Hot-dip Method Research Articles

In Situ Inorganic/Organic Protective Layer on Carbon Paper as Advanced Current Collector for Robust Li Metal Anode.

Lithium (Li) metal is regarded as the most promising anode for next-generation batteries with high energy density. However, the uncontrolled dendrite growth and infinite volume expansion during cycling seriously hinder the application of Li metal batteries (LMBs). Herein, an inorganic/organic protective layer (labeled as BPH), composed of in situ formed inorganic constituents and PVDF-HFP, is designed on the 3D carbon paper (CP) surface by hot-dipping method. The BPH layer can effectively improve the mechanical strength and ionic conductivity of the SEI layer, which is beneficial to expedite the Li-ion transfer of the entire framework and achieve stable Li plating/stripping behavior. As a result, the modified 3D CP (BPH-CP) exhibits an ultrahigh average Coulombic efficiency (CE) of ≈99.7% over 400 cycles. Further, the Li||LiFePO4 (LFP) cell exhibits an extremely long-term cycle life of over 3000 cycles at 5 C. Importantly, the full cell with high mass loading LiFePO4 (20mgcm-2) or LiNi0.8Co0.1Mn0.1O2 (NCM, 16mgcm-2) cathode exhibits stable cycling for 100 or 150 cycles at 0.5 C with high-capacity retention of 86.5% or 82.0% even at extremely low N/P ratio of 0.88 or 0.94. believe that this work enlightens a simple and effective strategy for the application of high-energy-density and high-rate-C LMBs.

Roles of Al and Mg on the Microstructure and Corrosion Resistance of Zn-Al-Mg Hot-Dipped Coated Steel.

In this work, a novel zinc-aluminum-magnesium (Zn-Al-Mg, ZM) coated steel was prepared using the hot-dip method. The microstructure and corrosion resistance of the ZM-coated steel were investigated. Compared to the conventional galvanized steel (GI), the ZM coating demonstrated a distinctive phase structure, consisting of Zn phase, binary eutectic (Zn/MgZn2), and ternary eutectic (Zn/Al/MgZn2). The corrosion resistance of the ZM-coated and GI-coated steels was evaluated by neutral salt spray test (NSST), polarization and electrochemical impedance spectroscopy (EIS). The results indicated that ZM-coated steel provided superior long-term corrosion protection in a NaCl environment compared to GI-coated steel. The scanning vibrating electrode technique (SVET) proved to be an effective method for investigating the evolution of the anodic and cathodic on the local coating surface. GI-coated steel exhibited a potential and current density distribution between the cathodic and anodic sites nearly three orders of magnitude higher than that of ZM-coated steel, suggesting a higher corrosion rate for GI-coated steel.

Corrosion Behavior of Zn-Al-Mg-Si Coatings in Sulfur Dioxide-Containing Environment

Zn-Al-Mg-Si coatings are an excellent alternative to conventional hot-dip galvanizing coatings. Their high corrosion resistance in corrosive environments containing chlorides and CO2 is well recognized. But sulfur dioxide is also an important stimulator of corrosion in the atmospheric environment. This article presents the results of microstructure (SEM/EDS/XRD) and corrosion behavior tests of Zn-Al-Mg-Si coatings obtained by a double hot-dip method on HSLA steel. The corrosion resistance of the coatings was determined in the sulfur dioxide test with general condensation of moisture (EN ISO 6988). In the corrosion test, Zn-Al-Mg-Si coatings showed twofold smaller weight loss compared to conventional hot-dip zinc coatings. It was found that the corrosion behavior of coatings was influenced by the structural components revealed in the outer layer: Al-rich dendritic and interdendritic areas with Zn/MgZn2 eutectic, MgZn2 intermetallic and Si precipitates and their electrochemical nature. The increase in corrosion resistance was caused by the formation of beneficial corrosion products: layered double hydroxides (LDHs) based on divalent Mg2+ and Zn2+ cations, trivalent Al3+ cations and SO42− anions, and zinc hydroxysulfate—Zn4SO4(OH)6∙5H2O. The presence of Si precipitates could cause pitting corrosion of coatings.

