Energy Dispersive Spectrometer Analysis Research Articles

Study on film forming characteristic of ε-polylysine grafted chitosan through TEMPO oxidation system and its preservation effects for pork fillet

The present study synthesized a new type of ε-polylysine (PL) modified chitosan film (TO-CH-PL) through TEMPO (2,2,6,6-Tetramethylpiperidine) oxidation system. Firstly, the physicochemical properties of the TO-CH-PL were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive spectrometer analysis. Results proved that PL was successfully grafted onto chitosan molecules. Based on the water vapor, oxygen permeability, and mechanical analysis, the TO-CH-PL film demonstrated higher physical properties than chitosan and PE films. Secondly, the TO-CH-PL film's preservation effect on pork fillets was evaluated. Due to the significant retardation of growth of the aerobic plate count (APC), total volatile basic nitrogen (TVBN), and thiobarbituric acid reactive substances (TBARS), as well as the changes of pH and color in packaged pork, TO-CH-PL film exhibited better preservation effects for the pork samples. According to the criteria of TVBN values (<15 mg/100 g), compared with CH and PE films, TO-CH-PL film can prolong the shelf life of pork for 2 to 3 days. Therefore, PL-modified chitosan films could be introduced as an alternative method to maintain the quality indices and extend the shelf life of pork during refrigerated storage.

Green synthesis of antimony sulphide (Sb2S3) nano-rods in plant oils and study of photocatalytic activity

This study reports the green synthesis of antimony sulphide (Sb2S3) nano-rods synthesized by thermolysis of antimony diethyldithiocarbamate (Sb [S2CNEt2]) complex as a single source precursor in various plants oils acting as capping agents through their carboxylic acid functionality. The reported method reflects a facile and single-step fabrication of antimony sulphide nanorods and reveales their orthorhombic stibinite phase characterized by p-XRD. The quantification of energy dispersive X-ray spectrometric (EDS) analysis depicted an atomic ratio of approximately 2:3 for Sb: S. The morphology of nano-rods was confirmed by scanning electron microscopy (SEM) analysis and crystallize size was observed ranging 8.09–8.27 nm. The band gap calculated from absorption spectra was found to be 1.93 eV to 2.01 eV for all studied samples. The photocatalytic efficiency of synthesized nanorods evaluated by photocatalysis of Janus Green and Rose Bengal showed the dye degradation up to 99.9% in the presence of biosynthesized catalysts at different times.

Study on corrosion behavior of 13Cr gate valve using weld deposited gate and seat in well operation environments

The different types of corrosion behavior occurred on a 13Cr gate valve using weld deposited gate and seat after about sixteen months of service in an oilfield in China, resulting in the leakage failure. In this study, the corrosion causes were investigated through visual inspection, mechanical performance testing, scanning electron microscopy, energy dispersive spectrometer and electrochemical analysis. The results demonstrated that the corrosion on the sealing surface of the valve body was related to the galvanic corrosion between the 304 SS ring gasket and 13Cr SS ring groove, which presented a significant potential difference in the spent acid environment. In addition, due to the C element diffusion from deposits during the spray weld on the surface of the gate and seat, a large amount of Cr enrich carbides were formed at the prior austenite grain boundaries in the 13Cr SS matrix side, which further induced the intergranular corrosion and cracking along the interface in service.

Collapse failure analysis of S13Cr-110 tubing in a high-pressure and high-temperature gas well

