High-temperature Tests Research Articles

Preparation and Performance Evaluation of CO2 Foam Gel Fracturing Fluid

The utilization of CO2 foam gel fracturing fluid offers several significant advantages, including minimal reservoir damage, reduced water consumption during application, enhanced cleaning efficiency, and additional beneficial properties. However, several current CO2 foam gel fracturing fluid systems face challenges, such as complex preparation processes and insufficient viscosity, which limit their proppant transport capacity. To address these issues, this work develops a novel CO2 foam gel fracturing fluid system characterized by simple preparation and robust foam stability. This system was optimized by incorporating a thickening agent CZJ-1 in conjunction with a foaming agent YFP-1. The results of static sand-carrying experiments indicate that under varying temperatures and sand–fluid ratio conditions, the proppant settling velocity is significantly low. Furthermore, the static sand-carrying capacity of the CO2 foam gel fracturing fluid exceeds that of the base fluid. The stable and dense foam gel effectively encapsulates the proppant, thereby improving sand-carrying capacity. In high-temperature shear tests, conducted at a shear rate of 170 s−1 and a temperature of 110 °C for 90 min, the apparent viscosity of the CO2 foam gel fracturing fluid remained above 20 mPa·s after shear, demonstrating excellent high-temperature shear resistance. This work introduces a novel CO2 foam gel fracturing fluid system that is specifically tailored for low-permeability reservoir fracturing and extraction. The system shows significant promise for the efficient development of low-pressure, low-permeability, and water-sensitive reservoirs, as well as for the effective utilization and sequestration of CO2.

CMAS corrosion behavior of interface for EB-PVD Gd2Zr2O7/YSZ thermal barrier coatings

Thermal barrier coatings (TBCs) of aero-engine surfaces are facing complex working conditions such as high-temperature oxidation, hot-cold cycling, and CMAS corrosion. Gd2Zr2O7 (GZO)/YSZ bilayer ceramic TBCs are one of the coating systems that have been applied in aero-engine TBCs. One of the failure problems faced by the columnar crystalline bilayer GZO/YSZ TBCs prepared by electron beam-physical vapor deposition (EB-PVD) technology in high-temperature environments is the CMAS high-temperature corrosion problem. In this study, CMAS corrosion tests of GZO/YSZ bilayer structure TBCs were conducted at 1200 °C for 1h, 2h and 4h, respectively. The focus was on exploring the corrosion characteristics and mechanisms of the coating interface and surface after high-temperature corrosion. It was found that CMAS corrosion was dominated at the coating interface, accompanied by coating sintering, resulting in coating spalling at the interface. The coating interface was also analyzed by TEM after 4h corrosion, and it was found that an apatite phase was formed at the GZO/YSZ interface, which was embedded in the lattice of YSZ. Finally, the corrosion failure mechanism of the GZO/YSZ bilayer structure TBCs was proposed by the above CMAS high-temperature corrosion test.

Tracking research on the performance changes of S31042 steel under long term service

S31042 is widely used in ultra-supercritical units due to its excellent comprehensive performance at high temperatures. Tracking and monitoring research was conducted on as-received S31042 tubes and tubes in service for 13k hours, 31k hours, and 52k hours at 650 °C. The results show that as the service time increased, a large quantity of M23C6 phase precipitated along the grain boundaries, gathered and grew up into the bulk. This weakened of the grain boundaries, which facilitated crack propagation and significantly reduced the plasticity and toughness of the S31042 heat-resistant steel. After 13k hours of operation, the dispersion strengthening of the precipitated phase inside the grain and grain boundary led to a substantial increase in hardness, while there was no obvious change in strength. However, after 52k hours of operation, the dispersed precipitated phase within the grain slowly aggregated and grew, decreasing the effectiveness of dispersion strengthening. Consequently, both the high-temperature strength and hardness of the S31042 steel gradually decreased. As the service time increased, the continuously distributed and similarly sized M23C6 phases on the grain boundaries of S31042 developed into an inhomogeneous coarsening chain structure. Additionally, the appearance of nanoscale secondary NbCrN and M23C6 phases within the grain and their resulting precipitation strengthening effects were the main reasons for the significant change in S31042 hardness values. Based on these findings, the residual life of S31042 heat-resistant steel in service was predicted using an extrapolation method based on high-temperature creep rupture tests and the relationship model between hardness and the P function. A comparison of the L-M parametric life prediction results with the strength extrapolation life prediction results based on the standard creep rupture test shows that the creep rupture strength extrapolation method is slightly conservative. Therefore, the prediction results based on the hardness L-M parameter method, which is simple and easy to perform, can be used for preliminary life prediction.

