Copper and zinc were recovered from waste diamond cutters through leaching with an ammonia–ammonium sulfate system and air as an oxidant. The effects of experimental parameters on the leaching process were investigat...Copper and zinc were recovered from waste diamond cutters through leaching with an ammonia–ammonium sulfate system and air as an oxidant. The effects of experimental parameters on the leaching process were investigated, and the potential–pH(E–pH) diagrams of Cu–NH_3–SO_4^(2-)–H_2O and Zn–NH_3–SO_4^(-2)–H_2O at 25°C were drawn. Results showed that the optimal parameters for the leaching reaction are as follows: reaction temperature, 45°C; leaching duration, 3 h; liquid-to-solid ratio, 50:1(mL/g); stirring speed, 200 r/min; ammonia concentration, 4.0 mol/L; ammonium sulfate concentration, 1.0 mol/L; and air flow rate, 0.2 L/min. The results of the kinetics study indicated that the leaching is controlled by the surface chemical reaction at temperatures below 35°C, and the leaching is controlled by diffusion through the product layer at temperatures above 35°C.展开更多
As a cutting tool,diamond films made by chemical vapor deposition(CVD) outperformed polycrystalline diamond(PCD) sintered under ultrahigh pressure.For example,the longevity of the CVD tools may be 2～5 times that of P...As a cutting tool,diamond films made by chemical vapor deposition(CVD) outperformed polycrystalline diamond(PCD) sintered under ultrahigh pressure.For example,the longevity of the CVD tools may be 2～5 times that of PCD inserts.In addition,the former cutting paths are strainghter with less chipping on the edge.However,there have been no report on CVD diamond films that were used as a roller scriber for splitting large glass panels.Our research demonstrated that the CVD diamond film could concentrate the energy in a smaller area(about 1/4),so the glass compressed by the tip of the diamond film was under a larger tensile stress in perpendicular to the direction of compression.The tensile stress then initiated the microcracks that were more in line with the direction of the compression. The reason that CVD diamond film could concentrate the compressive stress was due to its 100%diamond content.The high diamond content could allow the tip to be polished sharper.In contrast,the PCD cutting tip contained micro grains of cobalt that were softer than glass.As a result,the compressional stress was spreading out due to the larger area of contact.Consequently,the microcracks initiated at the PCD tip were random and they might not propagate along the direction of cutting.展开更多
聚焦离子束(focused Ion beam,FIB)作为一种用于金刚石微铣刀的特种加工方式,其引发的损伤程度直接关联到刀具的加工性能和寿命。课题组采用LAMMPS软件进行分子动力学(Molecular Dynamics,MD)模拟,结合SRIM软件的分析结果,探究单晶金刚...聚焦离子束(focused Ion beam,FIB)作为一种用于金刚石微铣刀的特种加工方式,其引发的损伤程度直接关联到刀具的加工性能和寿命。课题组采用LAMMPS软件进行分子动力学(Molecular Dynamics,MD)模拟,结合SRIM软件的分析结果,探究单晶金刚石亚表层损伤的形成机理和入射离子能量对损伤深度和范围的影响。模拟结果表明:随着入射离子能量的提升,离子束在材料内的渗透深度及引起的非晶层和点缺陷损伤均有所增加;进一步的研究发现损伤形成过程中材料局部温度的上升可能诱发自退火现象,且与离子入射能量成正比,该现象对于理解聚焦离子束加工引起的损伤有着至关重要的意义;而势能的变化与损伤形成之间的显著对应关系揭示了第一邻近原子的势能明显高于第二邻近原子,进而高于Other类型原子,这一发现有助于深入理解损伤形成的微观过程。因此,精确控制入射能量是实现金刚石材料高精度聚焦离子束加工的关键,且对自退火效应和势能变化的研究对损伤监控与控制同样重要。展开更多
基金financially supported by Disciplines Group Project of Jianghan University's Thirteenth Five-year Plan for Vehicle Material Development and Testing (No.03430001)the Wuhan Science and Technology Bureau (No.2013071004010468)the Scientific and Technological Research Project of Hubei Provincial Department of Education (No.B2014076)
文摘Copper and zinc were recovered from waste diamond cutters through leaching with an ammonia–ammonium sulfate system and air as an oxidant. The effects of experimental parameters on the leaching process were investigated, and the potential–pH(E–pH) diagrams of Cu–NH_3–SO_4^(2-)–H_2O and Zn–NH_3–SO_4^(-2)–H_2O at 25°C were drawn. Results showed that the optimal parameters for the leaching reaction are as follows: reaction temperature, 45°C; leaching duration, 3 h; liquid-to-solid ratio, 50:1(mL/g); stirring speed, 200 r/min; ammonia concentration, 4.0 mol/L; ammonium sulfate concentration, 1.0 mol/L; and air flow rate, 0.2 L/min. The results of the kinetics study indicated that the leaching is controlled by the surface chemical reaction at temperatures below 35°C, and the leaching is controlled by diffusion through the product layer at temperatures above 35°C.
文摘As a cutting tool,diamond films made by chemical vapor deposition(CVD) outperformed polycrystalline diamond(PCD) sintered under ultrahigh pressure.For example,the longevity of the CVD tools may be 2～5 times that of PCD inserts.In addition,the former cutting paths are strainghter with less chipping on the edge.However,there have been no report on CVD diamond films that were used as a roller scriber for splitting large glass panels.Our research demonstrated that the CVD diamond film could concentrate the energy in a smaller area(about 1/4),so the glass compressed by the tip of the diamond film was under a larger tensile stress in perpendicular to the direction of compression.The tensile stress then initiated the microcracks that were more in line with the direction of the compression. The reason that CVD diamond film could concentrate the compressive stress was due to its 100%diamond content.The high diamond content could allow the tip to be polished sharper.In contrast,the PCD cutting tip contained micro grains of cobalt that were softer than glass.As a result,the compressional stress was spreading out due to the larger area of contact.Consequently,the microcracks initiated at the PCD tip were random and they might not propagate along the direction of cutting.
文摘聚焦离子束(focused Ion beam,FIB)作为一种用于金刚石微铣刀的特种加工方式,其引发的损伤程度直接关联到刀具的加工性能和寿命。课题组采用LAMMPS软件进行分子动力学(Molecular Dynamics,MD)模拟,结合SRIM软件的分析结果,探究单晶金刚石亚表层损伤的形成机理和入射离子能量对损伤深度和范围的影响。模拟结果表明:随着入射离子能量的提升,离子束在材料内的渗透深度及引起的非晶层和点缺陷损伤均有所增加;进一步的研究发现损伤形成过程中材料局部温度的上升可能诱发自退火现象,且与离子入射能量成正比,该现象对于理解聚焦离子束加工引起的损伤有着至关重要的意义;而势能的变化与损伤形成之间的显著对应关系揭示了第一邻近原子的势能明显高于第二邻近原子,进而高于Other类型原子,这一发现有助于深入理解损伤形成的微观过程。因此,精确控制入射能量是实现金刚石材料高精度聚焦离子束加工的关键,且对自退火效应和势能变化的研究对损伤监控与控制同样重要。
