Effect of minor Nb on isothermal-oxidation and hot corrosion behavior of two Nickel-based superalloys under Na2SO4 / Na2SO4-NaCl

CORROSION ◽  
10.5006/3732 ◽  
2021 ◽  
Author(s):  
Yuebo Zhou ◽  
Hong Wang ◽  
Chenggang Mo ◽  
Lina Zhang
Keyword(s):  
Corrosion Resistance ◽  
Beneficial Effect ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Isothermal Oxidation ◽  
Chromia Scale ◽  
Vacuum Melting ◽  
Transient Stage ◽  
Beneficial Effects ◽  
Mixed Salts

Two nickel-based superalloys with and without minor Nb were prepared using double vacuum melting. The comparison of microstructure, isothermal-oxidation and hot corrosion behavior under molten Na2SO4 / Na2SO4+25wt. % NaCl at 900 C was evaluated. Results indicated that Nb accelerated the formation of chromia scale in a short transient stage, leading to a lower scaling rate. Nb also inhibited the internal oxidation/ nitridation. Both significantly improved the hot corrosion resistance under Na2SO4. However, the beneficial effect of Nb is slight under mixed salts with NaCl. The beneficial effects of Nb on oxidation and hot corrosion are discussed in detail.

Oxidation and hot corrosion behavior of a directionally solidified W richen cobalt-based superalloy

2021 ◽  
Vol 118 (3) ◽  
pp. 313
Author(s):  
Yuebo Zhou ◽  
Chenggang Mo ◽  
Hong Wang
Keyword(s):  
Corrosion Resistance ◽  
Molten Salt ◽  
Hot Corrosion ◽  
Isothermal Oxidation ◽  
Oxide Dispersion ◽  
Chromia Scale ◽  
Directionally Solidified ◽  
Internal Interface ◽  
Weight Percentage ◽  
Percentage Ratio

In this study, isothermal and hot corrosion in molten 75 mass% Na2SO4+25 mass% NaCl at 900 °C was carried out on an W richen Co-based directionally solidified Co-27.53Cr-9.85W-10.29Ni-0.75Al superalloy. For comparison, K38G with composition of 16.34Cr-4Al-1.77Mo-3.81Ti-2.66W-8.38Co were also conducted under same condition. Isothermal oxidation indicates that Co-based superalloy forms a Co-oxide dispersion chromia scale. However, K38G forms a purer chromia scale due to higher weight percentage ratio of Cr to Al. Under molten Na2SO4-NaCl salts, the defects in Ni/Co oxide dispersion chromia layer make it feasible that the molten salt can penetrates along grain boundaries into the internal interface to form internal sulfides, which causes the spallation of scales and significantly decreases its hot corrosion resistance.

Corrosion behavior of new type Co-based superalloys with different Ni contents

2017 ◽  
Vol 35 (6) ◽  
pp. 455-462 ◽  
Author(s):  
Bo Gao ◽  
Lei Wang ◽  
Yang Liu ◽  
Xiu Song ◽  
Shu-Yu Yang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Corrosion Layer ◽  
Corrosion Process ◽  
Corrosion Properties ◽  
Oxidation Processes ◽  
Ni Content ◽  
Ni Addition ◽  
New Type

AbstractThe corrosion properties of γ′-strengthened Co-xNi-Al-W-Cr (where x=15, 20, 25, and 30 at.%) superalloys were investigated in the mixture of 75 wt.% Na2SO4+25 wt.% NaCl at 900°C. The results showed that the corrosion behavior is associated with both sulfuration and oxidation processes. It was demonstrated that increasing the addition of Ni effectively promoted the formation of continuous Al2O3 scales, so that the hot corrosion resistance could be improved. When Ni content is more than 20 at.%, a large amount of Ni3S2 precipitates during the corrosion process. Sulfuration can destroy the integrity of the corrosion layer and increase the activity of oxygen. In this way, the internal oxidation of the alloys becomes more serious. Therefore, it is recommended that the optimum Ni addition is about 20 at.% for new type Co-Ni-Al-W-Cr superalloys.

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.

