Advanced Materials for Electromagnetic Shielding
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Transcript of Advanced Materials for Electromagnetic Shielding
Advanced Materials for Electromagnetic Shielding
Advanced Materials for Electromagnetic Shielding
Fundamentals, Properties, and Applications
Edited by
Maciej JaroszewskiFaculty of Electrical Engineering, Wrocław University of Science and TechnologyWrocław, Poland
Sabu ThomasInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University
and
School of Chemical Sciences, Mahatma Gandhi University, Kottayam, Kerala, India
Ajay V. RaneCurrent affiliation: Composite Research Group, Department of Mechanical Engineering Durban University of Technology, Durban, South Africa
and
International and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University, Kottayam, Kerala, India
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Library of Congress Cataloging‐in‐Publication Data
Names: Jaroszewski, Maciej Wladyslaw, 1966– editor. | Thomas, Sabu, editor. | Rane, Ajay V., 1987– editor.Title: Advanced materials for electromagnetic shielding : fundamentals, properties, and applications / edited by Maciej Wladyslaw Jaroszewski, Wrocław University of Science and Technology, Faculty of Electrical Engineering, Wrocław, Poland, Sabu Thomas, Mahatma Gandhi University, Priyadarshini Hills, Kottayam, Kerala, Ajay V. Rane, Composite Research Group, Durban University of Technology, South Africa and Mahatma Gandhi University, Priyadarshini Hills, Kottayam, Kerala.Description: First edition. | Hoboken, NJ, USA : Wiley, 2019. | Includes bibliographical references and index. | Identifiers: LCCN 2018022528 (print) | LCCN 2018028981 (ebook) | ISBN 9781119128649 (Adobe PDF) | ISBN 9781119128632 (ePub) | ISBN 9781119128618 (hardcover)Subjects: LCSH: Shielding (Electricity)Classification: LCC TK7867.8 (ebook) | LCC TK7867.8 .A38 2019 (print) | DDC 621.381–dc23LC record available at https://lccn.loc.gov/2018022528
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Contents
List of Contributors xv
1 EMI Shielding Fundamentals 1M. K. Aswathi, Ajay V. Rane , A. R. Ajitha, Sabu Thomas, and Maciej Jaroszewski
1.1 Fundamentals of EMI Shielding Theory 11.2 Materials for EMI Shielding 31.3 Mechanism of EM Shielding Materials 3 References 8
2 EM Noise and Its Impact on Human Health and Safety 11Halina Aniołczyk
2.1 Introduction 112.2 Impact of Non‐ionizing EMFs on Humans 132.3 Overview of Most Common Sources of EMFs in the Occupational and Residential
Modern Human Environment 162.4 Protection Against EMFs in European and International Law 192.5 Assessment of the Level of EMFs in the Workplaces 222.6 Assessment of EMF Levels in Inhabited Area 252.7 Assessment of the Level of EMF From Hi‐tech Equipment for Personal Use 262.8 Needs and Possibilities of Shielding to Reduce the Exposure to EMF 292.9 Summary 30 References 31
3 Electromagnetic Field Sensors 35Vishnu Priya Murali, Jickson Joseph, and Kostya (Ken) Ostrikov
3.1 Introduction 363.2 How are EMFs Produced? 363.2.1 Natural Sources 373.2.2 Man‐Made Sources 373.2.2.1 Low‐Frequency EMF Sources 373.2.2.2 High‐Frequency EMF Sources 383.3 Electromagnetic Field Measurements 383.3.1 Magnetic Field Measurement Techniques 383.3.1.1 Induction Based Sensors 393.3.1.2 Fluxgate Sensors 42
Contentsvi
3.3.1.3 SQUID Magnetometer 443.3.1.4 Hall Probes 463.3.1.5 Magneto‐Resistors 473.3.1.6 Scalar Magnetometers 493.3.2 Electric Field Measurements 513.3.2.1 Electric Field Probes 513.3.2.2 Electron Drift Instrument 533.3.3 Power Density Measurements 553.4 Conclusion 56 References 56
4 Shielding Efficiency Measuring Methods and Systems 61Saju Daniel and Sabu Thomas
4.1 Introduction 624.1.1 Mechanism of Shielding 624.1.2 Shielding Effectiveness 624.1.2.1 Absorption Loss 644.1.2.2 Reflection Loss 644.1.2.3 Multiple Reflection Correction Factor 654.2 Calculation of Electromagnetic Shielding Effectiveness 654.2.1 Calculation of SE of a Material by Using Plane Wave Theory 654.2.2 Calculation of SE of a Metal Foil 664.2.3 Calculation of SE for Near Field Shielding 674.2.4 Calculation of SE for Shielding a Low‐Frequency Magnetic Field Source 674.2.5 Calculation of Shielding Effectiveness from Scattering Parameters 674.3 Effect of Various Parameters on Electromagnetic Shielding Effectiveness 694.4 Types of EMI Shielding Effectiveness Tests 714.4.1 Open Field or Free Space Test 714.4.2 Shielded Box Test 714.4.3 Coaxial Transmission Line Test 724.4.4 Shielded Room Test 734.5 Shielding Effectiveness Measurement Methods and Systems 734.5.1 Test Methods Using Plaque Measurements 744.5.1.1 Testing Methods Based on MIL‐STD‐285T 744.5.1.2 Modified Radiation Method for Shielding Effectiveness Testing Based
