Table of Content

28 July 2023, Volume 23 Issue 7

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Contents

Cover and Contents

The Chinese Journal of Process Engineering. 2023, 23(7):  0. 

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Development of New Energy Industry

Theoretical design of new energy solid-state battery materials and development of battery technology under the background of carbon peaking and carbon neutrality

Hongjie XU Guanghui WANG Yujie SU Zhigao ZHANG Haitong LI Zhongzheng YANG Yuchen WANG Linyue HU Guoqin CAO

The Chinese Journal of Process Engineering. 2023, 23(7):  943-957.  DOI: 10.12034/j.issn.1009-606X.223113

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Rechargeable lithium metal batteries (LMBs) have attracted wide attention due to their high theoretical energy density and important applications in portable electronic devices, electric vehicles, and smart grids. However, the implementation of LMBs in practice still faces many challenges, such as low Coulombic efficiency, poor cycle performance, and complex interfacial reactions. An in-depth analysis of the physical basis and chemical science of solid-state batteries is of great significance for battery development. To confirm and supplement the experimental research mechanism, theoretical calculation provides strong support for exploring the thermodynamic and kinetic behavior of battery materials and their interfaces and lays a theoretical foundation for designing batteries with better comprehensive performance. In this review, the theoretical and structural design ideas of the Li10GeP2S12 system and argyrodite system in sulfide solid electrolytes are reviewed, including the transport mechanism and diffusion path of lithium ions. The theoretical design ideas of new anti-perovskite Li3OCl and double anti-perovskite Li6OSI2 electrolyte systems are analyzed. The transport mechanism of Li+ in oxide solid electrolyte systems under defect regulation is reviewed. In addition, the theoretical design of new halide electrolyte systems, and the role of computational materials science in the study of battery material properties are also introduced. The key issues such as ion transport mechanism, phase stability, voltage platform, chemical and electrochemical stability, the interface buffer layer, and electrode/electrolyte interface are analyzed by theoretical methods. Understanding the charge-discharge mechanism at the atomic scale and providing reasonable design strategies for electrode materials and electrolytes.

Advances in biosynthesis of diamine as core monomers of new nylon materials

Kun LIN Zhuang LI Kun WANG Ying BI Xiuling JI Zhigang ZHANG Yuhong HUANG

The Chinese Journal of Process Engineering. 2023, 23(7):  958-971.  DOI: 10.12034/j.issn.1009-606X.223147

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In the context of carbon neutrality, bio-diamine synthesis is an effective way to achieve the low-carbon production and sustainable development. Using synthetic biology, metabolic engineering, protein engineering strategies, we are able to design and construct efficient key enzymes and pathways for the biosynthesis of diamines. In this work, the progress of diamine synthesis is reviewed around two synthetic strategies: microbial de novo fermentation and whole-cell catalysis. The main diamines include 1,4-butanediamine, 1,5-pentanediamine, and 1,6-hexamethylenediamine. The biosynthesis of butanediamine mainly includes ornithine decarboxylation and lysine decarboxylation pathways, and butanediamine is mainly produced by fermentation. However, the current yield of butanediamine is low and cannot meet the requirments of industrial production. The biosynthesis of pentanediamine depends on the decarbosylation of L-lysine, mainly by de novo fermentation and whole-cell catalysis. The whole-cell catalysis for pentanediamine is more efficient, which has been widely used in large-scale production with the maturity of the technology. Hexamethylenediamine is currently synthesized by constructing artificial pathways. In addition, to address the challenges encountered in the biosynthesis of diamines, such as many by-products, poor strain activity, low yield, difficult separation, and purification, we proposed methods to improve the biosynthesis of diamines by combining metabolic engineering and protein engineering to optimize key enzyme catalysis, exploring the mechanism of cell damage caused by diamine accumulation, enhancing the specificity and activity of enzyme catalysis to improve production intensity, and optimizing the fermentation system to simplify the subsequent separation and purification steps. Finally, we foresee the future direction and development prospect of diamine biosynthesis.

