The lightness and high strength-to-weight ratio of the magnesium alloy have attracted more interest in various applications.However,micro/nanostructure generation on their surfaces remains a challenge due to the flamm...The lightness and high strength-to-weight ratio of the magnesium alloy have attracted more interest in various applications.However,micro/nanostructure generation on their surfaces remains a challenge due to the flammability and ignition.Motivated by this,this study proposed a machining process,named the ultraprecision diamond surface texturing process,to machine the micro/nanostructures on magnesium alloy surfaces.Experimental results showed the various microstructures and sawtooth-shaped nanostructures were successfully generated on the AZ31B magnesium alloy surfaces,demonstrating the effectiveness of this proposed machining process.Furthermore,sawtooth-shaped nanostructures had the function of inducing the optical effect and generating different colors on workpiece surfaces.The colorful letter and colorful flower image were clearly viewed on magnesium alloy surfaces.The corresponding cutting force,chip morphology,and tool wear were systematically investigated to understand the machining mechanism of micro/nanostructures on magnesium alloy surfaces.The proposed machining process can further improve the performances of the magnesium alloy and extend its functions to other fields,such as optics.展开更多
A new impregnated diamond bit was designed to solve the slipping problem when impregnated diamond bit was used for extra-hard, compact, and nonabrasive rock formation. Adding Si C grits into matrix, Si C grits can eas...A new impregnated diamond bit was designed to solve the slipping problem when impregnated diamond bit was used for extra-hard, compact, and nonabrasive rock formation. Adding Si C grits into matrix, Si C grits can easily be exfoliated from the surface of the matrix due to weak holding-force with matrix, which made the surface non-smooth. Three Ф36/24 mm laboratorial bits were manufactured to conduct a laboratory drilling test on zirconiacorundum refractory brick. The laboratory drilling test indicates that the abrasive resistance of the bit work layer is proportional to the Si C concentation. The higher the concentration, the weaker the abrasive resistance of matrix. The new impregnated diamond bit was applied to a mining area drilling construction in Jiangxi province, China. Field drilling application indicates that the ROP(rate of penetration) of the new bit is approximately two to three times that of the common bits. Compared with the common bits, the surface of the new bit has typical abrasive wear characteristics,and the metabolic rate of the diamond can be well matched to the wear rate of the matrix.展开更多
The H-terminated diamond films, which exhibit high surface conductivity, have been used in high-frequency and high-power electronic devices. In this paper, the surface conductive channel on specimens from the same dia...The H-terminated diamond films, which exhibit high surface conductivity, have been used in high-frequency and high-power electronic devices. In this paper, the surface conductive channel on specimens from the same diamond film was obtained by hydrogen plasma treatment and by heating under a hydrogen atmosphere, respectively, and the surface carrier transport characteristics of both samples were compared and evaluated. The results show that the carrier mobility and carrier density of the sample treated by hydrogen plasma are 15 cm^2·V^（-1）·s^（-1） and greater than 5 × 1012 cm^（-2）, respectively, and that the carrier mobilities measured at five different areas are similar. Compared to the hydrogen-plasma-treated specimen, the thermally hydrogenated specimen exhibits a lower surface conductivity, a carrier density one order of magnitude lower, and a carrier mobility that varies from 2 to 33 cm^2·V^（-1）·s^（-1）. The activated hydrogen atoms restructure the diamond surface, remove the scratches, and passivate the surface states via the etching effect during the hydrogen plasma treatment process, which maintains a higher carrier density and a more stable carrier mobility.展开更多
The adsorption behaviors of glycine on diamond （001） are systematically investigated by first-principles calculations. We have considered all possible adsorption configurations without a surface dangling bond and gi...The adsorption behaviors of glycine on diamond （001） are systematically investigated by first-principles calculations. We have considered all possible adsorption configurations without a surface dangling bond and give a quantitative analysis for the relationship between the deviation of carbon bond angle and adsorption energy. We found that a smaller distortion of carbon covalent bond angle results in a more stable adsorption structure, and the most stable adsorption has a benzene-ringlike structure with the highest adsorption energy of 5. 11 eV per molecule and the minimum distortion of carbon covalent bond angle.展开更多
The authors presented a facile approach to prepare highly-ordered sub-micrometer scaled cylindrical diamond arrays based on a chemical vapor deposition method,where the accurate control of the style of crystal seeds d...The authors presented a facile approach to prepare highly-ordered sub-micrometer scaled cylindrical diamond arrays based on a chemical vapor deposition method,where the accurate control of the style of crystal seeds dispersion and the growth time are very crucial.The as-prepared diamond array showed good conductivity which was originated from the proper boron doping,and moreover,it exhibited good field emission property with low turn-on field and high emission current.Importantly,this approach can be easily applied to the preparation of various micro-patterned one-dimensional diamond arrays.展开更多