Development of a thermoplastic constitutive model for steel based on the generalized Mises yield criterion

Steel is widely used in building structures, and the constitutive model that describes the steel's response to load is an essential component of structural mechanics analysis. This paper aims to investigate the thermoplastic behavior of steel at elevated temperatures. Based on the classical elastoplastic mechanics framework, this study introduces a generalized Mises yield criterion derived from energy theory, which takes into account the temperature effect. In conjunction with relevant assumptions, hardening condition, flow rule, the generalized Hooke's law, and consistency condition, we derive a novel incremental thermoplastic constitutive model for steel. And the new thermoplastic constitutive model's rationality is further verified by utilizing high-temperature steady-state tensile test data. It is encouraging that this new model can accurately describe the mechanical behavior of steel in high-temperature environment such as fire, which is of significant importance for fire safety design of building structures.

Effect of post-deposition heat treatments on high-temperature wear and corrosion behavior of Inconel 625

This study uses the arc-directed energy deposition method to fabricate and heat treatment of a Ni-based Inconel 625 wall structure. Heat treatment involved solution treatment at 980°C with and without aging at 720°C, comparing results to the as-built condition. The effects of these heat treatments were analyzed through microstructural investigations, nanoindentation tests, and high-temperature wear and corrosion tests in 0.5 M NaCl and 0.5 M HCl solutions. In the as-built state, the Inconel 625 alloy exhibited a columnar dendritic structure predominantly composed of a gamma matrix along with Laves phase and MC carbides. Solution treatment dissolved the Nb-rich Laves phases and encouraged the formation of needle-like particles in regions with high Nb segregation, while also reducing voids and minimizing corrosion susceptibility along grain boundaries. This resulted in the formation of a uniform oxide layer on the surface, significantly enhancing wear and corrosion resistance. Both heat-treated samples showed improvements in mechanical ratios such as H/E, H³/E², and H²/2E in the WAAM-produced Inconel 625 alloy, resulting in a 67 % enhancement in wear resistance compared to the as-built sample. Corrosion tests also revealed that solution treated samples showed the highest corrosion resistance, followed by aged treatment and as-built samples, respectively. In conclusion, this study provides a thorough understanding of the substantial impact of heat treatments on the microstructure, mechanical properties, and corrosion resistance of Inconel 625, offering valuable insights for advancements in the field.

Discovery and preclinical evaluation of BPB-101: a novel triple functional bispecific antibody targeting GARP-TGF-β complex/SLC, free TGF-β and PD-L1.

