Na2SO4 Salt Research Articles

Hot corrosion behaviour of constant and pulsed current welded Hastelloy X in Na2SO4, V2O5, and NaCl salt mixture at 900 °C

The high-temperature corrosion behavior of constant current gas tungsten arc (GTA) and pulsed current gas tungsten arc (PCGTA) welded Hastelloy X with different filler wires (C263 and ERNiCr-3) are studied for 50 cycles at 900 °C. Molten salt I (MS I) (75% Na2SO4 + 25% V2O5) and molten salt II (MS II) (75% Na2SO4 + 20% V2O5 + 5% NaCl) were coated on the welded specimens. MS II coated substrate shows the highest weight gain than MS I with a parabolic constant for GTA ERNiCr-3 as 21.440 × 10–6 mg2/(cm4.s). Whereas PCGTA C263 welded sample with MS I, revealed parabolic constant (lowest) of 0.008 × 10–6 mg2/ (cm4.s). Based on the results, an increasing pattern of hot corrosion resistance of substrates is arranged as GTA ERNiCr-3 < GTA C263 < PCGTA C263 < PCGTA ERNiCr-3. PCGTA shows more refined grains, higher grain boundary volume, better corrosion resistance, and more protective phases like Cr2O3, NiO, NiCr2O4, CoCr2O4, Al2O3, NiFe2O4, NbO than GTA weldment. But phases such as Fe2O3, MoO3, and Cr2S3 (non-protective phases) decrease corrosion resistance due to acid fluxing of alloying elements that promote the oxide scale exfoliation, spallation, chipping, and cracking. This study observed that PCGTA with C263 filler in MS I and MS II environment provides good corrosion resistance at high temperatures.

Influence of foreign salts on the CaCO3 pre-nucleation stage: application of the conductometric method

Electrical conductivity modeling applied to the fast controlled precipitation method data is used to underline the existence of different ion pairs during the prenucleation stage as a function of the foreign salts NaCl, MgCl2, Na2SO4 and MgSO4.

A systematic study on Na2SO4-induced hot corrosion behavior of plasma-sprayed La2(Zr0.75Ce0.25)2O7 coating

To better understand the hot corrosion behavior of LCZ ceramic coatings against Na2SO4 molten salts, three series of hot corrosion tests were performed from the perspectives of Na2SO4 content, corrosion duration and corrosion temperature. Different corrosion products of La2O2SO4, La2O2S and Ce7O12 were identified depending on the hot corrosion conditions and the probable reaction mechanisms were proposed. The effects of Na2SO4 content, corrosion duration and corrosion temperature on hot corrosion behavior were investigated systematically. Results show that Na2SO4 molten salt is hard to react chemically with LCZ coating. The chemical reaction between LCZ coating and Na2SO4 molten salt needs a long time. When the content of Na2SO4 salts is high, the corrosion reaction could be accelerated. The phase transition and decomposition of corrosion products are responsible for the different hot corrosion behaviors at 1050–1500 °C. Moreover, a model describing the hot corrosion process induced by Na2SO4 molten salt is built, which includes two stages of eroding LCZ coating.

Effect of different salts on the seed germination of halophyte Aksora (Suaeda Salsa Pall.)

The stress effects of a solution of salts and soil extract on the seeds of euhalophyte Aksora (Suaeda salsa Pall.) were studied. Treatment of euhalophyteSuaeda salsa Pall. seeds of salts (Na2SO4 and NaCl) and soil extract solutions in different concentrations (0; 0.6; 1.2; 1.8; 2.8; 3.6 g / 100 ml).Monitoring of the relationship between salts (Na2SO4 and NaCl) and soil extract solutions of grown Aksora seedlings after treatment. Additionally, provide the description of the germination of seedlings grown at different concentrations of solutions of different salts and soil extracts. Determination of endurance of seeds to different concentrations of Na2SO4 and NaCl salts and soil extract solution, based on the germination of Axora seeds. Study of the endurance of Axora seeds to salt stress. The experimental results showed that the growth rate of Aksora seedlings in different salts (Na2SO 4 and NaCl) and soil extracts is expected to be different. Based on the germination rate of seeds and Aksora seeds respond differently to stresses of different concentrations of Na2SO4 and NaCl salts and soil solution, the stress effect of Aksora seeds can be expressed by the following relationship NaCl&gt; soil extract&gt; Na2SO4. Due to the endurance of Aksora to salt stress, it was found that it is very prone to saline and saline soils. Key words:Saline soils, halophytes, Aksora (Suaeda).

