Microstructure of nanometer Al2O3 dispersion strengthened Ni-based high-temperature protective coatings by laser cladding

来源期刊:中国有色金属学报(英文版)2009年第3期

论文作者:王宏宇 ZUO Dun-wen 孙玉利 徐锋 张丹

文章页码:586 - 591

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

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.

基金信息:the Research Fund for Doctoral Program of Higher Education of China
the Opening Research Fund of Jiangsu Key Laboratory of Tribology, China
the Graduate Innovation Foundation of Jiangsu Province, China

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