Improve the Corrosion Behavior of Galvanized Coating by Incorporation of ZrO2 Particles Using a Hot-Dip Method

Improve the Corrosion Behavior of Galvanized Coating by Incorporation of ZrO2 Particles Using a Hot-Dip Method

Microstructure and Corrosion Behavior of ZnAl12Mg3Si0.3 Double-Batch Hot-Dip Coatings

This article presents the microstructure (SEM) and corrosion behavior of ZnAl12Mg3Si0.3 (ZAMS) coatings obtained by the double hot-dip method on Sebisty steel with increased strength. On the basis of chemical composition studies in micro-areas (EDS) and phase composition studies (XRD), structural components of the coating and corrosion products formed on the coating surface after exposure to the neutral salt spray (NSS) test (EN ISO 9227) were identified. The presence of the Fe(Al,Si,Zn)3 intermetallic phase was found in the Fe-Al intermetallic layer, while in the outer layer, dendrites rich in Al and Zn were identified. In these dendrites, the eutectics of Zn/MgZn2 and precipitates of the MgZn2 phase and Si were located. The NSS test showed better corrosion resistance of ZAMS coatings compared to conventional zinc hot-dip coatings. The increase in corrosion resistance is due to the formation of favorable corrosion products: simonkolleite-Zn5(OH)8Cl2·H2O and hydrozincite-Zn5(OH)6(CO3)2, and the presence of the MgZn2 phase in the coating, which is more anodic than other structural components.

Surface modification of a Mo-substrate to form an oxidation-resistant MoSi2 layer using a Si-saturated tin bath

Molybdenum disilicide (MoSi2) is one of the most heat and oxidation resistant materials used in high-temperature applications. In this work, the feasibility of forming an oxidation-resistant MoSi2 coating using a low-temperature Sn-Si bath by the hot dipping method was evaluated. It was found that a smooth and dense MoSi2 layer can be successfully synthesized on the surface of a Mo-substrate at 700 °C to 1000 °C. Using this method, MoSi2 can be synthesized more rapidly than using conventional methods and at much low operating temperatures. The diffusion through the product layer controlled the growth of the formed MoSi2 layer, and the growth rate was fastest at 800 °C. This was due to the replacement by the larger tin atoms that led to the expansion of the lattice, allowing the faster diffusion of silicon through the silicide layer towards the unreacted Mo-substrate. Oxidation resistance test at 1150 °C for 2 h confirmed that the MoSi2 layer formed by the present method protects the Mo-substrate from rapid oxidation at elevated temperatures.

Structure and Corrosion Resistance of Coatings Obtained by the Batch Double Hot Dip Method in Eutectoid ZnAl Bath with the Addition of Mg and Si

The article presents the results of the research determining the synergistic effect of Mg and Si additives in the ZnAl23 bath on the microstructure (SEM), growth kinetics, and corrosion resistance of coatings obtained by the batch double hot dip method. On the basis of the research on the chemical composition in micro-regions (EDS) and the research on the phase composition (XRD), the structural components of the coatings with a content of 3 and 6 wt.% Mg and 0.2–0.4 wt.% Si were identified. The corrosion resistance of the coatings was compared with that of the reference coating obtained in the ZnAl23Si0.4 bath in the neutral salt spray test (EN ISO 9227), and the test with sulfur dioxide in a humid atmosphere (EN ISO 6988). The parameters of electrochemical corrosion of the coatings were determined. This allowed for the conclusion that the addition of Mg and Si to the ZnAl23 bath improved the microstructural uniformity of the coating. In the area of the diffusion layer, the presence of the FeAl3 intermetallic phase was found, while in the outer layer the dendrite of the Al-rich solution with interdendritic spaces, where it locates areas of Zn-rich solution, eutectic Zn/MgZn2 or phase separation MgZn2 and Mg2Si are located. Additions of Mg and Si stabilize the kinetics of the coating’s growth, and its course is parabolic. The conducted corrosion tests showed better corrosion resistance of the coatings obtained in the bath with Mg addition compared to the reference coating obtained in the ZnAl23Si bath. The increase in corrosion resistance results from the presence of a more anodic MgZn2 phase, which, however, may be weakened by the presence of Mg2Si phase precipitates.

