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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 19    No. 3    June 2009

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Microstructure of nanometer Al2O3 dispersion strengthened Ni-based
high-temperature protective coatings by laser cladding
WANG Hong-yu(王宏宇)1, 2, ZUO Dun-wen(左敦稳)1, SUN Yu-li(孙玉利)1,
XU Feng(徐 锋)1, ZHANG Dan(张 丹)1

1. Jiangsu Key Laboratory of Precision and Micro-manufacturing Technology,
Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
2. School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China

Abstract:The nanometer Al2O3 dispersion strengthened NiCoCrAlY high-temperature protective coatings by crosscurrent CO2 laser on Ni-based superalloy GH4033 were produced. Microscopic morphologies, phase constitutions of cladding coatings and distribution of nano-Al2O3 particles were examined using SEM and XRD. The results show that the interface grains, after adding proper nano-Al2O3, grow from epitaxial to non-epitaxial shape gradually, and the columnar dendrites become thinner and denser with cellular shape. Cracks in the substrate close to the interface are eliminated. Moreover, dispersive nano-Al2O3 particles mainly distribute around cellular substructure and on grain-boundaries, which prevents the diffusion of alloying elements and restrains the formation of new phase. There is a critical value of nano-Al2O3 addition, and the most suitable content of nano-Al2O3 is 1% (mass fraction) in this experimental conditions. The “nanometer effect” of nano-Al2O3 particles plays an important role in the improvement of coating microstructure.

 

Key words: high-temperature protective coating; laser cladding; nano-Al2O3; microstructure

ISSN 1672-7029
CN 43-1423/U

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