on MIL‐G83528 754.5.1.3 Dual Mode Stirred Chamber 764.5.1.4 Apertured Transverse Electromagnetic (TEM) Cell in a Reverberating
Chamber 774.5.1.5 Dual TEM Cell Method 774.5.1.6 Split TEM Cell 784.5.1.7 ASTM ES‐7 Dual Chamber Test Fixture 784.5.1.8 ASTM ES‐7 Coaxial Transmission Line 784.5.1.9 ASTM D 4935 Circular Coaxial Transmission Line Holder 794.5.1.10 Enclosure Measurement Techniques 814.5.1.11 Injection Molded Enclosure Test Method 814.5.1.12 IEEE‐STD‐299 814.5.2 Free Space Methods 824.5.2.1 Free‐Space Measurement Techniques in the Frequency Domain 82
Contents vii
4.5.2.2 Free‐Space Measurement Techniques in the Time Domain 834.6 Transfer Impedance of Coaxial Cable 844.6.1 Measurement of Transfer Impedance of Coaxial Cable 844.7 Measurement of Transfer Impedance of Conductive Gasket 854.8 Summary 86 References 86
5 Electrical Characterization of Shielding Materials 89B. J. Madhu
5.1 Introduction 895.2 Basics of Electrostatics 895.2.1 Electrostatic Field 895.2.2 Electrical Potential Energy 915.2.3 Electric Potential and Electric Field Strength 925.3 Electrical Conductivity 935.3.1 Current and Current Density 935.3.2 Resistivity 945.3.3 DC Conductivity 955.3.4 AC Conductivity 975.4 Electric Fields in Materials 985.4.1 Dielectrics 985.4.2 Polarization 985.5 Dielectric Properties 1015.5.1 Static Dielectric Constant 1015.5.2 Complex Dielectric Constant and Dielectric Losses 1025.6 Electromagnetic Interference Shielding Materials 1035.6.1 Electromagnetic Interference Shielding 1035.6.2 Conductive Shielding Materials 1045.6.3 Dielectric Shielding Materials 105 References 105
6 Magnetic Field Shielding 109Qiang Zhang
6.1 Introduction 1096.2 Theories of Magnetic Field Shielding 1106.2.1 Magnetic Field 1106.2.2 Magnetic Circuit and Magnetic Reluctance 1116.2.3 Shielding of Magnetic Field 1126.2.3.1 Shielding of High Frequency Magnetic Field 1126.2.3.2 Shielding of Low Frequency or Static Magnetic Field 1126.2.4 Design of Multilayer Shielding 1146.2.4.1 Case (a) 1156.2.4.2 Case (b) 1156.2.5 Design of Magnetic Shielding Room 1166.3 Standard Shielding Materials 1166.3.1 Basic Magnetic Parameters 1166.3.2 Metallic and Ferromagnetic Materials 1186.3.3 Ferrite Materials 1196.3.4 Superconducting Materials 120
Contentsviii
6.3.5 Amorphous and Nanocrystalline Alloys 1206.4 Multilayer Ferromagnetic Matrix Composite Materials 1216.4.1 Fe–Ni Alloy/Fe/Fe–Ni Alloy Multilayer Composite 1226.4.1.1 Fabrication 1226.4.1.2 Microstructure Characterization 1226.4.1.3 Geomagnetic Shielding Property: Experiment and Calculation 1226.4.1.4 Shielding Mechanism 1286.4.2 Fe–Al Alloy/Fe/Fe–Al Alloy Multilayer Composite 1286.4.2.1 Fabrication 1286.4.2.2 Microstructure Characterization 1296.4.2.3 Geomagnetic Shielding Property: Experiment and Calculation 1306.4.2.4 Shielding Mechanism 1346.5 Sandwich Composite/Structure Shielding System 1346.5.1 Fe/Fe‐Al Alloy/Fe Sandwich Composite 1356.5.1.1 Fabrication 1356.5.1.2 Microstructure Characterization 1356.5.1.3 Magnetic Shielding Property 1366.5.1.4 Shielding Mechanism 1406.5.2 Composite/Polyester/Composite Sandwich Structure 1416.5.2.1 Fabrication 1416.5.2.2 Geomagnetic Shielding Property 1416.5.2.3 Shielding Mechanism 1436.6 Summary 143 References 144
7 Recent Progress in Electromagnetic Absorbing Materials 147Raghvendra Kumar Mishra, Aastha Dutta, Priyanka Mishra, and Sabu Thomas
7.1 Introduction 1477.1.1 Electromagnetic Wave Absorbing Materials 1497.2 Core–Shell Structured Electromagnetic Absorbing Materials 1517.3 CNM‐Based Electromagnetic Absorbing Material 1537.3.1 Carbon Nanotubes/Polymer Nanocomposites for Electromagnetic
Shielding 1547.3.2 Carbon Nanofiber Based EMI Shielding Materials 1567.4 Graphene Based Polymer Composites for EMI Shielding 1587.5 Challenges and Prospect 160 References 160
8 Flexible and Transparent EMI Shielding Materials 167Bishakha Ray, Saurabh Parmar, and Suwarna Datar
8.1 Introduction 1678.2 Theory of Transparent EMI Shielding 1688.3 Transparent Thin Films for EMI Shielding 1698.4 Nanocarbon Based Flexible, Transparent EMI Shielding Materials 1708.5 Conducting Polymer‐Based Flexible, Transparent EMI
Shielding Materials 1728.6 Nanowire Based Flexible, Transparent EMI Shielding Materials 1728.7 Conclusions 174 References 175
Contents ix
9 Polymer‐Based EMI Shielding Materials 177Chong Min Koo, Faisal Shahzad, Pradip Kumar, Seunggun Yu, Seung Hwan Lee, and Jun Pyo Hong
