Combustion synthesis of green Zn1-xCoxO nanopowders and their application in multi-spectral camouflage/stealth materials

• Published in: Materials express 2021-04, Vol.11 (4), p.492-505
• Main Authors: Yang, Tsung-Mao, Chang, Yu-Chai, Li, Jin-Shuh, Peng, Cheng-Hsiung, Lu, Kai-Tai
• Format: Article
• Language: English
• Subjects: Camouflage Paint; Combustion Synthesis; Microwave Absorbing Composite; Taguchi Experimental Design Method; Zn1-Xcoxo
• ISSN: 2158-5849
• DOI: 10.1166/mex.2021.1941

In this study, green Zn1-xCoxO (x = 0.025 - 0.200) nanopowders were synthesized by the combustion method using Zn(NO3)2 * 6H2O, Co(NO3) 26H2O and NH2CH2COOH as reactants. The synthesized products were identified and characterized by XRD, SEM-EDS, TEM-SAED, ITICs, CM and UV-Vis-NIR. Furthermore, the synthesized Zn1-xCoxO nanopowders were used to prepare Zn1-xCoxO/CNT/silicone rubber composites. The electromagnetic parameters and reflection loss values of the prepared composite materials were measured by VNAs. The synthesized Zn1-xCoxO nanopowders were also used to prepare Zn1-xCoxO/Al/siloxane resin paints. A Taguchi L9(33) orthogonal array was adopted to design experimental formulas. The intrinsic emissivities of the prepared paints were measured by ITICs. Experimental and analytical results showed that the particle size of the synthesized Zn1-xCoxO nanopowders after calcination was larger than that of the Zn1-xCoxO nanopowders before calcination, and their shape was close to spherical. The intrinsic emissivities in the 3-5µm and 8-12 µm wavebands were in the ranges of 0.247-0.338 and 0.753-0.781, respectively. The greenness and brightness of the synthesized Zn1-xCoxO nanopowders decreased with an increasing Co content. The characteristic analysis of the prepared Zn1-xCoxO/CNT/silicone rubber composites indicated that a Zn0.85Co0.15O/CNT/silicone rubber composite with a thickness of 4 mm exhibited the lowest RL value of -37.2 dB at 10.5 GHz, and its absorption range of less than -10 dB was located in the frequency range of 9.8-11.3 GHz. The characteristic analysis of the prepared Zn1-x Cox O/Al/siloxane resin paints revealed that the minimum intrinsic emissivities in the 3-5 µm and 8-12 µm wavebands were 0.415 and 0.716, respectively.