To elucidate the effects of physisorbed active ions on the geometries and electronic structures of hydrogenated diamond films, models of HCO3, H3O^＋, and OH^- ions physisorbed on hydrogenated diamond （100） surfaces...To elucidate the effects of physisorbed active ions on the geometries and electronic structures of hydrogenated diamond films, models of HCO3, H3O^＋, and OH^- ions physisorbed on hydrogenated diamond （100） surfaces were constructed. Density functional theory was used to calculate the geometries, adsorption energies, and partial density of states. The results showed that the geometries of the hydrogenated diamond （100） surfaces all changed to different degrees after ion adsorption. Among them, the H3O^＋ ion affected the geometry of the hydrogenated diamond （100） surfaces the most. This is well consistent with the results of the calculated adsorption energies, which indicated that a strong electrostatic attraction occurs between the hydrogenated diamond （100） surface and H3O^＋ ions. In addition, electrons transfer significantly from the hydrogenated diamond （100） surface to the adsorbed H3O^＋ ion, which induces a downward shift in the HOMO and LUMO energy levels of the H3O^＋ ion. However, for active ions like OH^- and HCO3^, no dramatic change appears for the electronic structures of the adsorbed ions.展开更多
In Germany, diamond grinding is frequently used to improve the evenness and skid resistance of concrete pavement surfaces. Since diamond grinding has been observed to affect tyre/pavement noise emission favourably, th...In Germany, diamond grinding is frequently used to improve the evenness and skid resistance of concrete pavement surfaces. Since diamond grinding has been observed to affect tyre/pavement noise emission favourably, the relationship among surface texture, concrete composition and noise emission of concrete pavement surfaces has been sys- tematically investigated. The simulation program SPERoN was used in a parameter study to investigate the main factors which affect noise emission. Based on the results of the simulations, textured concrete surfaces were produced by using a laboratory grinding machine. As well as the composition of the concrete, the thickness and spacing of the diamond blades were varied. The ability of the textured surfaces to reduce noise emission was assessed from the texture characteristics and air flow resistance of textured surfaces measured in the laboratory. It was found that concrete composition and, in particular, the spacing of the blades affected the reduction in noise emission considerably. The noise emission behaviour of numerous road sections was also considered in field investigations. The pavement surfaces had been textured by diamond grinding during the last years or decades. The results show that diamond grinding is able to provide good, durable noise- reducing properties. Several new pavement sections were investigated using thicknesses and spacings of the blades similar to those used in the laboratory to optimize noise emission reduction. It is concluded that diamond grinding is a good alternative to exposed aggregate concrete for the production of low-noise pavement surfaces.展开更多
基金supported by the Special Actions for Developing High-performance Manufacturing of Ministry of Industry and Information Technology(Grant No.:TC200H02J)the Research Grants Council of the Hong Kong Special Ad-ministrative Region,China(Project No.:PolyU 152125/18E)+1 种基金the National Natural Science Foundation of China(Project No.:U19A20104)the Research Committee of The Hong Kong Polytechnic University(Project Code G-RK2V).
文摘The lightness and high strength-to-weight ratio of the magnesium alloy have attracted more interest in various applications.However,micro/nanostructure generation on their surfaces remains a challenge due to the flammability and ignition.Motivated by this,this study proposed a machining process,named the ultraprecision diamond surface texturing process,to machine the micro/nanostructures on magnesium alloy surfaces.Experimental results showed the various microstructures and sawtooth-shaped nanostructures were successfully generated on the AZ31B magnesium alloy surfaces,demonstrating the effectiveness of this proposed machining process.Furthermore,sawtooth-shaped nanostructures had the function of inducing the optical effect and generating different colors on workpiece surfaces.The colorful letter and colorful flower image were clearly viewed on magnesium alloy surfaces.The corresponding cutting force,chip morphology,and tool wear were systematically investigated to understand the machining mechanism of micro/nanostructures on magnesium alloy surfaces.The proposed machining process can further improve the performances of the magnesium alloy and extend its functions to other fields,such as optics.
基金Project(51074180)supported by the National Natural Science Foundation of China
文摘A new impregnated diamond bit was designed to solve the slipping problem when impregnated diamond bit was used for extra-hard, compact, and nonabrasive rock formation. Adding Si C grits into matrix, Si C grits can easily be exfoliated from the surface of the matrix due to weak holding-force with matrix, which made the surface non-smooth. Three Ф36/24 mm laboratorial bits were manufactured to conduct a laboratory drilling test on zirconiacorundum refractory brick. The laboratory drilling test indicates that the abrasive resistance of the bit work layer is proportional to the Si C concentation. The higher the concentration, the weaker the abrasive resistance of matrix. The new impregnated diamond bit was applied to a mining area drilling construction in Jiangxi province, China. Field drilling application indicates that the ROP(rate of penetration) of the new bit is approximately two to three times that of the common bits. Compared with the common bits, the surface of the new bit has typical abrasive wear characteristics,and the metabolic rate of the diamond can be well matched to the wear rate of the matrix.
