Development of thermal barrier coating systems from Al microparticles. Part I: Influence of processing conditions on the mechanisms of formation

SURFACE & COATINGS TECHNOLOGY

卷:380

Article

Boissonnet, Germain¹  Gregoire, Benjamin¹  Bonnet, Gilles¹  Pedraza, Fernando¹ 

[1] Univ La Rochelle, LaSIE, UMR CNRS 7356, Ave Michel Crepeau, F-17042 La Rochelle 1, France

关键词: Aluminizing;    Thermal barrier coating;    Nickel;    Oxidation;    Diffusion;    Slurry;   

DOI  :  10.1016/j.surfcoat.2019.125085

来源: Elsevier

【 摘 要 】

This work presents the mechanisms of formation on pure nickel of full thermal barrier coating systems (aluminide coating, thermally grown oxide and thermal barrier top coating) from micro-sized Al particles dispersed in a slurry annealed in different atmospheres (Ar, synthetic air, water vapour and mixtures thereof). The simultaneous formation of nickel aluminides and of a thermal barrier made of sintered hollow alumina spheres involved self-propagating high-temperature synthesis in all conditions. However, the microstructures and adherence of the top coatings changed markedly with either a diffusion step (700 degrees C-2 h) or a complete heat treatment (700 degrees C-2 h + 1100 degrees C-2 h) depending on the atmosphere. Whereas fast consumption of Al occurred in Ar to form the nickel aluminides, synthetic air and water vapour fostered the peripheral oxidation of Al microsized particles that impeded the release of Al and its diffusion towards the substrate. This resulted in heterogeneous diffusion layers but thicker top coatings with better sintering and thicker alumina shells.

【 授权许可】

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