Influence of Alkalis on Natural Carbonation of Limestone Calcined Clay Cement Pastes

Vulnerability to atmospheric carbonation is one of the major durability concerns for limestone calcined clay cement (LC3) concrete due to its relatively low overall alkalinity. In this study, the natural carbonation behaviors of ternary ordinary Portland cement-metakaolin-limestone (OPC-MK-LS) blends containing various sulfate salts (i.e., anhydrous CaSO4, Na2SO4, and K2SO4) are studied, with the aim of revealing the influence of alkali cations (Na+, K+). Detailed analyses on the hydrated phase assemblage, composition, microstructure, and pore structure of LC3 pastes prior to and post indoor carbonation are conducted. The results show that the incorporation of sulfate salts accelerates the setting and strength gain of LC3 pastes, likely through enhancement of ettringite formation, but undermines its later age strength achievement due to the deleterious effect of alkali cations (Na+, K+) on late age OPC hydration. The carbonation resistance of LC3 systems is considerably undermined, particularly with the incorporation of Na2SO4 or K2SO4 salts, due to the simultaneous pore coarsening effect and reduced CO2-binding capacity. The carbonation-induced phase and microstructural alterations of LC3 pastes are discussed and compared with those of reference OPC pastes.

Responses of Soil Cadmium Desorption under Different Saline Environments and Its Controlling Factors

Heavy metal pollution of soil restricts the sustainable use of land and poses risks to human health throughout the world. Changes in the physicochemical properties of soil may increase the mobility of heavy metals in the soil ecosystem and lead to groundwater pollution. In this study, the effects of different salt solutions (NaCl, CaCl2, NaNO3, MgCl2, Na2SO4, and mixed salts) on the release of Cd from soil were investigated by batch desorption tests and the Freundlich isothermal sorption model. Increased concentrations of the salts, except for NaNO3, significantly promoted Cd release (R2 &gt; 0.9, p &lt; 0.01). Under the salt stress, Cd release from the test soils was promoted more by CaCl2 and MgCl2 than by the other salts, and the average desorption rates of eight soil samples at 3.5% salt concentration were 11.15% and 10.80%, respectively, which were much higher than those of NaCl (4.05%), Na2SO4 (0.41%), and NaNO3 (0.33%). Ca2+ and Mg2+ showed better ion exchange capacity than Na+ to promote Cd release; for anions, Cl− formed hydrophilic Cd chloride complexes with Cd in soil. In addition, principal component analysis results revealed that Cd release was mainly influenced by soil texture, cation exchange capacity, and iron–manganese oxide content of the soil. The Cd release level for different soil samples was most closely related to the proportion of fine particles in the soil. The higher the clay content was, the higher the Cd desorption rate.

Hydrogen Limitation By Background Salts in the Case of Trivalent Chromium Electrolytes

The toxicity of some chemical compounds for humans and the environment encouraged health authorities to adopt new legislations. This is the case for hexavalent chromium salts, CMR known, which are targeted by the REACH European regulation. These salts are used in various surface treatments processes and their use is subjected to authorization. This situation has severely impacted the 'hard' chromium plating industry. Several projects all over the world deal with alternative solution and most of them are based on non toxic trivalent chromium salts, but more difficult to implement. The present work is undertaken within CRONOS 2024 project supported by a consortium of 20 companies and led by the IRT M2P (Institute for Technological Research Metallurgy Materials Processes in Metz). Trivalent chromium ions form very stable hexa-aqueous complexes in solution, difficult to reduce. It is therefore necessary to introduce complexing agents in order to facilitate their reduction [1]–[3]. These complexing agents, mostly organic, add a difficulty in the realization of trivalent chromium electrolytes since various phenomena must be considered. In addition, the chromium based electrolytes have a low faradic yield which induces permanent competition between its own reduction and the one of protons to dihydrogen. Excessive consumption of protons near the cathode leads to a pH rise which can cause precipitation and incorporation of chromium hydroxides.In order to improve the performance of trivalent chromium electrolytes, it is possible to adjust different parameters such as the nature and concentration of the complexing agents, the pH, the temperature, the addition of additives, etc. In this study, we focused mainly on the nature and concentration of the support salt. Previous works demonstrated that over a given concentration of Na2SO4 or K2SO4 support salts, a diffusion plateau appears, which can be attributed to the reduction of protons to dihydrogen [4]. Irrespective of the substrate nature, the composition and concentration of the support salts have an impact. It has been shown that a modulation of this plateau towards the most negative potential values would be able to help in decreasing the part of current attributed to the generation of dihydrogen. Moreover, as demonstrated by Phuong et al. [5], a comparison is possible with faradaic yields. Finally, the influence of organic and inorganic complexing agents has also been studied.[1] S. Imer et T. Varnali, Applied Organometallic Chemistry, 14(10) p. 660-669, (2000)[2] Z. Zeng, Y. Sun, et J. Zhang, Electrochemistry Communications, 11(2), p. 331-334 (2009)[3] Y. Song et D.-T. Chin, Electrochimica Acta 48(4) p. 349-356 (2002)[4] Y. Mukouyama, M. Kikuchi, et H. Okamoto Journal of Electroanalytical Chemistry 617(2) p. 179-184 (2008)[5] S. De, J. White, T. Brusuelas, C. Patton, A. Koh, et Q. Huang Electrochimica Acta 338 p. 135852 (2020)

