Increase Of Corrosion Time Research Articles

Preparation and Properties of Carbon Fiber/Flexible Graphite Composite Grounding Material

In this paper, flexible conductive composite materials were prepared from flexible graphite and carbon fiber by mould pressing, and their micromorphology was studied by SEM. The influence of carbon fiber content on the mechanical properties and electrical conductivity of the flexible conductive composite material was studied, and the corrosion rate of the flexible conductive composite material coupling with galvanized steel in soil with different SO42− concentrations was studied. The results showed that the tensile strength reached 5.82 MPa when the mass ratio of carbon fiber to flexible graphite was 1:20, and the volume resistivity achieved 4.76 × 10−5 Ω·m when the mass ratio of carbon fiber to flexible graphite was 1:30. With the increase in molding pressure, tensile strength and electrical conductivity had a slight increase. When the flexible conductive composite material was coupled with galvanized steel, sulfate could accelerate the galvanic cell corrosion between the flexible graphite grounding material and galvanized steel. The increase in the sulfate concentration led to more corrosion acceleration. With the increase in corrosion time, the corrosion potential of the flexible graphite grounding material and galvanized steel coupling body decreased to its lowest at 30 days, and then increased gradually. The corrosion current was the highest at 30 days, and then decreased gradually.

Attenuation Law of Performance of Concrete Anti-Corrosion Coating under Long-Term Salt Corrosion

In saline soil areas, the concrete piers of concrete bridges experience long-term corrosion, mainly caused by chloride salts due to alternating temperature changes. Waterborne concrete coatings are prone to failure in this aggressive salt environment. Implementing coating protection measures can improve the durability of concrete and enhance the service life of bridges. However, the effectiveness and longevity of coatings need further research. In this paper, three types of waterborne concrete anti-corrosion coatings were applied to analyze the macro and micro surface morphology under wet–dry cycles and long-term immersion conditions. Various indicators such as glossiness, color difference, and adhesion of the coatings were tested during different cyclic periods. The chloride ion distribution characteristics of the buried concrete coatings in saline soil, the macro morphology analysis of chloride ion distribution regions, and the micro morphology changes of the coatings under different corrosion times were also investigated. The results showed that waterborne epoxy coatings (ES), waterborne fluorocarbon coatings (FS), and waterborne acrylic coatings (AS) all gradually failed under long-term salt exposure, with increasing coating porosity, loss of internal fillers, and delamination. The chloride ion content inside the concrete decreased with increasing depth at the same corrosion time, while the chloride ion content at the same depth increased with time. The chloride ion distribution boundary in the cross-section of concrete with coating protection was not significant, while the chloride ion distribution boundary in the cross-section of untreated concrete gradually contracted towards the concrete core with increasing corrosion time. During the corrosion process in saline soil, the coatings underwent three stages: adherence of small saline soil particles, continuous increase in adhered material area, and multiple layers of uneven coverage by saline soil. The failure process of the coatings still required erosive ions to infiltrate the surface through micropores. The predicted lifespans of FS, ES, and AS coatings, obtained through weighted methods, were 2.45 years, 2.48 years, and 2.74 years, respectively, which were close to the actual lifespans observed in salt environments. The developed formulas effectively reflect the corrosion patterns of different resin-based coatings under salt exposure, providing a basis for accurately assessing the corrosion behavior and protective effectiveness of concrete under actual environmental factors.

Investigation on electrochemical corrosion behavior of Cu-14Fe -(0, 0.05)Ce alloys

This work thoroughly investigated the electrochemical corrosion behaviors of Cu-14Fe-(0, 0.05) Ce alloys. Experimental findings revealed that the addition of Ce did not change the phase constituent, but refined α-Fe phase particle from 0.30 ± 0.04 to 0.22 ± 0.03 μm and increased its content from 1.24% to 2.17%. With the increase of corrosion time, adding Ce could increase the linear polarization resistance by up to 3 times, and correspondingly the corrosion rate was reduced to half. Moreover, Ce addition contributed to the densification of corrosion products. The α-Fe phase preferentially underwent anodic dissolution reaction, generating corrosion product Fe2O3. The increase of soaking time resulted in the occurrence of anodic dissolution of Cu-matrix phase, along with the formation of Cu2O and Cu2Cl(OH)3.

