Dissertation > Excellent graduate degree dissertation topics show

Preparation of Tetrapod ZnO Modified by CoFe2O4 and the Mocrowave Absorbing Properties

Author: ZhaoLingLing
Tutor: ZhaoNaiQin
School: Tianjin University
Course: Materials Science
Keywords: terapod zinc oxide cobalt ferrite epoxy resin CNT/ZnO absorbing propertie
CLC: TN304.21
Type: Master's thesis
Year: 2010
Downloads: 51
Quote: 0
Read: Download Dissertation

Abstract


Zinc oxide is a kind of multifunctional semiconductor crystal materials. Becauseof its low density, large aspect ratio and easy-forming three-dimensional networks, thetetrapod zinc oxide whiskers （T-ZnOw）with special morphology is excellent to act asthe electromagnetic wave absorber, composite reinforcement, damping and anti-slipmaterials. Exploring the preparation process and investigating the effect ofmodification on the electromagnetic properties of T-ZnOw, are important issues intheoretical and practical aspect for the development of the applications of T-ZnOw.T-ZnOw were prepared by thermal evaporation. The ratio of zinc to graphite,zinc to zinc acetate, the evaporation temperature and holding time, were studied. Thenthe growth mechanism of T-ZnOw was discussed. T-ZnOw/CoFe2O4 compositepowder can be obtained via chemical coprecipitation, and the influence on itselectromagnetic properties was investigated. T-ZnOw/CoFe2O4 was filled into theepoxy by molding method in different content and the absorbing properties werecompared. Besides, carbon nanotubes （CNT） covered with ZnO and polygonalstar-like ZnO were fabricated, and then the electrical and magnetic properties of themwere investigated.The results showed that the proportion of mixed powders and holding time hadrelatively minor influence on the T-ZnOw growth, but the evaporation temperaturewas an important impact on the final morphology of ZnO. When the zinc and graphitein the mass ratio of 5:1, holding at 950℃for 5min, it is available to obtain the bestmorphology of T-ZnOw, as well as a high purity, good crystallinity and high yield.According to comparison of the products T-ZnOw, T-ZnOw/CoFe2O4, CNT/ZnO andpolygonal star-like ZnO, it noticed that, the electromagnetic properties ofT-ZnOw/CoFe2O4 were reduced because of CoFe2O4 modification to T-ZnOw. Asincrease of the CoFe2O4 content, the dielectric constant of T-ZnOw/CoFe2O4 waslower than T-ZnOw without modification, and T-ZnOw/CoFe2O4 filled in epoxy resinhas the largest reflectivity around at -3dB. It was also indicated that the dielectricconstant of CNT/ZnO was higher than T-ZnOw, but polygonal star-like ZnO waslower than T-ZnOw because of different morphology.

Related Dissertations

  1. Preparation and Anticorrosion Properties of Doped Polyaniline/Epoxy Coating,TQ637
  2. Study on Carboxyl Side Groups Containing Poly Aromatic Ether Sulfone Ketone and Modification of Epoxy,O631.3
  3. Cobalt Ferrite and Its Performance,O611.4
  4. Electrically Conductive Adhesives Based on Epoxy Resins Modified by Polyimide Powder with Carboxyl Groups,TQ433.437
  5. Preparation and Property Study of Glass Cloth Reinforced F Class Laminates Based on Halogen-free Retardant Epoxy Resin,TQ323.5
  6. Study of Composite Drive Shaft for an Automobile,U465.6
  7. Research on Diallyl Bisphenol A Modified Bismaleimide High-temperature Adhesive,TQ433
  8. Research of Epoxy Resin Concrete (Mortar) Modified and Application,TU528.41
  9. Preparation and Properties of Melamine-formaldehyde Microcapsules and MicroPCMs/epoxy Composites,TB383.4
  10. The Preparation and Application of Polyaniline Compound on Epoxy Resin Anticorrosion Coating,TQ637
  11. Research on Interface Properties of Composite Seal Material Composed with Metal and Fluorine Rubber,TQ333.93
  12. Effects of Ultra-Fine Crystal Powder on Epoxy Resin Adhesive,TQ433.437
  13. The Study of Preparation and Properties of Water-borne Polyurethane Anti-corrosion Coating Modified by Epoxy Resin,TQ637
  14. Synthesis and Properties of Epoxy Resin and Acrylate Modified Waterborne Polyurethane,TQ323.8
  15. Preparation and Property of Epoxy/SiO2 Dental Composite Resin Materials,TQ323.5
  16. Biomechanics Analysis of Preparation of Curved Root Canals with Different Endodontic Instruments,R781.05
  17. Preparation and Properties of Epoxy/SiO2 Hollow Spheres Nanocomposites,TB383.1
  18. Study on Properties of Epoxy Resins Modified by Inorganic Nano-particles and Polyurethane,TB383.1
  19. Synthesis of Fluorinated Copolymer and Its Application in Epoxy Coating,TQ630.4
  20. Polymeric Matrix Composites with High Dielectric Constant,TB332

CLC: > Industrial Technology > Radio electronics, telecommunications technology > Semiconductor technology > General issues > Material > Compound semiconductor > Oxide semiconductor
© 2012 www.DissertationTopic.Net  Mobile