The evaluation of oxide scale formation during hot corrosion of Rene-80 superalloy under thermal shock at different dwell times

ABSTRACT In this study, the oxide scale formation on the Rene-80 superalloy after hot corrosion under thermal shock has been investigated. The X-ray diffraction (XRD) and field-emission scanning electron microscope (FE-SEM) were used for the phase identification and evaluation of oxide scale, respectively. The hot corrosion test under thermal shock was performed by depositing Na2SO4 salt at the beginning of each cycle on the surface of the specimens. The results showed that hot corrosion occurred intermittently with the basic fluxing mechanism of the oxide scale and re-precipitation of discontinuous and porous oxides. The growth rate of the Cr2O3 layer increased with decreasing the dwell time per cycle and the dissolution of titanium. Decreasing the dwell time in each hot corrosion cycle increased the growth rate of the Cr2O3 layer, the chromium depletion from the substrate/oxide scale interface, the internal oxidation of aluminium, and the internal sulfidation of chromium.

Na2SO4 and NaCl salts differentially modulate the antioxidant systems in the highly stress tolerant halophyte Prosopis strombulifera

Prosopis strombulifera (Lam.) Benth. is a halophytic shrub abundant in high-salinity areas in central Argentina, with high tolerance against NaCl but strong growth inhibition by Na2SO4. In the present study, the modulation of the antioxidant systems (enzymatic and non-enzymatic components) was analyzed under different salt treatments (NaCl, Na2SO4 and the iso-osmotic mixture) in hydroponic cultivation. Na2SO4-treated plants showed strong indications of oxidative stress (H2O2 and O2-• increase). Modifications in antioxidant enzymes activities were observed mainly under Na2SO4 treatment, where CAT seems to play an important role in early detoxification of H2O2 in roots, whereas SOD and APX have a predominant role in leaves. As part of the non-enzymatic system, 21 compounds were identified in leaves, being polyphenols the most abundant. Control plants contained the major variety of detected phytochemicals (14). Na2SO4-treated plants contained 10 compounds and NaCl-treated plants nine compounds, but with a different profile. NaCl-treated plants showed the highest antioxidant capacity. Our findings confirm that different types of salt treatments provoke a differential modulation of the antioxidant systems. Polyphenols and other ROS-detoxifying compounds, in a joint action with the enzymatic antioxidant system, are proposed to have a fundamental role in the cellular protection of P. strombulifera plants under severe oxidative stress. Our findings also highlight the potential of this halophyte as a valuable source of bioactive compounds with high antioxidant activity and health benefits.

Pilot-scale treatment of hypersaline coal chemical wastewater with zero liquid discharge

Coal to chemical processes produce substantial quantities of hypersaline organic wastewater. Zero liquid discharge (ZLD) is a strategy designed to minimize the wastewater discharge. Here, a pilot-scale ZLD system, consisting of nanofiltration (NF), disc tube reverse osmosis (DTRO), chemical softening, electro-oxidation (EO) and multiple-effect evaporator/crystallizer, was built for the treatment of coal chemical wastewater. The hybrid ZLD process is capable to treat 72 m3 influent per day and reached about 98% water recovery. First, bivalent and monovalent ions were separated from the raw water by a NF-DTRO process. Then the hardness and organic substances of the wastewater were removed by the chemical softening and the EO techniques. Eventually, industrial-grade salts of Na2SO4 and NaCl were recovered through an evaporator-crystallizer. The total operating cost is estimated to be 2.3 $ m−3 influent. This pilot-scale ZLD system is applicable to the treatment and reuse of hypersaline wastewater. The work will provide insights in large-scale application of the ZLD process for wastewater treatment.