9.1 Introduction 1789.1.1 Need for Polymer‐Based EMI Shielding Materials 1789.1.2 Factors Effecting EMI SE 1809.2 Types of Polymer Matrixes 1819.2.1 Insulating Polymers 1819.2.2 Intrinsically Conducting Polymers 1819.3 Polymer Composites for EMI Shielding Applications 1849.3.1 Carbon Based Filler Materials 1849.3.1.1 Graphite 1849.3.1.2 Carbon Fiber 1869.3.1.3 Carbon Nanotube 1869.3.1.4 Carbon Black 1889.3.1.5 Graphene 1899.3.2 Magnetic Fillers 1909.3.2.1 Magnetic Fillers and Carbon Materials in Insulating Polymer Matrix 1909.3.2.2 Magnetic Fillers with Carbon Materials in Conducting Polymer Matrix 1929.3.2.3 All‐Magnetic Fillers in Insulating Polymer Matrix 1949.3.2.4 All‐Magnetic Fillers in Conducting Polymer Matrix 1989.3.3 Metal‐Based Filler Materials 1999.4 Structured Polymer Composites for EMI Shielding 2039.4.1 Foamed Structures 2049.4.2 Sandwiched Structures 2099.4.3 Segregated Structures 2109.5 Future Perspectives 212 References 213
10 Textile Based Shielding Materials 219Julija Baltušnikaitė‐Guzaitienė and Sandra Varnaitė‐Žuravliova
10.1 Introduction 21910.2 Materials for Production of EMI Textiles 22010.2.1 Polymers in EMI Textiles 22110.2.2 Conductive Coatings 22210.2.3 Compounding with Conductive Fillers 22210.2.4 Inherently (Intrinsically) Conductive Polymers (ICP) 22310.3 Development Trends of Textile Based Shielding Materials 22410.3.1 Shielding Materials Based on Conductive Fillers 22410.3.2 Shielding Materials Based on Fabric Formation Technology 22610.3.3 Shielding Materials Based on Fabric Surface Modification 22610.4 Methods of Shielding Effectiveness Measurement 22810.4.1 Coaxial Transmission Line Method 22810.4.2 Shielded Box Method 22910.4.3 Shielded Room Method 23010.4.4 Open Field or Free Space Method 23010.4.5 Waveguide Method 23210.5 Conclusions 232 References 233
Contentsx
11 Graphene and CNT Based EMI Shielding Materials 241 M.D. Teli and Sanket P. Valia11.1 Introduction to Graphene and Carbon Nanotubes 24111.1.1 Introduction to Graphene Based Materials 24111.1.2 Introduction to CNT Based Materials 24111.2 Brief Outline of Synthesis of EMI Shielding Materials 24211.2.1 Brief Outline of Synthesis of Graphene Based Materials 24211.2.2 Brief Outline of Synthesis of CNT Based Materials 24411.2.2.1 Electric Arc Discharge 24411.2.2.2 Laser Ablation 24511.2.2.3 Chemical Vapor Deposition 24511.3 General Characteristic of EMI Shielding Materials 24511.3.1 General Characteristic of Graphene Based Materials 24511.3.2 General Characteristic of CNT Based Materials 24611.4 EMI Shielding Properties of EMI Shielding Materials 24611.4.1 EMI Shielding Properties of Graphene Based Materials 24611.4.2 EMI Shielding Properties of CNT Based Materials 25011.5 Overview of Structure and EMI Shielding Property Relationship and Their
Applications 25111.5.1 Structure and EMI Shielding Property Relationship of Graphene Based Materials 25111.5.2 Structure and EMI Shielding Property Relationship of CNT Based Materials 25411.6 Future Scope of Research and Application of these Materials 25611.7 Conclusions 257 References 257
12 Nanocomposites Based EMI Shielding Materials 263 Hossein Yahyaei and Mohsen Mohseni12.1 Nanomaterials and Nanocomposite Materials 26312.2 EMI Shielding Materials 26412.3 Electromagnetic Wave and EMI Shielding Mechanism 26512.4 Carbonous EMI Shielding Nanocomposites 26612.4.1 Graphene 26612.4.1.1 Graphene Synthesis 26712.4.1.2 Case Studies 26712.4.2 Carbon Nanotubes 27212.4.2.1 Single‐Walled Carbon Nanotubes 27312.4.2.2 Carbon Nanotube Properties 27412.4.2.3 Case Studies 27412.4.3 Carbon Nanofibers 27712.4.3.1 Vapor Grown CNFs 27712.4.3.2 Electrospun CNFs (ECNFs) 27812.4.3.3 Case Studies 27812.5 Other EMI Shielding Nanocomposites 28012.5.1 Mechanical Properties 28112.5.2 Corrosion Resistance 28112.5.3 Electrical Conductivity 28112.5.4 Synthesis of Metal Nanoparticles 28212.5.5 Case Studies 282 References 284
Contents xi
13 Silver Nanowires as Shielding Materials 289 Feng Xu, Wenfeng Shen, Wei Xu, Jia Li, and Weijie Song13.1 Introduction 28913.2 Scalable Synthesis of AgNWs 29013.3 Fabrication of Shielding Materials Based on Silver Nanowire/Polymer Conductive
Composites 29413.4 Properties of Shielding Materials Based on Silver Nanowire/Polymer Conductive
Composites 29513.4.1 Morphological Properties 29513.4.2 Electrical Properties 29713.4.3 EMI Properties 29813.5 Conclusion 301 References 302
14 Advanced Carbon Based Foam Materials for EMI Shielding 305 A. R. Ajitha, Anu Surendran, M. K. Aswathi, V. G. Geethamma, and Sabu Thomas14.1 Introduction 30514.2 Carbon Hybrid Materials for EMI Shielding 30614.2.1 Carbon Foam (CF) 30614.2.2 Graphene Foam 30914.2.3 Carbon–Carbon Composites 31514.2.4 Carbon Aerogels 31614.2.5 Colloidal Graphite 32014.3 Conclusion 322 References 322
15 Electromagnetic Interference Shielding Materials for Aerospace Application: A State of the Art 327
Raghvendra Kumar Mishra, Martin George Thomas, Jiji Abraham, Kuruvilla Joseph, and Sabu Thomas