Damage evolution behavior of tunnel lining concrete with non‐through crack under single‐sided sulfate attack

AbstractIn order to study the dynamic damage evolution law of tunnel‐lining concrete with non‐through crack under single‐side sulfate attack, a 420‐day sulfate attack concrete test was conducted and the uniaxial compression and acoustic emission (AE) tests were carried out on each corrosion time. The test results showed that the compressive strength of each group can be divided into rising stage and falling stage, and the existence of non‐through crack reduced the compressive strength of concrete specimens and accelerated the corrosion of concrete specimens by sulfate. AE ringing count can be divided into compaction stage, elastic stage, yield stage, and post‐peak stage; the variation patterns of AE varied at different stages. Sulfate attack caused the yield point of concrete to advance. With the increase of corrosion time, microcracks increased gradually, cement mortar was consumed continuously, concrete spalling occurred, the proportion of AE cumulative ringing count Stage II decreased gradually, and the proportion of Stage III increased. Non‐through crack changed the energy storage of Stages II and III and reduced the AE activity of concrete after corrosion. The deeper the crack was, the smaller the average cumulative ringing count was and the lower the AE activity was. AE cumulative ringing counts can be used to characterize the damage evolution of corroded concrete.

Study on mechanical properties and damage characteristics of acid corrosion in granite based on NMR technology

In acidic environments, rock masses are frequently subjected to severe chemical corrosion, resulting in the initiation of numerous geological engineering disasters. This study aimed to collect physical and mechanical parameters of granite exposed to prolonged acid corrosion and analyze fracture characteristics using acoustic emission (AE) techniques. Additionally, it examined the evolution of pore structure and damage mechanisms through the use of low-field nuclear magnetic resonance (NMR) and fractal theory. The results demonstrate a monotonic decrease in mass, volume, density, P-wave velocity, and S-wave velocity of granite with increasing corrosion time. Particularly notable is the phased reduction observed in uniaxial compressive strength and elastic modulus. The transition from brittle to ductile failure in corroded granite is accompanied by a gradual decrease in internal fracture strength. The trend in the correlation dimension reveals the relationship between the formation time of the main fracture surface and the pore structure. Additionally, total porosity and macropores (D, Da) exhibit significant fractal characteristics. The fractal dimension correlates positively with the damage variable and inversely with uniaxial compressive strength and elastic modulus. This indicates that more severe pore structure damage leads to a higher fractal dimension and lower mechanical performance. Among these, Da demonstrates higher sensitivity in characterizing rock mechanical properties. These findings provide important basis for evaluating the stability of granite geotechnical engineering in acidic environments.

Effect of seawater corrosion on the mechanical properties of basalt fiber reinforced polymer composites modified by silane coupling agent KH560 and carboxylated carbon nanotubes

Basalt fiber reinforced composite (BFRP) has been widely used in various engineering fields, while the corrosion resistance of BFRP in harsh environments needs to be improved. In this work, the effects of seawater corrosion on mechanical properties of silane coupling agent (KH560) and carboxylated carbon nanotubes (CNTs) modified basalt fiber reinforced epoxy resin composites (BF/EP) were studied by simulating seawater corrosion under different conditions. The results showed that with the increase in corrosion time and temperature, the flexural performance and interlaminar shear strength (ILSS) of the composite material significantly decreased. Under the same corrosion conditions, the modified basalt fiber composite has better corrosion resistance to seawater than the untreated one due to an enhanced "soft-rigid" multi-scale stress transfer region between the BF and resin matrix. The flexural strength, flexural modulus and ILSS of modified basalt fiber composites decreased by 17.7 %, 12.2 % and 11.3 %, respectively, after 7 weeks of seawater corrosion at 60 °C, while that of untreated basalt fiber composites decreased by 28.2 %, 20.4 % and 19.7 %, respectively. In addition, the corrosion of distilled water on basalt fiber composites was also studied. Similarly, the modified basalt fiber composites showed better corrosion resistance to distilled water compared to the untreated basalt fiber composites. The research shows that the synergistic modification of KH560 and CNTs can effectively improve the corrosion resistance of BF/EP. This work is significant for promoting the development of BFRP and its application in marine environment.