Characterization and hot corrosion behavior of D-gun sprayed Cr2O3-75% Al2O3 coated ASTM-SA210-A1 boiler steel in molten salt environment

2017 ◽  
Vol 64 (5) ◽  
pp. 515-528 ◽  
Author(s):  
Amita Rani ◽  
Niraj Bala ◽  
C.M. Gupta
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Molten Salt ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Degradation Mechanism ◽  
Effective Diffusion ◽  
Boiler Steel ◽  
Content Type ◽  
Scanning Electron

Purpose Hot corrosion is the major degradation mechanism of failure of boiler and gas turbine components. The present work aims to investigate the hot corrosion resistance of detonation gun sprayed (D-gun) Cr2O3-75 per cent Al2O3 ceramic coating on ASTM-SA210-A1 boiler steel. Design/methodology/approach The coating exhibits nearly uniform, adherent and dense microstructure with porosity less than 0.8 per cent. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of bare and coated boiler steel in molten salt environment (Na2SO4-60 per cent V2O5) at high temperature 900°C for 50 cycles. The corrosion products are analyzed by using X-ray diffraction, scanning electron microscopy (SEM) and field emission scanning electron microscope/energy-dispersive analysis (EDAX) to reveal their microstructural and compositional features for elucidating the corrosion mechanisms. Findings During investigations, it was found that the Cr2O3-75 per cent Al2O3 coating on Grade A-1 boiler steel is found to be very effective in decreasing the corrosion rate in the molten salt environment at 900°C. The coating has shown lesser weight gains along with better adhesiveness of the oxide scales with the substrate till the end of the experiment. Thus, coatings serve as an effective diffusion barrier to preclude the diffusion of oxygen from the environment into the substrate boiler steel. Research limitations/implications Therefore, it is concluded that the better hot corrosion resistance of the coating is due to the formation of desirable microstructural features such as very low porosity, uniform fine grains and the flat splat structures in the coating; as compared to the bare substrate under cyclic conditions. Practical implications This research is useful for coal-fired boilers and other power plant boilers. Social implications This research is useful for power generation plants. Originality/value There is no reported literature on hot corrosion behavior of Cr2O3-75 per cent Al2O3 coating deposited on the selected substrates by D-gun spray technique. The present work has been focused to study the influence of the Cr2O3-75 per cent Al2O3 coating developed with D-gun spraying technique on high temperature corrosion behavior of ASTM-SA210-A-1 boiler steel in an aggressive environment of Na2SO4-60 per cent V2O5 molten salt at 900°C under cyclic conditions.

Hot Corrosion Behavior of Sputtered Fe-Y Alloy Coatings with Different Y Contents

2011 ◽  
Vol 391-392 ◽  
pp. 1263-1267
Author(s):  
Guang Yan Fu ◽  
Jing Yu Chen ◽  
Qun Liu ◽  
Yong Su
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Alloy Coating ◽  
Good Adhesion ◽  
Corrosion Scale ◽  
Measurement Results ◽  
The Matrix ◽  
Better Than

Three Fe-Y alloy coatings with differernt kinds of Y contents were prepared on stainless steel by magnetron sputtering. The hot corrosion behavior of sputtered alloy coatings with Na2SO4 deposits at 800 °C was investigated by discontinuous weigh measurement. Results show that the sputtered Fe-Y alloy coatings exhibit good adhesion with the matrix of stainless steel, and the hot corrosion kinetic curves of the specimens approximately follow the parabolic rate law. The Fe oxides are the main substances in the corrosion scale, and the hot corrosion rate of the three Fe-Y alloy coatings increases as the Y content increases. Therefore, the hot corrosion resistance of Fe-15Y alloy coating is better than that of Fe-20Y or Fe-30Y alloy coating.

