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Ultrasonic spot welding (USW) is an emerging solid-state joining technology with great potential for solving joining challenges in Ni–Ti shape memory alloys and stainless steel (SS). In this study, USW was utilized to successfully lap weld Ni–Ti shape memory alloy and 304 SS, where copper and aluminum were introduced as separate interlayers to enhance the strength of the joint. The results show that USW can achieve effective bonding between Ni–Ti foil and 304 SS foil with or without an interlayer. In the absence of an interlayer, a mechanical interlocking structure is formed between Ni–Ti and 304 SS with a tensile strength of 404.71 N, which is lower than that of the joint with the addition of an interlayer. With the introduction of the interlayer, a double-interface structure is formed. It should be noted that the highest bond strengths were obtained with the aluminum interlayer, with a peak load of 890 N and edge fracture, although trace amounts of the brittle intermetallic compound Fe3Al14 were generated. A slightly lower joint strength of 690 N was obtained with the copper interlayer, but the formation of brittle intermetallic compounds was effectively avoided. These results have important implications for the successful bonding of NiTi with dissimilar materials. [ABSTRACT FROM AUTHOR]

The radioactive corrosion products 58Co and 60Co in the primary loops of pressurized water reactors (PWRs) are the main sources of radiation doses to which workers in nuclear power plants are exposed. To understand cobalt deposition on 304 stainless steel (304SS), which is the main structural material used in the primary loop, the microstructural characteristics and chemical composition of a 304SS surface layer immersed for 240 h in borated and lithiated high-temperature water containing cobalt were investigated with scanning electron microscopy (SEM), X-ray diffraction (XRD), laser Raman spectroscopy (LRS), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectrometry (GD-OES), and inductively coupled plasma emission mass spectrometry (ICP-MS). The results showed that two distinct cobalt deposition layers (an outer layer of CoFe2O4 and an inner layer of CoCr2O4) were formed on the 304SS after 240 h of immersion. Further research showed that CoFe2O4 was formed on the metal surface by coprecipitation of the iron preferentially dissolved from the 304SS surface with cobalt ions from the solution. The CoCr2O4 was formed by ion exchange between the cobalt ions entering the metal inner oxide layer and (Fe, Ni) Cr2O4. These results are useful in understanding cobalt deposition on 304SS and have a certain reference value for exploring the deposition behavior and mechanism of radionuclide cobalt on 304SS in the PWR primary loop water environment. [ABSTRACT FROM AUTHOR]

The establishment of heterojunction is a powerful strategy to enhance the photoresponse performance of photoanode. Here, TiO2/CuInS2 (T/CIS) composites were prepared via a two-step hydrothermal method, and their morphologies were controlled by adjusting the reaction time. The absorption spectra show that CuInS2 can significantly improve the absorption of visible light. The T/CIS2 (2 h reaction time) photoanode exhibited the most outstanding photoelectrochemical (PEC) performance, with a photocurrent density of 168% that of the pure TiO2 photoanode. Under simulated sunlight, this photoanode can supply a protective photocurrent of 0.49 mA cmâˆ'2 and a protective voltage of 0.36 V to stainless steel (304ss), which are about 4 and 2 times those of the TiO2 sample. The enhancement in the photocathodic protection performance is attributed to enlarged visible light absorbance and higher charge separation rate. This study demonstrates that the TiO2/CuInS2 photoanode is a promising candidate for application in photoinduced cathodic protection of metallic materials. [ABSTRACT FROM AUTHOR]

The protective ability of an organic inhibitor varies and is affected by the pH of the solution. Related with this fact, this work investigated corrosion inhibition performance of Bee Wax Propolis (BWP) extract on 304 SS in various environment (0–14 pH). The BWP extract inhibitor had formed a passive layer on the surface, indicated by the increase of the passive region. The inhibition efficiency changed randomly at all pH. The optimum inhibition efficiency for the acid and alkaline condition happened at pH 2 (96.60%) and 12 (97.75%). BWP was found to control corrosion better at pH 2 and 12.

