Fabrication and Evaluation of Low Density Glass-Epoxy Composites for Microwave Absorption Applications

Srikanth Ivaturi; P S.N.S.R. Srikar; K. Anusha; S. K. Majee; Himanshu Bhusan Baske; P. Rama Subba Reddy; P Ghosal

doi:10.14429/dsj.67.11331

Srikanth Ivaturi Advanced Systems Laboratory, Hyderabad - 500 058
P S.N.S.R. Srikar Central University of Karnataka, Gulbarga - 585 367
K. Anusha Rajiv Gandhi University of Knowledge Technologies, Nuzvid - 521 202
S. K. Majee Advanced Systems Laboratory, Hyderabad - 500 058
Himanshu Bhusan Baske Defence Materials Stores Research Development Establishment, Kanpur - 208 013
P. Rama Subba Reddy Defence Metallurgical Research Laboratory, Hyderabad - 500 058
P Ghosal Defence Metallurgical Research Laboratory, Hyderabad - 500 058

DOI: https://doi.org/10.14429/dsj.67.11331

Keywords: Light weight composites, Mechanical properties, Fracture morphology, electromagnetic properties, Radar absorbing structures, RAS

Abstract

In the present work, fabrication and evaluation of low density glass – epoxy (LDGE) composites suitable for absorbing minimum 80 per cent of incident microwave energy in 8 GHz to 12 GHz (X-band) is reported. LDGE composites having different densities were fabricated using a novel method of partially replacing conventional S-glass fabric with low density glass (LDG) layers as the reinforcement materials. Flexural strength, inter laminar shear strength and impact strength of the prepared LDGE composites were evaluated and compared with conventional High density glass-epoxy (HDGE) composites to understand the changes in these properties due to replacement of S-glass fabrics with LDG layers. To convert LDGE structures to radar absorbing structures controlled quantities of milled carbon fibers were impregnated as these conducting milled carbon fibers can act as dielectric lossy materials which could absorb the incident microwave energy by interfacial polarisation. Electromagnetic properties namely loss tangent and reflection loss of carbon fiber impregnated LDGE composites were evaluated in 8 GHz -12 GHz frequency region and compared with HDGE composites. It was observed that both LDGE and HDGE composites have shown loss tangent values more than 1.1 and minimum 80 per cent absorption of incident microwave energy. Thus the results indicates that, LDGE composites can show EM properties on par with HDGE composites. Furthermore these LDGE composite could successfully withstand the low velocity impacts (4.5 m/s) with 50 J incident energy. Due to their ability to show good mechanical properties and light weight, LDGE composites can be used as a replacement for conventional HDGE composites to realise radar absorbing structures.

Author Biographies

Srikanth Ivaturi, Advanced Systems Laboratory, Hyderabad - 500 058

Dr I. Srikanth obtained MTech (Corrision Science & Engineering) from IIT, Mumbai, in 2000 and MSc (Chemistry) from Andhra University Vizag, in 1998 and PhD from Metallurgical & Materials Engineering Department of IIT, Hyderabad, in 2014. Presently working as Scientist ‘E’ at Advanced Systems Laboratory, Hyderabad. He has published 25 papers, filed 4 Indian patents and one international patent. His areas of interest includes: Radar absorbing structures, ultra high temperature ceramics, and nano material added CFRP/GFRPs.

In this paper his contributions are planning the experimental work, executing it, compiling the data and interpreting the results.

P S.N.S.R. Srikar, Central University of Karnataka, Gulbarga - 585 367

Mr P.S.N.S.R. Srikar obtained MSc (Physics) from School of Physical Sciences, Central University of Karnataka, India in 2016. He worked as a project student for a brief period of time in 2016 at Advanced System Laboratories, Hyderabad. His research is centered on developing novel materials to study the microwave absorption of composites at varying frequencies.

In this paper, he is involved in the fabrication and testing of the composites.

K. Anusha, Rajiv Gandhi University of Knowledge Technologies, Nuzvid - 521 202

Mrs Anusha has graduated from Rajiv Gandhi University of Knowledge Technologies, Nuzvid, Andhra Preadesh. Currently associated with Advanced Systems Laboratory, DRDO. Her areas of interest are Polymer chemistry and composite materials.

In this paper she contributed in fabrication, testing of composites and compilation data.

S. K. Majee, Advanced Systems Laboratory, Hyderabad - 500 058

Dr Swarup Kumar Majee has completed his MSc (Physics) from Jadavpur University, Kolkata, in 2001 and PhD from Indian Association for the Cultivation of Science (Kolkata) and Presently working as a Scientist ‘D’ Presently working in non-destructive evaluation of composites structures using radiography, infrared thermography, ultrasonics.

In this paper, he contribued towards thermographic studies of impacted composits.

Himanshu Bhusan Baske, Defence Materials Stores Research Development Establishment, Kanpur - 208 013

Mr Himanshu Bhusan Baskey received MTech in RF & Microwave Engineering from the Indian Institute of Technology, Kanpur, India, in 2013. Currently, he is working towards the PhD, on radar cross section reduction using metamaterials/frequency selective surfaces and various dielectric and magnetic materials. Presently working as a scientist in the Defence Materials Stores Research Development Establishment, Kanpur, India. He is mainly involved in the electromagnetic characterisation of various types of advanced composites, nanocomposites, artificial dielectrics, electromagnetic absorbers, and radar cross section measurements for the defence stealth applications.

In this paper, he contributed towards electromagnetic property evaluation of composites.

P. Rama Subba Reddy, Defence Metallurgical Research Laboratory, Hyderabad - 500 058

Mr P. Rama Subba Reddy is working as a Scientist in Armour Technology Center (ATC) at DMRL. His area of research includes: Development of composite armour materials and its ballistic evaluation.

His specific contributions in present work is characterisation of composites using low velocity impact tester.

P Ghosal, Defence Metallurgical Research Laboratory, Hyderabad - 500 058

Dr P. Ghosal, received PhD in Metallurgical Engineering from IIT, Banaras Hindu University, in 1996. Currently, working as, Head, Electron Microscopy Group in DMRL, Hyderabad in the area of advanced characterisation techniques, along with SEM, EBSD, FIB, TEM, HRTEM and Raman-AFM systems. Current interests, includes in-situ mechanical testing and in-situ heating experiments of nano and advanced materials inside electron microscopes.

In this paper, he contributed towards SEM characterisation of raw materials, fractured composites.