CHEN Xiao-xiao,YAO Yang-guang,TAN Li-ming,GU Qing-shan,YUAN Jian-hui,ZHAO Wen-jie.Au-WO3 Coating Prepared by Liquid-phase Plasma Spraying and Sensing Mechanism[J],48(4):84-90
Au-WO3 Coating Prepared by Liquid-phase Plasma Spraying and Sensing Mechanism
Received:October 20, 2018  Revised:April 20, 2019
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DOI:10.16490/j.cnki.issn.1001-3660.2019.04.012
KeyWord:schottky junction  liquid-phase plasma spraying  WO3  doping  coating  gas sensitivity mechanism
                 
AuthorInstitution
CHEN Xiao-xiao 1.Shanghai University of Engineering Science, Shanghai , China
YAO Yang-guang 1.Shanghai University of Engineering Science, Shanghai , China
TAN Li-ming 1.Shanghai University of Engineering Science, Shanghai , China
GU Qing-shan 1.Shanghai University of Engineering Science, Shanghai , China
YUAN Jian-hui 1.Shanghai University of Engineering Science, Shanghai , China
ZHAO Wen-jie 2.Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Science, Ningbo , China
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Abstract:
      The work aims to improve the gas-sensitivity properties of WO3 based coatings. Au-WO3 composite coating was prepared by plasma spraying technology with mixed feedstock suspensions containing a precursor as WCl6 and a certain ratio of nano-Au. SEM, EDS and XRD were used to characterize the microstructures of Au-WO3 composite coating. The gas-sensitivity properties of prepared Au-WO3 composite coating were studied by a self-made gas-sensitivity test system and the gas sensitivity mechanism was researched. During the suspension plasma spraying, the solvent of the precursor droplets was evaporated and then the nucleation, crystallization and growth of WO3 occurred. Then, the formed WO3 solid particles were melted or semi-melted, and accelerated to impact the surface of the substrate to form a coating. The effects of the spraying distance on the crystallinity and morphology of the WO3 coatings were significant under the same conditions. A coating with integrity crystal and fine grains (20~50 nm) was obtained at the spraying distance of 170 mm which was conductive to gas-sensitivity properties. The gas-sensi?tive properties of the Au-WO3 composite coating were significantly better than that of the pure WO3 coatings. A schottky junction formed at the interface of Au and WO3 improves the gas-sensitive properties of composite coating and leads to a reduction in conductivity of the composite coating. Therefore, the height of the contact barrier increases and initial resistance becomes large.
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