Due to excellent CO2 corrosion resistance and low cost, martensitic stainless steels such as super 13Cr have been widely used as tubing strings in high-pressure and high-temperature wells. However, in recent years, with the further development of the oilfield, super 13Cr tubing failure accidents keep happening in high-pressure and high-temperature gas well, resulting in the loss of well integrity and huge economic losses. So a systematic research on the failure mechanism of the super 13Cr tubing in HPHT gas well under different service conditions is vital to the reduction of the failure accidents. In this paper, a collapse failure accident of S13Cr-110 tubing in a high-pressure and high-temperature gas well was investigated by metallographic microscope, scanning electron microscope, energy dispersive spectrometer, X-ray diffraction and finite element analysis, aiming to find out the root causes and put forward useful suggestion for the establishment of the preventive measures. The results showed that the chemical composition and mechanical properties of the tubing were all in accordance with the corresponding parameter requirements, and the collapse failure was attributed to the combined effect of formation sand production, high temperature and stress corrosion cracking on the outer surface. The tubing plugging induced by the formation sand production caused the increase of pressure difference between the annulus and tubing, which was the main reason for the collapse failure. In addition, high temperature in the downhole would result in a decreasing of the tubing’s anti-collapse ability. Meanwhile, the annular environment containing Cl-, PO43-, further induced the stress corrosion cracking under service stress. The presence of the cracks on the outer surface could cause a significant decrease of the pressure-bearing capacity of tubing strings, which would finally have an obvious influence on the acceleration of the failure process.

High volume waste foundry sand self-compacting concrete – Transitioning industrial symbiosis

In light of massive industrialization, Industrial symbiosis has gained traction by most countries to employ wastes of one industry as a resource to another. Waste foundry sand obtained from the metal casting industry is a threat to the environment and the health of living beings due to the presence of organic and inorganic materials. However, this waste can be a resource for the construction industry. Despite its broad application scope, usage of waste foundry sand is highly limited due to inadequate understating of its performance in concrete. It becomes essential to understand the behaviour of waste foundry sand in concrete, more importantly, for accessing a strength-efficient and durable structure. The concrete samples were examined by conducting a number of experiments to investigate ties between strength, durability and microscopic insights. It has been observed that the inclusion of waste foundry sand can improve strength properties at later ages. Particular attention is paid to study the detailed microstructural investigations conducted on the concretes having up to 50% waste foundry sand. In addition, a leaching analysis was performed that revealed an increase in heavy metal concentration with the increasing WFS content. However, its concentration was below the acceptable limit, as evidenced by USEPA. Mineral and compositional characteristics monitored the effect of calcium aluminosilicate in the concrete matrix from early to later ages by X-ray diffraction and energy dispersive spectrometer analysis for the solid constituents of the concrete specimen, respectively. In light of the above, this study reveals that the strength properties of blended SCC were improving at later ages; significant improvement was discovered after 91 days of curing time. The compressive strength results were observed to increase by 16.6% for the specimens containing 40% waste foundry sand relative to control concrete at 91 days. The highest strength properties were achieved at 365 days, with 50% replacement ratios of waste foundry sand. The values for UPV were observed to improve as the curing age increases with the reduction in the rate of carbonation resistance of concrete. The carbonation depth was observed to be less than 1 mm for specimens containing 40% and 50% waste foundry sand for accelerated and atmospheric carbonation at 56 days and 2 years, respectively. The originality of the study relies on the possibility of developing waste foundry sand-self compacting concrete with the maximum utilization of waste foundry sand, achieving the targeted results. The study showed a good agreement between the waste foundry sand and concrete that creates a ground for the enhanced application of industrial symbiosis.

Influence of recycled concrete aggregate enhancement methods on the change of microstructure of ITZs in recycled aggregate concrete

