High Temperature Corrosion Resistance Research Articles

Experimental study on deformation mechanism around indentation of GH4169 alloy

The GH4169 alloy is widely used in engineering structures due to its excellent high-temperature strength, corrosion resistance, and mechanical properties. However, local stresses during plastic deformation significantly impact its macroscopic mechanical performance. This study investigates the residual deformation fields and plastic deformation mechanisms around local indentations using digital image correlation (DIC), electron backscatter diffraction (EBSD), and nanoindentation. The results show that the indentation rate affects the accumulation of geometrically necessary dislocations (GNDs). Increasing the loading rate from 2mN/s to 20mN/s leads to a 32% increase in GNDs. When the loading strain rate increases from 0.01s-1 to 0.2s-1, GNDs increase by 43%. Moreover, indentations initiate more than two slip systems in the alloy crystals, with slip trace lines consistent with theoretical predictions. The plastic deformation field distribution around the indentations, obtained using DIC, reveals the influence range of slip generation due to indentations to be around 10 μm.

Development of Alumina Coatings on Ni-Cr Superalloy Turbine Blades Enhanced by Thoria-Integrated Yttria and Ceria-Stabilized Zirconia Nanoparticles for High-Temperature Thermal Barrier Coatings and Corrosion Resistance

Development of Alumina Coatings on Ni-Cr Superalloy Turbine Blades Enhanced by Thoria-Integrated Yttria and Ceria-Stabilized Zirconia Nanoparticles for High-Temperature Thermal Barrier Coatings and Corrosion Resistance

Microstructural and mechanical investigation of dissimilar U-groove weld of IN 718/ASS 304L employing ERNiCr-3 filler

This study investigates the dissimilar welding of Inconel 718 (IN 718) and austenitic stainless steel 304L (ASS 304L) using Gas Tungsten Arc Welding (GTAW) with Ni-based filler ERNiCr-3. IN 718 is valued for its high-temperature stability, oxidation, and corrosion resistance, while ASS 304L offers excellent ductility, formability, and corrosion resistance. The objective is to evaluate the impact of ERNiCr-3 on the weld’s metallurgical and mechanical attributes. The materials, prepared with U-groove edges, were optimized for manual multi-pass welding. Microstructural analysis revealed an austenitic matrix with dispersed Ti(CN) and NbC precipitates, enhancing strength through dispersion-strengthening mechanisms, with no solidification cracking due to Nb presence. FESEM/EDS and colour mapping identified elemental migration and stable carbide formation at the weld interfaces. Mechanical testing revealed uniform hardness within the weld zone and tensile resistance of 510 MPa, underscoring the robustness of ERNiCr-3 weld metal. These results indicate that ERNiCr-3 is highly effective for producing superior quality dissimilar welds amidst IN 718/ASS 304L, making it suitable for applications in elevated-temperature and mechanically demanding environments.

Effect of laser cladding layers on microstructure and mechanical properties of NiCoCrAlY bond coat

The NiCoCrAlY alloy is usually used as a bonding layer material in thermal barrier coatings (TBCs) system. Owing its excellent high-temperature oxidation resistance and corrosion resistance, it plays a crucial role in maintaining the structural integrity and functionality of TBCs. Laser cladding technology is a flexible and efficient processing technique for the manufacturing of NiCoCrAlY bond coat, with the characteristics of precisely control the layers of the laser cladding and further modulate the quality of the bond coat. Therefore, the investigation on the influence of cladding layers on the microstructure and mechanical properties of the bond coat is of great significance for improving the service performance and lifetime of aircraft engines. To this end, the scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) were used in this study to explore the influence of cladding layers on the microstructure and mechanical properties of the NiCrAlCoY bond coat. The results indicate that the microstructure of the cladded alloy can be divided into substrate, heat-affected zone, and cladded zone. The hardness of both the heat-affected zone and the cladded zone increases as the number of cladding layers increases, while the hardness of the substrate maintains constant. In addition, as the number of laser cladding layers increases, so does the residual stress of the cladded alloy.

