Proportion Of Phase Research Articles

Correlation Between the Magnetic Properties of Ce-Containing Magnets and the CeFe2 Phase at Various Sintering Temperatures

This article investigates the relationship between the magnetic properties of magnets and the percentage and distribution of the CeFe2 phase at different sintering temperatures. At the lower sintering temperature, the grain boundary phase flow of the magnet is poor, more hole defects are generated in the magnet, and the comprehensive magnetic properties of the magnet are poor. An increase in sintering temperature increases the ratio of CeFe2 phase, improves the fluidity of grain boundary liquid phase, fills the hole defects and causes an increase in remanence. However, an increase in grain size also inhibits the coercivity of the magnet at this temperature. When the sintering temperature reaches 1080 °C, the CeFe2 phase ratio continues to increase, providing more liquid phase. The phase Ce2Fe17 was also decomposed into liquid phase, the continuity and wettability of grain boundary phase were optimized, and the coercivity reached a maximum of 13.18 kOe. However, the orientation of the magnet changed and the proportion of the main phase decreased, resulting in a slight decrease in the remanence (Br = 13.17 kGs).

The Biomechanical differences in maximum snatch weight between elite and sub-elite weightlifters: A one-dimensional statistical parameter mapping study

Background: Current research primarily relies on discrete data collected at specific time points to analyze the weightlifting process, often overlooking the impact of continuous temporal changes on athletic performance. Purpose: This study aimed to quantitatively analyze the one-dimensional kinematic patterns of maximum snatch weight actions in elite and sub-elite weightlifters using statistical parameter mapping (SPM). It explores kinematic differences in snatch actions between elite and sub-elite weightlifters, which assists in summarizing the technical characteristics of elite athletes. Methods: Two cameras recorded three successful maximum snatch attempts of 10 elite and 10 sub-elite weightlifters at the World Weightlifting Championships and Chinese Olympic selection competitions. Simi Motion 10.2 was used for kinematic analysis. SPM was employed for comparative analysis of snatch kinematics among different levels of weightlifters, and independent sample t-tests were used for phase duration proportions. Results: Elite weightlifters showed significant advantages in multiple movement phases: smaller knee joint angles in M1 phase (p < 0.001, 35.82%–78.45%) and M3 phases (p = 0.047, 17.47%–24.74%; p = 0.036, 30.92%–49.38%; p = 0.040, 50.93%–65.85%); lower vertical body center of gravity (COG) height in M1 phase (p = 0.019, 0.00%–51.08%), M3 phase (p = 0.046, 48.27%–100.00%), and M5 phase (p = 0.045, 38.49%–59.54%); closer displacement between barbell COG and body COG in M1 phase (p = 0.006, 0%–38.18%; p = 0.048, 43.91%–48.94%) and M2 phase (p = 0.026, 0%–100%); greater barbell acceleration in M5 phase (p < 0.001, 0%–94.61%); and slower barbell descent speed in M6 phase (p = 0.001, 0%–30.58%; p = 0.046, 44.57%–51.37%; p = 0.048, 67.16%–72.41%). Moreover, elite weightlifters exhibited significantly higher phase duration proportions in M1 phase (p = 0.034, d = 1.03) than sub-elite weightlifters. Conclusion: Elite weightlifters demonstrated longer distance and time exerting work on the barbell in M1 phase, less energy consumption in barbell ascent in M2 phase, and greater upward power gain for the barbell in M1 and M3 phases. They showed faster squat-to-barbell catching speed in M4 phase and excellent braking and precise squat-to-barbell catching capabilities in M5 and M6 phases.

Improving electromagnetic wave absorption performance by adjusting the proportion of brittle BCC phase in FeCoNiCr0.4Mnx high-entropy alloys

Improving electromagnetic wave absorption performance by adjusting the proportion of brittle BCC phase in FeCoNiCr0.4Mnx high-entropy alloys

Experimental research on nonlinear vibration characteristics of double-layer mining string for deep-sea hydrate extraction under internal and external flow excitation