Quality assessment of Fritillariae cirrhosae using portable NIR spectrometer

This paper mainly focuses on the feasibility of rapidly identifying Fritillariae cirrhosae varieties, distinguishing its authenticity and detecting its components by using a portable near infrared (NIR) spectrometer. Five different varieties of Fritillariae cirrhosae, five common counterfeits and two main components (ethanol-soluble extractives and total alkaloids) were studied. The reference values of ethanol-soluble extractives were determined by hot dip method and the reference value of total alkaloid was determined by ultraviolet–visible spectrophotometry (UV–Vis). Linear discriminant analysis (LDA) algorithm was used to identify the sources of different varieties of Fritillariae cirrhosae and the common counterfeits of Fritillariae cirrhosae, respectively. As a result, the best models seemed to be effective, with accuracy of the two models' prediction sets reaches 83.33% and 90.91%, respectively. The partial least squares regression (PLSR) algorithm was used to relate the sample spectra with the reference values of ethanol-soluble extractives and total alkaloid content. Coefficient of determination of prediction (R2p) and root mean square errors of prediction (RMSEP) obtained were 0.8562 and 0.3911; 0.6917 and 0.0117, for ethanol-soluble extractives and total alkaloid content, respectively. The results showed that the portable NIR spectrometer could evaluate the quality of Fritillariae cirrhosae with high efficiency and practicability.

Corrosion and High Temperature Oxidation Behavior of Structural Steels Coated with Aluminum Alloys

Structural steels are among the most widely used materials in today's industry. Various surface coating processes are used to protect structural steels from corrosion in atmospheric or aggressive environments. The most commonly used method is the galvanizing process based on forming zinc coating on the steel surface by using the hot dip method. Zinc coatings are insufficient to protect against corrosion, especially in chlorinated environments. Aluminum and its alloys stand out as an alternative material group to zinc in chlorinated environments. In this study, aluminum and aluminum alloy coatings, which are thought to be an alternative to zinc coating, were coated on the structural steel surface using the hot dip method. To examine how different aluminum alloys affect the corrosion and high-temperature oxidation properties of steels, nearly pure AA1050, high Cu content AA2024, and high Mg content AA5083 alloys were coated on structural steels. The coating process was carried out by dipping the structural steels into molten aluminum baths kept at a constant temperature of 700°C for 1, 3, and 5 minutes. The optimum adhesion and surface properties were obtained from dipping time for 3 minutes. The properties of coatings and intermetallic structures formed at the coating-steel interface were examined using an optical microscope, X-ray Diffractometer (XRD), Scanning Electron Microscope (SEM), and Energy Scattering Spectroscopy (EDS) systems. To examine the high-temperature oxidation properties of the coatings, the coated samples were oxidized for 24 hours at 750°C under open-air conditions, and the changes in weight were investigated. Immersion corrosion tests were performed in 3.5% NaCl solution, and corrosion losses and degradation patterns were investigated. As a result of the studies, it has been determined that the Al coatings produced by the hot dip process significantly increase the oxidation and corrosion resistance of the structural steels.

