To improve the oxidation and graphitization resistances of the polycrystalline diamond(PCD), Ti coating was deposited on the diamond powders via magnetic sputtering method, which achieved a uniform Ti C protection bar...To improve the oxidation and graphitization resistances of the polycrystalline diamond(PCD), Ti coating was deposited on the diamond powders via magnetic sputtering method, which achieved a uniform Ti C protection barrier in PCD during the sintering process. The phase compositions, microstructures and thermal stability of Ti-PCD were characterized by X-ray diffraction(XRD), Auger electron spectroscopy(AES),scanning electron microscopy(SEM) and thermal gravimetric-differential scanning calorimetry(TG-DSC).The results demonstrate that the oxidation and graphitization resistances of PCD are strengthened due to the existence of Ti C phase, which acts as an effective inhibitor. The as-received inhibitor delays the oxidation and graphitization of PCD, elevating their initial temperature by ~50°C and ~100°C, respectively. During the annealing treatment of Ti-PCD, the priory oxidation of Ti C, which produces Ti O2 as an oxygen barrier, postpones the diamond oxide. Moreover, the Ti C barrier also protects diamond grains from direct contact with cobalt, thus a lower cobalt-catalytic graphitization, and yields to an improved graphitization resistance of PCD. The enhanced oxidation and graphitization resistances of PCD are of significant importance for practical applications to elevated temperatures.展开更多
Ti-coated SiCp particles were developed by vacuum evaporation with Ti to improve the interfacial bonding of SiCp/Al composites.Ti-coated SiC particles and uncoated SiC particles reinforced Al 2519 matrix composites we...Ti-coated SiCp particles were developed by vacuum evaporation with Ti to improve the interfacial bonding of SiCp/Al composites.Ti-coated SiC particles and uncoated SiC particles reinforced Al 2519 matrix composites were prepared by hot pressing,hot extrusion and heat treatment.The influence of Ti coating on microstructure and mechanical properties of the composites was analyzed by scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).The results show that the densely deposited Ti coating reacts with SiC particles to form TiC and Ti5Si3 phases at the interface.Ti-coated SiC particle reinforced composite exhibits uniformity and compactness compared to the composite reinforced with uncoated SiC particles.The microstructure,relative density and mechanical properties of the composite are significantly improved.When the volume fraction is 15%,the hardness,fracture strain and tensile strength of the SiCp reinforced Al 2519 composite after Ti plating are optimized,which are HB 138.5,4.02%and 455 MPa,respectively.展开更多
采用磁控溅射法在负极集流体铜箔表面镀上一层致密的钛膜,以石墨为活性物质制备成扣式电池进行了对比实验。实验结果表明以铜箔为集流体制备的石墨半电池4次过充之后比容量衰减了120 m Ah/g(全电池的过放过程对应着石墨半电池的过充过...采用磁控溅射法在负极集流体铜箔表面镀上一层致密的钛膜,以石墨为活性物质制备成扣式电池进行了对比实验。实验结果表明以铜箔为集流体制备的石墨半电池4次过充之后比容量衰减了120 m Ah/g(全电池的过放过程对应着石墨半电池的过充过程),以表面镀钛铜箔为集流体,4次过充之后比容量只衰减了25 m Ah/g。循环伏安曲线和交流阻抗分析表明铜箔表面镀一层钛膜,可有效地提高铜箔的电化学抗腐蚀性能,进而提高锂离子电池的耐过放性能。展开更多
In this research,the advantages and disadvantages of the cylindrical grinding process of Polycrystalline Diamond Compacts(short for PDC) with vitrified and resin bond diamond grinding wheel are compared.The research r...In this research,the advantages and disadvantages of the cylindrical grinding process of Polycrystalline Diamond Compacts(short for PDC) with vitrified and resin bond diamond grinding wheel are compared.The research results show that the vitrified bond diamond grinding wheels,which use Ti-coated diamond grains as abrasive and glass ceramic as bond,have many advantages in grinding PDC.Compared with resin diamond grinding wheel,vitrified bond wheels lead to 35% grinding cost reduced,40% grinding time of each PDC saved,and the size precision of PDC improved(from ±0.03mm to ±0.01mm).When grinding feed is <0.10 mm,the grinding ratio increases with increased grinding feed.However,when the grinding feed exceeds 0.10 mm,the grinding radio decreases rapidly with the increasing of grinding feed.The disadvantage of this kind of grinding wheel is that the brightness of the ground PDC cylinder is not as shining as that processed by resin bond diamond grinding wheel.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51875537,41572359 and 51375466)the Beijing Natural Science Foundation(No.3172026)+2 种基金the Beijing Nova program(No.Z171100001117059)the Fundamental Research Funds for the Central University(No.2652018094)the Natural Science Foundation of Ningxia Province(No.2018AAC03200)。