The vibration mechanism of the deep-sea hydrate mining string is extremely complex due to the combined effects of internal gas–liquid solid multiphase flow, structural contact collision, soil creep effect, and external ocean random load. Based on this, using the principle of similarity, a simulation experimental platform for the vibration of double-layer mining riser in deep-sea hydrate wells under internal and external flow excitation is developed, considering the vortex-induced effect of external flow field on the mining riser in the ocean section (which can simulate a maximum ocean flow velocity of 0.5 m/s), the three-phase flow-induced effect of gas–liquid–solid inside (which can simulate a maximum flow velocity of 2.0 m/s), and the coupling effect of mining string–conductor anchor node (CAN)–seabed. The influence of particle size, phase ratio, three-phase flow, and external flow velocity on the vibration response characteristics and nonlinear behavior of mining string are investigated. It is found that the vibration of vertical string is significantly affected by external ocean currents and internal three-phase currents. The vibration displacement amplitude of the horizontal section (average 0.08 mm) is significantly smaller than those of the vertical section (average 70 mm). The strong vibration positions of the vertical and horizontal sections of the mining string are different, in that the vertical section is mostly located below the middle section (just at 1800–2400 mm), while the horizontal section is mostly located at the three-phase inlet (just at 500 mm). The vertical section of the mining string presents a motion trajectory of oblique straight line, wide oblique straight line, or approximately wide oblique straight line, while the horizontal section is mostly a chaotic trajectory or an “8”-shaped chaotic trajectory. The decrease in particle mesh size and the increase in solid-phase proportion are reflected in the difficulty and accumulation of particle transport, leading to an increase in vibration displacement, as well as a decrease in vibration displacement amplitude and vibration energy. When the particle size set as 50 mesh, the displacement of mining string is largest, just for 110 mm of vertical section and 0.08 mm of horizontal section. The increase in the proportion of gas phase will lead to changes in the flow state of multiphase flow, which will affect the vibration displacement amplitude of the mining string to varying degrees. The increase in three-phase flow velocity further induces vibration of the mining string, and when the flow velocity is between 1.5 and 1.75 m/s, it will resonate with the string system, resulting in a sudden increase in the amplitude of vibration displacement. The research results can effectively guide operations and improve the service life of deep-sea hydrate mining riser.

Low-dimensional phase optimization and defect passivation of quasi-2D perovskite to enhance electroluminescence by introducing b-NA

The energy funnel effect holds significant potential for enhancing light-emitting diode (LED) performance in the Quasi-two-dimensional (Quasi-2D) perovskite, which feature a unique multi-quantum well structure. However, random phase distribution and defects within Quasi-2D films pose challenges, leading to inefficient energy transfer and nonradiative recombination, thereby limiting device performance. Here, sodium 2-naphthalene sulfonate (b-NA) is introduced into the Quasi-2D perovskite film to enhance its the optical and electrical properties. The strong interaction between the S = O group and Na+ in b-NA with the perovskite matrix leads to reduced grain size, facilitating agglomeration and densification. This modification decreases the proportion of the low-n phase, enhances thermal stability, and passivates surface defects. Therefore, compared to the control device, the maximum brightness and external quantum efficiency of Quasi-2D perovskite LEDs with the optimal concentration (8b-NA) more than double, and the operational lifetime (T50) of the unpackaged device extends from 70.1 min to 168.5 min.

Effect of Al2O3-SiO2 mass ratio and sintering temperature on the properties of water-soluble salt-based ceramic cores formed by binder jetting

Binder Jetting (BJ) technology, known for its cost-effectiveness and efficiency, is widely used for the rapid fabrication of complex ceramic cores. However, fabricating high-strength and water-soluble ceramic cores via BJ technology is particularly challenging due to the balance between mechanical properties and water solubility. In this work, BJ technology was employed to fabricate high-strength and water-soluble salt-based ceramic cores (SCC) regulated synergistically by Al2O3 and SiO2. The effects of the mass ratio of Al2O3 to SiO2 (A/S) and sintering temperature on the properties of Na2CO3-based samples were investigated, with detailed analyses of the regulation mechanism through thermodynamic, kinetic, and microstructural examinations. The results indicated that when A/S was 1:4, the bending strength of samples sintered at 760 °C for 60 min reached up to 62.38 MPa with good water collapsibility. Thermodynamic and kinetic analyses revealed that the formation of Na2SiO3 was prioritized over NaAlO2, and the content of Na2SiO3 as well as the proportion of liquid phase increased with the decrease of A/S and the increase of sintering temperature, resulting in the increase of sample density, as confirmed by microstructure analyses, which was the main strengthening mechanism of samples. Ultimately, complex-structure SCC samples were successfully fabricated. This study provides an insightful method for fabricating high-strength and water-soluble ceramic cores, with significant potential applications in the casting industry.