Recycled concrete aggregate (RCA) enhancement is an important method to improve the performance of recycled aggregate concrete (RAC). However, the quantitative studies on the change of microstructure of interfacial transition zones (ITZs) were few and far, especially after enhancement of RCA with different methods. This paper investigated the influence of carbonation enhancement (carbonation time, soaking in CH saturated solution and then carbonation) and chemical enhancement (respectively soaking in Na2SiO3 saturated solution and cement-silica fume (CEM-SF) slurries) of RCA on the change of microstructure of ITZs (including the ITZ between old aggregate-new paste (ITZ1) and ITZ between old paste-new paste (ITZ2)) in RAC. The porosity, the un-hydrated cement particles (UH) content, the volume fraction of hydration products (VFHP) in ITZs and the width of ITZs were obtained by backscattered electron imaging analysis (BSE-IA) and energy dispersive spectrometer (EDS) analysis. Results showed that the carbonation enhancement of RCA could not effectively strengthen ITZ1. However, soaking RCA in Na2SiO3 saturated solution and CEM-SF slurries could decrease the porosity and the UH content, develop the VFHP, and reduce the width of ITZ1, then strengthening ITZ1. Both carbonation and chemical enhancement could take obviously improvement on ITZ2. Additional calcium sources could be added to RCA by soaking in CH saturated solution, improving the effect of carbonation enhancement of RCA. Soaking in CEM-SF slurries had a better improvement effect on ITZs. After RCA was soaked in CEM-SF slurries, the porosity in ITZ1 and ITZ2 decreased by 36.8% and 44.0%, the UH content of ITZ1 and ITZ2 decreased by 22.6% and 53.6%, the VFHP of ITZ1 and ITZ2 increased by 22.6% and 20.9%, and the width of ITZ1 and ITZ2 decreased by 42.9% and 50%. EDS analysis showed that the Ca/Si atomic ratio of ITZs was reduced after RCA enhancement, which generated more hydration products and then decreased the porosity and the width of ITZs.

Effect of high temperature tempering on the phase composition and structure of steelmaking slag

Abstract Blast furnace slag and steelmaking slag, as the main accessory products of iron and steel smelting, are piled up in large quantities due to their huge output, high treatment difficulty and low comprehensive utilization rate, which has a serious impact on the land and environment. In order to improve the comprehensive utilization of steelmaking slag, low basicity blast furnace slag was added to the existing steel slag for quenching and tempering. The influence of basicity on the chemical composition and phase precipitation of mixed slag was analyzed. In the research process, the phase composition and morphology of blast furnace slag and steel slag of Baotou Steel were analyzed using FactSage7.1 thermodynamic calculation software, ZEISS high-resolution scanning electron microscope (SEM), modern fast high-resolution Bruker energy dispersive spectrometer and AMICS-Mining automatic mineral analysis software. The results show that the mineral phase composition of blast furnace slag is mainly calcium aluminum yellow feldspar and that of steelmaking slag is mainly dicalcium silicate(C2S), magnesium-iron phase solid solution, rose pyroxene and calcium iron aluminate. When the basicity of the mixed slag is 2.0, it can effectively inhibit the formation of non-cementitious mineral anorthite and promote the formation of better cementitious mineral C2S. At the same time, it is found that the melting temperature of mixed slag decreases with the increase in Al2O3 content.

Study on the Mechanical Properties and Durability of Hydraulic Lime Mortars Based on Limestone and Potassium Feldspar

Natural hydraulic lime (NHL) can be used as an inorganic cementitious material, as it exhibits low shrinkage, salt-alkali resistance, moderate strength, and good durability with cultural relics. There has been increasing interest in NHL, as it is considered an appropriate material for the restoration and reinforcement of architectural cultural relics. In this study, limestone and potassium feldspar were mixed and calcined at different ratios and high temperatures, and artificial hydraulic lime (HL) was produced. According to the X-ray diffraction (XRD) results, the resulting products after high-temperature calcination were mainly composed of calcium oxide, dicalcium silicate (C2S), and dicalcium aluminosilicate (C2AS). As a compromise, when potassium feldspar accounted for 30% of the total mass, HL contains a more suitable air-hardening component and hydraulic component. Scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS) analyses show that the phases of calcium carbonate (CaCO3) and hydrated calcium silicate (C-S-H) gradually increased with prolonged curing time for HL. To study the partial mechanical properties and durability of HL, a comparison was made with NHL. The mechanical properties were investigated with the flexural and compressive strengths and shrinkage. The results show that HL has higher strength than NHL, but NHL has smaller shrinkage. Accelerated aging tests indicated that HL and NHL5 led to higher resistance to water immersion, fluctuations in temperature and humidity, sulphate decay, an alkali environment, and frost–thaw action than NHL2. HL has excellent mechanical properties and durability and can be considered a conservation material for stone relics in the future.