文摘To improve the oxidation and graphitization resistances of the polycrystalline diamond(PCD), Ti coating was deposited on the diamond powders via magnetic sputtering method, which achieved a uniform Ti C protection barrier in PCD during the sintering process. The phase compositions, microstructures and thermal stability of Ti-PCD were characterized by X-ray diffraction(XRD), Auger electron spectroscopy(AES),scanning electron microscopy(SEM) and thermal gravimetric-differential scanning calorimetry(TG-DSC).The results demonstrate that the oxidation and graphitization resistances of PCD are strengthened due to the existence of Ti C phase, which acts as an effective inhibitor. The as-received inhibitor delays the oxidation and graphitization of PCD, elevating their initial temperature by ~50°C and ~100°C, respectively. During the annealing treatment of Ti-PCD, the priory oxidation of Ti C, which produces Ti O2 as an oxygen barrier, postpones the diamond oxide. Moreover, the Ti C barrier also protects diamond grains from direct contact with cobalt, thus a lower cobalt-catalytic graphitization, and yields to an improved graphitization resistance of PCD. The enhanced oxidation and graphitization resistances of PCD are of significant importance for practical applications to elevated temperatures.
基金Project(CXZZ20140506150310438)supported by the Science and Technology Program of Shenzhen,ChinaProject(2017GK2261)supported by the Science and Technology Program of Hunan Province,ChinaProject(2017zzts111)supported by the Fundamental Research Funds for the Central Universities of Central South University,China。
文摘Ti-coated SiCp particles were developed by vacuum evaporation with Ti to improve the interfacial bonding of SiCp/Al composites.Ti-coated SiC particles and uncoated SiC particles reinforced Al 2519 matrix composites were prepared by hot pressing,hot extrusion and heat treatment.The influence of Ti coating on microstructure and mechanical properties of the composites was analyzed by scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).The results show that the densely deposited Ti coating reacts with SiC particles to form TiC and Ti5Si3 phases at the interface.Ti-coated SiC particle reinforced composite exhibits uniformity and compactness compared to the composite reinforced with uncoated SiC particles.The microstructure,relative density and mechanical properties of the composite are significantly improved.When the volume fraction is 15%,the hardness,fracture strain and tensile strength of the SiCp reinforced Al 2519 composite after Ti plating are optimized,which are HB 138.5,4.02%and 455 MPa,respectively.
文摘采用磁控溅射法在负极集流体铜箔表面镀上一层致密的钛膜,以石墨为活性物质制备成扣式电池进行了对比实验。实验结果表明以铜箔为集流体制备的石墨半电池4次过充之后比容量衰减了120 m Ah/g(全电池的过放过程对应着石墨半电池的过充过程),以表面镀钛铜箔为集流体,4次过充之后比容量只衰减了25 m Ah/g。循环伏安曲线和交流阻抗分析表明铜箔表面镀一层钛膜,可有效地提高铜箔的电化学抗腐蚀性能,进而提高锂离子电池的耐过放性能。
文摘In this research,the advantages and disadvantages of the cylindrical grinding process of Polycrystalline Diamond Compacts(short for PDC) with vitrified and resin bond diamond grinding wheel are compared.The research results show that the vitrified bond diamond grinding wheels,which use Ti-coated diamond grains as abrasive and glass ceramic as bond,have many advantages in grinding PDC.Compared with resin diamond grinding wheel,vitrified bond wheels lead to 35% grinding cost reduced,40% grinding time of each PDC saved,and the size precision of PDC improved(from ±0.03mm to ±0.01mm).When grinding feed is <0.10 mm,the grinding ratio increases with increased grinding feed.However,when the grinding feed exceeds 0.10 mm,the grinding radio decreases rapidly with the increasing of grinding feed.The disadvantage of this kind of grinding wheel is that the brightness of the ground PDC cylinder is not as shining as that processed by resin bond diamond grinding wheel.