A review of heat storage performance improvement and power generation application of salt gradient solar pond

Hao MA Hua WANG

The Chinese Journal of Process Engineering. 2023, 23(7):  972-986.  DOI: 10.12034/j.issn.1009-606X.223111

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The salt gradient solar pond is a kind of large area of saline water that can simultaneously absorb and store solar energy in the thermal energy. It has attracted widespread attention from researchers due to its advantages such as long-term heat storage, large heat storage capacity, and the ability to provide a stable and clean low-temperature heat source. Traditional salt gradient solar pond stores thermal energy by sensible heat of the saline water, and the thermal storage density is limited. The application of salt gradient salt gradient solar ponds is very extensive. It can directly utilize the heat of salt gradient solar pond and provide a stable low-temperature heat source for industry, agriculture, and daily life. The thermal energy of the salt gradient solar pond can also be used for thermoelectric conversion to provide electricity for various fields. This work first analyzes the key factors affecting the heat storage performance of salt gradient solar pond, the methods to improve the thermal storage performance of salt gradient solar pond, compares and analyzes various heat extraction methods of salt gradient solar pond. Then, the application of salt gradient solar pond in the field of power generation at domestic and abroad is introduced, and the research of salt gradient solar pond power generation technology is summarized and analyzed, aims to provide references for the construction, operation, maintenance of salt gradient solar pond and also the application in power generation.

Efficient catalytic synthesis of cyclic carbonates from carbon dioxide by phosphine-based composite catalysts

Heming ZHANG Chan MENG Li DONG Qian SU Weiguo CHENG

The Chinese Journal of Process Engineering. 2023, 23(7):  987-994.  DOI: 10.12034/j.issn.1009-606X.223098

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Carbon dioxide (CO2) is both a major contributor to the greenhouse effect and an important C1 resource. The synthesis of cyclic carbonates from CO2 and epoxides is an important way of high efficiency and high value utilization. The development of high efficiency catalyst is the focus of research for this reaction. In the past, there were some problems such as poor stability, low catalytic activity and complex preparation of catalyst. Therefore, the aim of this study was to develop phosphine-based catalysts with high catalytic activity, low price and good stability. In this study, a binary composite catalytic system was formed between phosphine oxide compound and metal salt with high stability. By regulating different proportions of metal salts and phosphine oxide compounds, the binary composite catalytic system with different proportions was formed, and the optimal transition metal salts and the optimal ratio were selected (Bu3PO:ZnBr2=2:1, namely [2Bu3PO-ZnBr2]). The influence of catalyst dosage, CO2 pressure, reaction time, and reaction temperature on propylene oxide (PO) conversion and the selectivity of propylene carbonate (PC) was investigated. The results showed that under optimum reaction conditions (130℃, 3 h, 3 MPa), the PO conversion was 92%, the PC selectivity was 99% and the catalyst maintained high catalytic activity after five cycles. Finally, the interactions between the phosphine-based binary composite catalytic system and the reactants were revealed through relevant characterization, and the Lewis acid co-catalytic mechanism was proposed. The phosphine-based binary composite catalytic system proposed in this study provides a new idea for efficient and inexpensive catalyst utilization.

Design and controlled mass production of cathode catalysts for powerful fuel cell

Rongrong LI Honghong LEI Zhaoyan ZHAI Lei WU Xiaoli LI Baoyin LIU Yanna ZHANG Xi WANG Jianjun XIAO

The Chinese Journal of Process Engineering. 2023, 23(7):  995-1002.  DOI: 10.12034/j.issn.1009-606X.223110

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It has an important strategic significance to promote the utilization of clean energy, ensure the safety of electricity and then achieve carbon peaking and carbon neutrality goals. Therefore, we must promote the adjustment of energy structure, and develop technologies that are green, environmental protection, and low carbon energy saving. With excellent characteristics, such as high energy density, low cost, high safety, and clean and pollution-free, metal fuel cell has become a new generation of electric energy device, gained widespread traction in recent years. However, due to a lack of breakthroughs in key technologies and the high cost of cathode catalysts, metal fuel cells have not achieved large-scale application. There is great significance to developing non-precious metal catalysts, which can promote the development and promotion of metal fuel cells. In this work, carbon nanotubes, cobaltous acetate, manganese acetate, and sodium hydroxide were used as raw materials, which were much cheaper than platinum-carbon. Transition metal oxides were prepared and supported on the multi-wall carbon nanotube matrix through the method of coprecipitation, which was a spinel phase CoMn3Ox/CNTs catalyst. The XRD and oxygen reduction reaction (ORR) results indicated that increasing the pyrolysis temperature from 250℃ to 350℃ increased the crystallinity of the catalyst and the catalytic activity for oxygen reduction. The catalytic activity of CMO/CNTs-400 decreased as the particles grow a little larger. The SEM/EDS results showed that CoMn3Ox uniformly loaded on the surface of carbon nanotubes, with a particle size of nanoscale and a uniform distribution of each component element. The atomic number ratio of Co and Mn elements was close to 1:3. The current density and half-wave potential were 5.59 mA/cm2 and 0.75 V, respectively, which was obtained from ORR of CMO/CNTs-350. Furthermore, the CMO/CNTs-350 catalysts maintain good performance after macroscopic preparation. At 3 kW loaded, the aluminum air fuel cells assembled with CMO/CNTs-350 catalysts could operate at constant power for 12 h, with an average voltage of 1.14 V at the end of the test. Based on abundant and easy raw materials, a controllable production process and excellent electrochemical performance, CMO/CNTs-350 catalyst was a promising cathode for use in potential cathode catalysts for metal fuel cells.