In the tumor microenvironment (TME), the transforming growth factor-β (TGF-β) and programmed cell death receptor 1 (PD-1)/programmed death ligand 1 (PD-L1) signaling axes are complementary, nonredundant immunosuppressive signaling pathways. Studies have revealed that active TGF-β is mainly released from the glycoprotein A repetitions predominant (GARP)-TGF-β complex on the surface of activated regulatory T cells (Tregs), B cells, natural killer (NK) cells, and tumor cells. The currently available antibodies or fusion proteins that target TGF-β are limited in their abilities to simultaneously block TGF-β release and neutralize active TGF-β in the TME, thus limiting their antitumor effects. We designed and constructed a bispecific, trifunctional antibody, namely, BPB-101, that specifically targets the GARP-TGF-β complex and/or small latent complex (SLC), active TGF-β, and PD-L1. The binding ability of BPB-101 to the different antigens was determined by ELISA, FACS, and biolayer interferometry (BLI). The blocking ability of BPB-101 to the TGF-β and PD-1/PD-L1 signaling axes was determined by reporter gene assay (RGA). The antitumor effect and biosafety of BPB-101 were determined in a transgenic mouse tumor model and cynomolgus monkeys, respectively. Stability assessments, including stability in serum, after exposure to light, after repeated freeze-thaw cycles, and after high-temperature stress tests had been completed to evaluate the stability of BPB-101. BPB-101 bound efficiently to different antigenic proteins: the GARP-TGF-β complex and/or SLC, active TGF-β, and PD-L1. Data showed that BPB-101 not only effectively inhibited the release of TGF-β from human Tregs, but also blocked both the TGF-β and PD-1/PD-L1 signaling pathways. In an MC38-hPD-L1 tumor-bearing C57BL/6-hGARP mouse model, BPB-101 at a dose of 5 mg/kg significantly inhibited tumor growth, with a complete elimination rate of 50%. Stability assessments confirmed the robustness of BPB-101. Furthermore, BPB-101 showed a favorable safety profile in nonhuman primate (NHP) toxicity studies. BPB-101 is a potentially promising therapeutic candidate that may address unmet clinical needs in cancer immunotherapy, thus, BPB-101 warrants further clinical investigation.

Spinel oxide enables high-temperature self-lubrication in superalloys

The ability to lubricate and resist wear at temperatures above 600 °C in an oxidative environment remains a significant challenge for metals due to their high-temperature softening, oxidation, and rapid degradation of traditional solid lubricants. Herein, we demonstrate that high-temperature lubricity can be achieved with coefficients of friction (COF) as low as 0.10-0.32 at 600-900 °C by tailoring surface oxidation in additively-manufactured Inconel superalloy. By integrating high-temperature tribological testing, advanced materials characterization, and computations, we show that the formation of spinel-based oxide layers on superalloy promotes sustained self-lubrication due to their lower shear strength and more negative formation and cohesive energy compared to other surface oxides. A reversible phase transformation between the cubic and tetragonal/monoclinic spinel was driven by stress and temperature during high temperature wear. To span Ni- and Cr-based ternary oxide compositional spaces for which little high-temperature COF data exist, we develop a computational design method to predict the lubricity of oxides, incorporating thermodynamics and density functional theory computations. Our finding demonstrates that spinel oxide can exhibit low COF values at temperatures much higher than conventional solid lubricants with 2D layered or Magnéli structures, suggesting a promising design strategy for self-lubricating high-temperature alloys.

Impact of initial braking temperature on thermal-induced brake fade during long-downhill operations

The advancement of high-speed railways and the widespread application of complex terrains have highlighted the issue of performance degradation in braking friction pairs during long-downhill braking, especially under high-temperature conditions. This study addressed this problem using a self-developed high-speed train braking simulation test rig to investigate the effects of varying initial braking temperatures (IBTs) on the performance degradation of braking friction pairs. A combination of thermal imaging, energy dispersive spectroscopy (EDS), high-temperature hardness testing, and X-ray diffraction (XRD) was employed to assess performance changes under different temperature conditions. By controlling the IBT of the brake disc, a detailed analysis of the coefficient of friction (COF), frictional heat distribution, wear morphology, hardness variation, and residual stress were conducted to uncover the brake fade mechanisms. The findings reveal that as IBT increases, COF decreases with greater fluctuations, resulting in significantly extended braking times and distances. At elevated IBTs, the brake disc and friction block materials experience reduced hardness, increased tangential residual stress, decreased radial residual stress, and accelerated wear, leading to unstable COFs and extended braking distances. This work provides valuable insights into the mechanisms of thermal-induced brake fade during long-downhill braking, offering crucial technical guidance for enhancing the safety and reliability of high-speed train braking systems under extreme conditions.