Fast synthesis of thin SSZ-13 membranes by a hot-dipping method

Among zeolite membranes with CHA structure, SSZ-13 membrane has certain advantages over all-silica CHA and SAPO-34 membranes, like easy synthesis, good stability and insensitivity to moisture, however, its separation performance is not satisfactory. In this study, SSZ-13 membranes were prepared by a hot-dipping method, where the hot contact of seeded support and mother liquor at synthesis temperature resulted into fast crystallization kinetics and thin membranes. The obtained sub-micron SSZ-13 membranes exhibited outstanding CO2–CH4 mixture separation performance, CO2 permeance ~28 × 10−7 mol/(m2 s Pa) and CO2–CH4 selectivity ~180 at 0.14 MPa and room temperature. The hot-dipping method achieved the complete separation of seeding and crystallization (or membrane growth) by preventing the contact of mother liquor and seeded support before reaching synthesis temperature. This treatment avoids any undesirable change of the seed layer before membrane growth, which may help us to correlate the membrane performance with the properties of seed layer, like seed density, thickness and seed size. On the contrary, the CHA seed layer might be dissolved partially by mother liquor during the heating process of conventional membrane synthesis, which led to thick membranes due to unsatisfactory seeding. This method could be used for the synthesis of other zeolite membranes.

Effect of Mg on the Formation of Periodic Layered Structure during Double Batch Hot Dip Process in Zn-Al Bath

The article presents the results of studies on the influence of Mg on the formation of the periodic layered structure of the Zn-AlMg coatings. These coatings were produced by the double batch hot dip method in a Zn bath and then in a Zn-Al(Mg) bath with a content of 15, 23, 31 wt.% Al and 3, 6 wt.% Mg. The microstructure of the coatings (OM, SEM) was revealed and the phase composition (XRD) obtained in two-component Zn-Al baths and Zn-AlMg baths were determined. The periodic layered structure was found to consist of alternating FeAl3 phase layers and a bath alloy (Zn + Al + Mg). Moreover, it was observed that the addition of 3 wt.% Mg reduces the thickness of the coating in baths containing 23 and 31 wt.% Al. However, the addition of 6 wt.% Mg causes complete disappearance of periodic layered structure in a bath with 23 wt.% Al. In a bath with a content of 31 wt.% Al the addition of 6 wt.% Mg creates a compact layer consisting of the FeAl3 phase containing the precipitation of the MgZn2 phase and Fe2Al5 phase. Such a structure of the coating transition layer limits the growth of the periodic layered structure in the coating.

Enabling Stable Zn Anode via a Facile Alloying Strategy and 3D Foam Structure

AbstractAqueous zinc‐ion battery (AZIB) has become a promising candidate in grid energy storage due to its low cost, environmental friendliness, and high safety. However, AZIB usually suffers from uncontrollable zinc deposition and dendrite growth as well as hydrogen evolution and passivation on the surface of zinc anode. To address the above issues, a unique 3D Zn alloy foam anode built from Zn–Sn–Pb alloy in 3D Cu foam is constructed by a facile hot dipping method. The proposed 3D Zn alloy anode, through introducing elements Sn and Pb, enhances the hydrogen evolution overpotential, reduces the corrosion current, greatly mitigates the self‐corrosion in the electrolyte, and efficiently inhibits the growth of Zn dendrite during cycling. Importantly, such Zn alloy engineering together with a 3D Cu foam current collector enables highly stable Zn storage properties. The full cell assembled using the proposed 3D Zn alloy anode and MnO2 nanosheet cathode exhibits superior reversible capacity (103.4 mAh g−1) and excellent cycling stability (capacity retention of 87% over 4000 cycles) at 1.8 A g−1.

ANALYSIS AND MICROHARDNESS PROFILE OF HOT DIPPING COATING ON LOW-ALLOY STEEL

This research is an effort to understand the morphology of the coating produced during hot dipping process in pure zinc bath based on iron–zinc phase diagram. In this investigation, zinc coating on low-alloy steel AISI 4340 samples was applied by hot dipping method followed by an annealing process. Morphological characterizations of the steel surface layer were accomplished by optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectrometry (EDS). Results revealed that the coating is bonded to the steel surface through a sequence of Fe–Zn layers namely alpha ([Formula: see text], delta ([Formula: see text] and zeta ([Formula: see text] with uniform sloping hardness profile.