THE EFFECT OF ANNEALING REGIME ON THE PRECIPITATION OF FeCoNiAl0.75Nb0.25 HIGH ENTROPY ALLOY

This paper investigates the effect of the annealing regime on the precipitation of FeCoNiAl0.75Nb0.25 high entropy alloy. The as-cast microstructure consists of coarse dendritic phases that are replaced by equiaxed morphology, and the distribution of the interdendritic phase becomes regularly better with increasing time and annealing temperature up to 825ºC. The precipitated process begins at 700ºC for 8 hours, shortening to 4 hours when the annealing temperature increases. The size of this phase is only a few μm. The fraction of the precipitated phase increases and the size of the dendritic phase is reduced as the annealing temperature is up to 825ºC, while this size rises in the 925ºC/16 hours regime. The microstructure is coarse, and the precipitated phase gradually disappears when the annealing is at 1000ºC. The HV3 hardness of the alloy increases with annealing time when the temperature is lower than 825ºC and reaches the highest value of ~ 614 kg/mm2 at 600ºC/ 24 hours; this value begins to decrease for the 925ºC/16 hours regime. Meanwhile, the hardness gradually decreases with increasing annealing time at 1000ºC. It can be expected due to the rapid coarsening of the dendritic phase, the decrease in the proportion of the precipitated phase in the alloy, and the appearance of plastic flow phenomena at grain boundaries.

Effect of induction heat treatment on microstructure, mechanical and corrosion properties of stainless steel 308 L fabricated using wire arc additive manufacturing

Induction solution heat treatment can change the mechanical characteristics and corrosion resistance properties of 308 L manufactured via wire arc additive manufacturing (WAAM). Moreover, compare with traditional heat treatment methods, this method can reduce heat treatment time and achieve in-situ local heat treatment. In this paper, in-situ induction heat treatment at 1100 °C for 2, 4, and 6 min were applied on 308 L thin-walled parts produced by WAAM. The result show that ferrite and austenite phase proportions were changed after induction solution heat treatment. Heat treatment at 1100 °C effectively reduced the δ-Fe and σ-Fe content, resulting in a slight decrease in UTS and microhardness, while YS and EL have a certain degree of increase. σ-Fe exhibits a more pronounced strengthening effect than austenite, albeit at the potential expense of steel’s elasticity. At the same time, induction heat treatment alters the ferrite to austenite ratio, which also enhances the anti-corrosion properties of the stainless steel. However, the presence of σ-Fe will cause a worsening of the corrosion resistance of the steel. In addition, as the heat treatment progresses, the ferrite’s microstructure in the deposition direction undergoes a significant transformation, changing from continuous dendrites to a few equiaxed grains.

A Review of Welding Process for UNS S32750 Super Duplex Stainless Steel.

Super duplex stainless steel UNS S32750 is widely used in marine industries, pulp and paper industries, and the offshore oil and gas industry. Welding manufacturing is one of the main manufacturing processes to make material into products in the above fields. It is of great importance to obtain high-quality welded UNS S32750 joints. The austenite content and ferrite content in UNS S32750 play an important role in determining UNS S32750 properties such as mechanical properties and corrosion resistance. However, the phase proportion between the ferrite phase and austenite phase in the welded joint will be changed during welding. Lots of research has been done on how to weld UNS S32750 and how to obtain welded joints with good quality. In this work, the recent studies on welding UNS S32750 are categorized based on the welding process. The welding process for UNS S32750 will be classified as gas tungsten arc welding, submerged arc welding, plasma arc welding, laser beam welding, electron beam welding, friction stir welding, and laser-MIG hybrid welding, and each will be reviewed in turn. The microstructure and properties of the joints welded using different welding processes will also be discussed. The critical challenge of balancing the two phases of austenite and ferrite in UNS S32750 welded joints will be discussed. This review about the welding process for UNS S32750 will provide people in the welding field with some advice on welding UNS S32750 super duplex stainless steel.