Review

Research progress on desulfurization technology for blast furnace gas

Xindong WANG Tingyu ZHU Yuran LI

The Chinese Journal of Process Engineering. 2023, 23(7):  1003-1012.  DOI: 10.12034/j.issn.1009-606X.222334

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The desulfurization technology for blast furnace gas as a source of emission reduction technology is of great significance to promoting ultra-low emission for the whole process in the iron-steel industry. The sulfur-containing components in the blast furnace gas are mainly organic sulfur, coexisting with other complex components. This work discusses the emission limits of sulfur-containing components in various occurrence forms (SO2, H2S, and S), and analyzes their transformation relationship through the mass balance of sulfur. The bottleneck of desulfurization technology for blast furnace gas is to remove the carbonyl sulfur (COS). The aluminum-based catalyst and carbon-based catalyst used for COS catalytic hydrolysis are analyzed in detail, in which γ-Al2O3 is both a carrier and an active component, and activated carbon has the functions of catalyst and adsorbent. The effect mechanism of the complex components O2, and Cl- on the deactivation of hydrolysis catalyst is further elucidated due to the formation of deposition products. For the gaseous H2S formed after the COS hydrolysis, the two kinds of wet removal technology, mainly including the chemical absorption method and catalytic oxidation method, are compared in the reaction mechanism, desulfurizer and product. The difference among the zinc oxide, iron oxide, and activated carbon adsorbent used in the dry removal technology is also concretely elaborated in the reaction mechanism, sulfur capacity, and temperature adaptability. In view of the integrated adsorption of organic sulfur and inorganic sulfur, molecular sieve adsorbent is briefly described in the selective adsorption principle and regeneration process. The "hydrolysis+wet", "hydrolysis+dry", and integrated removal processes have been explored and applied currently, which are preliminarily evaluated. Finally, it is pointed out that the research and development of desulfurization technology focus on how to improve the activity of the hydrolysis catalyst and reduce the influence of complex components in blast furnace gas on catalyst activity and improve the applicability of the technology.

Research progress of coalbed methane combustion deoxidation technology

Feiqiong ZHANG Xuefeng YIN Jianan HU Wei HE Jing WANG Pengfei DAI Zichen WANG Na ZHANG

The Chinese Journal of Process Engineering. 2023, 23(7):  1013-1023.  DOI: 10.12034/j.issn.1009-606X.222299

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Coal bed methane (CBM) is a kind of unconventional natural gas energy that is mostly made of methane and is held as an adsorbed substance in coal seams. It has received a lot of attention both domestically and internationally due to its benefits of plentiful reserves and clean combustion. China has the third largest CBM deposits in the world, and the exploitation of CBM is expanding due to the increased interest in CBM in recent years, although the utilization rate is consistently low. The fundamental cause is a lack of effective low-concentration CBM utilization, where oxygen is essential to limiting safe CBM utilization. Deoxygenation is a requirement for safe utilization since low-concentration coalbed methane poses an explosion danger due to the presence of oxygen. This work introduces the basic principle and characteristics of combustion deoxidation, including the coke combustion method, catalytic combustion method, and chemical looping combustion method, with emphasis on carbon material, catalyst, oxygen carrier analysis of the current research status. In particular, the new technology of chemical looping combustion is discussed and analyzed. The findings demonstrate that the coke combustion process has a better deoxidation effect but has the shortcoming of high deoxidation temperature (650~1000℃), the key of current research is to improve the performance of carbon material and effectively control the reaction temperature. Methane will be consumed during catalytic combustion deoxidation, and the catalyst is easily poisoned and rendered inactive, the key to this technique is to investigate and develop a powerful catalyst, and this technique is not suitable for treating low-concentration CBM deoxidation. For the chemical looping combustion deoxidation method, the oxygen carrier material is inexpensive and simple to get, the reaction temperature is low, and this method can retain the maximum amount of methane. The thorough comparison reveals that deoxygenating low-concentration coalbed methane is more effectively accomplished using the chemical looping combustion approach.