Liquefied hydrogen storage vessels (LHSVs) are vulnerable to surface-crack initiation, propagation, and fracture on their surfaces because they are under high-pressure, low-temperature conditions. Defects can also occur in the coatings of the storage containers used to prevent hydrogen permeation, and these lead to surface defects such as pitting corrosions. Together, these increase the probability of liquid hydrogen leaks and can cause serious accidents. Therefore, it is important to detect surface defects during periodic surface inspections of LHSVs. Among the candidate non-destructive evaluation (NDE) techniques, testing using guided waves (GWs) is effective for detecting surface defects. Because of the ability of GWs to travel long distances without significant acoustic attenuation, GW testing has attracted much attention as a promising structural monitoring technique for LHSVs. In this study, an ultrasonic NDE method was designed for detecting surface defects of 304SS plate, which is the main material used for fabricating LHSVs. It involves the use of linear discriminant analysis (LDA) based on short-time Fourier transform (STFT) pixel information produced from GW data. To accomplish this, the differences in the number of STFT pixels between sound and defective specimens were used as a major factor in distinguishing the two groups. Consequently, surface defects could be detected and classified with 97% accuracy by the newly developed pixel-based mapping method. This indicates that the newly developed NDE method with LDA can be used to detect defects and classify LHSVs as either sound or defective. [ABSTRACT FROM AUTHOR]

Abstract In this work, an electrophoretic deposition technique was used to deposit graphene oxide (GO) on 304 stainless steel. Its corrosion performance was evaluated in a simulated polymer electrolyte membrane fuel cell environment. The corrosion current density (icorr) and interfacial contact resistance (ICR) were measured at 8.9 µA/cm2 and 19.3 mΩ cm2, respectively. The icorr of GO coated 304SS is several orders lower than bare SS 304. Similarly, the ICR of GO coated 304SS is nearly half of bare 304SS at a compaction pressure of 150 N/cm2. The potentiodynamic polarization plot indicates the prevalence of multiple corrosion mechanisms. A prolonged corrosion study for 30 days immersed in the simulated PEM cell environment shows the formation of rounded pits that corroborate the activity of pitting corrosion.

Liquefied hydrogen storage vessels (LHSVs) are vulnerable to surface-crack initiation, propagation, and fracture on their surfaces because they are under high-pressure, low-temperature conditions. Defects can also occur in the coatings of the storage containers used to prevent hydrogen permeation, and these lead to surface defects such as pitting corrosions. Together, these increase the probability of liquid hydrogen leaks and can cause serious accidents. Therefore, it is important to detect surface defects during periodic surface inspections of LHSVs. Among the candidate non-destructive evaluation (NDE) techniques, testing using guided waves (GWs) is effective for detecting surface defects. Because of the ability of GWs to travel long distances without significant acoustic attenuation, GW testing has attracted much attention as a promising structural monitoring technique for LHSVs. In this study, an ultrasonic NDE method was designed for detecting surface defects of 304SS plate, which is the main material used for fabricating LHSVs. It involves the use of linear discriminant analysis (LDA) based on short-time Fourier transform (STFT) pixel information produced from GW data. To accomplish this, the differences in the number of STFT pixels between sound and defective specimens were used as a major factor in distinguishing the two groups. Consequently, surface defects could be detected and classified with 97% accuracy by the newly developed pixel-based mapping method. This indicates that the newly developed NDE method with LDA can be used to detect defects and classify LHSVs as either sound or defective.

To study the compatibility especially the corrosion characteristic of structural material stainless steel (SS) with liquid lithium (Li) is an important factor for the simultaneous application of liquid Li and SS as a blanket material or potential plasma facing material (PFM) in future fusion devices. The corrosion behaviors of 304SS exposed to liquid Li at 700 K for 1320 hr under high vacuum were investigated. After exposure to liquid Li, 304SS produces non-uniform corrosion which includes corrosion products and grain boundary corrosion. Compared with the corrosion behaviors at 600 K and 640 K, temperature plays an important role in the corrosion behaviors of 304SS in static liquid Li. The weight loss, corrosion depth and corrosion products of 304SS specimens increase with the corrosion temperature. In general, the compatibility between 304SS and static liquid Li is relatively good under the experimental conditions. And besides, it is unexpectedly found that the compatibility of copper with Li is not good.

Electrochemical noise has an important reference role in the study of early corrosion; however, a direct correlation between the microscopic morphology and the electrochemical noise of the corrosion process is lacking. This study uses a back propagation artificial neural network (BPNN) optimized by three intelligent optimization algorithms to real-time monitor the local corrosion of 304 stainless steel in HCl solution with joint recognition and feature extraction of corrosion images and electrochemical noise. The results show that the corrosion monitoring model established by optimized BPNN with genetic algorithms exhibits the highest convergence speed and accuracy. • Corrosion area of 304SS in HCl solution is identified by real-time image recognition. • EN trend is related to the type of corrosion and the diffusion rate of corroded area. • A clear correlation between image features and electrochemical noise is observed. • The description of corrosion process of 304SS is established by feature extraction. • The optimised BPNN with joint image feature and EN is useful in monitoring corrosion. [ABSTRACT FROM AUTHOR]

