More than 1 000 tons of saw diamond grits were consumed worldwide in 2007.Even with such a mature industry,there are still major improvements possible in developing new grits.The DiaCan<sup>TM</sup> techno...More than 1 000 tons of saw diamond grits were consumed worldwide in 2007.Even with such a mature industry,there are still major improvements possible in developing new grits.The DiaCan<sup>TM</sup> technology with patterned diamond seeding can boost the production yield of coarse mesh diamonds（e.g. 30/40）.Moreover,the DiaMind crystals formed contain a visible core.This diamond-in-diamond architecture allows self-sharpening during sawing application.Furthermore,a revolutionary polycrystalline diamond superabrasive with cubical shape was fabricated to further increase the sawing efficiency and tool longevity.Such DiaCube<sup>TM</sup> polygrits were made tools by brazing them on pearls of wire saws and on the surface of turbo grinders. The pros and cons of major designs of high-pressure equipment for diamond synthesis were discussed with the recommendation to combine the merits of belt apparatus and cubic press.This tooling synergism may increase diamond yield at reduced cost for massive production of saw grits. In 1997 Sung Chien-Min filed a series US patents that described the art of making patterned diamond tools with diamond grits forming an array in three dimensions.He also made the debut of the world’ s first brazing tools with patterned diamond distribution at the stone exhibition in Verona in 1998（also in Nuremberg in 1999）.The patterned diamond saws were introduced by Korean companies in 2005 with the demonstration of increased cutting speeds and prolonged tool lives.展开更多
Recent results on conversion from graphite to diamond by aid of non-metallic catalysts are reviewed. The current status of experimental advances is presented and typical examples from relevant literature are provided ...Recent results on conversion from graphite to diamond by aid of non-metallic catalysts are reviewed. The current status of experimental advances is presented and typical examples from relevant literature are provided for understanding the mechanism of the graphite-diamond conversion by aid of these non-metallic catalysts. Furthermore, a tendency of graphite-diamond transformation assisted by carbonates, sulfates or phosphorus under high pressure and high temperature has been investigated by calculating the activation energy and transformation probability of the carbon atoms over a potential barrier. It was found that the activation energy is highly sensitive to the catalyst chosen. The probability sequence of graphite-diamond transformation with these catalysts was put forward.展开更多
As a wide energy gap semiconductor, diamond is expected to play a role in UV light-emitting diode or laser. However, the impurities and vacancies in diamond exert a great influence on optical properties of the crystal...As a wide energy gap semiconductor, diamond is expected to play a role in UV light-emitting diode or laser. However, the impurities and vacancies in diamond exert a great influence on optical properties of the crystals. It is important, therefore, to study the relation between impurities and the optical properties, and furthermore, to study the control of the impurities.展开更多
The transformation of β-carbine to diamond was studied by FTIR and XRD.The results indicated that the transformation was achieved with the pressure of 0.45MPa and temperature of 400 ℃.In the process,catalyst and dia...The transformation of β-carbine to diamond was studied by FTIR and XRD.The results indicated that the transformation was achieved with the pressure of 0.45MPa and temperature of 400 ℃.In the process,catalyst and diamond-crystal seeds were needless.展开更多
Based upon the thermodynamic analysis of the nucleation of d iamond crystal, the effects of synthesis temperature and pressure on the nucleat ion of diamond crystal, diamond growth and output of diamond crystal, parti...Based upon the thermodynamic analysis of the nucleation of d iamond crystal, the effects of synthesis temperature and pressure on the nucleat ion of diamond crystal, diamond growth and output of diamond crystal, particle s ize and strength were discussed. The results show that the excess pressure has a n important effect on the critical radius of nucleation and thermodynamic b a rrier in the formation of a critical nucleus. Considering the excess pressure, t he expression of diamond nucleation rate was obtained.展开更多
In order to ascertain the mechanism of interaction between carbide and metallic catalyst and formation of diamond under high pressure and high temperature, and find a new method to synthesize diamond with special prop...In order to ascertain the mechanism of interaction between carbide and metallic catalyst and formation of diamond under high pressure and high temperature, and find a new method to synthesize diamond with special properties, it is necessary to investigate the reaction behavior of different carbides and metallic solvent_catalysts under high pressure and high temperature. A system of Cr-3C-2 powder and Ni 70Mn 25Co 5 alloy in weight ratio of 1∶6 was treated under 6 0 GPa and 1 500℃ for 20, 30 or 60 min respectively. X_ray diffraction of the samples indicated the Cr 3C 2 decomposed partially after high pressure and temperature treatment, and Cr 7C 3, Cr and diamond formed respectively. There was not any trace of graphite in the samples. The result suggested that the separated carbon atoms could form diamond directly without conversion process of graphite into diamond. The observation of SEI, WDX and EDX also showed that diamond crystals were synthesized in the system, which have perfect surfaces and shapes, with the average grain size of about 40 μm. The properties of the crystals are being investigated.展开更多