Effects of spherical Al2O3 grades on crack initiation of thermal conductive silicone pads under high-temperature aging

ABSTRACT In this paper, the rule and mechanisms of crack initiation and propagation in the aging process of thermal conductive silicone pads (TCSP) were investigated by designing Al2O3 particle grading schemes with different particle sizes and mass ratios. Scanning electron microscope and energy dispersive spectrometer analysis showed that TCSP prepared with Al2O3 particles of various sizes according to the gradation ratio had the best anti-aging effect at high temperatures. At this time, the aging was mainly due to the aging degradation of the polymer matrix; When the proportion of small-size Al2O3 particles increases, aggregates and pore defects appear in TCSP. At this time, the main reason for its aging is that the high-temperature expansion of gas in pore defects accelerates the aging degradation of the polymer matrix; When the proportion of small-sized Al2O3 particles decreases, a large number of holes appear in TCSP and the coverage rate of the polymer matrix on Al2O3 particles decreases. The main reason for the high-temperature aging crack is that the gas between the holes expands at high temperature, resulting in the rapid extension of the crack and the polymer matrixes falling.

Effects of Al-Mg on the Microstructure and Phase Distribution of Zn-Al-Mg Coatings

In this work, the composition of the zinc–aluminum–magnesium alloy coating was designed to have a fixed aluminum–magnesium ratio of 1:1, while the content of aluminum and magnesium elements increases gradually within the range of 1–2 wt.%. The micro-morphology of the coating with different compositions was observed by a scanning electron microscope (SEM). Combined with the surface distribution results of energy dispersive spectrometer (EDS) analysis elements and the phase analysis results of diffraction of X-rays (XRD), the phase distribution of the coating is understood. The statistical calculation of the phase distribution was carried out after staining the SEM image by ImageJ, This is consistent with the solidification simulation results of the thermodynamic simulation software (PADAT). The influence of magnesium and aluminum elements on the microscopic morphology and phase distribution of the zinc–aluminum–magnesium (ZnAlMg) coating was studied, and the mechanism of action was analyzed. The results show that the volume ratio of binary eutectic phase (Zn/MgZn2) and ternary eutectic phase (Zn/Al/MgZn2) in the coating tends to increase as the contents of the two elements elevate. The quantity of MgZn2 is the critical factor for the corrosion resistance of the coating; the more MgZn2, the better the corrosion resistance.

Effect of Pseudomonas aeruginosa on corrosion of X65 pipeline steel

Microbiologically influenced corrosion (MIC) has caused great losses to many industries. This paper aimed to study the corrosion behavior of P. aeruginosa on X65 steel. The corrosion behavior of P. aeruginosa on X65 steel under aerobic and anaerobic conditions was studied by scanning electron microscopy, energy dispersive spectrometer and electrochemical analysis techniques. The results showed that the corrosion rate of X65 steel in bacterial environment is higher than that in sterile environment. In anaerobic environment, the corrosion of P. aeruginosa is mainly secreted acidic metabolites, and alkaline substances are corroded in aerobic environment. In general, the corrosion of X65 steel by P. aeruginosa in aerobic environment is more serious than that in anaerobic environment.

Synthesis of Ce, N co–doped carbon dots as green and effective corrosion inhibitor for copper in acid environment

Background: A new high-effectively corrosion inhibitor was used to replace the traditional corrosion inhibitor and reduce the environment pollution.Methods: Through hydrothermal synthesis, Ce and N co-doped carbon dots (Ce@N-CDs) were generated. Before the performance characterization, the microstructure and chemical composition of Ce@N-CDs were firstly investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) techniques. The electrochemical test revealed that the IE of Ce-10% (200 mg/L) on copper was as high as 98%, presenting the best inhibition effect. According to the adsorption isotherm analysis, the Ce@N-CDs mainly adsorbed according to the Langmuir model, and the adsorption process was completed by combining physical and chemical adsorption.Significant findings: Through the morphology, energy dispersive spectrometer (EDS) and XPS analysis of copper surface after corrosion process, it was found that the Ce@N-CDs formed a dense adsorption/passivation film on the copper surface. The adsorption film mainly came from the pairing of unsaturated bonds between N-doped CDs (N-CDs) and copper surface. The passivation film mainly came from the oxide formed by the reaction between Ce and the surrounding environment. Their dense structure could effectively inhibit the infiltration and erosion of corrosive medium.

