Study On The Physical Properties And Surface Modificaton Of The Superfine Hollow Nickel Spheres

In recent years, increasing interest has been given to the synthesis of submicrometer-sized materials with hollow structures, such as nanotube, submicrometer hollow spheres, which often exhibit novel properties dramatically different from their solid counterparts in the fields of chemistry, physics, biotechnology, and material science.Recently, we fabricate submicrometer-sized nickel hollow spheres(NHSs) by a facile autocatalytic reduction method. In this paper, we analyze the electromagnetic properties of NHSs, and investigate the complex permittivity , permeability and the microwave absorption properties of the composite samples prepared by homogeneously mixing the nickel powders with polyvinyl butyral (PVB) to explore the application of NHSs in microwave absorption materials. The study shows that the composite of NHSs with average diameter 1.2μm exhibits better microwave absorption property and broader bandwidth. Additionally, we also explore the application of NHS in building solar selective absorption materials. Basing on the metal-dielectric medium model, we use NHSs as the dispersion metal particles, acrylic resin as the dielectric medium, aluminium sheet as the basal body to fabricate the solar selective absorption coating by dipping method. We study the solar absorption properties of NHSs in UV-Visible-IR wavelength range and the effects of the particle sizes and the thickness of the coatings on solar selective absorption. It is investigated that with the decrease of particle sizes, the absorptivity will be increased and the emissivity will remain unchanged. Meanwhile, when the coating thickness is increased ,the emissivity will be enhanced as a result. However, when the thickness value exceeds the threshold, the emissivity will be decreased.In order to improve the magnetic performance and microwave absorption properties of the NHSs, we coat the NHSs surface with porous Co shells by...