Preparation And Study Of ZnO Low Infrared Irradiation And Microwave Absorption Composite Materials

Infrared/radar compatible stealth is the focus of current research of stealth materials. Zinc Oxide (ZnO) is a semiconductor material with good thermal stability, and microwave absorbing performance were improved by adding low-density multi-walled carbon nanotubes (MWCNTs). Magnetic metal-doped ZnO coated aluminum flakes (ZnO/Al) composites were an important direction for infrared/radar compatible stealth materials research.In this work, the ZnO powder and ZnO-based composite materials were firstly prepared. The morphology and structure of samples were characterized by XRD, SEM, TEM, FT-IR, et al. The infrared emissivity in the8-14μm band were tested by IR-2dual-band emissometer, while the microwave absorption performance were characterized by a vector network analyzer in the2-18GHz. The main works and results are as following:1. The ZnO powder was prepared by chemical precipitation method. The effects of reaction temperatures, reaction time, pH, calcinating temperature, zinc sources, the type and dosage of precipitants and surfactants on the infrared emissivity and microwave absorption performance of ZnO powder were investigated. The result showed that the as-prepared ZnO powder with good infrared stealth performance with infrared emissivity of0.83and the value of maximum reflection loss is-2dB by using zinc nitrate hexahydrate as zinc sources, ammonia water as precipitant, polyethylene glycol as surfactant, then adjusting pH to9under55℃for2hours and then after2hours calcination under400℃.2. ZnO/MWCNTs composite materials were prepared by chemical precipitation method using nitric acid modified multi-walled carbon nanotubes and zinc nitrate hexahydrate as raw materials, ammonia as precipitant. The morphology and thermostability of samples were characterized by SEM and TGA. The effects of MWCNTs on the infrared emissivity and microwave absorption performance of composite materials were investigated. The result demonstrated that MWCNTs were evenly loaded with ZnO particles and ZnO/MWCNTs composite materials has a better thermal stability compared with pure MWCNTs. Moreover, the maximum reflection loss of composite materials was-4.5dB and its infrared emissivity was0.81. Therefore, the infrared stealth and microwave absorbing performance of ZnO/MWCNTs composites were improved compared with pure ZnO.3. The precursor of zinc hydroxide coated flake aluminium powder was prepared by precipitation method using zinc nitrate hexahydrate, magnetic metal nitrate, flaky aluminum powder and ammonia water as raw materials, then magnetic metal-doped zinc oxide coated flake aluminium composites were prepared through high temperature calcination. The effects of dispersant types on dispersion of aluminium powder were investigated, and the effects of coated quantity of ZnO, the type and doping amount of magnetic metal elements on infrared emissivity and microwave absorption performance of composites were also explored. The results showed that metal oxides loading on the surface of flake aluminium powder presented a honeycomb-like structure. The Ni-doped ZnO/Al composites showed the best infrared/radar compatible stealth performance with the infrared emissivity of0.37and the value of maximum reflection loss is-32.5dB in13.6GHz when Ni (12%, in mole precent) doped ZnO/Al composite materials (mass ratio of Zinc oxide and flake aluminium powder was1:1).