On revealing the mechanisms involved in brittle-to-ductile transition of fracture behaviors for γ-TiAl alloy under dynamic conditions

To understand the high-temperature behaviors of γ-TiAl is essential for its applications in aerospace industries. In this study, the high-temperature mechanical tests were carried out with strain rates ranging from 0.001 to 0.1 s−1 for the forged Ti-46Al-5Nb-1.8Cr-0.2Ta-0.1B alloy. The dynamic behaviors, fracture modes and microstructure evolution at elevated temperatures were analyzed to reveal the mechanisms involved in damage evolution. The results show that the brittleness of γ-TiAl is enhanced by strain rate hardening, and the brittle-to-ductile transition temperature (BDTT) increases with the increase of strain rates. The fracture morphology shows that the fracture characteristics transfer from the brittle fracture with mixed mode of intergranular and transgranular below and within the BDTT to the ductile fracture above BDTT. In addition, micro-cracks appear in fracture zones at the transitory stage, and cavities appear at the ductile stage, which is related to dynamic recrystallization (DRX). In this case, it is deduced that the brittle-to-ductile transition is induced by the competition between plastic deformation and crack propagation, and the results can be used to optimize the processing parameters towards high surface integrity when manufacturing γ-TiAl components.

Study on the surface state induced by ultrasonic impact treatment and its influence on high-temperature tension-tension fatigue behavior

To reveal the influence of ultrasonic impact treatment (UIT) parameters on surface state and the influence of surface state on high-temperature tension-tension fatigue behavior, UIT tests were conducted and 400 ℃ high-temperature fatigue tests were performed on UIT specimens with different surface states. The relationship between surface state and process parameters was analyzed, and the fatigue failure mechanism of UIT specimens was revealed. The finite element method was used to explore the influence of different residual stress distributions on the distribution of stress intensity factors at the crack front and the evolution of crack shape. The results show that the surface roughness changes between 0.43 μm and 0.72 μm with the variation of UIT intensity. As the increase of UIT intensity, the maximum residual stress can reach −1085 MPa, located approximately 30 μm below the surface. And the corresponding maximum surface hardness can reach 561 HV0.025. Microstructure elongation and extrusion intensification results in a maximum deformation layer depth of 9 μm, with a nanocrystalline layer on the outermost surface. The maximum average fatigue life is 6.431×106 cycles and the cracks initiate under the surface with quasi-cleavage as the initiation mode. As the cracks deepen, the stress intensity factor increases, and the crack shape eventually tends to be circular. Alterations in residual stress amplitude and depth do not influence the final crack shape. However, increased amplitude and depth can accelerate the consistency of the stress intensity factor outside the compressive stress region.

Optimization of Ti-3Al-2.5V titanium tubes by differential heating push-bending based on a modified Johnson−Cook constitutive model

This study addresses the challenges associated with the difficult formation and low quality of formed Ti-3Al-2.5 V titanium alloy thin-walled tubes with small bending radii (r / D < 1.5, where r is the bending radius, D is the outer diameter of the tube) by proposing a differential heating push-bending (DHP-B) forming approach. Initially, the stress−strain curves of Ti-3Al-2.5 V at various strain rates and temperatures were obtained through high-temperature uniaxial tensile tests. Subsequently, a modified Johnson−Cook (JC) model for Ti-3Al-2.5 V within the temperature range of 25℃ to 800℃ was developed to enhance the accuracy of the finite element model. Based on the static implicit and dynamic explicit algorithms, a thermomechanically coupled finite element model for differential heating push-bending of titanium alloy thin-walled tubes has been established. Taking the heating temperature, friction coefficient, counterthrust force and rubber block thickness as the optimization parameters, the prediction model of the maximum wall thinning rate and thickening rate is obtained by using the response surface method, and the best parameter combination is obtained via the NSGA-II algorithm and the minimum distance selection method, which realizes the optimization of differential heating push-bending parameters, as verified by experiments in which the maximum wall-thinning rate is reduced to 9 %, and the maximum wall thickness thickening rate is reduced to 14.2 %, which improves the forming quality of the titanium tube.

