 5.3 ± 1.3 MPA · m 1/2 .