Vacuum plasma sprayed FeAl/Al2O3 functionally graded coatings for fusion reactor applications

In the design of liquid–metal fusion blankets, Al 2 O 3 ceramic is one of the most promising coating materials. In this study, functionally graded FeAl/Al 2 O 3 coatings were deposited on China Low Activation Martensitic (CLAM) steel substrates with vacuum plasma spraying (VPS) method. The SEM investigation revealed that the adhesion between adjacent layers in the coatings was sound. X-ray diffraction showed that stable alpha alumina dominated in the top alumina layers, while γ-Al 2 O 3 and β-Al 2 O 3 were also detected. The coating/substrate adhesive tensile strength test showed that adhesive strength of graded coatings was about 2.5 times that of duplex FeAl/Al 2 O 3 coatings. Thermal shock resistance test indicated that the graded coatings could tolerate more thermal shock cycles than duplex coatings.