基金financially supported by the National Natural Science Foundation of China (No. 51402013)the China Postdoctoral Science Foundation (No. 2015T80037)the Fundamental Research Funds for Central Universities (No. FRF-TP-15-052A2)
文摘The H-terminated diamond films, which exhibit high surface conductivity, have been used in high-frequency and high-power electronic devices. In this paper, the surface conductive channel on specimens from the same diamond film was obtained by hydrogen plasma treatment and by heating under a hydrogen atmosphere, respectively, and the surface carrier transport characteristics of both samples were compared and evaluated. The results show that the carrier mobility and carrier density of the sample treated by hydrogen plasma are 15 cm^2·V^（-1）·s^（-1） and greater than 5 × 1012 cm^（-2）, respectively, and that the carrier mobilities measured at five different areas are similar. Compared to the hydrogen-plasma-treated specimen, the thermally hydrogenated specimen exhibits a lower surface conductivity, a carrier density one order of magnitude lower, and a carrier mobility that varies from 2 to 33 cm^2·V^（-1）·s^（-1）. The activated hydrogen atoms restructure the diamond surface, remove the scratches, and passivate the surface states via the etching effect during the hydrogen plasma treatment process, which maintains a higher carrier density and a more stable carrier mobility.
基金supported by the National Natural Science Foundation of China(Grant Nos.51272278,91323304,10774177,and 11374341)the National Basic Research Program of China(Grand No.2009CB930502)+2 种基金the Knowledge Innovation Project of Chinese Academy of Sciences(Grand No.KJCX2-EW-W02)the Fundamental Research Funds for the Central Universities of Ministry of Education of Chinathe Research Funds of Renmin University of China
文摘The adsorption behaviors of glycine on diamond （001） are systematically investigated by first-principles calculations. We have considered all possible adsorption configurations without a surface dangling bond and give a quantitative analysis for the relationship between the deviation of carbon bond angle and adsorption energy. We found that a smaller distortion of carbon covalent bond angle results in a more stable adsorption structure, and the most stable adsorption has a benzene-ringlike structure with the highest adsorption energy of 5. 11 eV per molecule and the minimum distortion of carbon covalent bond angle.
基金Supported by the National Natural Science Foundation of China(Nos.20601005,20125102 and 20571077)the National Basic Research Program of China(Nos.2010CB934700,2009CB930404 and 2007CB936403)+1 种基金the Special Fund for Special Prize of the President Awardthe Chinese Postdoctoral Fund and K. C. Wong Education Foundation
文摘The authors presented a facile approach to prepare highly-ordered sub-micrometer scaled cylindrical diamond arrays based on a chemical vapor deposition method,where the accurate control of the style of crystal seeds dispersion and the growth time are very crucial.The as-prepared diamond array showed good conductivity which was originated from the proper boron doping,and moreover,it exhibited good field emission property with low turn-on field and high emission current.Importantly,this approach can be easily applied to the preparation of various micro-patterned one-dimensional diamond arrays.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China under Grant No. 51575004 and the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions. The authors would like to thank School of Materials Science and Engineering of Tsinghua University for providing computing server.
文摘To elucidate the effects of physisorbed active ions on the geometries and electronic structures of hydrogenated diamond films, models of HCO3, H3O^＋, and OH^- ions physisorbed on hydrogenated diamond （100） surfaces were constructed. Density functional theory was used to calculate the geometries, adsorption energies, and partial density of states. The results showed that the geometries of the hydrogenated diamond （100） surfaces all changed to different degrees after ion adsorption. Among them, the H3O^＋ ion affected the geometry of the hydrogenated diamond （100） surfaces the most. This is well consistent with the results of the calculated adsorption energies, which indicated that a strong electrostatic attraction occurs between the hydrogenated diamond （100） surface and H3O^＋ ions. In addition, electrons transfer significantly from the hydrogenated diamond （100） surface to the adsorbed H3O^＋ ion, which induces a downward shift in the HOMO and LUMO energy levels of the H3O^＋ ion. However, for active ions like OH^- and HCO3^, no dramatic change appears for the electronic structures of the adsorbed ions.
文摘In Germany, diamond grinding is frequently used to improve the evenness and skid resistance of concrete pavement surfaces. Since diamond grinding has been observed to affect tyre/pavement noise emission favourably, the relationship among surface texture, concrete composition and noise emission of concrete pavement surfaces has been sys- tematically investigated. The simulation program SPERoN was used in a parameter study to investigate the main factors which affect noise emission. Based on the results of the simulations, textured concrete surfaces were produced by using a laboratory grinding machine. As well as the composition of the concrete, the thickness and spacing of the diamond blades were varied. The ability of the textured surfaces to reduce noise emission was assessed from the texture characteristics and air flow resistance of textured surfaces measured in the laboratory. It was found that concrete composition and, in particular, the spacing of the blades affected the reduction in noise emission considerably. The noise emission behaviour of numerous road sections was also considered in field investigations. The pavement surfaces had been textured by diamond grinding during the last years or decades. The results show that diamond grinding is able to provide good, durable noise- reducing properties. Several new pavement sections were investigated using thicknesses and spacings of the blades similar to those used in the laboratory to optimize noise emission reduction. It is concluded that diamond grinding is a good alternative to exposed aggregate concrete for the production of low-noise pavement surfaces.
