Spark plasma sintering of a multilayer thermal bather coating on Inconel 738 superalloy: Microstructural development and hot corrosion behavior

作者：Pakseresht A H; Javadi A H; Bahrami M; Khodabakhshi F; Simchi A

来源：Ceramics International, 2016, 42(2): 2770-2779.

DOI：10.1016/j.ceramint.2015.11.008

• Multilayer thermal barrier coating
• Spark plasma sintering
• Microstructure
• Hot corrosion
• Thermally grown oxide

In the present work, spark plasma sintering (SPS) process was employed to prepare a nanostructured yttria-stabilized zirconia (8YSZ) coating on a nickel-based superalloy (INCONEL 738) with functionally graded structure. A stack layer of INCONEL 738/NiCrAlY powder/Al foil/NiCrAlY YSZ powder/YSZ powder was SPSed in a graphite die at an applied pressure of 40 MPa under an vacuum atmosphere (8 Pa). The sintering temperature was similar to 1040 degrees C. For comparison purpose, the air plasma spray (APS) technique was employed to prepare the thermal bather coating (TBC). Microstructural studies by scanning electron microscopy showed that the SPSed coating was sound and free of interfacial cracks and large pores. Energy dispersive X-ray spectroscopy determined a limited inter-diffusion between the layers. A significant improvement (similar to 26%) in the Vickers micro-hardness was also measured. In order to examine the functionality of the coatings, hot corrosion test was performed at 1050 degrees C in a molten bath of Na2SO4 and V2O5 (45 to 55 weight ratio). The results showed that spallation occurred after 12 and 20 h for the SPSed and APS coatings, respectively.

• 出版日期2016-2-1