Effects of different application amounts of potassium fulvic acid on yield and quality of Fritillaria thunbergii

Fritillaria thunbergii is a commonly used traditional Chinese medicine, which has the effects of clearing heat and resolving stagnation, eliminating phlegm and relieving cough. At present, it is mostly produced by cultivation, and the cultivation process requires application of base fertilizer, winter fertilizer, seedling fertilizer and late top dressing. Now farmyard manure or organic fertilizer can be used to replace the base fertilizer and winter fertilizer, but the research on the replacement of organic fertilizer has not been completed for the late top dressing. Potassium fulvate is a kind of fulvate fertilizer, which can not only regulate the growth of crops but also supplement potassium necessary for the growth of crops. In this paper, using F. thunbergii as a model plant with mature cultivation techniques, the effect of potassium fulvate on the quality and yield of rhizome traditional Chinese medicine F. thunbergii was systematically studied for the first time. HPLC-ELSD was used to determine the contents of peimine A and peimine B, hot dip method was used to determine the content of alcohol extract, and the SPAD-502 Plus chlorophyll meter was used to detect SPAD value. The results showed that applying 1.5 to 2.25 kg·hm~(-2) of potassium fulvic acid per hectare could effectively improve the yield of F. thunbergii and there was significantly difference between potassium phosphate monobasic and potassium fulvic acid in terms of quality. After the application of range 1.5 to 2.25 kg·hm~(-2) of potassium fulvic acid per hectare, the content of alcohol soluble extract of F. thunbergii was ranged 21.61% to 22.27%, the total amount of peimine A and peimine B were ranged 0.09% to 0.10%. Applying 1.5 to 2.25 kg·hm~(-2) of potassium fulvic acid per hectare could replace the conventional pure chemical fertilizer potassium phosphate monobasic, which could be used as top dressing fertilizer for the cultivation of F. thunbergii.

Preparation of high performance LiFePO4/C by extracting iron element from iron tailings by concentrated sulfuric acid hot dip method

LiFePO4/C cathode materials are synthesized by carbothermal reduction process using FePO4 as iron and phosphorus source, and starch as carbon source. The FePO4 precursor was prepared by leaching iron tailings with concentrated sulfuric acid and then leaching with phosphoric acid and hydrogen peroxide. The morphology and structure of FePO4 precursors prepared under different pH conditions were studied by using thermogravimetric-differential analysis (TG-DTA), infrared analysis (FTIR), x-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The effect of the FePO4 material on the properties of the synthesized LiFePO4 cathode was investigated by charge and discharge cycles. On this basis, the effects of different molar ratios of C and LiFePO4 on the performance of synthetic product LiFePO4/C were studied using starch as carbon source. The results show that the FePO4 precursor prepared under the condition of pH 2 is the raw material, and the LiFePO4/C cathode material synthesized by adding 45% carbon has the best performance. The first cycle discharge capacity reached 142.6 mAh g−1 at a current density of 0.1 °C, reaching 83.9% of its theoretical capacity. This work proposes a novel and effective method to utilize the iron tailings.

Interfacial reaction between solid Ni and liquid Al in tens of seconds: Dissolution kinetics of solid Ni and formation of intermetallic compounds

The interfacial reaction between solid Ni and liquid Al, such as dissolution behaviors of solid Ni and formation mechanisms of intermetallic compounds, are not thoroughly clarified yet, especially under the conditions of short holding time and high reaction temperature. In this study, a hot-dip method was designed to investigate the isothermal interfacial reaction mechanism of solid Ni and liquid Al at temperature of 700 °C, 800 °C and 900 °C for 0–40 s. The dissolution behavior of solid Ni in liquid Al was analyzed. The dissolution rate constant, KNi, and dissolution activation energy, Ea, were calculated. The microstructure analysis with scanning electron microscope (SEM) and transmission electron microscopy (TEM) revealed that the dissolved thickness of solid Ni in pure liquid Al has linear relationship with the reaction time. The microstructure of the reaction interface consisted of Ni, Ni based solid solution, Al3Ni2 layer, adhered Al3Ni layer, free Al3Ni, Al3Ni + Al eutectic structure and Al. Ni based solid solution structure firstly formed at the holding stage. Nano-scale Al3Ni2 and irregular adhered Al3Ni appeared at the interface during fast cooling stage.