Gait Training of Healthy Older Adults in a Sitting Position using the Wearable Robot to Assist Arm-swing Rhythm, WALK-MATE ROBOT

Although various walking training robots have been developed and their effectiveness has been recognised, operating these robots requires the implementation of safety measures to avoid the risk of falling. This study aimed to confirm whether arm swing rhythm training in the sitting position using an arm swing rhythm-assisted robot, WMR, improved subsequent walking. Healthy older adults (N = 20) performed arm swing rhythm training in a sitting position for 1 min ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document} three times while being presented with tactile stimulation synchronised with the arm swing rhythm from a robot. An increase in walking performance was observed with increases in stride length and speed. In addition, the stabilisation of the gait pattern was observed, with a decrease in the proportion of the double-foot support phase and an increase in the proportion of the swing phase in one gait cycle. These results suggest that arm swing rhythm training in a sitting position using WMR improves gait in older adults. This will lead to the realisation of safe and low-cost robot-based walking training in sitting position.

Dissolution of Volcanic Ash in Alkaline Environment for Cold Consolidation of Inorganic Binders.

A systematic study on the dissolution in concentrated alkali of two volcanic ashes from Cameroon, denoted as DAR and VN, is presented here. One volcanic ash, DAR, was 2 wt% richer in Fe and Ca and 4 wt% lower in Si than the other, designated as VN. Such natural raw materials are complex mixtures of aluminosilicate minerals (kaersutite, plagioclase, magnetite, diopside, thenardite, forsterite, hematite, and goethite) with a good proportion of amorphous phase (52 and 74 wt% for DAR and VN, respectively), which is more reactive than the crystalline phase in alkaline environments. Dissolution in NaOH + sodium silicate solution is the first step in the geopolymerisation process, which, after hardening at room temperature, results in solid and resistant building blocks. According to XRD, the VN finer ash powders showed a higher reactivity of Al-bearing soluble amorphous phases, releasing Al cations in NaOH, as indicated by IPC-MS. In general, dissolution in a strong alkaline environment did not seem to be affected by the NaOH concentration, provided that it was kept higher than 8 M, or by the powder size, remaining below 75 µm, while it was affected by time. However, in the time range studied, 1-120 min, the maximum element release was reached at about 100 min, when an equilibrium was reached. The hardened alkali activated materials show a good reticulation, as indicated by the low weight loss in water (10 wt%) when a hardening temperature of 25 °C was assumed. The same advantage was found for of the room-temperature consolidated specimens' mechanical performance in terms of resistance to compression (4-6 MPa). The study of the alkaline dissolution of volcanic ash is, therefore, an interesting way of predicting and optimising the reactivity of the phases of which it is composed, especially the amorphous ones.

Cermet coatings obtained by electric spark alloying to increase service life of dental instruments

The article presents the results of our study of protective cermet coatings obtained by the method of electric spark alloying on a dental instrument (excavator) using SHS (self-propagating high-temperature synthesis) electrodes based on TiC-NiCr. The influence of discharge energy during electric spark alloying on the roughness, thickness, and proportion of the TiC carbide phase in the cermet coating has been established. It has been shown that during electric spark alloying, the material of the used SHS electrode and the surface of the substrate melt, their convective mixing occurs, and during crystallization, coatings are formed that consist of a strengthening phase TiC and iron-based solid solutions: Fe9.64Ti0.36, F1.88C0.12, and Cr-Ni-Fe-C. It has been found that the maximum size of TiC grains is formed on the surface of the cermet coating, and as they approach the substrate, their size decreases to less than 10 nm. It has been found that the microhardness of the surface of the resulting cermet coatings increased to 6.2 times compared to the microhardness of the original metal base, which was 2 GPa. The results of scanning electron microscopy and energy dispersive analysis of the surface of samples with and without cermet coating before and after corrosion tests are presented. The influence of disinfectants (2 and 100 % Trilox, Wendelin, MegaDes-ortho) on the corrosion resistance of samples with and without developed protective cermet coatings at room and elevated temperatures up to 50 °C and their exposure for 120 h has been established.

Investigation of Wetting Behavior and Brazing Reliability of Zn-15Al-xGa Filler Metals in Cu/Al Joints

Ga elements with different contents (0.1-1.5wt.%) were melted into the Zn-15Al filler metal to change the microstructure and thus improve the properties of the Cu/Al joints. The results showed that the addition of Ga element reduced the solidus and liquidus temperatures as well as the surface tension of the Zn-15Al filler alloy. Low concentrations of Ga (≤0.5wt%) can effectively increase the wettability of the filler metal. With increasing Ga addition amount, the size and proportion of the CuAl2 phase within the Cu/Zn-Al/Al brazed joint microstructure were increased, and also guided the transformation of the interfacial constituent phases on the Cu side interface from Al4.2Cu3.2Zn0.7/Al3Cu5Zn2 to Al4.2Cu3.2Zn0.7/CuAl2/Al3Cu5Zn2, which effectively adjusted the crack propagation path and increased the shear strength during the fracture process of the shear strength test on the brazed joint. The shear strength test results indicated the Cu/Zn-Al-0.5Ga/Al joint have the highest shear strength (85.8MPa, 15% improvement over the Cu/Zn-Al/Al joint). Consequently, appropriate Ga addition (0.5wt%) enhanced both the meltability and wettability of Zn-15Al filler metal, which was suitable for obtaining high-quality Cu/Al brazed joints.

