Formation and Microstructural Characterization of Silicon-modified Aluminide Coating on Nickel-based Superalloy IN738LC
来源期刊：材料热处理学报2004年第5期
论文作者：A. Monshi F. Shahriari F.Ashrafizadeh
关键词：aluminide; silicon; pack cementation; characterization; growth mechanism;
摘 要：In this investigation, aluminide coatings used to protect industrial components at high temperature and corrosive environments were modified with silicon addition and the microstructural features and formation mechanism were evaluated. The coating on the nickel-based superalloy IN738LC was carried out by a two stage process including siliconizing at first and aluminizing thereafter. Pack cementation siliconizing performed at 950℃ for 2, 4 and 6 hours in several powder mixtures of Si, Al2O3 and NH4Cl, then aluminum was diffused into the surface of the specimens by an industrial aluminizing process. The modified coatings were characterized by means of standard metallography, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction methods. The results show that Si in the coatings mainly presents in the form of secondary phases including Cr3Si, Mo5Si3 and Ni16Ti6Si7, well distributed within the NiAl matrix. The advantages of this two stage modified coating is discussed.
A. Monshi1，F. Shahriari1，F.Ashrafizadeh1
(1.Materials engineering department, Isfahan University of Technology, Isfahan, Iran)
摘要:In this investigation, aluminide coatings used to protect industrial components at high temperature and corrosive environments were modified with silicon addition and the microstructural features and formation mechanism were evaluated. The coating on the nickel-based superalloy IN738LC was carried out by a two stage process including siliconizing at first and aluminizing thereafter. Pack cementation siliconizing performed at 950℃ for 2, 4 and 6 hours in several powder mixtures of Si, Al2O3 and NH4Cl, then aluminum was diffused into the surface of the specimens by an industrial aluminizing process. The modified coatings were characterized by means of standard metallography, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction methods. The results show that Si in the coatings mainly presents in the form of secondary phases including Cr3Si, Mo5Si3 and Ni16Ti6Si7, well distributed within the NiAl matrix. The advantages of this two stage modified coating is discussed.
关键词:aluminide; silicon; pack cementation; characterization; growth mechanism;
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