Hot corrosion behaviors of a Cr13Ni5Si2-based metal silicide alloy in Na2SO4+25wt.% K2SO4 and Na2SO4+25wt.% NaCl molten salts

2010 ◽  
Vol 18 (3) ◽  
pp. 324-329 ◽  
Author(s):  
L. Yuan ◽  
H.M. Wang
Keyword(s):  
Hot Corrosion ◽  
Molten Salts ◽  
Metal Silicide ◽  
Corrosion Behaviors

scholarly journals Hot Corrosion Behavior of BaLa2Ti3O10 Thermal Barrier Ceramics in V2O5 and Na2SO4 + V2O5 Molten Salts

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 351 ◽  
Author(s):  
Hui Liu ◽  
Jin Cai ◽  
Jihong Zhu
Keyword(s):  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Molten Salts ◽  
Main Reaction ◽  
Thermal Barrier ◽  
Dense Layer ◽  
Reaction Products ◽  
Corrosion Medium ◽  
Barrier Coating ◽  
Salt Corrosion

BaLa2Ti3O10 ceramics for thermal barrier coating (TBC) applications were fabricated, and exposed to V2O5 and Na2SO4 + V2O5 molten salts at 900 °C to investigate the hot corrosion behavior. After 4 h corrosion tests, the main reaction products resulting from V2O5 salt corrosion were LaVO4, TiO2, and Ba3V4O13, whereas those due to Na2SO4 + V2O5 corrosion consisted of LaVO4, TiO2, BaSO4 and some Ba3V4O13. The structures of reaction layers on the surfaces depended on the corrosion medium. In V2O5 salt, the layer was dense and had a thickness of 8–10 μm. While in Na2SO4 + V2O5 salt, it had a ~15 μm porous structure and a dense, thin band at the bottom. Beneath the dense layer or the band, no obvious molten salt was found. The mechanisms by which the reaction layer forms were discussed.

Sintering and hot corrosion of yttria silicate tablets in molten salts prepared by spark plasma sintering

2019 ◽  
Vol 66 (6) ◽  
pp. 782-790
Author(s):  
Merlina A. Navarro Villanueva ◽  
Luis A. Soto Hernández ◽  
Melquisedec Vicente Mendoza ◽  
Ángel de J. Morales Ramírez ◽  
Fernando Juárez López
Keyword(s):  
Spark Plasma Sintering ◽  
Hot Corrosion ◽  
Molten Salts ◽  
Crystal Morphology ◽  
Corrosion Behaviour ◽  
Thick Layer ◽  
Powder Synthesis ◽  
Content Type ◽  
Plasma Sintering ◽  
Spark Plasma

Purpose This paper aims to study the microstructural hot corrosion behaviour of the sintered Y2SiO5 ceramic silicate under a Na2SO4 + V2O5 mixture at an engine representative temperature of 1150°C. Y2SiO5 is a promising candidate for thermal barrier coatings (TBC) due to its excellent chemical stability at high temperatures. As a continuous source of Y3+, it is expected that Y2SiO5 environmental barrier coating may prolong the lifetime of TBC systems by stopping the degradation caused by the loss of the Y2O3 stabilizer. Design/methodology/approach Two routes were chosen for the yttria silicate powder synthesis by sol-gel from TEOS and APTES precursors as the difference in Si source changed the ratio of Y2SiO5/Y2Si2O7 phases. Hot corrosion studies using Na2SO4 and V2O5 mixtures were conducted on both surfaces of APTES and TEOS tablets at 1150°C for 8 h in atmospheric air. The morphology and microstructure analyses of the silicate samples after hot corrosion tests were carried out using a SEM and X-ray diffraction analyse techniques. Findings Based on the degradation, the general status of the APTES tablet after hot corrosion presents a better hot corrosion resistance at a temperature of 1150°C than does that of the TEOS tablet. In the TEOS tablet, the crystal morphology of NaY9Si60O26 woodchip shapes with a size of 60 µm is developed on the surface for finally initiating some cracks. In the APTES case, the crystal morphology of rod-like shapes with a size of 100 µm is developed; hence, a dense thick layer predominately postpones the reaction of V2O5 and Na2SO4 with yttria silicate, and consequently, less damage is observed. Originality/value Coating yttria silicate preparation is very complicated; the problems of a high synthesis temperature, long production period and low yield still need to be solved. Under these perspectives, ceramics prepared via spark plasma sintering (SPS) can reach theoretical high densities and a fine grain size can be retained after the SPS process; hence, well resistance to the corrosion in molten salts is expected to obtain for the sintered yttria silicate tablets.

HOT-CORROSION BEHAVIOR OF THERMAL BARRIER COATED DZ125 SUPERALLOY EXPOSED TO ATOMIZED SEAWATER AND KEROSENE

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3155-3160
Author(s):  
ZHIMING BAI ◽  
LE ZHOU ◽  
TIANQUAN LIANG ◽  
HONGBO GUO ◽  
SHENGKAI GONG
Keyword(s):  
Corrosion Resistance ◽  
Electron Beam ◽  
Thermal Barrier Coating ◽  
Corrosion Behavior ◽  
Bond Coat ◽  
Hot Corrosion ◽  
Thermal Barrier ◽  
Average Mass ◽  
Barrier Coating ◽  
Corrosion Behaviors

The bare superalloy DZ 125 alloy, the aluminide coated specimens and electron beam physical vapor deposited (EB-PVD) thermal barrier coating (TBC) consisting of yttria stabilizied zirconia (YSZ) topcoat and NiCoCrAlY bond coat specimens were exposed to atomized seawater and kerosene at 900°C and the cyclic hot-corrosion behaviors of the specimens were investigated. Disastrous spallation of the bare superalloy occurred within 50 h hot-corrosion. In contrast to this, after 100 h hot-corrosion, the average mass change for the aluminized and TBC coated specimens is 0.7 mg/cm2 and 0.63 mg/cm2, respectively, exhibiting excellent hot-corrosion resistance.

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