Abstract Nanohybrid films containing multiwalled carbon nanotubes (MWCNTs) were successfully coated on 304-stainless steel (304ss) for anti-corrosion use. The nanocompositewas made by a self-assembly of poly (dopamine), wrapped with MWCNTs (CNT@PDA) through a mussel inspired method. In order to enhance the corrosion protection, an inner layer of L-cysteine, an adhesive amino acid to 304ss surface through thiol (-SH) functional group were constructed through a dip-coating process. Potentiodynamic polarization measurements and electrochemical impedance spectroscopy revealed that the double nano-layer could act as a noble anticorrosive coating in 3.5% NaCl, which was assigned to the hydrophobicity, robustness, and dense double layer coating. Highlights • Novel green nano-hybrid film coatings were implanted on 304ss using L-cys/CNT@PDA. • L-cys/CNT@PDA coated on 304ss inhibits the anodic reaction. • The large value of Rp confirms inhibitory efficiency of the L-cys/CNT@PDA coating. • The nano-hybrid film can make the reduction of the localized corrosion attacks. [ABSTRACT FROM AUTHOR]

Highlights • CANDU-6 core follow-up simulations for accident tolerant fuels are studied for normal and accidental conditions. • Effects of enrichment and spectral hardening on core breeding ratio, boron poisoning, and power distributions are quantified. • Operations compliances are compared with CANDU-6 license limits. • Liquid zone controllers and adjusters effects on power flattening are investigated. • Cores' dynamic performances during on-power refueling operations are studied. Abstract The 3D DRAGON-DONJON capabilities are exploited to simulate CANDU-6 (Canada Deuterium Uranium) core follow-up with alternate cladding materials. Aluminium-based alloys (FeCrAl and APMT), nickel-based alloys (304SS and 310SS) and silicon carbide (SiC) are compared with Zircaloy-II. High thermal captures in aluminium and nickel-based systems imply 235U enrichment, which results in a lower breeding ratio and a 1.1 ppm to a 1.4 ppm higher boron concentration than the current CANDU-6 reactor. Natural enrichment is preserved for SiC system, while providing a 3.4 mk increase in core reactivity with boron poisoning conditions similar to the reference CANDU bundle. The enriched systems' spectral hardenings result in a 246 kW lower channel power. Throughout the cycle, the new ATF operation compliances are compared to the CANDU-6 license limits. The liquid zone controllers and adjusters effects on power flattening are investigated. An 8-bundle shift on power refueling scheme based on the CANDU channel age model is implemented and tested. The cores' dynamic responses to a loss of regulation control event and to an instantaneous or gradual recovery of reactivity regulation devices are also studied. By uniformly perturbing the core global and bundle local parameters, new reactivity coefficients are determined and cores' responses are compared over a large spectrum of moderate and severe accident scenarios. [ABSTRACT FROM AUTHOR]

• A corrosion-induced failure of 304SS in rural atmosphere is researched. • Intergranular corrosion is the main cause of the failure. • Cracking propagates along grain boundaries but not along the interface of MnS. An unexpected cracking of a 304SS nut exposed to a rural atmosphere caused gas leakage. Aiming at identifying the failure cause, this study has conducted crack morphology analysis and corrosion product analysis using X-ray computed tomography, electron backscatter diffraction, and scanning electron microscope. The results revealed that the primary failure is attributed to intergranular corrosion cracking, where corrosion has played a predominant role. Initial corrosion was induced by MnS inclusions and chromium carbides. The application of additional force during re-examination promoted crack propagation. MnS inclusions played an auxiliary role in crack propagation due to the high stress concentration around them. The main contributing factor to the failure is the unqualified material, which contains excessive amounts of carbon and sulfur, significantly reducing the corrosion resistance and toughness. Based on these findings, recommendations for preventing further failures were proposed. This study has provided a failure case in mild environment and demonstrate that failure of 304SS would also occur even if the environment is the rural atmosphere, as long as the material is sensitized. [ABSTRACT FROM AUTHOR]