Mechanical responses of chemically corroded sandstone under cyclic disturbance: Insights from fatigue properties and macro-micro fracturing mechanism

Engineering rock masses are likely to be subjected to coupled chemical corrosion and cyclic load disturbance, deteriorating the internal structure of rocks and further threatening the long-term stability of engineering structures. In this study, to investigate the combined effect of cyclic loading and chemical corrosion, the cyclic uniaxial compression tests are conducted on sandstone specimens chemically corroded by different corrosion times (0, 20, 40, 60 days) and pH values (1, 3, 7, 11, 13). Our results indicate that chemically corroded sandstone specimens featured by an increase in irreversible strain and hysteresis energy density compared with natural rocks. A coupling damage variable is proposed to reflect the initial damage induced by chemical corrosion and the mechanical damage induced by cyclic disturbance, and the accumulation rate of coupled chemical-fatigue damage variables significantly increases with increasing corrosion time or enhancing acidity and alkalinity. Fatigue failure modes of tested specimens transform from splitting failure to unidirectional shear failure as corrosion time increases, and chemically corroded specimens are featured by ductile failure characteristics compared to natural state. Moreover, X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) are employed to analyze the micro-fracturing mechanism of sandstone. Cement minerals dominate the reactions in acidic solutions, whereas quartz takes the lead in alkaline conditions. Due to pronounced influence of cement minerals on the macroscopic mechanical properties of sandstone, acid corrosion specimens tend to experience more severe damage. Micro-cracks inside rocks under cyclic loading have sufficient time to pass through weakly bonded particles, and chemical reactions markedly weaken inter-particle bonding degree, and thus the fatigue fracture of chemically corroded specimens predominantly exhibits intergranular (IG) fracture.

Cracking characteristics and axial capacity degradation of precast segmental bridge piers connected with corroded tapered sleeve locking-type splicing

The tapered sleeve locking-type splicing (TSLTS) reinforcement joint is a new method of steel mechanical connection. When applying the TSLTS reinforcement joints to precast segmental bridge (PSB) piers in coastal environments, the durability need to be taken into account. After the TSLTS reinforcement joint is corroded, the connection performance of the TSLTS reinforcement joint is degraded. Therefore, the mechanical properties of PSB piers decrease due to the corrosion of the joints, which brings some potential hazards. In this paper, the durability of PSB piers with TSLTS reinforcement joints in coastal environments was studied. The corrosion-induced cracking characteristics, failure mode and axial capacity of PSB piers with TSLTS reinforcement joints were investigated by means of accelerated corrosion test and axial loading failure test. The results indicated that, with increasing corrosion time, the total length of the corrosion-induced cracks on the surface of the pier specimens increased, but the increasing rate of the total length decreased. The mass loss of TSLTS reinforcement joints increased linearly with the maximum width of longitudinal corrosion-induced cracks on the concrete cover of the self-compacting concrete (SCC) segment, and the critical mass loss of TSLTS reinforcement joints was approximately 4.0 % when longitudinal corrosion-induced cracks appeared. The probability distribution type of the width of longitudinal corrosion-induced cracks on the surface of pier specimens was mainly a lognormal distribution. When the mass loss of TSLTS reinforcement joints was less than 7.2 %, the damaged area of the pier specimens was mainly concentrated in the SCC segment, while when the mass loss of TSLTS reinforcement joints was higher than 8.8 %, the damaged area was located in the ordinary Portland concrete segment near the top of the pier specimens, and the corroded TSLTS reinforcement joints could still maintain their connection performance. With an increase in the corrosion degree of the steel bars, the axial capacity of the pier specimens decreased, and the equivalent stiffness also degraded. The degradation rate of the axial capacity of the pier specimens increased linearly with the mass loss of the TSLTS reinforcement joints, and the degradation of the axial capacity occurred only when the mass loss of the TSLTS reinforcement joints was greater than 4.6 %. The research results can provide a theoretical reference for the application of TSLTS reinforcement joints in PSB piers.