15.1 Introduction 32715.2 Radiation in Space Environment 32815.3 Electromagnetic Radiated Field 33015.3.1 Low Intensity Radiated Field 33115.3.2 High Intensity Radiated Field 33215.4 Electromagnetic Interference in Aerospace 33215.4.1 Classification of Electromagnetic Interference 33315.4.2 Effect of Electromagnetic Shielding 33315.5 Electromagnetic Interference Shielding Mechanism for Various Materials 33615.6 Requirement of Shielding Materials for Aerospace 33715.7 Types of Shielding Materials for Aerospace 33815.7.1 Metals Enclosure Based EMI Shielding Materials 33815.7.1.1 Design Consideration of Metallic Enclosure for EMI Shielding 34215.7.2 Porous Structure for EMI Shielding Materials 34415.7.3 Polymer Composites for EMI Shielding 34615.7.3.1 Metal Coated Polymer for EMI Shielding 34615.7.3.2 Conducting Polymer Based Materials for EMI Shielding 34815.7.3.3 Carbonanotube Based Composites for EMI Shielding 34915.7.3.4 Graphene Based Composites for EMI Shielding 352
Contentsxii
15.8 Conclusion 354 References 355
16 Metamaterials as Shielding Materials 367 Yogesh S. Choudhary and N. Gomathi16.1 Introduction 36716.2 The Need for EMI Shielding 37016.3 Why Metamaterials for Shielding Applications? 37116.4 Metamaterials for Electromagnetic Shielding 37116.4.1 Microwave Shielding 37316.4.2 Optical and Near IR Shielding 37516.4.3 Frequency Selective Shielding 37616.5 Design and Fabrication of Metamaterials 37816.5.1 Designing Metamaterials 37816.5.2 Fabrication of Metamaterials 38316.6 Other Applications 38516.6.1 Superlensing 38516.6.2 Antennas 38516.7 Challenges in Metamaterials 38616.8 Summary 386 References 387
17 Double Percolating EMI Shielding Materials Based on Polymer Blend Nanocomposites 393
P. Mohammed Arif, Jemy James, Jiji Abraham, K. Nandakkumar, and Sabu Thomas
17.1 Introduction 39417.2 Concept of Double Percolation 39417.3 Carbon Black and Carbon Nanofiber Based Composites 39517.3.1 Carbon Black Based Composites 39517.3.2 Carbon Nanofibers 40017.4 Carbon Nanotube Based Nanocomposites 40017.5 Hybrid Filler Based Nanocomposites 40517.6 Conclusion 407 References 407
18 Mechanical Performance Characterization of EMI Shielding Materials Using Optical Experimental Techniques 409
Wenfeng Hao, Can Tang, and Jianguo Zhu18.1 Introduction 40918.2 Characterizing the In‐Plane Mechanical Performance of EMI Shielding
Materials 41018.2.1 Digital Image Correlation (DIC) 41018.2.2 Moiré Interfere 41118.2.3 Photoelastic Method 41318.3 Characterizing Out‐of‐Plane Mechanical Performance of EMI Shielding
Materials 41418.4 Characterizing the Fracture and Fatigue Performance of EMI Shielding
Materials 415
Contents xiii
18.4.1 Caustics 41518.4.2 Coherent Gradient Sensing (CGS) 41618.4.3 Digital Gradient Sensing (DGS) 41818.5 Concluding Remarks 420 Acknowledgments 420 References 420
Index 425
xv
List of Contributors
Jiji AbrahamInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
A. R. AjithaInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
Halina AniołczykNofer Institute of Occupational Medicine Lodz Poland
P. Mohammed ArifInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
M. K. AswathiInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
Julija Baltušnikaitė‐GuzaitienėCenter for Physical Sciences and Technology Textile Institute Kaunas Lithuania
Yogesh S. ChoudharyDepartment of Chemistry Indian Institute of Space Science and Technology Thiruvananthapuram, Kerala India
Saju DanielInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
St. Xavier’s College Vaikom Mahatma Gandhi University Kottayam, Kerala India
Suwarna DatarDepartment of Applied Physics Defence Institute of Advanced Technology Deemed University Girinagar, Pune 411021 India
Aastha DuttaDepartment of Plastic and Polymer Engineering, G.S. Mandal’s Maharashtra Institute of Technology Aurangabad, Maharashtra India
V. G. GeethammaInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
List of Contributorsxvi
N. GomathiDepartment of Chemistry, Indian Institute of Space Science and Technology Thiruvananthapuram, Kerala India
Wenfeng HaoFaculty of Civil Engineering and Mechanics Jiangsu University Zhenjiang, Jiangsu P. R. China
Jun Pyo HongCenter for Materials Architecturing Korea Institute of Science and Technology Seoul Republic of Korea
Jemy JamesInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
School of pure and Applied Physics Mahatma Gandhi University Kottayam, Kerala India
FRE CNRS 3744, IRDL University of Southern Brittany Lorient France
Maciej JaroszewskiFaculty of Electrical Engineering Wrocław University of Science and Technology Wrocław Poland
Jickson JosephSchool of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology Brisbane, Queensland 4000 Australia
CSIRO−QUT Joint Sustainable Processes and Devices Laboratory, Commonwealth Scientific and Industrial Research Organisation P. O. Box 218, Lindfield New South Wales 2070 Australia
