中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 19 No. 3 June 2009 |
high-temperature protective coatings by laser cladding
（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
