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Microwave absorption properties of Graphite flakes-Phenolic Resin Composite

Microwave absorption properties of Graphite flakes-Phenolic Resin Composite. The work focused on….

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Microwave absorption properties of Graphite flakes-Phenolic Resin Composite

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  1. Microwave absorption properties of Graphite flakes-Phenolic Resin Composite

  2. The work focused on… The compatibility of electronic devices with various electromagnetic environments has become an important issue in recent years with increasing use of gigahertz electromagnetic waves in wireless communications, satellite communications, radar systems, and military applications. This in turn increases the demands on electromagnetic interference shielding and electromagnetic wave absorbing materials in the GHz range.

  3. Applications of microwave absorber

  4. Challenges in developing radar absorbing material (RAM) • Consistent absorption over a range of frequencies (broad banding). • The reduction of dimension (as absorption is thickness dependent). • Durability, corrosion resistant and thermal stability. • Cost effective

  5. Material Parameter influencing microwave absorption… Parameter influencing materials behavior to microwaves: Complex permittivity ,Complex permeability dielectric loss tangent ,Magnetic loss tangent Wave impedance *The behavior of a composite material to microwave is considered as inactive when m//<<m/ (m//~ 0) & e / / <<e / (e / / ~0) ** The behavior of a composite material to microwave is considered as active whenm//, m/, e / / & e / values are comparable.

  6. er , mr Plane wave PEC a(thickness) Theory for microwave absorption….. According to the transmission line theory, the input impedance at the surface of the absorber is given by Fig.1 Sketch map of incidence of electromagnetic wave in single-layer absorber

  7. Experimental • Material selection: • Graphite Flakes(GF) as inclusions & Novolac Phenolic resin (NPR) as polymer matrix. • GF has light weight, low cost, good corrosion resistance and high thermal conductivity and stability. • NPR has good heat resistance, dimensional stability, flame & chemical resistance and cost effective.

  8. Experimental Contd... GF NPR Mixed in dry form Grinding Fill in the die-mould Compressed Fig.2. Block diagram of composite preparation Composite sample after natural cooling Composite sample of size 10.38 mm × 22.94mm × 3.7 mm is prepared by compression molding technique with varying the ratio of resin and fillers (7 and10 wt. %).

  9. Microstructural characterization X-Ray Diffraction and Scanning Electron Micrographs Figure 3: XRD patters of Graphite flakes (inset: SEM picture of GF)

  10. Microwave characterization of GF-NPR composites using Agilent 85071E material measurement software Figure 4: Complex permittivity of GF-NPR composites (a) Real part & (b) Imaginary part

  11. Calculated reflection loss(RL) values of single layered GF-NPR composite Fig.5. Calculated RL values of GF-NPR composites

  12. Microwave absorption studies • Absorption sheet synthesis • Technique: Free Space measurements

  13. Preparation of GF/NPR composites of dimension 152 mm x 152 mm x 4 mm for measuring reflection loss using fee space technique Thermal treatment Sample holder Fig.7. RAM sheet preparation technique GF/NPR Sheet

  14. Free space technique using Agilent E8362C Vector Network Analyzer Fig.6. Free space measurement set up

  15. Measured reflection loss(RL) values of single layered GF-NPR composite. • A maximum RL values of -25dB, -9dB are observed for 7 wt% and 10 wt% GF with absorption peak at 9.8GHz and 9.4 GHz respectively. • A maximum RL ~-25dB is observed for 7 wt. % composition at 9.8 GHz with 10dB bandwidth of 0.3 GHz. Fig.8. Calculated RL values of GF-NPR composites

  16. References [1] Yusoff AN,Abdullah MH, Ahmad SH, Jusoh SF,Mansor AA and Hamid SAA, “Electromagnetic and absorption properties of some microwave absorbers,” J. Appl. Phys, 92, 876-882 (2002). [2] A.N. Yusoff, M.H. Abdullah, S.H. Ahmad, S.F. Jusoh, A.A. Mansor, and S.A.A. Hamid, “Electromagnetic and absorption properties of some microwave absorbers,” J Appl Phys, 92, 876-882 (2002). [3] C. Brosseau, W.N. Dong, and A. Mdarhri, “Influence of uniaxial tension on the microwave absorption properties of filled polymers,” Appl. Phys, 104, 074907-7(2008) [4] Y Yonglai, Gupta M C, Dudley K L and Lawrence R W., “ Novel carbon nanotube – polystyrene foam composites for electromagnetic interference shielding,” Nano Letters, 5, 2131-34 (2005). [5] Z. Liu, G. Bai, Y. Huang, Y. Ma, F. Du, F. Li, T. Guo, and Y. Chen, “Reflection and absorption contributions to the electromagnetic interference shielding of single-walled carbon nanotube/polyurethane composites,” Carbon, 45, 821–827(2007). [6] I. M. De Rosa, A. Dinescu, F. Sarasini, M. S. Sarto, and A. Tamburrano, “Effect of short carbon fibers and MWCNTs on microwave absorbing properties of polyester composites containing nickel-coated carbon fibers,” Comp. Sci. Technol,70, 102–109 (2010). [7] Fan Y, Yang H, Li M and Zou G.,“Evaluation of the microwave absorption property of flake Graphite, ”J.Mater Chem Phys, 115, 696-98, (2009). [8] Kakati B K and Deka D., “Effect of Resin Matrix Precursor on the Properties of Graphite Composite Bipolar Plate for PEM Fuel Cell,” Energ Fuel, 21, 1681-87 (2007).

  17. THANK YOU

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