Kuruvilla JosephIndian Institute of Space Science and Technology Thiruvananthapuram, Kerala India
Chong Min KooCenter for Materials Architecturing Korea Institute of Science and Technology Seoul Republic of Korea
Nanomaterials Science and Engineering University of Science and Technology Daejeon Republic of Korea
KU‐KIST Graduate School of Converging Science and Technology, Korea University Seoul Republic of Korea
Pradip KumarCenter for Materials Architecturing Korea Institute of Science and Technology Seoul Republic of Korea
Jia LiNingbo Institute of Material Technology and Engineering, Chinese Academy of Sciences Ningbo P. R. China
Seung Hwan LeeCenter for Materials Architecturing Korea Institute of Science and Technology Seoul Republic of Korea
B. J. MadhuDepartment of Post Graduate Studies in Physics, Government Science College Chitradurga 577 501, Karnataka India
Raghvendra Kumar MishraInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
List of Contributors xvii
Priyanka MishraDeen Dayal Upadhyay Gorakhpur University Gorakhpur, Uttar Pradesh India
Mohsen MohseniDepartment of Polymer Engineering and Color Technology, Amirkabir University of Technology Tehran Iran
Vishnu Priya MuraliDepartment of Biomedical Engineering University of Memphis Memphis, Tennessee USA
K. NandakkumarInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
School of Pure and Applied Physics Mahatma Gandhi University Kottayam, Kerala India
Kostya (Ken) OstrikovSchool of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology Brisbane, Queensland 4000 Australia
CSIRO−QUT Joint Sustainable Processes and Devices Laboratory, Commonwealth Scientific and Industrial Research Organisation P. O. Box 218, Lindfield New South Wales 2070 Australia
Saurabh ParmarDepartment of Applied Physics Defence Institute of Advanced Technology Deemed University Girinagar, Pune 411021 India
Ajay V. RaneInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
Composite Research Group Department of Mechanical Engineering Durban University of Technology Durban South Africa
Bishakha RayDepartment of Applied Physics Defence Institute of Advanced Technology Deemed University Girinagar, Pune 411021 India
Faisal ShahzadNational Center for Nanotechnology Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS) Islamabad Pakistan
Center for Materials Architecturing Korea Institute of Science and Technology Seoul Republic of Korea
Nanomaterials Science and Engineering University of Science and Technology Daejeon Republic of Korea
Wenfeng ShenNingbo Institute of Material Technology and Engineering, Chinese Academy of Sciences Ningbo P. R. China
Weijie SongNingbo Institute of Material Technology and Engineering, Chinese Academy of Sciences Ningbo P. R. China
List of Contributorsxviii
Anu SurendranInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
Can TangFaculty of Civil Engineering and Mechanics Jiangsu University Zhenjiang, Jiangsu P. R. China
M. D. TeliDepartment of Fibres and Textile Processing Technology, Institute of Chemical Technology, Matunga (E) Mumbai, Maharashtra India
Martin George ThomasInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
Sabu ThomasInternational and Inter University Centre for Nanoscience and Nanotechnology Mahatma Gandhi University Kottayam, Kerala India
School of Chemical Sciences Mahatma Gandhi University Kottayam, Kerala India
Sanket P. ValiaDepartment of Fibres and Textile Processing Technology, Institute of Chemical Technology, Matunga (E) Mumbai, Maharashtra India
Sandra Varnaitė‐ŽuravliovaCenter for Physical Sciences and Technology Textile Institute Kaunas Lithuania
Feng XuNingbo Institute of Material Technology and Engineering, Chinese Academy of Sciences Ningbo P. R. China
Wei XuNingbo Institute of Material Technology and Engineering, Chinese Academy of Sciences Ningbo P. R. China
Hossein YahyaeiDepartment of Polymer Engineering and Color Technology, Amirkabir University of Technology Tehran Iran
Seunggun YuCenter for Materials Architecturing Korea Institute of Science and Technology Seoul Republic of Korea
Qiang ZhangDepartment of Materials Science Key Laboratory of Advanced Structure-Function Integrated Materials and Green Manufacturing Technology School of Materials Science and Engineering Harbin Institute of Technology Harbin P. R. China
Jianguo ZhuFaculty of Civil Engineering and Mechanics Jiangsu University Zhenjiang, Jiangsu P. R. China
Advanced Materials for Electromagnetic Shielding: Fundamentals, Properties, and Applications, First Edition. Edited by Maciej Jaroszewski, Sabu Thomas, and Ajay V. Rane. © 2019 John Wiley & Sons, Inc. Published 2019 by John Wiley & Sons, Inc.
