53.
Hot corrosion is one of the main destructive factors in thermal barrier coatings (TBCs) which come as a result of molten salt effect on the coating–gas interface. Hot corrosion behavior of three types of plasma sprayed TBCs was evaluated: usual CSZ, layer composite of CSZ/Micro Al
2O
3 and layer composite of CSZ/Nano Al
2O
3 in which Al
2O
3 was as a topcoat on CSZ layer. Hot corrosion studies of plasma sprayed thermal barrier coatings (TBCs) were conducted in 45 wt% Na
2SO
4+55 wt% V
2O
5 molten salt at 1050 °C for 40 h. The graded microstructure of the coatings was examined using scanning electron microscope (SEM) and X-ray diffractometer (XRD) before and after hot corrosion test. The results showed that no damage and hot corrosion products was found on the surface of CSZ/Nano Al
2O
3 coating and monoclinic ZrO
2 fraction was lower in CSZ/Micro Al
2O
3 coating in comparison with usual CSZ. reaction of molten salts with stabilizers of zirconia (Y
2O
3 and CeO
2) that accompanied by formation of monoclinic zirconia, irregular shape crystals of YVO
4, CeVO
4 and semi-cubic crystals of CeO
2 as hot corrosion products, caused the degradation of CSZ coating in usual CSZ and CSZ/Micro Al
2O
3 coating.
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