Effect of downstream processing on the structure and rheological properties of xanthan gum generated by fermentation of Melaleuca alternifolia residue hydrolysate

Low-cost Melaleuca alternifolia residue hydrolysate has great potential as a promising substrate for xanthan gum production but further downstream processing in addition to traditional alcohol-precipitation is necessary to obtain purified xanthan gum from this substrate. In this study, the effect of downstream processing on the structure and rheological properties of xanthan gum generated by fermentation of Melaleuca alternifolia residue hydrolysate was evaluated for the first time. Compared with acid-precipitation and alkali-precipitation, dialysis was much more suitable for xanthan gum purification as demonstrated by the energy dispersive spectrometer (EDS) and thermogravimetric analysis (TGA) results, and the xanthan gum with relatively high purity could be obtained after alcohol-precipitation and dialysis. Dialysis after alcohol-precipitation showed little influence on the functional groups of xanthan gum but the microstructure of xanthan gum changed greatly in that a filamentous structure was formed after this treatment. The fermentation performance could be evaluated accurately based on the suitable downstream processing. The purified xanthan gum had similar rheological properties (pseudoplasticity and solid-like/gel-like behavior) to the typical xanthan gum according to its flow curves and linear viscoelastic analysis. However, some rheological properties (existence of Newtonian plateau in flow curves, and crossover of storage modulus (G′) and loss modulus (G″) in frequency sweep test) of the purified xanthan gum solution were different from that of the typical xanthan gum. Overall, this study can offer some important information for efficient and effective purification of xanthan gum with a good rheological performance from low-cost Melaleuca alternifolia residue hydrolysate. • Effect of downstream processing on xanthan gum structure was evaluated. • Effect of downstream processing on xanthan gum rheological properties was learned. • Melaleuca alternifolia residue hydrolysate was suitable for xanthan gum production. • Purified xanthan gum with good rheological performance was obtained.

Synthesis and luminescent properties of red-emitting Li2CaSnO4: xEu3+ phosphors

Abstract Red emitting Li2CaSnO4: xEu3+ phosphors were successfully synthesized by the high-temperature solid-state method. The crystal structure, composite and luminescence properties (e.g. the excitation and emission spectra, fluorescent lifetimes, and CIE chromaticity coordinates) of the samples were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), energy dispersive spectrometer (EDS) and spectral analysis technique. The emission spectra consist of the characteristic peak resultant to Eu3+ under the excitation of 395 nm and the dominant emission peak is at 621 nm (7F0→5L6). The optimal red emission was obtained through 4% Eu3+ doping. These new red Li2CaSnO4: Eu3+ phosphors have the potential application for white LEDs.

Preparation of an environmentally friendly demulsifier using waste rice husk as raw materials for oil–water emulsion separation

Demulsification of crude oil emulsions still face many difficulties in the petroleum industry. Therefore, it is very important to develop innovative materials to achieve the effective separation of oil–water emulsions. In this work, an environmentally friendly RHC-0.5 demulsifier was prepared via a simple one-step hydrothermal route using rice husk (RH) as raw materials. It was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, energy dispersive X-ray spectrometer and thermogravimetric analysis. The possible breaking mechanism was analyzed by particle size analysis, Zeta potential, interfacial activity, interfacial tension, self-assemble of interfacial film and microscopic analysis. The influence of some important factors such as dosage, temperature, standing time and salinity on the demulsifying efficiency (DP) was explored through bottle tests. The optimal DP of 95.01 % could be obtain with 300 mg/L of RHC-0.5 at 70 °C for 10 min. Meanwhile, RHC-0.5 had a good salt tolerance even at the salinity of 40000 mg /L. In addition, its DP was compared with that of commercial demulsifiers such as SP169, CH-66 and AR-32. This work not only can promote the efficient utilization of biological waste (RH), but also provides an insight into the exploration of new demulsifying materials with excellent performance.