1
1.1 Fundamentals of EMI Shielding Theory
Electromagnetic shielding is process of reducing the dispersion of electromagnetic waves into a desired space by hindering the waves with a shield made of conductive material. The effective performance of electrical instruments or the working of electrical instruments is interrupted, degraded, obstructed, or limited due to the electromagnetic interference (EMI). In a material the main mechanisms for EMI attenuation are reflection, absorption, and multiple reflection [1, 2]. Reflection is the primary mechanism of EMI shielding. For reflection the material must possess mobile charge carriers such as electrons or holes that interact with the electromagnetic radiation. Metals are the most common material for EMI shielding and the available free electrons in metals interact with the electromagnetic waves [3]. If the material is highly conductive the shielding against EM (electromagnetic) waves will occur through the reflection mechanism. However, conductivity is not a condi-tion for EMI shielding but it does enhance the reflection mechanism of an EMI shielding material.
The secondary mechanism for EMI shielding is absorption, which requires the existence of electric or magnetic dipoles to interact with the electromagnetic radiation. It changes with the thickness of the material. Materials that have a high dielectric constant provide electric dipoles and materials with high magnetic permeability provide magnetic dipoles for the EMI shielding by absorption [1].
The third mechanism is multiple reflections, which is the reflections at different surfaces or at the interface of the material. Materials that have large specific internal surfaces or composites with fillers show a multiple reflection mechanism. Generally, multiple‐reflection decreases the total shielding value if the material is thinner than the skin depth and the value can be neglected if the material has a higher thickness than the skin depth. At higher frequencies electromagnetic radiation penetrates only to the near surface region of the electrical conductor. This is known as the skin effect. The intensity of penetration of an electromagnetic wave decreases exponentially with increasing depth of the conductor [4].
1
EMI Shielding Fundamentals M. K. Aswathi1, Ajay V. Rane1,2, A. R. Ajitha1, Sabu Thomas1,3, and Maciej Jaroszewski4
1 International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala, India2 Composite Research Group, Department of Mechanical Engineering, Durban University of Technology, Durban, South Africa3 School of Chemical Sciences, Mahatma Gandhi University, Kottayam, Kerala, India4 Faculty of Electrical Engineering, Wrocław University of Science and Technology, Wrocław, Poland
1 EMI Shielding Fundamentals2
The skin depth is the depth of the conductor at which the intensity of the incident field drops in to 1/e of the incident value and is denoted by δ [5]:
Skin depth, 1
f
Here f is the frequency, μ is the magnetic permeability, and σ the electrical conductivity in Ω−1 m−1. Skin depth is not directly proportional to frequency, magnetic permeability, and conductivity, i.e. skin depth decreases with increase in frequency, magnetic permeability, or electrical conductivity. Owing to this skin effect, a material that contains a conductive filler with a small unit size of filler is more effective for shielding than a filler with a large unit size. The complete cross section of the filler unit can be used only when the unit size of the filler is less than or comparable with the skin depth.
Shielding effectiveness, which is expressed in dB, is the sum of reflection loss, absorption loss, and multiple reflections [6]. When electromagnetic waves strike the surface of an object they undergo reflection, multiple reflection, absorption, and transmission as shown in Figure 1.1. To be a shield against the EM wave, the material should reflect or absorb the electromagnetic wave. Factors determining shielding effectiveness (SE) are classified in Figure 1.2.
Incident waves
Absorption
Multiple reflection
Reflection
Transmission
Figure 1.1 Schematic representation showing mechanism of electromagnetic shielding.
Factors determining SE
Frequency of incidentelectromagnetic
field
Source to shield distance
Shield thickness
Type ofelectromagnetic
field source
Conductivity, permeability, permittivity of
shield material
Shieldingdegradation
Figure 1.2 Factors determining shielding effectiveness [7]. Source: Adapted from Gooch 2007.
1.3 Mechanism of EM Shielding Materials 3
1.2 Materials for EMI Shielding
Owing to the increasing use of electronic equipment the shielding of other instruments and of human beings from electromagnetic waves is a very serious issue in the present scenario, which is detailed in Chapter 2. The EM waves harmfully affect both the device performance and human beings. Nowadays, a reduction in the use of electronic equipment is not always practi-cal. What we are able to do is to reduce the penetration of EM waves produced from electronic instruments. To decrease the penetration we must use a shield or block the EM waves from the desired surface.
Metals are commonly used for EMI shielding application in the form of thin sheets or sheathing in automotive applications. But, metal is expensive, prone to corrosion, heavy, and the cost of manufacturing processes is also very high, which makes them an undesired choice for electronic application. Conductive polymer nanocomposites have attracted a great deal of academic and industrial interest by considering the cost‐effectiveness, easy processability, and their possible applications in many areas including EMI shielding. Polymer nanocom-posites based on CNTs (carbon nanotubes), carbon black (CB), graphene, metal nanoparti-cles, carbon fibers, foams, and magnetic nanoparticles show good shielding capacity against EM waves. Several groups have studied and reported the EMI shielding effectiveness of dif-ferent materials and mechanisms behind the EMI shielding ability of those materials. Characterization and requirement for EMI shielding materials are mentioned in the classifi-cation chart in Figure 1.3. Chapters 7–14, 16, and 17 describe these materials in detail in accordance to EM shielding.
