ISSN:
1662-0356
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Allgemeine Naturwissenschaft
,
Technik allgemein
Notizen:
High-purity, single-phase polycrystalline diamond and cBN have been successfullysynthesized by direct conversion sintering from graphite and hBN, respectively, under static highpressure and high temperature. The high-purity polycrystalline diamond synthesized directly fromgraphite at ≧15 GPa and 2300-2500 °C has a mixed texture of a homogeneous fine structure (grainsize : 10-30 nm, formed in a diffusion process) and a lamellar structure (formed in a martensiticprocess). The polycrystalline diamond has very high hardness equivalent to or even higher than thatof diamond crystal. The high-purity polycrystalline cBN synthesized from high-purity hBN at 7.7GPa and 2300 °C consists of homogeneous fine-grained particles (〈0.5 μm, formed in a diffusionprocess). The hardness of the fine-grained high-purity polycrystalline cBN is obviously higher thanthat of single-crystal cBN. The fine microstructure features without any secondary phases andextremely high hardness of the nano-polycrystalline diamond and the fine-grained polycrystallinecBN are promising for applications in next-generation high-precision and high-efficiency cuttingtools
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.45.885.pdf
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