Research Progress on the Relationship Between Microstructure and Properties of AISI 321 Stainless Steel

AISI 321 stainless steel is widely used in chemical pipelines and nuclear power, prompting research on its high-temperature performance and corrosion resistance. This review focuses on the effects of alloy elements, second-phase particle formation, and heat treatment processes on the microstructure and properties of AISI 321 stainless steel. Fine tuning of alloying elements can affect the mode and effect of dynamic recrystallization, altering the high-temperature flow deformation of AISI 321 stainless steel. In order to achieve phase equilibrium, the relationship between corrosion resistance and high-temperature creep behavior and high-temperature mechanical behavior in the presence of second-phase particles was also analyzed. This review outlines the basic heat treatment procedures for improving material properties, providing a new perspective for solution treatment and improving corrosion resistance. In addition, the latest research progress on other factors affecting the high-temperature performance of AISI 321, such as coatings, was briefly introduced.

Efficient carburization of high-entropy alloys from polyethylene microplastics using a green mechanochemical process to obtain excellent wave absorbing performance

Polyethylene as a major white pollutant has a significant negative impact on the environment and the human health. Beneficial recycling of polyethylene through mechanochemical processes not only can eliminate environmental hazards, but also enable some beneficial industrial applications. In this work, polyethylene was used as the raw materials of carburization of FeCoNiMn high-entropy alloys (HEAs) by a green mechanochemical method. The phase structure, magnetic properties, high-temperature oxidation resistance, corrosion resistance and electromagnetic-wave absorbing performance of the obtained carburized HEAs were investigated in detail. The carburized-FeCoNiMn HEAs exhibited excellent corrosion resistance, suggesting great application potential for use in harsh environments. Besides, the impedance matching was optimized and the electromagnetic-wave absorption bandwidth was expanded by this carburization process. Specifically, the reflection loss of C10 (FeCoNiMnC0.1) at 8.88 GHz reached −65.07 dB at a thickness of 2.79 mm, and both the C50 (FeCoNiMnC0.5) and C90 (FeCoNiMnC0.9) exhibited a maximum absorption bandwidth of 5.45 GHz. This work provides a new concept of utilizing common microplastic pollutants to achieve efficient carburization of HEAs by a green mechanochemical process.

Phase evolution and steam oxidation behavior of nickel-based composite coatings fabricated by laser cladding

In this study, a variety of synthesized carbides are used as reinforcing phases for Inconel 625 alloy to enhance the performance of surface coatings. The effects of scanning rate and laser power on the microstructure and mechanical properties of coatings were studied, and specific energy was introduced to comprehensively evaluate the mechanisms of their influence. The results show that the percentage of macroscopic defects in the nickel-based composite coatings decreases and the dilution rate increases gradually with increasing specific energy density and the mechanical properties of the composite coating deteriorate gradually. It is worth noting that when the specific energy density is 153.33 J/mm2, the comprehensive performance of the composite coating is the best, which is mainly due to the uniform distribution of the contained (Ti, W)C and Cr carbides. The coating exhibits excellent hardness, corrosion resistance, and high-temperature oxidation resistance. In addition, after determining the optimal process parameter combination, the high-temperature steam oxidation performance of the nickel-based composite coating is analyzed in depth. At 1200°C, the corrosion degree of the composite coating gradually increased with increasing oxidation time. Research shows that the ceramic phase structure of (Ti, W)C and Cr plays a significant inhibitory role in high-temperature environment, effectively decelerating the increase of corrosion rate. Interestingly, before the first 48 h of the oxidation process, the thickness of the oxidation layer on coating surface increases slowly. However, when the oxidation time reaches 96 h, large amounts of WO3 and NiCr2O4 phases are formed, leading to the generation of pores and cracks in the coating. This causes the oxide film to fall off, resulting in a sharp increase in the corrosion layer thickness. The research in this paper is of great significance for optimizing coating materials and preparation processes, as well as improving the long-term high-temperature corrosion resistance of coatings.