Data-driven AI for the automated classification of the isothermal heat-treated thermal barrier coatings using pulsed infrared thermography

Abstract Development of reliable age prediction models are crucial in monitoring the formation of oxide layer and degradation of TBC at regular intervals. This study proposes an automated classification of isothermal heat-treated TBC samples using temperature data, which helps in predicting the TBC life and monitoring the TBC degradation. TBC-coated samples are isothermal heat-treated at 1000 °C, and the initial growth of thermally grown oxide is monitored using a non-destructive thermal imaging technique. The proposed study integrates data-driven AI (DAI) models and feature extraction techniques to interpret complex thermal patterns measured from the TBC coating surface. The performance of the proposed classification framework is tested using deep learning and classical machine learning models with different types and window sizes of input data. Input data used for validation are raw experiment data, logarithmic of experiment data, polynomial fit data, and thermal signal reconstruction fit coefficients. The maximum classification performance is obtained with gated recurrent unit with accuracy and F1-score of 89.2% and 89.0%, respectively with raw temperature data as input of window 300. The study demonstrates that the proposed DAI approach effectively predicts the age of thermal barrier coatings under isothermal heat-treatment conditions by correlating the thermal response with coating degradation.

Design of a Thermal Performance Test Equipment for a High-Temperature and High-Pressure Heat Exchanger in an Aero-Engine

For next-generation power systems, particularly aero-gas turbine engines, ultra-light and highly efficient heat exchangers are considered key enabling technologies for realizing advanced cycles. Consequently, the development of efficient and accurate aero-engine heat exchanger test equipment is essential to support future gas turbine heat exchanger advancements. This paper presents the development of a high-pressure and high-temperature (HPHT) heat exchanger test facility designed for aero-engine heat exchangers. The maximum temperature and pressure of the test facility were configured to simulate the conditions of the last-stage compressor of a large civil engine, specifically 1000 K and 5.5 MPa. These conditions were achieved using multiple electric heater systems in conjunction with an air compression system consisting of three turbo compressor units and a reciprocating compressor unit. A commissioning test was conducted using a compact tubular heat exchanger, and the results indicate that the test facility operates stably and that the measured data closely align with the predicted performance of the heat exchanger. A commissioning test of the tubular heat exchanger showed a thermal imbalance of 1.02% between the high-pressure (HP) and low-pressure (LP) lines. This level of imbalance is consistent with the ISO standard uncertainty of ±2.3% for heat dissipation. In addition, CFD simulation results indicated an average deviation of approximately 1.4% in the low-pressure outlet temperature. The close alignment between experimental and CFD results confirms the theoretical reliability of the test bench. The HPHT thermal performance test facility will be expected to serve as a critical test bed for evaluating heat exchangers for current and future gas turbine applications.

Properties of Si/Yb2SiO5/LaMgAl11O19 tri-layered EBCs in high-temperature water vapor environment

SiCf/SiC with fully wrapped Si/Yb2SiO5/LaMgAl11O19 tri-layered environmental barrier coatings (EBCs) were subjected to high-temperature water vapor corrosion tests for 40, 100, and 200 h at 1200 °C. The flexural strength of the specimens was then evaluated. These results demonstrate that the EBCs exhibit excellent resistance to water vapor corrosion. After 40 h of exposure, the flexural strength retention rate of the specimens with EBCs was greater than 96 %, which was more than three times higher than that of the specimens without EBCs. Conversely, the flexural strength of the SiCf/SiC without EBCs decreased significantly following the water corrosion test. Within 100 h of exposure, the SiCf/SiC specimens without EBCs still showed “pseudo-plastic” fractures, while after 200 h, the entire specimens became loose and deformed due to severe corrosion.