Elucidating morpho‐anatomical, physio‐biochemical and molecular mechanism imparting salinity tolerance in oats (Avena sativa)

AbstractSoil salinization drastically affects crop growth, development and yield. In order to tackle salinity, knowledge about stress tolerance mechanism is important to expedite the development of salt‐tolerant cultivars. In this study, 20 oat genotypes consisting of 11 cultivated and nine wild Avena species were evaluated at different levels of salinity with 1:1 NaCl and Na2SO4 salts mixtures under hydroponics and pot experimental set‐up. Drastic reduction was observed in chlorophyll, relative water and K+/Na+ contents, along with yield traits in sensitive genotypes (HFO‐103, Kent and JHO‐2000‐4) when compared with tolerant (HJ‐8, JHO‐99‐2, HFO‐873 and HFO‐878) under elevated salinity. Root anatomical section studies were also critical to screen salinity tolerance among the oat genotypes. Furthermore, the effect of salinity at the transcriptomic level resulted in upregulation of sodium/hydrogen exchanger and potassium transporter genes along with WRKY17 transcription factor, regulating the signalling and osmotic roles in tolerant genotypes (HJ‐8 and HFO‐873). The identified salt‐tolerant oat genotypes reflected wide genetic diversity using SSR markers which can serve as a crucial donor for salt tolerance in oat breeding programmes.

Electrochemically Exfoliated Graphite Nanosheet Films for Electromagnetic Interference Shields

Electrochemical exfoliation of graphite is one of the most efficient and easiest processes to produce high-quality graphene materials. In this study, the efficiency of exfoliation methods for graphite to develop graphene-based electromagnetic interference (EMI) shields with high electrical conductivity was investigated. Exfoliation of graphite was performed in four aqueous solutions of inorganic salts of Na2SO4, (NH4)2SO4, NH4NO3, and (NH4)2HPO4, and the electrochemically exfoliated graphene (EEG) was thoroughly screened to separate out the more defective and small sheets. A 30 μm thick film composed of stacked and overlapped co-doped EEG sheets prepared in (NH4)2SO4 had a room-temperature electrical conductivity of 28 400 S/m and an EMI shielding effectiveness (EMI SE) of ∼62 dB in the X-band frequency (8.2–12.4 GHz), without any reduction of EEG sheets. These are both high values compared to values reported in the literature for “graphene” films with comparable thickness. This is an excellent EMI SE for a shield thickness of just 30 μm, compared to the very thick initial graphite sheet’s EMI SE of ≈70 dB with a thickness of 1.5 mm (50 times thicker). An original finding in this paper is that using the (NH4)2HPO4 electrolyte, we were able to prepare thermally stable EEG films with excellent EMI performance (shielding effectiveness of ∼50 dB after 3-day exposure to 500 °C in air). These high values for overall EMI shielding and electrical conductivity confirm the feasibility of electrochemical exfoliationfor high-performance EMI shields; i.e. it is possible to use a method that does not involve treatment with harsh chemicals or oxidizers and does not require high energies or high temperatures.

Influence of Pre-Oxidation on High Temperature Oxidation and Corrosion Behavior of Ni-Based Aluminide Coating in Na2SO4 Salt at 1050°C

Aluminide coating is prepared on K438 Ni-based superalloy by pack cementation. The hot corrosion test of as-received and pre-oxidation aluminide coating in Na2SO4 salt are carried out at 1050°C. The coating morphologies, phase composition, and corrosion products are characterized by XRD, SEM, EDS, and TEM. The conclusion is that the pre-oxidation aluminide coating has excellent hot corrosion properties. After hot corrosion, the oxide scale of pre-oxidation aluminide coating is the thinnest and maintains good integrity. However, the oxide scale of as-received aluminide coating fluctuates greatly and there are corrosion cavities. CrS is formed in the alloy immediately below the oxide scale for the two coating systems.