Study on the influence of corrosion degree on the high-temperature oxidation and combustion characteristics of AZ91, WE43 and ZE10 magnesium alloys

Based on magnesium alloy materials, different degrees of corrosion occur on the surface during use, and the corrosion state significantly affects its high-temperature oxidation and combustion characteristics. This study examines various corrosion conditions, investigates the impact of different corrosion levels on the combustion characteristics of magnesium alloys, and analyses the adsorption performance, state density, and oxygen atom diffusion barrier of alloy elements in AZ91, WE43, and ZE10 magnesium alloys based on first-principles calculations. It reveals the mechanism of the impact of each alloy element on the surface oxide film of magnesium alloys and explains the principles of the experimental results. The results indicate that with increasing corrosion time, temperature, and pressure, the time for the surface oxide film to rupture significantly decreases. In the six magnesium alloy systems of quantum calculations, the Mg–Re structure exhibits the strongest stability. According to adsorption energy calculations, the Mg–Al and Mg–Y systems show the best oxygen adsorption performance. Magnesium alloys doped with Y and Ce elements have the highest oxygen atom diffusion barrier. Hence, magnesium alloy systems doped with Y and Ce elements have a dense surface oxide film that remains undamaged even at very high temperatures, demonstrating excellent high-temperature corrosion resistance and providing an explanation for the experimental results.

New insight on the formation of uneven oxide scales on AFA steel in supercritical CO2: Roles of recrystallization degree on the high temperature corrosion resistance

Uneven oxide scale is a common phenomenon in high-temperature corrosion, but the formation mechanism has not been fully uncovered. A new alumina-forming austenitic (AFA) stainless steel with superior corrosion resistance in 650°C/15 MPa SC-CO2, has been systematically investigated. It is demonstrated that the uneven oxide was formed by the significant impact of the recrystallization behavior of AFA steel on its microstructural evolution and subsequent corrosion behavior. Compared with the thin oxide scale, the thick oxide scale was caused by the relatively higher density of dislocations and grain boundaries of matrix resulting from delayed recrystallization, which facilitated the rapid outward diffusion of ions.

Electrochemical Machining of Micro-Pit Arrays on a GH4169 Alloy with a Roll-Print Mask Using a C6H5Na3O7-Containing NaNO3 Mixed Electrolyte.

GH4169 alloy, a nickel-based superalloy known for its excellent high temperature resistance, corrosion resistance, mechanical properties, and high-temperature tribological properties, is widely used in industrial applications, such as in gas turbines for space shuttles and rocket engines. This study addresses the issue of electrolyte product residue in the electrochemical machining process of a GH4169 alloy by utilizing a C6H5Na3O7-containing NaNO3 new mixed electrolyte. Comparative investigations of the electrochemical behavior and electrolyte product removal mechanisms at different concentrations of C6H5Na3O7 additive in NaNO3 solutions were conducted. The effects of additives, applied voltage, and the rotating speed of the cathode tool on the processing performance of micro-pit arrays on a GH4169 alloy were analyzed. The results indicate that the mixed solution containing C6H5Na3O7 significantly improves the localization and geometric morphology of the micro-pits compared to a single NaNO3 solution. The optimal electrochemical machining parameters were identified as 0.5 wt% C6H5Na3O7 + 10 wt% NaNO3 mixed electrolyte, 12 V applied voltage, and 0.1 r/min rotating speed of the cathode tool. Under these conditions, high-quality micro-pit arrays with an average diameter of 405.85 μm, an average depth of 87.5 μm, and an etch factor (EF) of 1.67 were successfully fabricated, exhibiting excellent morphology, localization, and consistency.