文摘More than 1 000 tons of saw diamond grits were consumed worldwide in 2007.Even with such a mature industry,there are still major improvements possible in developing new grits.The DiaCan<sup>TM</sup> technology with patterned diamond seeding can boost the production yield of coarse mesh diamonds（e.g. 30/40）.Moreover,the DiaMind crystals formed contain a visible core.This diamond-in-diamond architecture allows self-sharpening during sawing application.Furthermore,a revolutionary polycrystalline diamond superabrasive with cubical shape was fabricated to further increase the sawing efficiency and tool longevity.Such DiaCube<sup>TM</sup> polygrits were made tools by brazing them on pearls of wire saws and on the surface of turbo grinders. The pros and cons of major designs of high-pressure equipment for diamond synthesis were discussed with the recommendation to combine the merits of belt apparatus and cubic press.This tooling synergism may increase diamond yield at reduced cost for massive production of saw grits. In 1997 Sung Chien-Min filed a series US patents that described the art of making patterned diamond tools with diamond grits forming an array in three dimensions.He also made the debut of the world’ s first brazing tools with patterned diamond distribution at the stone exhibition in Verona in 1998（also in Nuremberg in 1999）.The patterned diamond saws were introduced by Korean companies in 2005 with the demonstration of increased cutting speeds and prolonged tool lives.
基金Project supported by the National Natural Science Foundation of China (Grant No. 19674970).
文摘Recent results on conversion from graphite to diamond by aid of non-metallic catalysts are reviewed. The current status of experimental advances is presented and typical examples from relevant literature are provided for understanding the mechanism of the graphite-diamond conversion by aid of these non-metallic catalysts. Furthermore, a tendency of graphite-diamond transformation assisted by carbonates, sulfates or phosphorus under high pressure and high temperature has been investigated by calculating the activation energy and transformation probability of the carbon atoms over a potential barrier. It was found that the activation energy is highly sensitive to the catalyst chosen. The probability sequence of graphite-diamond transformation with these catalysts was put forward.
文摘As a wide energy gap semiconductor, diamond is expected to play a role in UV light-emitting diode or laser. However, the impurities and vacancies in diamond exert a great influence on optical properties of the crystals. It is important, therefore, to study the relation between impurities and the optical properties, and furthermore, to study the control of the impurities.
文摘The transformation of β-carbine to diamond was studied by FTIR and XRD.The results indicated that the transformation was achieved with the pressure of 0.45MPa and temperature of 400 ℃.In the process,catalyst and diamond-crystal seeds were needless.
文摘Based upon the thermodynamic analysis of the nucleation of d iamond crystal, the effects of synthesis temperature and pressure on the nucleat ion of diamond crystal, diamond growth and output of diamond crystal, particle s ize and strength were discussed. The results show that the excess pressure has a n important effect on the critical radius of nucleation and thermodynamic b a rrier in the formation of a critical nucleus. Considering the excess pressure, t he expression of diamond nucleation rate was obtained.
文摘In order to ascertain the mechanism of interaction between carbide and metallic catalyst and formation of diamond under high pressure and high temperature, and find a new method to synthesize diamond with special properties, it is necessary to investigate the reaction behavior of different carbides and metallic solvent_catalysts under high pressure and high temperature. A system of Cr-3C-2 powder and Ni 70Mn 25Co 5 alloy in weight ratio of 1∶6 was treated under 6 0 GPa and 1 500℃ for 20, 30 or 60 min respectively. X_ray diffraction of the samples indicated the Cr 3C 2 decomposed partially after high pressure and temperature treatment, and Cr 7C 3, Cr and diamond formed respectively. There was not any trace of graphite in the samples. The result suggested that the separated carbon atoms could form diamond directly without conversion process of graphite into diamond. The observation of SEI, WDX and EDX also showed that diamond crystals were synthesized in the system, which have perfect surfaces and shapes, with the average grain size of about 40 μm. The properties of the crystals are being investigated.
