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Preparation and Microwave Absorption Properties of Oxide Semiconductor Coated Absorbents

Author: WuXiaoBing
Tutor: WanZuoZao
School: Tianjin University
Course: Materials Science
Keywords: Oxide semiconductor Microwave absorption Carbon fiber Carbonyl iron Coated-materials
CLC: TB34
Type: Master's thesis
Year: 2012
Downloads: 2
Quote: 0
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Abstract


The ideal microwave absorbent is expected to possess strong absorption, widebandwidth, thin thickness and light mass. However, there is no such kind of absorbentthat could meet all the above-mentioned requirements. Composite microwaveabsorbent consists of two or more kind of absorbents has already become the researchhotspot. In this work, three kinds of oxide semiconductor coated absorbents weresuccessfully fabricated by different methods and their morphology, crystal structure,formation mechanism, electromagnetic parameters and microwave absorption werestudied systematically.The SnO2-coated carbonyl irons were synthesized by combining ball milling andhydrothermal treatment and their electromagnetic parameter and microwaveabsorption performance were analyzed contrastively. The results showed that SnO2particles with0.2μ of the rutile structure were stable and repeatable, and themicrowave absorption properties were improved remarkably due to the uniformcoating of submicron-SnO2on the surface of the carbonyl iron particles and thestrongest reflection loss could reach-57.8dB.Nano SnO2-coated carbon fibers were obtained by a facile electrochemicaldeposition method, and then heat-treated under argon atmosphere. Theelectromagnetic parameter and microwave absorption of carbon fiber, nanoSnO2-coated carbon fibers and after heat-treated nano SnO2-coated carbon fibers werestudied systematically. SnO2grains of clad layer was tetragonal structure with a sizeof about5nm, and heat treatment increased the particle size and caused no structurechange. After heat-treatment nano SnO2-coated carbon fibers possessed bettermicrowave absorption properties than the other two samples which had a strongabsorption （RL＜20dB） in3.5-18.0GHz and its maximum RL value reached-44.9dBwith a thickness of1.32mm at15.8GHz.Cottony, flaky and grainy ZnO were synthesized on the surface of carbon fiber byfacile electrochemical deposition method, and their electromagnetic parameter andmicrowave absorption properties were studied comparatively. ZnO crystal of differentmorphologies had the same structure which was hexagonal （wurtzite） structure with a preferential [001] growth direction. Cottony ZnO-coated cabon fiber had the bestmicrowave properties which had a strong absorption （RL＜-10dB） in3.4-18.0GHzand its maximum RL value reached-46.6dB with a thickness of1.21mm.Oxide semiconductor-coated absorbent had stronger microwave absorption, widerbandwidth, thinner thickness and smaller mass than single absorbent, and wouldbecome very promising and potential materials in microwave absorption field.

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