Corrosion of alloys is a serious problem in many industries because it can induce huge economic losses. Therefore, a suitable strategy needs to be applied to control the alloys' structural integrity. Stainless steels, which are widely used in the seawater environments, are susceptible to localized attack mechanisms, mainly to pitting corrosion. Therefore, the use of corrosion inhibitors and protective films is an essential approach to delay corrosion. Due to the enhanced awareness of ecological issues, green types of corrosion inhibitors are urgently needed for practical applications. In this study, muscle extracted protein, polydopamine (PDA) coating on 304 stainless steel (304ss), was successfully prepared using a self-assembly process. In order to enhance the adhesion of PDA on a substrate surface, a self-assembled of green inhibitors (L-gly and L-cys) was first implanted on a steel surface. The inhibitory properties of the coatings were verified by potentiodynamic polarization measurements and electrochemical impedance spectroscopy in sterile seawater. The electrochemical analysis demonstrated a positive shift in the corrosion potential and a decrease in the corrosion current density, especially for double-layer nanohybrid coatings. The FT-IR spectroscopy measurements of the coated surface confirmed the modification of 304ss surface by L-gly and L-cys and the PDA modified by L-gly and L-cys. The surface morphologies of the coatings were analyzed using SEM. The results showed that the formation of a low porosity and dense double-layer coatings could effectively retard corrosion. [ABSTRACT FROM AUTHOR]

The neutronic penalty and advantages are quantified for potential accident tolerant claddings in a CANDU-6 (Canada Deuterium Uranium) reactor. Ferritic-based alloy (FeCrAl and APMT), steel-based alloy (304SS and 310SS) and silicon carbide (SiC) claddings are compared with Zircaloy-II. High thermal capture in nickel-59 and iron-56 imply a neutronic penalty in iron and steel-based bundles. A minimum enrichment of 1.0% and 1.1% is required for ferritic and steel-based claddings, respectively, to achieve the CANDU-6 burnup average criticality. An average increase of 0.35% in reactivity is introduced when SiC is considered, while keeping a natural enrichment condition. Average thermal neutron absorption rate is found to be 203, 8 and 6 times higher in UO 2 pellets than in silica, iron and steel-based claddings, respectively. A spectral hardening is observed in fuel, cladding and coolant for all enriched cells. Neutron flux is 30.5% higher at 0.0253 eV in SiC and Zr bundles. For FeCrAl, APMT, 304SS and 310SS, less 239 Pu is produced during all fuel residence time and a minimum of 50 % more 135 Xe poison is being produced at equilibrium. As well, a minimum of 60% more 235 U is left at end-of-life. For bundles cladded with SiC and Zr, 7.6% higher fission rates are found on the pellet periphery. Decreasing the cladding thickness by 200 μm made it possible to satisfy the criticality requirements for all claddings with an enrichment below 1%. Moderator and coolant temperature coefficients are found higher in SiC and Zr bundles. At mid-burnup, the Doppler effect and the voiding effect are higher in FeCrAl, APMT, 304SS and 310SS cladded cells. [ABSTRACT FROM AUTHOR]

Small scale mechanical testing has gained significant attention in recent times due to its advantages for materials research and development; however, the ability to extend small scale testing results to larger scale applications remains difficult, and questions remain with regards to quantifying macroscale properties from microscale tests. In this study, 304SS, HT-9, and CuCrZr samples of various conditions were tested using the SS-J sample geometry with thicknesses ranging from 800μm to 30μm. Starting at thicknesses below 200μm, significant reductions in material properties such as uniform elongation and ultimate tensile strength were observed. The presence and magnitude of the changes varied across material and material condition, indicating the coupling of both geometric and microstructural effects. Finite element analysis was performed on the overall test setup used, revealing potential flaws in using the SS-J and other related sample geometries to increasingly extreme sample aspect ratios. Microhardness and nanoindentation were also performed for comparison and revealed discrepancies in values at these different length scales. [Display omitted] [ABSTRACT FROM AUTHOR]

This work is a preliminary study with the purpose to find some information about the effectiveness of Ceraflava (CF) extract as inhibitor in 3.5%NaCl, CF or yellow bees wax from honey farm used as corrosion inhibitor. In particular the purpose of this study is to determine the ability of CF in inhibiting the corrosion rate. The inhibition of the CF extract on304SS in 3.5% NaCI is carried out with potentiodynamic polarization, EIS and SEM. The findings show that CF can be used as corrosion inhibitor in SS 304 even though CF can only be categorized as moderate performance of inhibitors. However, it was observed that inhibitors can be adsorbed on the 304SS surface so it inhibits the corrosion rate. Based on the potentiodynamic polarization and EIS results, the inhibition efficiencies are 59.77% and 53.84% in 0.2g/L inhibitor concentration. Potentiodynamic polarization curves indicate the mixed type of the inhibitors. The adsorption of the inhibitors on the 304SS surface was found to obey to Langmuir adsorption isotherm. Thermodynamic adsorption parameter were calculated and discussed. It is expected this research may be recommended in the use of CFCs in saline solution or other solutions on the science of corrosion controlling using organic inhibitors. [ABSTRACT FROM AUTHOR]