1.3 Mechanism of EM Shielding Materials
Carbon nanotubes, a 1D nanostructure, are rolled up sheets of graphene, made up of a hexagonal lattice of sp2 hybridized carbon atoms. Depending upon the number of graphene sheets used to form the cylindrical shape the carbon nanotubes are of different types, namely single walled, double walled, multiwalled. Carbon fibers (CFs) come under 1D carbon nano‐allotropes, having interlocked sheets of graphene. Carbon black is a good filler to enhance the EMI shielding effectiveness of a material; it is produced by the thermal decomposition of hydrocarbons. Carbon black has graphite layers different from that of amorphous carbon.
Characterization and requirements
Shieldingeffectivenessmeasurement
Surface finish
Electricalconductivity
Contactinterface
compatibility
Thermalconductivity
Formability
Permeability
Manufacturability
Permittivity
On fieldevaluation
Mechanicalproperties
Figure 1.3 Characterization and requirements for EMI shielding materials [8]. Source: Adapted from Tong 2009.
1 EMI Shielding Fundamentals4
Every carbon atom in the graphite layer forms three covalent bonds with neighboring carbon atoms and the free p‐orbits from each carbon atom overlap to from delocalized π electrons. The presence of these freely moving π electrons make carbon black a good conducting material.
Carbon fiber paper (CFP) and nickel coated carbon fiber paper (NCFP) reinforced epoxy composites show EMI shielding efficiencies of 30 and 35 dB, respectively, in the frequency range 3.22–4.9 GHz for 0.5 mm thick sheets at 8 wt% fiber content. This is due to the increased conductivity shown by the nanocomposites; in addition, both absorption loss and reflection loss contribute to the total EMI shielding but the major contribution is from reflection. The material shows higher electrical conductivity due to the presence of mobile charge carriers. These charge carriers interact with the EM waves, which induces reflection as the major mechanism for the shielding [9].
Carbon black reinforced cement composites show a good EMI shielding value due to the presence of freely moving π‐bond electrons. The shielding effectiveness increased with increase in carbon black content because of the conductive network path and through the reflection mechanism [10].
Carbon black reinforced polyaniline/poloxalene composites can be used as a lightweight EMI shielding material with a shielding effectiveness of 19.2–19.9 dB at 10 wt% CB. The good EMI shielding value obtained is due to the formation of a network between carbon black and the blend system. The interconnected network contributes to the shielding value obtained through reflection as the shielding mechanism [11].
Carbon micro coils (CMCs) are another material used as a filler in making EMI shielding mate-rial. The polyurethane composites with CMCs show an increased EMI shielding value that depends on the layer thickness of the material. Hence the mechanism is based on absorption [12].
In the case of multiwalled carbon nanotube (MWCNT)/polypropylene (PP) composites the contribution of absorption loss to the total EMI shielding is higher than reflection so the major mechanism is absorption and reflection is the secondary shielding mechanism [13]. Here, multiple‐reflection is excluded from the discussion because it lowers the overall EMI SE.
Figures 1.4a–c show power balance graphs for different MWCNT/PP composites with various amounts of MWCNT and different plate thickness. The percentage of power blocked by reflection is increased with increase in MWCNT content in all three cases (Figures 1.4a–c), but in the case of 0.34 and 1 mm plates the percentage of absorption ini-tially increases with increasing MWCNT content and then decreases. In the third case (2.8 mm thick plates) the contribution by absorption increases linearly with increasing MWCNT content [13].
The EMI shielding effectiveness shown by samples of MWCNT, CNF, and high structure carbon black (HS‐CB) nanoparticles with acrylonitrile–butadiene–styrene (ABS) polymer [14] showed that whatever the nanofiller type the reflection loss was always less than the absorption loss (Figure 1.5a and b). The contribution of absorption loss to total EMI SE is 75%. When the shielding by absorption exceeds 10 dB most of the re‐reflected wave will be absorbed within the shield itself and so multiple reflections were ignored.
The electromagnetic interference shielding effectiveness of lightweight graphene/polystyrene composite [15] is shown in Figure 1.6a and b. The graphs show that the contribution of reflec-tion loss is negligible over the entire frequency range. The composite has a porous structure. This means that power is dissipated as heat rather than reflected back from the composite’s surface, which clearly describes why absorption is the primary mechanism and the secondary mechanism is reflection for such conductive porous composites in the X‐band frequency region.
The EMI shielding mechanism of PTT/MWCNT composites was studied by resolving the total EMI SE into absorption and reflection loss. Figure 1.7 shows the effect of MWCNT
1.3 Mechanism of EM Shielding Materials 5
content on absorption and reflection. The graphs shows that with increasing amounts of MWCNT both SEA and SER increased, but the rate of increase of SEA was higher compared to that of SER. At 0.24 vol.% of MWCNT the absorption contribution was 16% but with 4.76 vol.% of MWCNT the absorption contribution increased to 73%. These results show
1.0
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er (
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er (
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er (
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IncidentAbsorbedReflectedTransmitted
IncidentAbsorbedReflectedTransmitted
Figure 1.4 Power balance graph for MWCNT/PP nanocomposite in the X‐band frequency range of plate thickness (a) 0.34, (b) 1, and (c) 2.8 mm [13]. Reproduced with permission of Elsevier.
