DURING COMBUSTION in the gas turbine, sulfur from the fuel reacts with sodium chloride from ingested air at elevated temperatures to form sodium sulfate. The sodium sulfate then deposits on the hot-section components, such as nozzle guide vanes and rotor blades, resulting in accelerated oxidation (or sulfidation) attack. This is commonly referred to as “hot corrosion.” Sulfur in the fuel is gen...

In this study, the hot corrosion of TiAl, TiAlNb, and Ti3AlNb intermetallics with or without enamel coating and sputtered TiAlCr coating in (Na, K)2SO4 + NaCl melts at 750oC is investigated. The interfacial reaction between enamel and those alloys during hot corrosion has also been evaluated. The results indicate that severe corrosion of bare alloys occurs due to the self catalysis chlorination...

In the present study NiCrAlY bond coating layer was produced by electroplating against common atmospheric plasma spraying (APS). Both types of the bond coats were applied on IN738LC base metal then, the YSZ (ZrO2-8% Y2O3) thermal barrier top layer was coated by atmospheric plasma spray technique. Hot corrosion is one of the main destructive factors in thermal barrier coatings (TBCs) which come ...

HVOF-sprayed CoNiCrAlYSi coatings were tested at 900 °C in a hot corrosion environment containing sodium-potassium sulphates. The HVOF spraying caused the typical splat-on-splat structure. The results after the hot corrosion testing showed that the corrosion preferentially occurred at the coating surface and the splat boundaries. The oxidation along the splat boundaries can isolate the splat fr...

Investigations were conducted on hot corrosion of Nickel base, NIMONIC-90 at 675°C and 725°C. The tests were carried out on small test coupons coated with a chemical containing Sodium sulphate and Sodium Vanadate which is representative of the corrosive deposit that usually forms during service in the coal fired boiler and the likes operating in marine atmospheres. Corrosion rates were measured...

In this paper a functional graded material (FGM) thermal barrier coating (TBC) is prepared using Atmospheric Plasma Spraying (APS) method. The FGM layers were deposited by varying the feeding ratio of CYSZ/NiCrAlY and conventional CYSZ on a NiCrALY-coated Inconel 738 substrates. Hot corrosion behavior, bonding strength and the related failure mechanisms of a conventional TBC and a FGM TBC are i...

The present paper describes fuzzy logic simulation of an experimental study on the behavior of hot corrosion in molten salt (Na2SO4) of steel-T21 coated by simultaneous yttrium-doped aluminizing-siliconizingprocess . Diffusion coating was carried out at 1050C for 6 hr under Aratmosphere . The weight change measurements made on the coated steel during the cyclic tests are used to determine kinet...

Development of submicrocrystalline structure in biomedical alloy such as Ti-13Nb-13Zr (in wt%) through warm-rolling process has been found to enhance mechanical properties compared to conventional thermomechanical processing routes including hot-rolling process. The present study investigated the tribological and corrosion behaviors of warm-rolled (WR) and hot-rolled Ti-13Nb-13Zr alloys which h...

The present work investigates the high temperature oxidation and corrosion behaviour of high entropy superalloys (HESA). A high content of various solutes in HESA leads to formation of complex oxides, however the Cr and Al activities of HESA are sufficient to promote protective chromia or alumina formation on the surface. By comparing the oxidation and corrosion resistances of a Ni-based supera...