The establishment of heterojunction is a powerful strategy to enhance the photoresponse performance of photoanode. Here, TiO 2 /CuInS 2 (T/CIS) composites were prepared via a two-step hydrothermal method, and their morphologies were controlled by adjusting the reaction time. The absorption spectra show that CuInS 2 can significantly improve the absorption of visible light. The T/CIS2 (2 h reaction time) photoanode exhibited the most outstanding photoelectrochemical (PEC) performance, with a photocurrent density of 168% that of the pure TiO 2 photoanode. Under simulated sunlight, this photoanode can supply a protective photocurrent of 0.49 mA cm -2 and a protective voltage of 0.36 V to stainless steel (304ss), which are about 4 and 2 times those of the TiO 2 sample. The enhancement in the photocathodic protection performance is attributed to enlarged visible light absorbance and higher charge separation rate. This study demonstrates that the TiO 2 /CuInS 2 photoanode is a promising candidate for application in photoinduced cathodic protection of metallic materials., (© 2022 IOP Publishing Ltd.)

Abstract: Cyclic oxidation of nano-crystalline 304SS coating was compared with that of conventional, micro-crystalline 304SS in both dry and wet (10% H2O) air at 900°C. The nanocrystalline alloys were prepared by direct current magnetron sputtering coating. Weight change kinetics were measured by continuous thermogravimetry. For micro-crystalline alloy in dry air, a small initial weight gain was followed by gradually increasing spallation. Addition of water vapour to air produced immediate spallation, and led to significant breakaway oxidation. Microstructural analyses revealed the formation of iron-rich oxides on the surface. The addition of water vapour also accelerated the development of internal oxidation in the form of fine spinel precipitates dispersed in the chromium depleted matrix. In contrast, nano-crystalline 304SS, underwent relatively rapid oxidation in the very early cycles of reaction, but then the reaction slowed down. No spallation was apparent in either gas. The weight gain was higher in wet air than in dry air. In both gases a dense and continuous chromium oxide layer was formed at the surface, together with other oxides distributed inside the coating layer. The effects of cyclic reaction, grain size and water vapour on the resistance of 304SS to breakaway oxidation are discussed. [Copyright &y& Elsevier]

• WO 3 /BiVO 4 was synthesized by spin coating and hydrothermal method. • WO 3 /BiVO 4 /Bi 2 S 3 was constructed in situ in the photocathodic protection tests. • The OCP of 304SS coupled with WO 3 /BiVO 4 reduced to −690 mV. • The protection on 304SS in the dark could last for 10 h. Photocathodic protection, benefiting from semiconductor materials with outstanding photoelectrochemical characteristics, has raised extensive attention because of its energy-saving and environment-protecting properties. In this work, WO 3 /BiVO 4 composite film was synthesized by spin coating and hydrothermal method. BiVO 4 in the composite film reacted with Na 2 S, used as electrolyte in the photoelectrochemical cell, to generate Bi 2 S 3 in-situ , and constructed a ternary heterojunction WO 3 /BiVO 4 /Bi 2 S 3. As a photoelectrode, it boosted photocathodic protection performance for 304SS. The results revealed that the OCP of 304SS coupled with the heterojunction in 3.5 wt% NaCl solution could be further reduced to −690 mV, as well as it could protect 304SS steadily up to 10 h in the dark. The above could be attributed to alleviating the recombination and promoting the separation of photogenerated carriers. This work provides unique reference for constructing photoanodes on photocathodic protection of metal. [ABSTRACT FROM AUTHOR]

• PPy/TiO 2 core-shell nanorods (PTNRs) films are successfully synthesized. • PTNRs film exhibits superior absorption ability in visible light region. • PTNRs film displays excellent cathodic protection performance under visible light. • Under dark condition, PTNRs film can provide continuous protection for the steel. In this study, polypyrrole (PPy)/TiO 2 core-shell nanorods (PTNRs) films were successfully synthesized through hydrothermal treatment and electrochemical polymerization method. The structure and optical properties of the as-prepared films were characterized. The results showed that the core-shell PTNRs film exhibits superior visible-light absorption ability. The composite films with different deposition conditions were systematically studied on the performance of the photocathodic protection (PCP). The photoelectrochemical performance of the samples are related to their structures which are strongly influenced by the deposition time of PPy layer. Meanwhile, compared with other reported as-prepared films, PTNRs film under visible light illumination could negatively shift the potential of the coupled 304 stainless steel (304SS) to -640 mV vs. Ag/AgCl, exhibiting more efficient PCP effect. More importantly, it can continuously provide protection for the steel in the darkness based on the electron pool effect of PPy. The possible PCP mechanism of PTNRs film was also discussed. [ABSTRACT FROM AUTHOR]