Study on the influence of thermal properties of paraffin on flexible PTC materials

Abstract This paper experimentally studied paraffin’s influence on flexible PTC materials’ temperature resistance and flexibility. Their resistance-temperature characteristics are notably influenced by PA’s phase transition range thermal properties. Specifically, the Curie temperature is intricately linked and determined by the PA’s phase transition temperature. PA’s phase state and proportion in the composite directly impact PTC material flexibility significantly. Specifically, a lower PA phase transition temperature results in better flexibility of PTC materials at room temperature. Additionally, a lower PA content minimizes interference with the overall flexible mesh structure, further enhancing material flexibility. The PTC of this series of formulations showed good adaptive temperature control ability. The thermal control performance can be customized by adjusting the PA.

Effect of Interlayer Cooling Time on Microstructure and Properties of 2205 Duplex Stainless Steel Made by Cold Metal Transfer

By adjusting the parameters in the additive manufacturing process, the optimization of the microstructure and mechanical properties of 2205 duplex stainless steel (DSS) is of great significance to ensure the reliability of the material in harsh environments. The 2205 DSS samples are prepared by cold metal transfer conditions of interlayer cooling time of 0, 30, 60, and 120 s, respectively, and the microstructure and properties of the samples are characterized in detail. With the increase of cooling time, the height of the samples increases, and the width decreases, and no defects are found in all the samples. It also reduces the grain size and contributes to the uniform distribution of grains. With the extension of cooling time, the proportion of austenitic phase gradually increases from 41.60% to 47.36%, while the proportion of ferrite decreases correspondingly. The mechanical properties of the samples are tested. With the increase of cooling time, the hardness of the samples increases from 646.32(±1.46) to 679.36(±7.27) MPa, and the ductility decreases from 60.10(±0.50)% to 43.67(±2.10)%. The results show that the interlayer cooling time can be used to regulate the formation, microstructure, and properties of DSS.

Efficient perovskite light-emitting diodes on a flexible substrate.

The surface properties of target substrates are crucial for the in situ crystallization and growth of metal halide perovskite films fabricated by the anti-solvent method. In this work, a high-quality quasi-2D perovskite film with various-n phases is fabricated on the commonly used poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) by introducing a branched polyethylenimine (PEI) modifying layer. PEI suppresses the influence of acidic surface of the PEDOT:PSS and regulates the components of the perovskite film, increasing the proportion of large-n phases. Additionally, PEI reduces the formation of defects in perovskite films, leading to higher photoluminescence quantum efficiency and longer photoluminescence lifetime. Based on this high-quality perovskite film, a flexible light-emitting diode with an ultimate current efficiency of 63.2 cd/A is achieved, nearly twofold higher than that of the device (35.1 cd/A) without a PEI modifying layer.

Mechanical response analysis of asphalt microstructure under tensile and compressive loading based on finite element methods

This study investigates the micro-mechanical response of asphalt microstructure under tensile and compressive loads using atomic force microscopy (AFM) and digital image processing (DIP). AFM captured images of asphalt surface morphology, and DIP extracted geometric information on microstructures such as bee structures, peri phase, and interstitial structures. Five finite element models were created in ABAQUS to simulate their load-bearing capacities and stress-strain distributions under 1 % and 5 % tensile and compressive strains. The results showed minimal differences in load-bearing capacities among the five models under identical strain loads. However, compressive load-bearing capacity was significantly higher than tensile load, with the asymmetry becoming more pronounced as the load increased. Under 1 % compressive strain, the external load was about 3 % higher than under tensile strain, increasing to 36 % higher under 5 % strain. The bee structure exhibited the smallest stress distribution, while the interstitial structure showed the largest. The average maximum stress in the interstitial structure was 1.2 times that of the bee structure, with stress concentration observed at the interface between the peri phase and interstitial structure. The interstitial structure experienced the smallest strain distribution, while the bee structure endured the highest tensile or compressive strain, with the average maximum strain of the bee structure being approximately 1.25 times that of the interstitial structure. Under compressive loads, the maximum stress and strain on the asphalt surface exceeded those under tensile loads, with the difference averaging around 10 % higher. As the proportion of the peri phase increased, stress and strain distribution became more uniform, alleviating stress concentration phenomena. This study provides a potential method for analyzing the mechanical response of asphalt microstructure. The results deepen our understanding of the complex relationship between asphalt microstructure and its micro-mechanical response. Additionally, they suggest possible directions for improving asphalt performance through microstructure adjustment.