Enhancing high-temperature chloride molten salts corrosion resistance of 310S steel with Si-added Ni–Al coating

Ni–Al based coating is one of the common high temperature and corrosion resistant protective coatings. In the present paper, the effect of Si content on the formation of Al2O3 layer and the corrosion resistance of Ni–Al coating to chloride molten salt was studied. The research results show that the Ni–Al coatings with varying Si content mainly form NiAl2O4 and Al2O3 oxide layers after pre-oxidation, and form a three-layer structure after molten salt corrosion. The appropriate amount of Si added to the Ni–Al coating can promote the formation of the α-Al2O3 layer during pre-oxidation and thermal corrosion, improving the corrosion resistance of the coating to high temperature chloride molten salt, and hindering the diffusion of Cr elements. Particularly, the Ni–Al coating with Si content of 1.2 at.% has the thickest and densest Al2O3 protective layer, showing the best corrosion resistance. The simulation results shows that compared with the Ni–Al coating without Si, the Cl atoms in the Si-added Ni–Al coating need to overcome greater energy barriers to diffusion during the molten salt corrosion process, which also indicates that the addition of Si can improve the corrosion resistance of the coating.

Effect of grain size on high-temperature corrosion performance of laser cladding inconel 625 coating

As the calorific value of waste-to-energy incineration continues to rise, the corrosion damage to boilers becomes increasingly severe. The impact of the grain size on the high-temperature corrosion resistance of Inconel 625 coating was investigated. The results indicated that the corrosion performance of the coating in 1:1 NaCl–KCl salts at 700 °C for 120 h was highly dependent on the grain size of the coating. The coating fabricated with a laser power of 1800 W and an overlapping distance of 1.5 mm had an average grain size of 13.7 μm and highest hardness, exhibiting the best corrosion performance, with a corrosion weight loss of 1.4 mg/cm2. Coatings processed under different conditions all formed a three-layered structure, with a NiO outermost layer, a Cr2O3 intermediate layer, and an innermost Cr-depletion zone. Coatings with finer grains formed a continuous and dense protective oxide layer of NiO and Cr2O3 due to the rapid diffusion of alloy elements, effectively preventing the invasion of corrosive media and protecting the substrate from corrosion.

Enhanced thermal insulation and corrosion resistance in Ni-Fe cermet through incorporation of high-entropy spinel oxides

The influence of high-entropy spinel oxide (HESO) content on the microstructure, electrical conductivity, and high-temperature corrosion resistance of HESO/NiFe cermets were investigated. The results found that the addition of 10–30 wt% HESO enhanced sintering densification and thermal insulation, although it also resulted in reduced electrical conductivity. Isothermal oxidation tests conducted at 900 °C for 10 hours revealed that cermets containing 30–50 wt% HESO exhibited significantly lower weight gains (0.954–1.167 mg cm⁻²) and oxidation rate constants (0.1057–0.1525 mg² cm⁻⁴ h⁻¹). Furthermore, static corrosion tests in AlF₃-KF-Al₂O₃ molten salt demonstrated that HESO effectively mitigated the erosion of the metallic phase by the fluoride molten salt. This study holds significant potential by providing new insights for the design of inert anodes for aluminum electrolysis and exploring the practical applications of high-entropy oxide materials.

Characterization of nickel cladding on type 316H stainless steel for enhanced corrosion resistance in molten chloride salts

This study explores the corrosion protection characteristics of nickel (Ni) cladding on Type 316H stainless steel in molten chloride salt environments, relevant to molten salt reactors (MSRs) which are gaining interest as advanced and sustainable nuclear energy sources. Type 316H stainless steel, while noted for its high-temperature strength and corrosion resistance, faces significant challenges when exposed to corrosive molten salts. To address this, Ni cladding was applied using gas tungsten arc (GTA) welding and directed energy deposition (DED) laser cladding. Characterization of the cladding layers was performed using field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS), identifying precipitates such as Ti(C,N) and Cr₂O₃. Mechanical integrity was verified through bending tests in accordance with ASTM E190-21, which revealed no cracks in the cladding layers. Corrosion resistance was assessed through immersion tests in a 57 mol% NaCl - 43 mol% MgCl₂ mixture at 650 °C for 502 h. Results demonstrated superior corrosion resistance of Ni-clad specimens compared to uncoated Type 316H stainless steel and Incoloy 800H, with the Ni cladding exhibiting a weight increase due to Fe deposition from the Fe-base alloys. The study concludes that Ni cladding, irrespective of the application method, enhances the durability and longevity of Type 316H stainless steel in the harsh environments typical of MSRs, suggesting a promising approach to improving the performance of structural materials in these systems.