Effect and regulation mechanism of oxidation degrees on the O–MoS2 structure and separation performance of nanofiltration membrane

Oxidized molybdenum disulfide (O–MoS2) as a two-dimensional (2D) functional nanosheets material, has been used to fabricate high separation performance nanofiltration (NF) membranes for water treatment. However, the effect and regulation mechanism of the degree of oxidation on structure and separation performance of O–MoS2 modified NF membrane has not yet been fully understood. In this work, O–MoS2 with different oxidation degrees was synthesized by adjusting the oxidation time and KMnO4 oxidant content via Hummers’ method. The results demonstrated that the O–MoS2 synthesized under with an oxidation time of 3 h and MoS2:KMnO4 ratio of 1:2 had excellent stability under acidic, neutral and alkaline conditions. The pure water flux increased 2.5 times and the Na2SO4 salt rejection increased to 97.6% with this O–MoS2 incorporation compared to the control membrane. The influence of different oxidation degrees on the performance of O–MoS2 is a breakthrough finding of this work to provide a theoretical basis for the application of O–MoS2 in the field of membrane separations.

The impact of glycine on the zeta potential of calcite at different temperatures and brine compositions

This study presents zeta potential (ZP) measurements of synthetic calcite in glycine solutions using the electrophoretic method. We tested samples with glycine concentrations of 1, 3, and 5 wt% at 25°C, while the ZP of 5 wt% glycine solutions was also measured at 50 and 75°C. The first set of measurements consisted of single-component brines prepared with CaCl2, MgCl2, Na2SO4, and NaCl salts with an ionic strength of 0.05 M. The second set of measurements consisted of formation brine (FB) with an ionic strength of 6.37 M and FB diluted 2-, 10-, and 100-times (2dFB, 10dFB, 100dFB, respectively). Results show that the effect of glycine on calcite’s ZP depended on its initial ZP value. Moreover, the increase in temperature significantly decreased calcite’s ZP in most samples. The ZP values in CaCl2 and MgCl2 brines were initially positive and decreased with the addition of glycine. Conversely, the ZP values of calcite in NaCl and Na2SO4 brines were initially negative and increased with the addition of glycine. The trends of ZP versus glycine concentration for 2dFB and 10dFB were analogous to the ones with CaCl2 and MgCl2 brines. Similar trends were observed between 100dFB, NaCl, and Na2SO4 brines. Finally, the increase of temperature from 25°C to 50°C and 70°C significantly reduced the ZP of calcite’s particles in CaCl2, Na2SO4, and NaCl brines, while the ZP of FB and its dilutions slightly decreased at 50°C. This is the first time the ZP measurements of calcite in glycine solutions were reported, to the best of our knowledge. Results are mainly explained by (1) the adsorption of glycine anion onto the calcite’s surface, (2) the decrease of the brine’s pH from the addition of glycine, and (3) the complex formation of glycine with divalent ions. Given the ubiquity and abundance of calcite in nature, we expect this study to increase the understanding of the electrostatic interactions between amino acids and calcite in phenomena such as wettability alteration and biomineralization.

Synergistic effect of salt ions and water‐soluble amphiphilic compounds of acidic crude oil on surface and interfacial tension

AbstractThis study investigated the effect of solubility of amphiphilic compounds of acidic crude oil in water on the surface and interfacial tension (IFT) with NaCl, MgCl2, CaCl2, and Na2SO4 salts. Accordingly, distilled water, along with the salts mentioned in zero ionic strength up to 2 mol were put in contact with crude oil to become saturated with amphiphilic compounds. The effects of these compounds were investigated on the properties of contact water by pH, total organic carbon (TOC), FTIR (Fourier transform infrared spectroscopy), water‐air surface tension (ST), and water‐n‐decane IFT tests. The results showed that some of the organic components of crude oil, especially acidic and basic compounds, are present or soluble in water, which have a significant effect on reducing the surface and IFT. The IFT reduction of water‐n‐decane was greater than the water‐air ST system. Also, the observations showed that for both NaCl and Na2SO4 salt water, with increasing ionic strength of water, there was an optimum salinity within the range of 0.1‐0.25 mol/L for both salts with the amount of surface and IFT minimized at this point. In the other two salts, this point was delayed upon elevation of ionic strength and was observed at high salinity. In this case, divalent cations reduce tension rate compared to monovalent cations. Due to solubility of acidic and basic groups in water, pH of salt water illustrates an acidic trend. Results of the FTIR test confirmed solubility of these compounds as well.