1 EMI Shielding Fundamentals6
0
40Reflection loss
Reflected power
Absorbed power
Transmitted power
Absorption loss
EMI total
1.0
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er (
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15SE
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02 4 6 8
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CNFwt%
10 12 14 16
0 2 4 6 8 10 12 14 16
Figure 1.5 Shielding mechanisms: (a) absorption loss, reflection loss, and total shielding as function of CNF content; (b) power balance as function of CNF content [14]. Reproduced with permission of Elsevier.
8 9
35(a) (b)
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I SE
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SEtotal
SEA
SER
Figure 1.6 Comparison of SEtotal, SEA, and SER for GPS045 (a) and GPS027 (b) in the 8.2–12.4 GHz range [15]. Reproduced with permission of the Royal Society of Chemistry.
1.3 Mechanism of EM Shielding Materials 7
that for PTT/MWCNT composites the primary shielding mechanism is absorption rather than reflection in the observed frequency range [16].
The composite fabricated by dip‐coating process using silver nanowire (AgNW)‐coated cellulose papers shows a reflection dominant EMI shielding mechanism. Figure 1.8 shows that there was a rapid increase in the reflectance, R, at three dip‐coating cycles, which means the dominant shielding mechanism changed from absorbance to reflectance around the number of cycles [17].
An EMI shielding investigation of PET fabric/PPy composite showed that absorption as well as reflection contributes to the total EMI shielding of the composite and that with increasing electrical conductivity the EMI shielding through reflection increased. Figure 1.9 shows that the reflection dominated absorption by considering the total EMI shielding. As shown in Figure 1.9, with decreasing specific volume resistivity shielding effectiveness by reflection increased, and shielding effectiveness by absorption decreased. The increase in reflection mechanism is due to a smaller skin depth of the composite [18].
Graphene is a single sheet of carbon nanostructure in which the carbon atoms are in sp2 hybridization. Graphene is a 2D carbon nanostructure. Graphite is the next member of the
0
–3
–6
–9
–12
–15
SE
A &
SE
R (
dB)
–18
–1 0 1 2 3
MWCNT (vol.%)
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Reflection loss at 8.2 GHzAbsorption loss at 8.2 GHz
Figure 1.7 Graph showing contribution of reflection and absorption loss to total EMI SE in PTT/MWCNT composites [16]. Reproduced with permission of Springer.
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R, A
, T
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Electrical conductivityin in-plane directionReflectivity (R)Absorptivity (A)Transmissivity (T)
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App
aren
t ele
ctric
al c
ondu
ctiv
ity (
S c
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0
Figure 1.8 Graph showing contribution of reflection, absorption, and transmittance to total EMI shielding of AgNW/cellulose papers and their dependence on electrical conductivity at 1.0 GHz [17]. Reproduced with permission of the American Chemical Society.
1 EMI Shielding Fundamentals8
graphene family, made by the stacking of graphene monolayers. These layers interact through Van der Waals forces of attraction.
Graphene nanosheets consist of a monolayer or a few monolayers of graphene and act as an EMI shielding material. These carbon forms are made from sp2 hybridized carbon atoms, with the edges or deformation sites showing the presence of some sp3 hybridized carbon atoms. Graphene oxide (GO), another two‐dimensional material coming under the graphene family, is formed by the introduction of covalent CO bonds in graphene. These graphene forms also contain delocalized π bond electrons – the presence of these freely moving electrons make them conducting.
Graphene nano‐platelets with polyaniline and poly(3,4‐ethylenedioxythiophene) (PEDOT)/ poly(styrene sulfonate) (PSS) with different ratios give paint like layers and act as an EMI shielding material. The contribution of absorption and reflection to the total EMI shielding value depends on the graphene/polyaniline ratios [19].
Graphene nanoplatelets (GNPs) in the insulating polymer matrix ultrahigh molecular weight polyethylene (UHMWPE) form a conductive network, and with 15 wt% filler the material shows 99.95% EMI shielding attenuation. The presence of a conductive path and the calculation using the power balance point out that the material absorbs more radiation than it reflects [20].
Another EMI shielding material obtained from PEDOT coated MWCNT and polyurethane matrix shows EMI shielding effectiveness through the absorption mechanism [21].
This chapter focuses the fundamentals of EMI shielding (reflection, absorption, and multiple reflections). Details on materials used for EMI shielding are given in further chapters of this book. The materials used for EMI shielding are fabricated in the form of an enclosure, i.e. a shielding enclosure. A shielding enclosure is a box or housing or cover providing isolation to the EMI emitter or receiver. This specialized cover is fabricated by considering the require-ments for a particular EMI application. The materials covered in this book are fabricated and form part of a shielding enclosure. General principles for designing an enclosure should be followed; the current book deals only with materials for EMI shielding and with advance-ments in material sciences related to EMI shielding.
References
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40
35
30
25
EM
I SE
(dB
)
20
15
100.0 0.5 1.0
Speci�c volume resistivity (ohm cm)
1.5 2.0 2.5 3.0
1.0
AR
SE
0.8
0.6
0.4
0.2
Re�
ecta
nce
or a
bsor
banc
e
0.0
Figure 1.9 Graph showing contribution of absorbance, reflectance, and total EMI SE of PET fabric/PPy composites with various specific volume resistivities [18]. Reproduced with permission of Elsevier.
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