Comparisons between basalt for continuous fiber and ordinary basalt

Continuous basalt fiber (CBF) is a novel, green and eco-friendly material drawn with basalt, featuring exceptional properties such as high-temperature resistance, corrosion resistance, and superior strength. It finds extensive applications in various fields including defense and military industry, aviation and aerospace, construction and bridges. Basalt is the most widely distributed aluminosilicate volcanic rock on Earth. However, not all basalts are suitable for the stable CBF production due to the variations in composition and structure across different regions, which result in differences in the crystallization characteristics of basalt melts that impact the stability and continuity of the wire drawing process. Therefore, investigating the crystallization characteristics of basalt glass melt holds significant value for CBF production. This paper focuses on the various types of high-quality basalt for CBF and ordinary basalt in China. They were melted at a temperature of 1450 °C for 1 h, followed by cooling in the furnace and quenching with water, resulting in the preparation of 18 pieces of basalt glasses. The basalt glasses were characterized using DSC, XRD, FT-IR, SEM, EDS and polarizing microscope techniques. The research findings suggest that: (1) The chemical compositions of high-quality basalt for CBF do not exhibit significant differences from that of ordinary basalt; (2) All the basalt glasses quenched with water produced from high-quality basalt for CBF and ordinary basalt exhibit an amorphous phase, uniform glass structure, and enhanced melting behavior at this temperature; (3) In the furnace-cooled process, the glasses from high-quality basalt for CBF lacks any crystalline phase while the glasses from ordinary basalt display varying degrees of crystallization primarily due to cooling-induced crystallization. This work holds great significance for evaluating and screening the basalt raw materials for CBF.

Combinatorial synthesis of AlNi alloys by low-pressure cold spray deposition and post-laser alloying process

Aluminum-Nickel (AlNi) alloys are of great interest due to their exceptional high-temperature wear and corrosion resistance, making them valuable in transport, energy, and materials processing applications. However, challenges in the production and shaping of these alloys, particularly as thick coatings, remain significant. This study introduces an innovative method for the high-throughput synthesis of AlNi coatings, utilizing a two-step process: low-pressure cold spray deposition followed by laser surface alloying. The combination of these two techniques not only improves the synthesis process but also opens avenues for exploring new material compositions with specific application requirements. This approach holds significant potential for accelerating the development and optimization of advanced coatings and multiphase compounds in applications such as repair and additive manufacturing.Aluminum and nickel powders were co-sprayed to create coatings with controlled compositions ranging from 50Al50Ni to 10Al90Ni (wt%). Subsequent laser treatment induced in-situ alloying and homogenization, resulting in dense, uniform AlNi coatings. The microstructure and chemical composition were characterized using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), while X-ray Diffraction (XRD) identified the formation of various phases, including Al3Ni and AlNi3 phases. The process demonstrated effective alloying and microstructural homogeneity, with residual alumina present at the surface. Despite the presence of some microstructural defects, such as cracking, this method provides a robust foundation for further refinement and opens new possibilities for tailoring alloy properties through combinatorial cold spray and laser alloying techniques.

Microstructure, Hardness and High-Temperature Corrosion Behaviors in Sulfur-Containing Environment of Laser Cladding Y2O3/IN625 Composite Coating.

Water-cooled wall tubes are susceptible to high-temperature corrosion during service. Applying high-performance coatings via laser cladding on the tube surfaces can significantly enhance corrosion resistance and extend the service life of the tubes, providing substantial economic advantages. This paper prepared Y2O3/IN625 composite coating by means of high-speed laser cladding. Furthermore, the effects of Y2O3 addition on the microstructure evolution, hardness, as well as the high-temperature corrosion behaviors have been systematically investigated. The results show that Y2O3 addition can effectively refine the microstructure of the Inconel 625 coating, but the phase composition has little change. The coating's hardness can also be improved by about 7.7%, reaching about 300 HV. Compared to Inconel 625 coating, the Y2O3-added composited coating shows superior high-temperature corrosion resistance, with the corrosion mass gain decreased by about 36.6%. The denser and tightly bonded Cr-rich oxides layer can be formed adjacent to the coating surface, which plays a predominant role in improving the coating corrosion resistance.