Diffusion Aluminide Coatings for Hot Corrosion and Oxidation Protection of Nickel-Based Superalloys: Effect of Fluoride-Based Activator Salts

The influence of two different fluoride-based activator salts (NH4F and AlF3) was studied for diffusion aluminide coatings obtained via pack cementation on a Ni-based superalloy (René 108DS). The resistance to oxidation and hot corrosion was assessed as a function of the concentration of activator salts used during the synthesis process by means of pack cementation. Two different concentrations were selected for activator salts (respecting the equimolarity of fluoride in the synthesis) and the obtained diffusion coatings were compared in terms of morphology, thickness and composition, as well as in terms of microstructural evolution after high temperature exposure. Isothermal oxidation tests were conducted at 1050 °C in air for 100 h in a tubular furnace. The oxidation kinetics were evaluated by measuring the weight variation with exposure time. The microstructural evolution induced by the high temperature exposure was investigated by SEM microscopy, EDS analysis and X-ray diffraction. Results showed that the coatings obtained with AlF3 activator salt are thicker than those obtained using NH4F as a consequence of different growth mechanism during pack-cementation. Despite this evidence, it was found that the NH4F coatings show a better oxidation resistance, both in terms of total mass gain and of quality of the microstructure of the thermally grown oxide. On the other hand, coatings produced with high concentration of AlF3 exhibited a better resistance in hot corrosion conditions, showing negligible mass variations after 200 h of high temperature exposure to aggressive NaCl and Na2SO4 salts.

The corrosion resistance mechanisms of the cr-coated SiC in molten Na2SO4 salt: Strengthened boundaries and protective scales

The corrosion resistance of pressureless-sintered silicon carbide (SiC) plates in the molten Na2SO4 salt was greatly enhanced by their surfaces coated with magnetron-sputtered chromium (Cr) coatings. The Cr-coated SiC plates remained good structural integrity in the 1000 °C molten Na2SO4 salt for >20 h, in contrast to the uncoated ones that completely crushed into pieces after 4 h. The corrosion-resistance mechanisms mainly depend on the strengthened boundaries by formation of the Cr-C and Cr-Si compounds to avoid the preferred corrosion of boundaries, and the barrier effect of the Cr2O3/Cr/Cr-Si-C protective scale.

Effect of Concentrated Salts Solutions on the Stability of Immobilized Enzymes: Influence of Inactivation Conditions and Immobilization Protocol.

This paper aims to investigate the effects of some salts (NaCl, (NH4)2SO4 and Na2SO4) at pH 5.0, 7.0 and 9.0 on the stability of 13 different immobilized enzymes: five lipases, three proteases, two glycosidases, and one laccase, penicillin G acylase and catalase. The enzymes were immobilized to prevent their aggregation. Lipases were immobilized via interfacial activation on octyl agarose or on glutaraldehyde-amino agarose beads, proteases on glyoxyl agarose or glutaraldehyde-amino agarose beads. The use of high concentrations of salts usually has some effects on enzyme stability, but the intensity and nature of these effects depends on the inactivation pH, nature and concentration of the salt, enzyme and immobilization protocol. The same salt can be a stabilizing or a destabilizing agent for a specific enzyme depending on its concentration, inactivation pH and immobilization protocol. Using lipases, (NH4)2SO4 generally permits the highest stabilities (although this is not a universal rule), but using the other enzymes this salt is in many instances a destabilizing agent. At pH 9.0, it is more likely to find a salt destabilizing effect than at pH 7.0. Results confirm the difficulty of foreseeing the effect of high concentrations of salts in a specific immobilized enzyme.

Effects of Hot Corrosion on Fatigue Performance of GH4169 Alloy

In this study, GH4169 alloy was hot-corroded using NaCl+Na2SO4 salts; the microstructures, composition and hardness of hot corrosion (HC) layer were investigated, and fatigue tests were conducted on the as-received and hot-corroded GH4169 alloy. The results show that HC causes oxidation and sulfidation in GH4169 alloy. The formed sulfide layer is beneath the oxide layer, and the hardness obtained by nano-indentation analysis follows a sequence of oxide layer > alloy matrix > sulfide layer. HC accelerates fatigue crack initiation and significantly reduces GH4169 alloy fatigue life. It is believed the reduced fatigue life is probably ascribed to spallation of HC layer, stress concentration effects caused by HC pits, plastic deformation in sulfide layer and microcracks in oxide layer.