Corrosion, permeation and mass transfer mechanisms of alkali metals in corundum refractories

During the operation of the waste liquid incinerator, the alkali metal slag might adhere to the surface of the refractory material to form an inhomogeneous solid slag layer, causing the furnace lining to be simultaneously corroded by three phases of alkali metals: vapor, molten salt, and slag. This phenomenon intensifies the damage to the refractory material. Therefore, this paper investigates the mass transfer and permeation process, phase change process and corrosion rate of Na2CO3 inside corundum refractory materials in three phases: Na vapor, molten Na2CO3 and Na-slag. The results showed that alkali vapor penetrated the interior through the pores, and the NaAlO2 and β-Al2O3 generated by the reaction led to the volume expansion and microcracks. Na vapor continued to penetrate the interior along the cracks and eroded the sample, and the higher the temperature the greater Na vapor penetration. In vapor phase corrosion, the effect of corrosion time on the erosion resistance of corundum refractories is less than that of temperature, and the increase in corrosion time does not lead to the formation of additional new phases. In the molten salt corrosion experiments, it was found that the molten salt corrosion was accompanied by vapor phase corrosion at 1100 °C, and the amount of Na2CO3 has a greater effect on the corroded mass than the temperature. Comparing the corrosion of refractory materials by the three phases of Na2CO3, the molten salt corrosion rate was the highest, followed by the vapor phase corrosion, and finally the slag corrosion. It is concluded that the slag layer can effectively prevent the corrosion of the refractory material by alkali metal molten salts and vapors, thus prolonging the service life of refractories.

Influence of corrosion on seismic performance of steel beam-to-column connections

Steel structures are not only subjected to the threaten of single hazard (e.g., earthquake), but also suffers from the coupling environmental effect such as corrosion throughout the entire service life cycle. This study explores the seismic performance of steel beam-to-column connections after corrosion. Accelerated corrosion tests were conducted on a series of practical steel beam-to-column connections, and the seismic performances of the specimens before and after corrosion were compared. A modeling method of corroded steel members that considers distribution randomness of corrosion depth was proposed. Finally, the proposed method is applied to conduct time-dependent seismic performance prediction of corroded beam-to-column connections. The results show that corrosion mainly influences the buckling and post buckling behaviors of steel beam-to-column connections. Due to earlier appearance of local buckling, more evident stiffness degradation is observed for the corroded specimen. Corrosion also induces performance degradation of the panel zone. For the corroded specimen with cover plate, multiple small cracks initiate at the junction between the cover plate and beam flange, and fracture damage is more likely to happen for the beam-to-column connections after corrosion. Both yield and ultimate load-carrying capacities of the connections decrease linearly with the increase of accelerated corrosion time, and the load-carrying capacity deterioration rate of the cover plate strengthened connection is quicker than that of the un-strengthened connection. The initial stiffness approximately degrades linearly with the increase of corrosion time. Corrosion degree also influences the energy dissipation capability of the beam-to-column connections, especially after the occurrence of local buckling.

Durability of Prestressed Piles in a Leachate Environment.

