Processing and Characterization of Aerospace Composites for Advanced Radome Applications

Abstract

This research presents the development and characterization of innovative composite materials for aerospace radome applications. Radomes, which protect radar and antenna systems in hostile environmental conditions, must maintain structural integrity while minimizing signal attenuation, especially in the high-frequency Ku-band (10-14.5 GHz). The study explores the use of commercially available reinforcements such as Kevlar and quartz combined with cyanate ester matrices. Three manufacturing techniqueshand layup, infusion molding, and autoclave processingwere employed to fabricate composite samples. Mechanical characterization included tensile, impact, and flexural strength tests, as per American Society for Testing and Materials (ASTM) standards, while electromagnetic testing was conducted using a state-of-the-art anechoic chamber. Among both combinations, the cyanate ester/quartz composite manufactured through autoclave processing demonstrated superior electromagnetic performance with an insertion loss of less than 1 dB across the Ku-band while maintaining adequate mechanical properties. Kevlar-based composites showed higher mechanical strength but slightly compromised signal transparency. This work contributes to the field by providing a data-driven framework for optimizing material selection and processing techniques in aerospace composite manufacturing, aligning with national goals for indigenously developed high-performance materials.

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Process of the synthesis of a composite of cyanate ester with Kevlar and cyanate ester with quartz.

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Specimen geometry for mechanical and physical testing. All samples were fabricated with a fiber volume fraction of 60% and a matrix volume fraction of 40%.

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XRD patterns of cyanate ester composites reinforced with Kevlar and quartz fibers.

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FTIR of Kevlar- and quartz-reinforced composites of cyanate ester with hand layup, infusion molding, and autoclave processes. The main vibrations are C=C (1600–1700 cm^–1), C–N (∼1350 cm^–1), C–O–C (1200–1250 cm^–1), and N–H stretching (3300–3400 cm^–1) in Kevlar composites. Quartz composites show Si–O–Si peaks (1000–1100 cm^–1). Sample dimensions were 10 × 10 × 1 mm, tested by using PerkinElmer Spectrum 100 FTIR.

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SEM micrographs of the cross-sectional area of composite samples, captured on a 50 μm scale. The images show the fiber-matrix interface, voids, and resin dispersion. These samples were not fractured but were cross-sectioned for detailed microstructural analysis.

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EDX spectra of cyanate ester composites: (A) cyanate ester/Kevlar composite; (B) cyanate ester/quartz composite.

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(a) Density of cyanate ester/Kevlar composites; (b) density of cyanate ester/quartz composites fabricated using different processing techniques: hand layup, infusion molding, and autoclave. Each processing method involved the fabrication of 10 samples per composite system. The error bars represent the standard deviation, indicating the variation in density values among the 10 independently prepared samples for each method.

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Tensile stress–strain curves of cyanate ester composites processed using three different fabrication techniques: hand layup, infusion molding, and autoclave. (a) Cyanate ester/Kevlar composites. (b) Cyanate ester/quartz composites. Each processing method involved the fabrication and testing of three individual samples per composite system. The curves represent the average tensile response, and the error bars show the standard deviation across the three replicates for each method.

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Impact energy (J) of cyanate ester/Kevlar and cyanate ester/quartz composites processed by hand layup, infusion molding, and autoclave.

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Ternary plot representing the normalized mechanical properties (tensile strength, flexural strength, and load) of the cyanate ester/Kevlar and cyanate ester/quartz composites. All values are unitless and normalized concerning the maximum value in each category.

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Comparison of the dielectric loss tangent (tan δ) and estimated Ku-band insertion loss (dB) for cyanate ester composites reinforced with Kevlar and quartz fibers, fabricated using autoclave, infusion molding, and hand layup techniques. Each data box represents the results obtained from 25 independent samples (n = 25).