Research Paper

CFD simulation study on influence of multi structural parameters of Y-shaped pleated clean filter bag on filtration resistance

Wanying SUN Fuping QIAN Simin CHENG Jinli LU Yunlong HAN Qianshuang ZHUANG

The Chinese Journal of Process Engineering. 2023, 23(7):  1024-1034.  DOI: 10.12034/j.issn.1009-606X.222326

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It has been proved by long-term practice that pleated filter bags can solve the problem of increasing the filtering area without changing the main equipment and the floor area of the bag filter. However, the filtering performance of this folded filter bag is acceptable only when the number of folds is low. When the number of folds is high, the shortening of the fold spacing will have a certain impact on the filtering and ash removal. In order to study the influence of the change of pleat spacing caused by the increase of pleat number on the filtration performance of pleated filter bags, a new Y-shaped pleated filter bag is proposed in this study to explore the influence of multivariate geometric characteristics on the filtration pressure drop. The three-dimensional filter medium model of polyester fiber filter material is constructed by using GeoDict, and the filter medium penetration model is obtained for the macro numerical simulation of Y-shaped pleated filter bag. Based on the response surface method, the influence of multi structural parameters of Y-shaped pleated filter bag on its filtration performance is explored. The research results show that within a certain range of filtration velocity, GeoDict simulation can be used to replace the experimental test. And the filtration pressure drop of Y-shaped pleated filter bag is lower than that of conventional 8 and 16 pleated filter bags. Wherein, compared with the conventional 8-pleated filter bag the filtration area of Y-shaped pleated filter bag increases by 58.04% when the number of Y-pleats (NY) is 8, the opening angle (α) is 30°, and the concave diameter (d ) is 228 mm, and the outlet velocity distribution uniformity increases by 21.23%. The uniformity of outlet velocity distribution is 28.51% higher than that of conventional 16-pleated filter bag. The optimal structural parameter of Y-shaped pleated filter bag is NY=12, α=20.17°, d=240.18 mm, and the filtration pressure drop reaches the minimum value of 136.67 Pa.

Study of micromixing performance of a spinning disk reactor under spiral flow type

Chengjun GU Cheng SUN Dongxiang WANG

The Chinese Journal of Process Engineering. 2023, 23(7):  1035-1041.  DOI: 10.12034/j.issn.1009-606X.222273

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Spinning disc reactors are widely used in the process of intensification of micromixing such as the treatment of wastewater, synthesis of nanoparticles, and photocatalytic reactions, and the flow type transition of its surface liquid film has an important influence on the micromixing performance. The flow type transition of the surface liquid film of the disc was investigated by changing the rotational speed and flow rate, and the flow patterns were initially classified into unsteady (U), spiral flow type, transitional wave (TS), irregular wave (I) and reverse spiral wave (RS), and the regularity of the spiral wave was found by comparing the flow types with each other and deriving the existence range of the spiral flow type. The micromixing performance of the spinning disc reactor was investigated under the spiral flow type by using the iodide-iodate reaction system to characterize the microscopic mixing performance with the dissociation index (XS), and the influence of the disc rotational speed, flow rate, viscosity, flow ratio and H+ concentration on the micromixing effect of the spinning disc reactor was investigated. The improvement of micromixing performance was limited by increasing the rotational speed, and when the rotational speed increased to a certain value (ω=125.6 rad/s), the improvement of micromixing performance was limited by continuing to increase the rotational speed. Decreasing the viscosity of the liquid, decreasing the flow ratio of the liquid, and decreasing the H+ concentration were all beneficial to improve the micromixing performance of the reactor. The results of the study provide a reference for the application and optimization of the spinning disc reactor in micromixing reactions.

Study on failure probability of tempered vacuum glass under steel ball impact

Shuai GAO Gaowei YUE Minmin LI Haixiao LIN

The Chinese Journal of Process Engineering. 2023, 23(7):  1042-1053.  DOI: 10.12034/j.issn.1009-606X.222257

