Dissertation > Excellent graduate degree dissertation topics show

Preparation and Microwave Absorption Properties of Fe-based Magnetic Particles

Author: HaoZhi
Tutor: WangJianBo
School: Lanzhou University
Course: Materials Science
Keywords: Ball feed ratio Complexes Ferrite Milling time Lanzhou University Mechanical alloying Microwave characteristics Alloy particles Carbon Nanotubes Magnetic loss
CLC: TB34
Type: Master's thesis
Year: 2009
Downloads: 145
Quote: 0
Read: Download Dissertation

Abstract


In recent years,considerable experimental investigations have been focused on the effective microwave absorption materials in order to solve the expended electromagnetic interference problems.Three microwave absorption mechanisms were found in the materials:dielectric loss,conduction loss and magnetic loss. Magnetic loss materials have been investigated broadly for their high complex permeability.Magnetic metals and alloys are ideal electromagnetic wave absorber materials because of higher complex permeability at high frequency.Metal Fe has higher saturation magnetization and lower coercive force,and iron alloys also attract much attention in the field of microwave absorption materials. Many research work have been done on Fe-Co,Fe-Ni and Fe-Si alloy,etc.However, only few reports about microwave absorption properties of Fe-Zr alloy were reported until now.We prepared Fe-Zr alloy by mechanical alloying method and studied the microwave absorption properties.Meanwhile,in order to find low density microwave absorb materials,we also explored the fabrication method to obtain ferrite/carbon nanotubes composites using improved co-precipitation method.The main results are: Fe90Zr10 alloy prepared by MA has high saturation magnetization and low coercive force.It exhibits irregular spherical particle after dry milling,and has good microwave absorption properties.The microwave absorption of Fe90Zr10 alloy/paraffin composite is less than -20 dB（more than 99%energy were absorbed） at frequency range from 4.5 to 17.6 GHz by changing ball-mill parameters and thickness. If NaCl was used as process control agent,Fe90Zr10 alloy shows flake morphology, and better microwave absorption properties can be obtained.It is possible to get absorption intensity less than -20 dB at frequency range from 2.8 to 15.9 GHz by changing ball-mill parameters and thickness.The microwave absorption mechanism of the composite is ferromagnetic loss.Multiwalled carbon nanotubes have been coated with cobalt ferrite and nickel zinc ferrite by an improved co-precipitation method.The MWCNTs coated with different ferrites could be used as a new low density microwave absorber.

Related Dissertations

  1. Thermal Stability of Complexes of Chitosan Quaternary Ammonium Salt and Metal Ion,O634
  2. Metallization Iridium (Ⅲ) Complexes and their luminescent properties of the rigid ring,O641.4
  3. Design and Realization of the Magnetic Antenna in MW and SW Bands Based on Genetic Algorithm,TN820
  4. Theoretical Analysis of the Circular Dichroism Spectra of Transition Metal Schiff-Base Complexes,O641.4
  5. Carbon Nanotubes Compound Polymer Film Modified Electrode and Its Application for Electroanalytical Chemistry,O657.1
  6. Synthesis of 5-Cl-salicylate-Chromium(Ⅲ) Complexes, and Properties and Their Lipid-lowering Activity,O627.63
  7. Research on Fuel Gas Production from Catalytic Gasification of Municipal Solid Wastes,X799.3
  8. Complexes of two iodine three Allylthiourea together Synthesis and Characterization of cadmium,O627
  9. Chitosan Supported Metal Complexes and Their Catalytic Oxidation Resistance,O634
  10. Cobalt Ferrite and Its Performance,O611.4
  11. Aza- β- diimine complexes and hypophosphorous acid synthesis and structural characterization,O627.51
  12. Pyridine Metal Complexes electronic spectra and redox properties of theoretical research,O627
  13. 1,3 - propanediamine shrink o-vanillin 3d-4f heteronuclear bimetallic complexes synthesis, structure and properties of,O627.3
  14. Multi-dimensional charge transport group modify iridium complex design, synthesis and optical properties,O627.8
  15. Blue phosphorescent iridium complex dendritic Design, Synthesis and Properties,O641.4
  16. SnO 2 / CNTs composite Controllable Preparation and Gas Sensitivity Study,TB383.1
  17. MWCNTs and ZnO / SnO 2 Composites and NO gas research,TB33
  18. Inorganic / organic magnetic suspension preparation and application,TB383.1
  19. Construction of Protic Ionic Liquid Modified Electrode and Its Enhanced Action in Direct Electron Transfer of GOD,O646
  20. Studies on Synthesis and Catalytic Reactivity of Titanium and Zirconium Complexes Incorporating Imidazole Ligands,O627
  21. Determination of Trace Sulfonamides Residues in Animal Food,S859.84

CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Functional Materials
© 2012 www.DissertationTopic.Net  Mobile