Prestressed pipe piles are common concrete components characterized by dense concrete structures and favorable mechanical properties, and thus, extensively used as coastal soft soil foundations. However, their durability in harsh environments has not been fully clarified. In this study, leachate from an actual landfill site was collected from the east coast of China as the corrosive medium, and the corrosion process was accelerated by electrifying prestressed pipe piles. The results demonstrated that the concentration of chloride ions in the concrete of the prestressed pile increased with the increase in corrosion time. Moreover, the experimental corrosion of these prestressed piles in the drying-wetting cycle proved to be the most severe. However, a protective layer of epoxy resin coating can effectively inhibit the diffusion of chloride ions into the interior of the piles. The final theoretical corrosion amounts of the piles were 1.55 kg, 1.20 kg, and 1.64 kg under immersion, epoxy resin protection, and a drying-wetting cycle environment. The application of epoxy resin reduced chloride penetration by 22.6%, and the drying-wetting cycle increased chloride penetration by 5.8%, respectively, with corresponding corrosion potentials following similar patterns. The actual corrosion depth of the welding seam was 3.20 mm, and there was a large corrosion allowance compared with the requirement (6.53 mm) for the ultimate bending moment. In summary, these prestressed piles exhibited good durability in a leachate environment.

Active and passive monitoring of corrosion state of reinforced concrete based on embedded cement-based acoustic emission sensor

In this paper, a cement-based acoustic emission sensor is embedded in reinforced concrete, and the corrosion damage inside the concrete is activated by swinging ball impact. The changes of low frequency and high frequency acoustic emission signals are captured and analyzed by the sensor, and the concept of low-high-frequency (LH) is proposed. The changes of acoustic emission characteristics during the corrosion of steel bars were studied, and the effects of protective layer thickness and activation site on the ratio of LH were analyzed. The results show that with the increase of the corrosion degree, the amplitude of the frequency signal in the range of 13 kHz–22 kHz decreases gradually, from 2.59 mV to 1.29 mV. The amplitude of the frequency signal near 170 kHz increases first and then decreases with the increase of corrosion time. The frequency signal near 22 kHz is used as the low frequency signal, the amplitude of the frequency signal near 170 kHz is used as the high frequency signal, and the ratio of the two is used as the low-high-frequency (LH). The evaluation result of this ratio is consistent with the ultrasound test results. As the sound source continues to move to both ends of the concrete sample, the distance between this sound source and the sensor gradually increases, the low frequency signal decreases significantly, and LH changes significantly, influenced by the reflection of the boundary.

Mechanical performance of Q345 steel after corrosion: Experimental and theoretical investigation

Corrosion significantly influences the mechanical performance of steel, and the accurate prediction of stress-strain curves (S-SC) for steel after corrosion is crucial for the safety evaluation of in-service steel structures in engineering. This study focuses on assessing the degradation performance of Q345 steel following corrosion. Copper accelerated acetic acid salt spray testing (CASS) is employed to corrode Q345 specimens, and a power model is established to relate the mass loss rate to the corrosion time of Q345 steel. Uniaxial tension tests are then conducted to observe the mechanical behavior of corroded Q345 steel. Results indicate that the strength and ductility of Q345 steel decrease with an increase in the mass loss rate, and the yield plateau of the S-SC gradually shortens until it disappears. With the increase of corrosion time, the microstructure of the steel surface is transformed from spherical structure to needle-like structure. Two constitutive models are developed, incorporating the S-SC with and without the yield plateau, based on existing models. These models demonstrate good agreement with various test data, providing valuable insights into the mechanical behavior of corroded Q345 steel.

Corrosion Behavior of Homogenized and Extruded 1100 Aluminum Alloy in Acidic Salt Spray.