Hot Corrosion of T122 and 347HFG Steels in Na2SO4 Salts at 800 and 900 °C

2013 ◽  
Vol 711 ◽  
pp. 128-133
Author(s):  
Chun Yu Xu ◽  
Dong Bok Lee
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Oxide Scales ◽  
Good Corrosion Resistance ◽  
Ni Alloy

The T122 steel (ferritic Fe-Cr-W alloy) and 347HFG stainless steel (austenitic Fe-Cr-Ni alloy) were corroded in the Na2SO4salt at 800 and at 900 °C, and their hot corrosion behavior was studied. They displayed good corrosion resistance owing to the formation of the protective Fe3O4and (Fe0.6Cr0.4)2O3scales. These oxides effectively suppressed sulfidation by the Na2SO4salt. The oxide scales that formed were thin and loosely adherent. The displayed good corrosion resistance was mainly attributed to the large amount of Cr in the alloys.

scholarly journals INFLUENCE OF ISOTHERMAL OXIDATION ON CORROSION RESISTANCE OF TITANIUM IN BOVINE SERUM

2018 ◽  
Vol 24 (1) ◽  
pp. 65
Author(s):  
Benidiktus Tulung Prayoga ◽  
Suyitno - Suyitno ◽  
Rini Dharmastiti
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Surface Properties ◽  
Corrosion Behavior ◽  
Bovine Serum ◽  
Isothermal Oxidation ◽  
Furnace Chamber ◽  
Surface Microhardness ◽  
Oxidation Treatment ◽  
Cp Ti

The thermal oxidation treatment is an innovative and simple method for modifiying the surface properties of titanium such as enhance corrosion and wear resistance. The effects of isothermal oxidation immersion time on the surface properties and corrosion behavior under bovine serum of cp-Ti were studied in this paper. The treatment was done at 700<sup>o</sup>C for 0 to 36 hours in furnace chamber. The surface microhardness, surface roughness, wettability and polarization potentiodynamic corrosion of cp-Ti were determined. The result shows the surface microhardness, surface roughness, wettability and corrosion resistance of the cp-Ti enhanced by isothermal oxidation treatment. The presence of the oxide layer on the surface in the form of TiO<sub>2</sub> rutile and Ti<sub>3</sub>O are responsible to enhance the surface properties and corrosion behavior

Hot-corrosion behavior of Ti3SiC2in a eutectic mixture of LiCl–KCl salts in air

RSC Advances ◽  
2015 ◽  
Vol 5 (28) ◽  
pp. 21629-21633
Author(s):  
Ning Wang ◽  
Changming Cheng ◽  
Jie Tian ◽  
Sheng Hu ◽  
Haibin Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Eutectic Mixture ◽  
Protective Layer ◽  
Excellent Corrosion Resistance

Ti3SiC2exhibits excellent corrosion resistance at 550 °C and forms an oxide protective layer at 650 °C and 750 °C.

Hot Corrosion Behavior of AlCuFeCr Quasicrystalline Coating on Titanium Alloy with the Mixture of NaCl and Na2SO4 Deposit

2007 ◽  
Vol 546-549 ◽  
pp. 2313-2316 ◽  
Author(s):  
Feng Feng Wang ◽  
Chun Gen Zhou ◽  
Sheng Kai Gong ◽  
Hui Bin Xu
Keyword(s):  
Growth Rate ◽  
Corrosion Resistance ◽  
Titanium Alloy ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Oxide Morphology ◽  
Linear Rate ◽  
Solid Mixture ◽  
Kinetics Of ◽  
Na2so4 Deposit

The hot corrosion behavior of titanium alloy and AlCuFeCr quasicrystalline coating on titanium alloy in the presence of a solid mixture of NaCl and Na2SO4 deposit at 700°C was studied. The result shows that weight-gain kinetics for titanium alloy exhibited a linear rate law, while the kinetics of AlCuFeCr quasicrystalline coating displayed parabolic growth rate. The corrosion resistance of the titanium alloy was improved by applying the AlCuFeCr quasicrystalline coating. The corrosive oxide morphology formed on titanium alloy was porous. For AlCuFeCr quasicrystalline coating with the mixture of NaCl and Na2SO4 deposit, the scale formed on the coating surface was compact and uniform. Oxide formed on the surfaces of Al-Cu-Fe-Cr quasicrystalline coatings after hot corrosion consisted of Al2O3.

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