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Enhanced hardness of CVD diamond after high pressure and high-temperature treatments

MetadataDetails
Publication Date2015-10-02
JournalHigh Pressure Research
AuthorsYongkun Wang, Shuai Yin, Li Lei, Qiming Wang, Wendan Wang
InstitutionsNortheastern University, China Academy of Engineering Physics
Citations2

The diamond thick layers prepared using chemical vapor deposition (CVD) methods have been treated at high pressures and high temperatures (HP-HT). It was found that the Vickers hardness of the HP-HT treated bulks was nearly two times as high as that of the starting CVD diamond samples. The hardness of the samples treated at 8 GPa and 1800°C is ∼80 GPa at a loading force of 49 N, close to that of the single-crystal diamond (∼100 GPa). In addition, the oxidation resistance of CVD diamond samples was also enhanced greatly after HP-HT treatments, and the diamondization of sp2 bonded carbon in the CVD diamond samples could occur at 7-8 GPa and 1600-1800°C. The HP-HT conditions of diamondization in our works are much lower than the case of the graphite-to-diamond direct transformation without the presence of catalyst (>15 GPa and 2000°C).