Water invasion and residual gas distribution in partially filled fractures via phase-field method

Water invasion is a significant factor affecting the conductivity of fractures in coal seams. The partially contact characteristics of deep coal seam fractures are pronounced, and surface wettability varies significantly. However, there is a limited understanding of how water invasion behavior in partially filled fractures affects the gas produced by these fractures. In this study, a high-temperature and high-pressure contact angle testing device was employed to assess the wettability of coal seams under in situ conditions. The geometry of partially filled fractures was reconstructed using random functions, while the phase field method was employed to calculate the interactions at the two-phase interface during water invasion. The results indicate that the deep coal seams in the Ordos Basin demonstrate weak air-wetting properties under in situ conditions. The partially contact characteristics of the filled fractures in the deep coal seams categorize the fractures into distinct pore and throat regions. The variations in connectivity levels lead to the gas exhibiting uninvaded, clustered, and fully invaded characteristics following water invasion. The change in gas saturation during water invasion is more sensitive to larger values of lgCa and higher cos(θ). A larger displacement pressure difference and a smaller contact angle enable the invasion fluid to penetrate smaller throats, resulting in a higher number of clusters of residual gas and a smaller cluster radius. The results enhance our understanding of water invasion behavior, and the variability of fracture surface properties and gas-water two-phase flow in deep coal seams deserves further investigation.

High temperature sand erosion failure mechanism of ceramic/metal multilayer coating

This paper investigates the high-temperature erosion mechanism of TiAlN/TiAl ceramic/metal multilayer coating within the temperature range of 200 °C to 500 °C. The phase and element analysis results indicate that c-TiAlN is stable under 200°C∼500°C. The elastic modulus and hardness of TiAlN/TiAl are 230 GPa and 26.7 GPa at 200 °C. When the temperature increases to 300 °C and higher, the elastic modulus and hardness rise to 295.7 GPa and 30.5 GPa. However, the hardness and elastic modulus of TiAl coating increase from 11 GPa and 120 GPa at 200°C to 24 GPa and 260 GPa at 500°C. High-temperature sand erosion test results reveal a trend in erosion rate for the TiAlN/TiAl multilayer coating, initially increasing and then decreasing with temperature elevation. The highest erosion rate, reaching 0.6×10-3 mm3·g-1, occurs at 300 °C. Failure analysis of sand erosion indicates longitudinal cracking propagation downwards at high temperatures, merging with transverse cracks, leading to a delamination failure mode layer by layer. However, with the temperature elevation from 300 °C to 400 °C, transverse cracks shift from the interfacial layer to the TiAl layer within the TiAlN/TiAl multilayer coating. Finite element analysis demonstrates that the hardness and elastic modulus of the TiAl layer increase, leading to increased stress on the TiAl layer of the TiAlN/TiAl multilayer coating, resulting in TiAl cracking.

Tribological response of pack-boronized inconel 601 superalloy surfaces at elevated temperatures

Inconel 601 superalloy sample surfaces were pack-borided at 1000 °C for 4 h and 6 h to investigate the effect of boriding treatment on the mechanical and high temperature wear performance. The boride layers were characterized using SEM, EDS, XRD, microhardness tests, nanoindentation and high-temperature wear tests at room temperature and 500 ℃ under 7 N and 15 N normal loads. Boriding led to nearly 300 % increase in the hardness and up to 11-fold increase in the wear performance of the Inconel 601 surfaces. Despite lower COF and specific wear rates, borided surfaces were more susceptible to temperature increase than the non-treated Inconel 601 surfaces due to the lower tendency of wear debris with hard phase content to form a consistent lubricating layer.