Preparation of porous macromolecule oxazine poly‐ionic liquid solid acid catalyst and its application in an esterification reaction

AbstractBackgroundChinese research on citrate is typically into plasticizer alternatives to the carcinogenic phthalate (PAEs) plasticizers. PAEs plasticizers can induce obesity and metabolic disorders, whereas citric acid vinegar plasticizers have the advantages of low biological toxicity and environmental friendliness.ResultsNovel porous macromolecule oxazine poly‐ionic liquid solid acid catalysts were prepared and characterized by scanning electron microscopy (SEM), Brunner−Emmet−Teller(BET) measurements, Fourier transform infrared spectroscopy (FTIR), energy dispersive spectrometer (EDS) and thermogravimetric analysis (TGA). Characterization results showed that the synthesized catalyst was a porous polymer with good heat stability. The catalytic performance of the catalyst was evaluated by synthesis of tributyl citrate from citric acid and n‐butanol.ConclusionThe optimal reaction conditions were determined as 9% (wt%) citrate mass. The experimental results showed that the optimal reaction conditions were determined as amount of catalyst 9% (wt% citrate mass), 150 °C reaction temperature, 3.5 h reaction time and 1:3 ratio of citric acid and n‐butanol. Under optimal conditions, the conversion rate of citrate acid was ≤91.74%. The catalytic activity did not reduce obviously after being reused for ten times. Then, the reaction conditions were fited by the surface optimization method. The fitted optimum conditions were as follows: 8.881% amount of catalyst (mass of citric acid), 148.259 °C reaction temperature, 3.331 h reaction time, 1:2.958 citric acid:n‐butanol ratio; this gave a conversion rate of citric acid of ≤92.998%. The simulation results are in good agreement with the experimental results. © 2022 Society of Chemical Industry (SCI).

Effect of Y2O3 and TiO2 addition of dispersed powder on phase evolution and microstructural analysis of (Al, Cu)3Ti intermetallic synthesised via mechanical alloying and powder metallurgy route

ABSTRACT Aluminium-based alloys are the most widely used structural material owing to their lightweight, high stiffness with moderate strength, ductility, and toughness. However, these alloys still have several issues in engineering applications, such as moderate strength, high temperature, wear-resistant, unstable mechanical characteristics, etc. Intermetallics offer tremendous possibilities for the development of advanced novel material with enhanced mechanical properties for aerospace and automotive applications due to the range of reinforcement materials and flexibility in their primary processing. The current research provides a detailed study of the formation of Cu9Al4, AlCu, and AlTi3 intermetallic compounds via mechanical alloying and powder metallurgy route. The microstructural characterisation, compositional analysis, and evolution of different aluminium-based intermetallic compounds with respect to milling time were investigated through field emission scanning electron microscope (FESEM), energy-dispersive spectrometer (EDS), and X-ray diffraction (×RD) analysis. Microstructural analysis revealed that the elemental powder became fine and homogenous as the milling progressed. In addition, the grain structure is homogeneously distributed with a few enlarged and dispersed phases of Y2O3 and TiO2 in the base alloy. The porosity of the sintered compacts was significantly improved by the addition of 1 wt % each of Y2O3 and TiO2 dispersoids to 60 h milled base alloy.

A Promising Mortar Produced with Seawater and Sea Sand.