Enhanced high-temperature corrosion resistance of Cr-modified phosphate/aluminum powder composite coatings: Mechanisms and thermodynamic insights

Phosphate composite coatings are regarded as one of the tangible solutions for surface protection in salt spray environments, benefiting from their cost-effectiveness and prominent structure stability upon high-temperature exposure. However, rapid curing of these coatings often leads to crack formation, and the underlying corrosion mechanisms in service conditions remain insufficiently understood, limiting their practical applications. In this study, we developed chromium-incorporated phosphate/aluminum powder composite (Cr-P/Al) coatings and evaluated their corrosion resistance under alternating conditions of salt spray corrosion and oxidation at 450 °C. By integrating experimental results, ab initio calculations, and thermodynamic analysis, we demonstrate that the incorporation of Cr significantly enhances the performance of the P/Al coatings. The structural evolution was first revealed that Cr’s modification reduced tensile stress and prevented cracks in the coating. A mixed layer of amorphous oxides and phosphates forms on the surface of the Al powder, providing robust binding strength. A novel corrosion mechanism was identified that Cl2 and volatile chlorides facilitated the removal of Cl-. This process is more ineffective with Cr-P/Al coating, as amorphous Cr oxide has low reactivity at a high log[p(Cl2)] and low log[p(O2)] compared with amorphous Mg and Fe oxide, thereby enhancing the corrosion resistance of the coating. These coating densification methods and corrosion protection mechanisms provide a critical foundation for the future application of phosphate composite coatings.

PS-PVD thermal barrier coatings microstructure modulation and high-temperature erosion resistance study

Plasma spray-physical vapor deposition (PS-PVD) enables the modulation of both the microstructure and the performance of the coating by modulating the ratio of the three phases (gas, liquid, and solid) present in the jet. Considering the observed deficiency in the erosion resistance of PS-PVD coatings, the study explores improving high-temperature erosion resistance in PS-PVD thermal barrier coatings by adjusting Ar/He flow ratios. At a plasma gas flow rate of 90 SLPM, increasing the Ar/He ratio enhances nanohardness and elastic modulus. An Ar/He ratio of 2:1 provides erosion resistance comparable to standard APS coatings. Raising the plasma flow to 120 SLPM with the same Ar/He ratio forms a dense coating with low erosion rates. The study identifies a strong correlation between the hardness of the coating and erosion resistance. Lateral cracking from high-temperature and high-speed particle erosion is identified as the primary cause of failure.

Research status on the effect of energy density on the forming microstructure and properties of nickel-based superalloys for laser additive manufacturing

Abstract Nickel-based superalloys have excellent high-temperature mechanical properties, corrosion resistance and oxidation resistance, and strong machinability. It is widely used in aerospace, submarine and shipbuilding, petrochemical, electronic industry and other industries. However, there are still challenges in the popularization and application of nickel-based superalloys for alloy components with complex structures and extremely harsh working conditions. In this paper, the research status of the influence of energy density on the microstructure and properties of laser additive fabrication of nickel-based superalloys at home and abroad is reviewed. The influence of energy density on the microstructure evolution behavior and mechanical properties improvement effect of laser additive manufacturing nickel-based superalloys is summarized. The mechanism of energy density was discussed from the perspectives of microstructure evolution and macroscopic performance change. Based on the individual effects and synergistic effects of each process parameter, the influence of laser energy density on dendrite growth, phase precipitation characteristics, element distribution and porosity defect control effect of nickel-based superalloy was expounded, as well as the influence mechanism on microhardness, wear resistance and residual stress. Finally, the energy density optimization and development prospect of laser additive fabrication of nickel-based superalloys are prospected.