Method of out-of-pile high-temperature tests of low-melting materials in conditions of modeling a severe nuclear reactor accident

This article is devoted to the technique for conducting experiments to study the nature of the interaction of low-melting metals with corium in the conditions of simulating a severe nuclear reactor accident. A feature of such experiments is the need to ensure thermophysical conditions for the occurrence of a severe accident and the organization of the interaction of the metals under study with liquid corium after its obtaining. In this regard, special device for solid metal fragments discharging into liquid corium were designed and manufactured to provide such conditions. At the same time, modeling of the temperature field of the experimental assembly of the VCG-135 test bench to study the interaction between model corium and candidate metal-coolers in the conditions of a severe accident was conducted. The need for modeling is associated with to the probability of metal melting in the discharge device due to the heat flow from the heating crucible of the experimental assembly. The operability of the developed technique was shown as a result of modeling and subsequent experiments at the VCG-135 test bench. The experiments made it possible to obtain products of the interaction of metals with corium for further study of their structural and phase state.

Study on the Mechanical and Permeability Evolution of a Composite Rock Mass in an Aquifuge Under Hydraulic Coupling

The lithology and composition type of an aquifuge in overburden play a crucial role in influencing the crack evolution and permeability changes of the aquifuge. This study utilized the high-temperature and high-pressure rock triaxial seepage test system to conduct triaxial compression tests on mudstone, sandstone, and their combined rock samples. The mechanical characteristics and permeability evolution of each lithology law during the failure were investigated. Furthermore, computed tomography (CT) scanning technology was utilized for the three-dimensional (3D) reconstruction and theoretical permeability calculation of single and combined rock samples. The results indicated that the stress–strain curves for single and combined rock samples exhibited similar patterns, which were divided into four stages: pore compaction, linear elasticity, yield deformation, and post-peak residual deformation. The peak strength of rock samples positively correlated with confining pressure. Permeability trends for mudstone and sandstone exhibited an “N”-type pattern characterized by “slow decrease–gradual stabilization–sudden increase–rebound decrease”, while the permeability of mudstone–sandstone combined rock followed a “U”-type pattern of “initial decrease–stabilization–subsequent increase”. Notably, the permeability of the combined rock samples was significantly lower compared to the single rock samples. The failure mode indicated that fractures in a single rock sample transversed the entire sample, whereas failures in the combined rock samples were confined to the mudstone component. This observation accounted for the differences in the permeability changes between the rock sample types. Additionally, the theoretical permeability results from the 3D reconstruction correlated with the experimental results.

Ceramic matrix composites for corrosion-resistant next-generation nuclear reactor systems: A conceptual review of enhancements in durability against molten salt attack

Ceramic matrix composites (CMCs) are emerging as a key material class for enhancing corrosion resistance in next-generation nuclear reactor systems, particularly in high-temperature molten salt environments. These environments, critical for advanced nuclear reactors such as molten salt reactors (MSRs), present severe challenges, including aggressive chemical attacks that degrade traditional structural materials over time. This conceptual review explores the development and application of CMCs to improve the durability and corrosion resistance of nuclear reactors exposed to molten salt attacks. CMCs, which consist of ceramic fibers embedded in a ceramic matrix, offer significant advantages, such as high thermal stability, mechanical strength, and improved corrosion resistance compared to conventional materials. This review examines how CMCs can be tailored to withstand harsh operational conditions, with a focus on the selection of ceramic phases, fiber-matrix interactions, and innovative fabrication techniques that enhance their protective capabilities. Key challenges addressed include the optimization of composite design to resist molten salt corrosion, the effects of temperature on the material properties, and the long-term stability of CMCs under extreme conditions. Advances in surface treatments, coatings, and the development of hybrid CMC systems are also discussed, highlighting their potential to further enhance durability. The review outlines the use of advanced characterization techniques, such as high-temperature corrosion testing and in situ microscopy, to evaluate CMC performance in molten salt environments. Additionally, it identifies knowledge gaps in current research, emphasizing the need for long-term studies on CMC behavior under realistic reactor conditions. This review concludes by proposing future research directions and technological advancements required to integrate CMCs into next-generation nuclear reactor designs, aiming to improve system reliability and operational safety.