Barium titanate flakes based composites for microwave absorbing applications

Abstract

Barium titanate (BT) has attained research focus in recent past owing to considering its high dielectric constant and stealth capabilities in microwave region. Shape effects of BT viz. powder, micron size flakes, nano particles and nanotubes have been studied vastly for its stealth capabilities. Present study aims at the preparation of millimetric size barium titanate flakes (BTFs) via controlled sol-gel process followed by tape casting. BTFs were mixed in varied weight ratio (50-90 wt.%) with polyurethane resin to fabricate composite laminates. Electromagnetic properties measurement in X and Ku band revealed high values of real and imaginary permittivity. Reflection loss measurements demonstrated more than 20 dB loss in wide frequency range (11.4-13.6 GHz). For single layer microwave absorber, reflection loss values have been calculated and it is observed that calculated and measured reflection loss values are in good agreement to each other. Developed material can find applications in broadband radar signature reduction.

Effect of hydrogenation on the microwave absorption properties of BaTiO3 nanoparticles

“…5B. 34 BaTiO 3 akes with an average size of 500 nm aer annealing at 1250 C reached a maximal reection loss of À27 dB at 12 GHz with 80 wt% mass loading in a polyurethane matrix, 35 and composites of BaTiO 3 nano-torus and epoxy resin displayed a maximum reection loss of À28.38 dB at 11.36 GHz. So, hydrogenation improved the reection loss or absorption of the microwave irradiation and shied its peak position to lower frequencies.…”

“…The hydrogenated BaTiO 3 nanoparticles showed two sharp dips of the RL with values of À16.4 and À36.9 dB around 8.1 and 11.9 GHz, respectively. 11,[32][33][34][35] For example, composites of BaTiO 3 nanotubes ($10 nm in diameter) and polyaniline only displayed the largest microwave absorption of À3.7 dB at 8.84 GHz, 11 and composites of BaTiO 3 nanotubes ($10 nm in diameter) and paraffin wax had a maximal reection loss of À21.8 dB. This indicated that hydrogenated BaTiO 3 nanoparticles had excellent reection loss of microwave irradiation at these frequencies.…”

Stealth technology: Methods and composite materials—A review

“…Broadband RAM was developed after the World War II (1945‐1950) that is also used in anechoic chambers now a day . Many materials including carbon loaded plaster of Paris, graphite, powder iron, iron oxide, powder aluminum, steel, copper, wool, metal wires, sand powdered “Advanced,” and “Constantin” were studied for microwave attenuation. Various binders including ceramics and plastics, while supports with air at interference included excelsior, foams and fibers, were also studied .…”

Comparison of microwave absorption properties between BaTiO3/Epoxy and NiFe2O4/Epoxy composites

“…BaTiO 3 is the most common choice for ceramic filler material due to its widely availability . In general microwave absorption properties of BaTiO 3 depend on complex permittivity ( ‐ ) and complex permeability ( ‐ ) constant throughout the frequency range . However, epoxy resins are one of the most important candidate thermoset due to having excellent electrical insulators, surface coatings, adhesives, and fiber‐reinforced composites.…”