Effect of annealing on microstructure and corrosion resistance of W+in-situ TiC enhanced CoCrFeNiSi0.2 high entropy alloy coatings by laser cladding

The W+in-situ TiC reinforced CoCrFeNiSi0.2 high-entropy alloy coating (The alloy coating) was prepared using laser cladding, and the effect of different annealing temperatures on the microstructure and corrosion resistance of the alloy coating was studied. The results indicated that annealing induces changes in the proportion of FCC and BCC phases in the coating matrix as well as the shape of carbides in the coating. Potentiodynamic polarization and electrochemical impedance experiments in 3.5 wt% NaCl solution revealed that the coating annealed at 1100°C exhibits the best corrosion resistance due to the presence of a single FCC phase and the formation of spherical carbides. Surface morphologies after corrosion showed deeper pits on the coating annealed at 700°C, which exhibited the poorest corrosion resistance due to the combined effects of galvanic and occluded cell corrosion. Potentiodynamic polarization curves demonstrated the presence of passive films on the surfaces of all four samples, and surface scan results after corrosion suggest that the passive film on the coating surface mainly consists of Ti- and W-containing oxides.

High-temperature mechanical behavior and microstructural destabilization evolution of the lightweight refractory high-entropy alloy prepared by laser additive manufacturing

Lightweight refractory high-entropy alloy (LRHEA) has lower density and higher specific strength, which makes it very promising for future applications in rocket engine components. Their high-temperature resistance to softening and high microstructure stability in a wide temperature range are also essential to sustaining their performance due to being used in harsh, high-temperature situations. In this work, the high-temperature tensile behavior of Al0.3NbTi3VZr1.5 LRHEA fabricated by laser additive manufacturing has been systematically investigated from 400 °C to 800 °C, and the relationship between the deformed microstructure and the mechanical behavior was revealed, and analyzing the reasons for the thermodynamic instability of the solid solution in LRHEA are discussed in detail. It is found that the weakening of the high entropy effect at intermediate temperatures reduces the stability of the solid solution, and the accelerated diffusion between elements further promotes the solid solution destabilization, mainly manifested as the Laves phase and the local chemical fluctuation (LCFs). The high dislocation density introduced by the additive manufacturing technology leads to the irregular connection of the Laves phases within the grains, and it can be improved by grain growth. The high negative mixing enthalpy competes with the high-entropy effect, and temperature is the decisive factor. In this situation, the atomic clusters were promoted and induced spinodal decomposition for generating LCFs. The formation of LCFs exhibits solute competition with the emergence of the C14 Laves phase, and the phase proportions fluctuate at different temperatures. This work provides new thinking and attention for developing lightweight, heat-resistant materials.

Research on the corrosion mechanism of Q345R steel under water-oil two-phase flow with the HCl and NH4Cl corrosive medium in low-temperature system of petrochemical plants

The serious corrosion failure phenomenon of HCl and NH4Cl in the water-oil two-phase flow are usually occurred in the low-temperature system of petroleum refinery facilities. In this paper, the corrosion mechanism of these corrosive medium in two-phase flow environment was investigated in detail by using corrosion weight loss, electrochemical measurement methods, surface analysis techniques, and numerical research methods. The results indicate that the corrosion rate of Q345R steel in an HCl-NH4Cl coupling medium falls between the rates observed with each medium alone. The stirring of the corrosive fluid creates an unstable oil-in-water emulsion. The formation of an oil film on the surface of Q345R steel slows down the corrosion process and alters the surface corrosion morphology when the oil phase was not originally present. Increasing the proportion of the water phase accelerates the corrosion rate, and the stronger wettability of the oil phase makes the loose γ-FeOOH products easier to cover the surface, which can effectively prevent the mass transfer and corrosion reaction process.