The 1100 aluminum alloy has been widely used in many industrial fields due to its high specific strength, fracture toughness, excellent thermal conductivity, and corrosion resistance. In this study, the corrosion behavior of the homogenized and hot-extruded 1100 aluminum alloy in acid salt spray environment for different time was studied. The microstructure of the 1100 aluminum alloy before and after corrosion was characterized by an optical microscope (OM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and a laser scanning confocal microscope (LSCM). The difference in corrosion resistance between the homogenized and extruded 1100 aluminum alloy was analyzed via the electrochemical method. The results indicate that after hot extrusion at 400 °C, the microstructure of the 1100 aluminum alloy changes from an equiaxed crystal structure with (111) preferentially distributed in a fibrous structure with (220) preferentially distributed. There was no obvious dynamic recrystallization occurring during extrusion, and the second-phase particles containing Al-Fe-Si were coarse and unevenly distributed. With the increase in corrosion time, corrosion pits appeared on the surface of the 1100 aluminum alloy, and a corrosion product layer was formed on the surface of the homogenized 1100 aluminum alloy, which reduced the corrosion rate. After 96 h of corrosion, the CPR of the extruded samples was 0.619 mm/a, and that of the homogenized samples was 0.442 mm/a. The corrosion resistance of the extruded 1100 aluminum alloy was affected by the microstructure and the second phase, and no protective layer of corrosion products was formed on the surface, resulting in a faster corrosion rate and deeper corrosion pits.

Corrosion behavior and microstructure analysis of butt welds of Q690 high strength steel in simulated marine environment

Steel components that have served in the marine environment for extended periods often face challenges in preventing surface damage caused by corrosion protection measures. These challenges can ultimately diminish the expected service life of structures. To investigate the corrosion behavior and time-varying effects in butt welds of Q690 high strength steel in the ocean splash zone, a macroscopic morphology analysis was conducted using various corrosion times involving indoor saltwater immersion and hot-humid cycling accelerated corrosion. Quantitative analysis of corrosion pits' size and distribution range was performed in both the weld zone (WZ) and heat-affected zone (HAZ) to establish a relationship between roughness parameters and corrosion time. Experimental results were compared with corrosion parameters of regular steel. The findings reveal a gradual reduction in metallic luster with increasing corrosion time on specimen surfaces. Moreover, a greater accumulation of corrosion products is observed in the butt weld region, leading to progressive corrosion damage. High strength steel (HSS) exhibits superior corrosion resistance compared to ordinary steel. However, the corrosion damage of HSS weld joints gradually approaches that of ordinary steel in the later stage of corrosion. Microscopic scanning indicates that the accumulated corrosion layer effectively impedes the penetration of corrosive media into the matrix's interior, while the surface microstructure transitions from pitting to corrosion pits. These research findings significantly contribute to assessing the performance and analyzing the reliability of high strength steel in marine environments.

Corrosion Behavior of 17-4PH Martensite Stainless Steel Sprayed with Sodium Hypochlorite Disinfectant

Sodium hypochlorite (NaClO) solution, as an effective and low-cost disinfectant, is widely utilized to achieve disinfection in the industry, but introducing chloride ions causes metal material corrosion. To understand actual corrosion behavior, a comprehensive study of the corrosion behavior of 17-4PH martensitic stainless steels (MSs) by spraying NaClO disinfectant was investigated in this work. The x-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry were used to investigate the element distribution and corresponding valence states of the corrosion product on the surface of the 17-4PH MSs. Hypochlorite ions in the disinfectant decrease the atomic ratio of iron/chromium (Fe/Cr) in the corrosion product layer with the increasing corrosion time, which enhances the corrosion resistance of the studied samples. However, strongly oxidizing hypochlorite ions will promote the formation of trivalent Fe ions (Fe3+), which provokes the initiation and growth of pitting in surfaces where the existence of a Cu-riched domain is due to disinfectant migration.