The effect of Lead (Pb) Hot dipping on seawater corrosion rate in ASTM A36 Steel

Corrosion attacks are a scourge on offshore industrial structures. The hot dipping method is a common method used in protecting submerged material from corrosion attacks. The main objective of this study was to investigate the effect of variations in hot dipping time in Lead (Pb) on corrosion attack by performing corrosion rate test, weight loss measurement, microstructure analysis and fatigue test. The results revealed that the longer the hot dipping was carried out there was a decrease in the value of corrosion rate and weight loss of ASTM A36.

Establishment of extraction method for Gardeniae Fructus extract and its application in evaluating different Gardeniae Fructus decoction pieces

In this experiment,the gradation analysis method was used to evaluate the quality of different pieces of Gardeniae Fructus through the extraction rate difference and the difference analysis of the main components in the extract. In this experiment cold-dip and hot-dip methods were used to compare the yield of Gardeniae Fructus extract and the content of chemical constituents with water,25%,50%,75% and 95% ethanol fractions. By weighted calculation,the optimal extraction method of Gardeniae Fructus was determined,and this was verified by practical application. RESULTS:: showed that for the water-soluble extract,cold dip method was better than the hot dip method; and for alcohol-soluble extract,75% ethanol under cold dip method was best. The verification results showed that water-soluble extracts under cold dip methods could be used to significantly distinguish the raw Gardeniae Fructus( GF) and processed( stir-baked) GF( GFP) collected from the market. Meanwhile,this method could be also used to distinguish the same batch of GF,GFP and carbonized GF( GFC) with significant differences,respectively( P<0. 05). Ethanol-soluble extract can be used to clearly distinguish GFP and GFC pieces in the same batch( P<0. 05). The results of content determination showed that the variation coefficient of components in GF processed products was higher than that in extracts,and the content of hydroxygeniposide was the most significant component between GF and its processed products. It is suggested that the method of water-soluble extract of GF and the determination of the content of gardoside should be combined together to evaluate the quality of GF and its heat processed products.

Temporal and spatial variation of polysaccharides and alcohol-soluble extractives of Polygonatum cyrtonema

To reveal the variation of polysaccharides and alcohol-soluble extractives of rhizomes Polygonatum cyrtonema from different producing areas,growing years,and harvesting seasons,25 wild samples from the main producing areas( provenances) of China and 6 artificial cultivated samples were collected and detected. The 6-year-old rhizomes of the artificial cultivation were gathered from Qingyuan,Zhejiang every 2 months during 2016 to 2017. Anthrone-sulfuric acid method and hot-dip method were used to determine the contents of polysaccharides and alcohol-soluble extractives respectively. The results showed that provenances,age sections and harvesting seasons affected the quality of Polygonati Rhizoma significantly. The content of polysaccharides from different provenances varied from 6. 96% to 20. 09%,and the content of extractives varied from 32. 08% to 78. 99%. The polysaccharides and extractives' content were the highest at 2-year-age sections,active constituents accumulation peaked in the third year,then decreased significantly with age increasing. The contents of polysaccharides and extractives accumulated were highest when aerial parts,up to 15. 39% and 78. 99% respectively. In summary,the activity and consistency fluctuated with producing areas. while such phenomenon indicated a huge potential of breeding. Additionally,the results showed that collecting Polygonati Rhizoma in February or August as herbal textual recorded were unreasonable,neither in spring or autumn according to the Chinese Pharmacopoeia( 2015 edition). Because these collecting periods didn't have the highest contents of polysaccharides and extractives. Therefore,based on phenological options,the rhizomes of P. cyrtonema should be harvested when the aboveground parts had just withered.

Structures of coatings obtained in a ZnAl23Mg3Si0.4 bath by the batch hot dip method

Structures of coatings obtained in a ZnAl23Mg3Si0.4 bath by the batch hot dip method