This paper presents a new electromagnetic functional material developed byelectron-less nickel deposition technique, with a single hollow micro-sphere as the core templateand a thin nickel layer as the shell. The micr...This paper presents a new electromagnetic functional material developed byelectron-less nickel deposition technique, with a single hollow micro-sphere as the core templateand a thin nickel layer as the shell. The micrograph taken by a scanning electron microscope showsthe microstructures of the materials in detail. Scattering parameters of the waveguide sample holderfilled with the materials have been obtained over X band. The electromagnetic parameters computedfrom the measured S parameters show that the material with metallic hollow spheres has as highrelative permeability μ'_r as 19.0 with about 0.6 magnetic loss tangent over the whole bandwidth.Compared to the material with non-metallic spheres, the permeability μ'_r and the magnetic losstangent μ'_r increase greatly, while the permittivity remains lower than 1.8.展开更多
In order to improve the interface bonding of SiCp/AZ61 composites prepared by powder metallurgy followed by hot extrusion, the electroless plating of Ni-P coating on SiCp was carried out. The influence of Ni coating o...In order to improve the interface bonding of SiCp/AZ61 composites prepared by powder metallurgy followed by hot extrusion, the electroless plating of Ni-P coating on SiCp was carried out. The influence of Ni coating on microstructure and mechanical properties of the composites was analyzed. The results show that SiC particles distribute more uniformly in the composites after surface Ni plating and there are fewer defects in Ni-coated composite. The Ni coating reacts with the magnesium matrix forming the Mg2Ni interfacial compound layer during the sintering process. The relative density of the composite increases from 97.9% to 98.4% compared with uncoated one and the hardness of the Ni-coated composite increases more rapidly as the volume fraction of SiCp increases. The tensile test results show that the tensile strength increases from 320 to 336 MPa when the volume friction of SiC particle is 9% and the Ni-coated composites have larger elongation, indicating that Ni coating improves the interfacial bonding strength and the performance of the composites. In addition, the fracture properties of SiCp/AZ61 composites were analyzed.展开更多
Fouling induction period of CaCO3 on heated surface was studied with the micro video technology. The rates of nucleating and nuclei growing were measured under various experimental conditions. The experimental results...Fouling induction period of CaCO3 on heated surface was studied with the micro video technology. The rates of nucleating and nuclei growing were measured under various experimental conditions. The experimental results showed that both nucleating and nuclei growing rates of CaCO3 increased obviously with surface temperature and concentration of reagents. In addition, the experiment of fouling induction period on the surface material of chemical plated nickel-phosphorus-polytetrafluoroethylene indicated that not only the nucleate rate of CaCO3 decreased but also some fouling particles with certain size were easy to peel off from the heated surface under shearing stress, which means that the property of surface material is one of the most important factors influencing fouling induction periods.展开更多
文摘This paper presents a new electromagnetic functional material developed byelectron-less nickel deposition technique, with a single hollow micro-sphere as the core templateand a thin nickel layer as the shell. The micrograph taken by a scanning electron microscope showsthe microstructures of the materials in detail. Scattering parameters of the waveguide sample holderfilled with the materials have been obtained over X band. The electromagnetic parameters computedfrom the measured S parameters show that the material with metallic hollow spheres has as highrelative permeability μ'_r as 19.0 with about 0.6 magnetic loss tangent over the whole bandwidth.Compared to the material with non-metallic spheres, the permeability μ'_r and the magnetic losstangent μ'_r increase greatly, while the permittivity remains lower than 1.8.
基金Project(CXZZ20140506150310438)support by the Science and Technology Program of Shenzhen,ChinaProject(2017GK2261)supported by the Science and Technology Program of Hunan,ChinaProject(2017zzts111)supported by the Fundamental Research Funds for the Central Universities of Central South University,China
文摘In order to improve the interface bonding of SiCp/AZ61 composites prepared by powder metallurgy followed by hot extrusion, the electroless plating of Ni-P coating on SiCp was carried out. The influence of Ni coating on microstructure and mechanical properties of the composites was analyzed. The results show that SiC particles distribute more uniformly in the composites after surface Ni plating and there are fewer defects in Ni-coated composite. The Ni coating reacts with the magnesium matrix forming the Mg2Ni interfacial compound layer during the sintering process. The relative density of the composite increases from 97.9% to 98.4% compared with uncoated one and the hardness of the Ni-coated composite increases more rapidly as the volume fraction of SiCp increases. The tensile test results show that the tensile strength increases from 320 to 336 MPa when the volume friction of SiC particle is 9% and the Ni-coated composites have larger elongation, indicating that Ni coating improves the interfacial bonding strength and the performance of the composites. In addition, the fracture properties of SiCp/AZ61 composites were analyzed.
基金Supported by the National Natural Science Foundation of China.
文摘Fouling induction period of CaCO3 on heated surface was studied with the micro video technology. The rates of nucleating and nuclei growing were measured under various experimental conditions. The experimental results showed that both nucleating and nuclei growing rates of CaCO3 increased obviously with surface temperature and concentration of reagents. In addition, the experiment of fouling induction period on the surface material of chemical plated nickel-phosphorus-polytetrafluoroethylene indicated that not only the nucleate rate of CaCO3 decreased but also some fouling particles with certain size were easy to peel off from the heated surface under shearing stress, which means that the property of surface material is one of the most important factors influencing fouling induction periods.