Preparation and Characterization of Slurry Aluminide Coating on TP347H FG Stainless Steel

Aluminide coating was prepared on the surface of austenitic TP347H FG stainless steel through a slurry deposition process. SEM (Scanning Electron Microscope), EDS (Energy Dispersive Spectrometer), and XRD (X-Ray Diffraction) analyses were employed to understand the influence of deposition parameters on the microstructures and phase compositions of slurry aluminide coatings. The study found that a two-layered aluminide coating with an interdiffusion layer and an outer layer formed on all conditions. The outer layer mainly consisted of (Fe, Ni)Al phase or (Fe, Ni)Al + Fe₃Al + CrSi phases, while those of in the interdiffusion layer are (Fe, Ni)Al + α-Fe + Cr_xSi_y phases. The variation curve of the coating thickness followed a parabolic law as the holding time changed and an index law as the deposition temperature changed, respectively. The shot-peening effect on the formation of aluminide coating was indistinctive for slurry aluminizing at 930 °C. Besides, a controlling method of the thickness of aluminide coatings was proposed by simplifying the diffusion process.