High temperature corrosion behaviour of the 316 stainless steel in NaCl-KCl-AlCl3 molten salt and its vapour

The corrosion behavior and kinetics of the 316 stainless steel (316SS) in the NaCl-KCl-AlCl3 molten salt and salt vapor were investigated at 400 °C. The corrosion rate of 316 SS in salt vapor is faster than that in molten salt. The corrosion depth of the corroded 316 SS increases with the increase of corrosion time. The corrosion rate of 316 SS did not show a continuous downward trend as usual, but showed a multi-stage trend of stable stage, rapid rise stage and slow growth rate stage due to the formation and evolution of aluminum oxide layer on the alloy surface.

High temperature corrosion behaviour of calcium magnesium aluminosilicate coated oxide-oxide ceramic matrix composites

Corrosion on turbine blades in calcium magnesium alumino-silicate (CMAS) environment is a crucial failure for turbine engines and its components. In this study, oxide-oxide (O-O) ceramic matrix composites (CMCs) (AS-N610), the potential materials for gas turbine components are examined for its corrosion behaviour at high temperatures at various intervals of time in presence of CMAS. The corrosion studies indicated that dip coated with CMAS revealed a weight gain of ∼3% owing to the formation of α-Al2O3 at 1400 °C. The SE images indicated cracks at the interface due to thermal mismatch between CMAS and O-O substrate. With increase in corrosion time, cracks at the interface propagated onto the matrix and fibres of O-O CMCs. This crack propagation is attributed to the diffusion of calcium aluminosilicate (CAS) with small traces of Mg which wicks the columns of O-O CMCs. Indentation fracture toughness of O-O CMCs degraded by ∼22% for 1400 °C in presence of CMAS compared to un-corroded sample.

A method to calculate seismic behavior of a corroded beam-to-column joint considering distribution randomness of corrosion depth

When conventional uniform corrosion method and equivalent material property method are applied to predict the seismic performance of corroded steel beam-to-column joints, distribution randomness of corrosion depth can't be considered, once damage occurs at a position where there is a large corrosion pit, there will be a great error between the actual damage and the damage predicted by the two methods. The current work aims to overcome this problem. Firstly, accelerated corrosion test was conducted on mild steel coupons. Secondly, topography of the corrosion pits was scanned, and distribution characteristic of the corrosion depth was obtained. According to the distribution characteristic, a FE modeling method (namely, stochastic corrosion method) that considers distribution randomness of the corrosion depth was proposed. The proposed method, together with uniform corrosion method and equivalent material property method were then applied on the seismic performance prediction of a corroded steel beam-to-column joint. The results show that 1) The depth of the corrosion pits on the specimens subjected to accelerated corrosion approximately obeys lognormal distribution. 2) The corroded steel beam-to-column joints' hysteretic behavior predicted by stochastic corrosion method is more accurate than those predicted by the other two methods. Compared with uniform corrosion method, the maximum calculation accuracy improvement of stochastic corrosion method can reach 90%. 3) The reason which leads to prediction error of uniform corrosion method is that localized buckling of some positions on the structural member is overlooked, while the reason leads to prediction error of equivalent material property method is that the kinematic hardening parameter C is assumed to increase with the increase of corrosion time period. Both the prediction errors of the two methods increase with the increase of corrosion time.

Interaction and infiltration behavior between calcium–ferrum–alumina–silicate and Yb4Hf3O12 ceramics at various temperatures

AbstractThe interaction and infiltration behavior between typical calcium–ferrum–alumina–silicate (CFAS) and Yb4Hf3O12 ceramics at 1300, 1400, and 1500°C for different duration times were investigated. At 1300°C, the CFAS melt first crystallized and then generated massive anorthite with high‐melting point, reducing the wettability of CFAS melt and physically blocking CFAS penetration paths. As the temperature increased to 1400°C and 1500°C, the wettability of the molten CFAS correspondingly increases. A continuous reaction layer, composed of apatite, fluorite, and garnet, was formed over Yb4Hf3O12 ceramic due to the penetration of CFAS melt. Furthermore, the infiltration rate of CFAS decreases with increasing corrosion time because of the barrier effect primarily derived from the as‐mentioned continuous reaction layer.