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207 results on '"Ouyang, Jiahu"'

10. Process and Mechanism of Removing Micro-Arc Oxidation Coating on Titanium Alloy by Plasma Electrolysis

Author

ZOU Yongchun, WANG Shuqi, WANG Yaming, CHEN Guoliang, ZHANG Kaiwei, OUYANG Jiahu, JIA Dechang, ZHOU Yu

Subjects
plasma electrolysis, coating removal, micro-arc oxidation, titanium alloy, Materials of engineering and construction. Mechanics of materials, TA401-492, Technology
Abstract

During the preparation and service process of micro-arc oxidation coatings，phenomena such as uneven growth or surface wear and peeling emerged，so the micro-arc oxidation coatings should be removed to achieve the purpose of secondary preparation and reuse.Aiming at the bottleneck problem of difficulty to remove micro-arc oxidation coating with high bonding strength，a novel plasma electrolytic removal(PER) technique was presented in this work.By comparing and analyzing the coating removal rates at different voltages，thickness change，and microstructure after coating removal at different times，it was found that the coating removal efficiency was the lowest with the applied voltage of 260 V，and the coating was completely removed after 11 min.When the voltage was increased to 320 V，the coating was completely removed in only 6 min.This was due to the large applied voltage，which made it easier to generate multiple and stable plasma discharge channels，thus realizing rapid removal of micro-arc oxidation coating.Furthermore，a synergistic mechanism of peeling，thinning，and dissolution in the removal of coatings by plasma electrolysis was proposed.The PER technique exhibits high efficiency and environmental protection，which has broad application prospects in the fields of aerospace，medical instruments and so on.

Published
2023
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32. Improvement strategy on thermophysical properties of A2B2O7-type rare earth zirconates for thermal barrier coatings applications: A review.

Author

Peng, Zijian, Wang, Yuhao, Wang, Shuqi, Yao, Junteng, Zhao, Qingyuan, Xie, Enyu, Chen, Guoliang, Wang, Zhigang, Liu, Zhanguo, Wang, Yaming, and Ouyang, Jiahu

Abstract

The A2B2O7-type rare earth zirconate compounds have been considered as promising candidates for thermal barrier coating (TBC) materials because of their low sintering rate, improved phase stability, and reduced thermal conductivity in contrast with the currently used yttria-partially stabilized zirconia (YSZ) in high operating temperature environments. This review summarizes the recent progress on rare earth zirconates for TBCs that insulate high-temperature gas from hot-section components in gas turbines. Based on the first principles, molecular dynamics, and new data-driven calculation approaches, doping and high-entropy strategies have now been adopted in advanced TBC materials design. In this paper, the solid-state heat transfer mechanism of TBCs is explained from two aspects, including heat conduction over the full operating temperature range and thermal radiation at medium and high temperature. This paper also provides new insights into design considerations of adaptive TBC materials, and the challenges and potential breakthroughs are further highlighted for extreme environmental applications. Strategies for improving thermophysical performance are proposed in two approaches: defect engineering and material compositing. [ABSTRACT FROM AUTHOR]

Published
2024
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43. A Promising Radiation Thermal Protection Coating Based on Lamellar Porous Ca‐Cr co‐Doped Y3NbO7 Ceramic

Author

Chen, Guoliang, primary, Fu, Haoyang, additional, Zou, Yongchun, additional, Wang, Shuqi, additional, Gao, Yongwang, additional, Yue, Tongtong, additional, Cao, Jianyun, additional, Wang, Yaming, additional, Qiu, Jun, additional, Zhao, Junming, additional, Ouyang, Jiahu, additional, Jia, Dechang, additional, Shuai, Yong, additional, and Zhou, Yu, additional

Published
2023
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47. A Promising Radiation Thermal Protection Coating Based on Lamellar Porous Ca‐Cr co‐Doped Y3NbO7 Ceramic.

Author

Chen, Guoliang, Fu, Haoyang, Zou, Yongchun, Wang, Shuqi, Gao, Yongwang, Yue, Tongtong, Cao, Jianyun, Wang, Yaming, Qiu, Jun, Zhao, Junming, Ouyang, Jiahu, Jia, Dechang, Shuai, Yong, and Zhou, Yu

Subjects
RADIATION protection, HEAT radiation & absorption, DOPING agents (Chemistry), MULTIPLE scattering (Physics), SURFACE coatings, CHROMIUM isotopes, THERMAL conductivity
Abstract

Dissipation of heat efficiently from a hot object via radiation while minimizing the inward heat conduction is the key requirement of radiation thermal protection. In this study, a Ca‐Cr co‐doped Y3NbO7 coating with lamellar porous structure is fabricated, which shows an ultra‐low thermal conductivity (<0.7 W m−1 K−1) and near‐unity emissivity (>0.9) across a broad wavelength range of ≈1–24 µm. This record high emissivity to thermal conductivity ratio (≈1.3) is experimentally and theoretically revealed from a multi‐scale perspective. The diffusoin‐mediated thermal conduction feature of niobates combined with lamellar porous structure of the coating reduces its thermal conductivity to an impressive 0.5 W m−1 K−1 at 25 °C, surpassing the theoretical amorphous limitation of 0.72 W m−1 K−1. Experiments and FDTD calculation results demonstrate that the intrinsic emissivity dips at shallow extinction wavelengths (1 and 8 µm) and strong phonon‐polariton resonances wavelengths (>13 µm) can be effectively compensated by the multiple scattering/absorption and gradual modulation of conical shape/effective refractive index induced by surface micro‐protrusion structures, respectively. Furthermore, the coating exhibits robust mechanical and thermal stability with a high bonding strength (18.3 MPa) and thermal expansion coefficient (≈11 × 10−6 K−1 at 1200 °C) comparable to YSZ, showing great potential in the radiation thermal protection field. [ABSTRACT FROM AUTHOR]

Published
2023
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48. High temperature oxidation and hot corrosion behaviors of PEO and PEO/polysilazane preceramic-based dual-layer coatings on Ti6Al4V alloy

Author

Wang, Shuqi, primary, Wang, Yaming, additional, Cao, Gui, additional, Chen, Cuoliang, additional, Zhu, Yixing, additional, Serdechnova, Maria, additional, Blawert, Carsten, additional, Zheludkevich, Mikhail L., additional, Zou, Yongchun, additional, Ouyang, Jiahu, additional, Jia, Dechang, additional, and Zhou, Yu, additional

Published
2023
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