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The superior sound, heat, and safety performance of tempered vacuum glass (TVG) is drawing increasing attention, but more research needs to be done on the material's impact resistance and impact failure. The mechanical properties of the glass during the impact process were studied using finite element software. Tests were used to confirm the viability of the numerical simulation of the impact of a falling ball on TVG. Based on the reliability theory, MATLAB software was used to analyze the failure probability of the glass when the falling ball impacted any position at various heights. The outcomes demonstrated that there was good agreement between the outcomes of the numerical simulation and those of the experiments. It was feasible to use the physical model of TVG falling ball impact to study the impact resistance of TVG. The Tresca stress on the glass was impacted by the collision, it first rose dramatically and then fell off quickly. The Tresca tension produced by the shattered glass grew as the height of the falling ball rose. When TVG was struck, the impact traveled in the form of stress waves in all directions. After the stress wave's crest emerged at the impact area, the Tresca stress immediately dropped. Due to the uneven stress distribution on the tempered vacuum glass in a static state, the height of the ultimate falling ball in different positions of impact resistance was very different, and the supporting position had the smallest impact resistance. When a falling ball was struck at random positions on TVG at any height, the failure probability of the glass was positively correlated with the height of the ball. The closer to the support position, the greater the likelihood that the impact failed TVG, while the failure probability of the falling ball impacting TVG was lowest in the middle of the two supports.

Study on corrosion characteristics of porcelain insulator steel cap of transmission line

Hong WU Lei CHEN Jinpeng HAO Shitao LIU Yue YANG Ziyi FANG Ping LI

The Chinese Journal of Process Engineering. 2023, 23(7):  1054-1062.  DOI: 10.12034/j.issn.1009-606X.222284

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Porcelain insulator corrosion seriously threatens the safe and stable operation of transmission lines. In this work, the corrosion behavior of porcelain insulator steel caps in NaHCO3 solution, NaCl solution, and dust filtrate was investigated by electrochemical method, and the electrochemical impedance spectroscopy and polarization curve analysis showed that the electrochemical corrosion rates of NaHCO3 and NaCl solution on porcelain insulator steel caps were positively correlated with the solution concentration, the corrosion rate of steel caps was the largest in NaCl solution, and the corrosion rate in the dust filtrate increased with the increase of pollution equivalent salt density. Among them, the corrosion rate of the filtrate of contamination in the highly polluted degree area was close to that of the low concentration NaHCO3 solution. Through the comparison of the color and micromorphology of the corrosion experimental solution, it can be found that there was a deposition of corrosion products and oxidation products on the surface of the sample in NaHCO3 solution and dust filtrate, while comprehensive corrosion occurred on the corrosive surface in NaCl solution, and no obvious brown-red Fe(OH)3 deposition occurred. Therefore, the anti-corrosion of insulator metal accessories in highly polluted areas was of great significance to prevent insulator failure and pollution flashover.

Screening of ionic liquids as entrainer for separation of water+acetic acid system using COSMO-RS model

Qing LI Meng SHI Yimin GUO Ruining HE Yun ZOU Zhangfa TONG

The Chinese Journal of Process Engineering. 2023, 23(7):  1063-1072.  DOI: 10.12034/j.issn.1009-606X.222245

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The high-effect wastewater purification has become a serious problem for acetate ester production. The traditional technology for the separation of acetic acid and water including extractive distillation, azeotropic distillation and other methods, which is low efficiency in the selection of entrainer. Conductor-like Screening Model -Real Solvents (COSMO-RS) model can predict the thermodynamic properties of the fluid through quantitative calculation, which is helpful to select the high-effect entrainer for the acetic acid+water system, then simplifying operation and improving efficiency in the research. The latest research shows that organic solvents containing nitrogen and phosphorus have a good extraction effect on the water+acetic acid system. In this study, COSMO-RS model was applied to screen the high-effect entrainer for the separation of water+acetic acid system in extractive distillation, and the high-effect entrainer were specified in the ionic liquids composed of 5 phosphorus anions and 12 imidazole cations. The geometric structures of ions which were not included in COSMO software's original database were optimized by TURBOMOLE quantitative calculation module, and the solvent capacities of water in different ionic liquids, the selectivity of acetic acid to water in different ionic liquids, and the excess enthalpies when ionic liquids were mixed with water or acetic acid were analyzed. The results showed that the extraction effects of [MIM][DBP], [ODMIM][DEP], and [ODMIM][Me2PO4] were better than others. When water or acetic acid was mixed with ionic liquids, hydrogen bonding dominated the intermolecular interaction absolutely. Imidazole cations had strong ability to provide hydrogen bonding, and was easy to combine with acetic acid, so as to improve the relative volatility of water and acetic acid and achieve the purpose of separation. Comparing the excess enthalpy value, the interaction between [ODMIM]+ cation and acetic acid was the strongest intermolecular force. Finally, [ODMIM][DEP] was selected as the high-effective entrainer for the separation of water+acetic acid system. The results provide basic data for the separation of components in water+acetic acid system.