The aim of the study is the deep understanding of the essential reactivity of the environmentally friendly mortar by which its applicability can be justified. Created in the study was the environmentally friendly mortar, which helped relieve the increasing requirements on conventional building materials that are produced from exhausted freshwater and river sand nowadays. Seawater (SW) and sea sand (SS) collected from the Eastern Seas of China were used to produce the mortar at various ages, including 10-day, 33-day, and 91-day. Both the curing and working conditions of the mortar were natural marine ones. The physicochemical-mechanical behaviors were investigated using uniaxial compression tests (UCTs), Energy Dispersive Spectrometer (EDS), X-ray Diffraction (XRD), and thermal-field emission scanning electron microscopy (SEM) analysis to understand the essential reactivity of the mortar with age accumulation. The results indicated that hydration products and favorable components were generated promisingly in the mortar: the C-S-H (xCaO·SiO2·zH2O) development was certainly achieved in the critical environment during the curing and working period; the extensive generation of C-A-S-H (CaO·Al2O3·2SiO2·4H2O) helped densify the C-S-H grid, which caused the promising development of the uniaxial compression strength (UCS); the framework porosity of the mortar was restrained effectively due to the development of Friedel’s salt that re-bonded the interfacial cracks between SS and the hydration products with the age accumulation in the critical environment. Consequently, UCS and the resistance against damage of the mortar showed increasing behavior even in the critical environment. The study established Friedel’s salt working models and strength and damage models to interpret the physicochemical reactivity of the mortar as: the source of the strength and toughness was the proper polymerization between the native saline components and the hydration product mixture generated throughout the production, curing, and application without the leaching phenomenon. The novel models and interpretation of the physicochemical reactivity ensured the applicability of the mortar produced with SW and SS in the critical environment.

Fabrication of hydrophobic AlCoCrFeNi high-entropy alloy and superior corrosion resistance to NTO aqueous solution

Hydrophobic AlCoCrFeNi high-entropy alloy (HEA) was prepared by electrochemical dealloying using 5% of weight percent H2SO4 aqueous solution at low temperature. The results of energy-dispersive spectrometer (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the element contents of Al and Ni were greatly reduced after dealloying treatment, leading to the increase of body centered cubic (BCC, Fe-Cr) phase and consequently, the achievement of the protective barrier of Cr- enriched oxide film on the substrate surface. The static water contact angle increased with the extension of dealloying period and reached a maximum value of 127 ± 1°, showing pronounced hydrophobic performance after dealloying treatment. Meanwhile, the AlCoCrFeNi HEA specimens showed excellent mechanical properties involved compressive strength and micro-hardness. Compared with the as-cast AlCoCrFeNi HEA, the HEA specimens after dealloying treatment exhibited superior corrosion resistance in an acidic aqueous solution of 3-nitro-1, 2, 4-triazole-5-one (NTO) aqueous solutions confirmed by potentiodynamic polarization tests and electrochemical impedance spectra (EIS) analyses, which was credited to the Cr- and Fe- enriched oxide and hydrophobic surface.

A Novel Treatment: Effects of Nano-Sized and Micro-Sized Al2O3 on Steel Surface for the Shear Strength of Epoxy-Steel Single-Lap Joints.

Traditional steel surface treatment (e.g., sand blasting, or silane treatment) was regarded as an effective method to improve the bonding strength of steel–epoxy single-lap joints. In the present study, a new steel surface treatment method was developed. With this method, the steel surfaces were treated with suspensions of nano-sized and micro-sized Al2O3 particles in ethanol/water mixture using the dip-coating method. Both Al2O3 particle sizes were previously treated or not treated with silane. Single-lap shear tests of the steel–epoxy bonds were conducted to compare the effects of the treating methods. According to the testing results, the highest increase in the bonding strength (by 51.8%) was found for the steel coated with the suspension of silane treated nano-Al2O3 particles. Scanning electron microscopy (SEM) analysis and energy dispersive spectrometer (EDS) analysis indicates that the nano-Al2O3 particles were clearly attached to the treated steel surfaces. Moreover, the steel surface with the silane-treated nano-Al2O3 particles was found to clearly enhance the contact angle between the steel and epoxy resin. The fracture morphology analysis of the single-lap shear testing specimen shows that the bonding between the steel and adhesive changed from steel–epoxy interfacial failure to cohesive failure when the steel surfaces were treated with the nano-Al2O3 particles suspension. The developed steel surface treatment method with the suspension of nano-particles proves to be effective and reliable in enhancing the bonding strength of the steel-to-epoxy adhesives.