Interface characteristics and properties of 22MnB5/6061 dissimilar metal CMT+A+P fusion brazing

Xiaohui YIN Zhengying ZHU Kai CHEN Zihang CHEN Wei MENG

The Chinese Journal of Process Engineering. 2023, 23(7):  1073-1080.  DOI: 10.12034/j.issn.1009-606X.222263

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22MnB5 hot-formed steel and 6061 aluminum alloy are generally used in the automobile industry. Realizing the connection of these two materials and giving full play to the excellent properties of both materials will no longer only achieve the purpose of lightening the vehicle, but also make certain automobile safety. The low strength of aluminum/steel dissimilar welded joint has been a significant issue restricting their use. The CMT (cold metal transfer) Advanced Pulse (CMT+A+P) welding approach and ER4043 welding wire with a diameter of 1.2 mm were used in this work to achieve effective joining of dissimilar joints in 6061 aluminum alloy and 22MnB5 hot-formed steel with low heat input. The macroscopic morphology, microstructure, and interfacial properties of the fusion brazed joints were analyzed, and the fracture location and fracture morphology were observed by the usage of metallographic microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that when welding heat input increased, the melt width of fusion brazed joint grew steadily and the wetting angle rose initially and fell subsequently. The welding zone was arranged as α-Al equiaxed and Al-Si eutectic, with the Al-Si eutectic equally distributed on the α-Al grain boundary. The grain became coarse because the heat affected zone on the side of the aluminum alloy was subjected to thermal cycling during the welding process. Al and Fe atoms near the interface zone diffuse with each other along the interface layer, and generate various Fe-Al intermetallic compounds. When the heat input increases from 41.8 J/mm to 127.6 J/mm, the thickness of the interface layer grew from 1.49 to 2.85 μm. The fracture appeared at the aluminum alloy base material, the welded joint, and the interface layer, which were ductile fracture, ductile/brittle mixed fracture, and brittle fracture, respectively. The specimen with the highest tensile strength fractured at the aluminum alloy base material, exhibiting ductile fracture, and the tensile and shear loading is 3.88 kN.

Effect mechanism of calcium hydroxide on morphology of calcium sulfate hemihydrate in magnetized water

Xingtong LIN Dashi LEI Yubin WANG Shuai ZHANG Liang LI Kaiqiang HUA

The Chinese Journal of Process Engineering. 2023, 23(7):  1081-1088.  DOI: 10.12034/j.issn.1009-606X.222285

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To clarify the influence of calcium hydroxide on the morphology of calcium sulfate hemihydrate hydrothermal products in the magnetized water system, scanning electron microscopy (SEM), conductivity analysis, and X-ray diffraction (XRD) were used to characterize the calcium sulfate hemihydrate samples. On this basis, the effect mechanism of calcium hydroxide on hydrothermal products of calcium sulfate hemihydrate crystal morphology was clarified. The results revealed that calcium hydroxide with different concentrations had an extremely significant regulatory effect on the morphology of hydrothermal products of calcium sulfate hemihydrate in the magnetized water system. With the increment of calcium hydroxide concentration, the morphology of hydrothermal products first changed from fibrous to plate-like, then to columnar. In this process, granular morphology was observed, which may be a mixture of calcium hydroxide and calcium sulfate dihydrate crystals. When the concentration of calcium hydroxide was 5.0×10-7 mol/L, hydrothermal products mainly existed as fibrous. With calcium hydroxide concentration increased to 5.0×10-5 mol/L, Ca2+ inhibited the dissolution of calcium sulfate dihydrate through the common ion effect, resulting in a diminishing of SO42- in the solution. Meanwhile, OH- and SO42- competitively adsorbed on the (002) crystal plane of calcium sulfate hemihydrate crystal in the form of chemical adsorption, which was not conducive to the precipitation of growth components on the crystal plane and led to the morphology transition from fibrous to plate-like. With the concentration of calcium hydroxide further expanded to 5.0×10-3 mol/L, excessive Ca2+ concentration in the solution was beneficial to the growth of hemihydrate calcium sulfate crystals along (200) and (110) crystal planes, while OH- restrained the growth of hemihydrate calcium sulfate crystals on (002) crystal plane. Beneath the combined influence of the above two factors, calcium sulfate hemihydrate transformed into columnar. This work provides references for the preparation of calcium sulfate hemihydrate hydrothermal products with different morphologies in magnetized water systems.