bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of rope zone of multi-point multi-layer winding lifting system in ultra-deep mine
Authors: Wang H L , Gong X S , Deng Y , Cheng X R
Published: March 2020

In the mining of ultra-deep resources, workers need to use ultra-deep mine lifting equipment to lift minerals, in order to ensure the synchronization between ropes during the lifting process. The article analyzes the change in the length difference between the steel ropes from the perspective of rope groove deformation. This work considers the influence of the weight of the vertical rope, analyzes the variation of surface load on the rope groove, establishes the expressions for deformation at the rope groove, and analyzes the influence of rope groove deformation on the difference in the length of the wire ropes. The results show that in the ultra-deep mine multi-layer winding lifting system, the rope groove load varies with the height of the rope. The rope groove deformation curve is similar to the quadratic function curve, and the maximum point is close to the middle position. Based on these results, the article studies the influence of the imbalance between the circles, the winding gap, and the rope-out method on the difference in the length of the wire ropes. It is found that, the extent of the lack of synchronization between the rings has a greater influence on the change in the length of the wire rope, and a wire rope wound under the reel is more conducive to ultra-deep mine lifting.
Influence of resin content on mechanical properties of composite laminates
Authors: Yang K , Yue Y M , Zhao W P , Liang Y , Mei L , Xue J J
Published: March 2020

The resin content has an important effect on the mechanical properties of composite laminates. In order to study the influence of different resin content on the mechanical properties of composite laminates, the mechanical properties of the standard samples of carbon fiber composite laminates with resin content of 30, 35, 40, 45, and 50% have tested, and the fracture regions of the samples have scanned by scanning electron microscope. The test results show that the tensile strength of the carbon fiber composite laminates increases first and then decreases with the change of resin content. When the resin content is 35%, the tensile strength reaches the maximum. Moreover, the elastic modulus decreases with resin content.
Metallurgical modeling of intergranular HAZ liquation cracking during laser welding newly developed crystallography-dependent aerospace materials. Part II: Grain boundary alloying segregation of microstructure modification
Authors: Gao Z G
Published: March 2020

Metallurgical modeling of the nonequilibrium grain boundary segregation was coupled with a nonequilibrium weld pool solidification to numerically analyze the contributing factors to liquation cracking resistance. The effect of the welding conditions, material composition, and average grain size on the kinetics of the grain boundary segregation in the Inconel 718-type nickel-based superalloy during laser welding were optimized. The grain boundary segregation of boron near the fusion boundary is of particular interest, and is closely correlated to the intergranular heat-affected zone (HAZ) liquation cracking. It is indicated that the low heat input, fine-grained material and full penetration contribute to the reversible desegregation of boron and suppress the grain boundary segregation of boron to significantly minimize the segregation-induced grain boundary liquation and improve the weldablity. The subsolidus temperature due to nonequilibrium weld pool solidification is capable of ameliorating the segregation kinetics to reduce the HAZ grain boundary segregation. Intergranular HAZ liquation cracking is evitable with a crack-free weld without using filler wire. The grain boundary segregation decreases and the threshold tensile stress of solid-liquid interfacial decohesion across the intergranular liquid film simultaneously increases in the recrystallized HAZ during the weld shape change from partial penetration to full keyhole penetration. Furthermore, the numerical analysis results are verified indirectly by the experiment results of the total crack length. In addition, this metallurgical modeling is also applicable for the alloying segregation behavior prediction of other nickel-based superalloys with similar metallurgical properties.
Investigating the influence of flowing fluid on the resistance of materials to sulfide stress cracking
Authors: Rihan R , Al-Wakaa B , Tanoli N
Published: March 2020

The study aims to investigate the effect of flowing fluid on the susceptibility of metals and alloys to sulfide stress cracking (SSC) using the fracture mechanics circumferential notched tensile (CNT) specimen. The CNT specimen has never been used in the presence of flowing fluid. A novel testing flow loop was invented for performing the experimental work. The new testing rig can be used for determining the stress intensity factor (KI), threshold stress intensity factor (KIssc), and crack growth rate in flowing fluid for different materials in different corrosive environments at different temperatures. The testing flow loop has been registered as a patent in recognition of its novelty and practical applications in several industries. The experimental conditions were testing the resistance of heat treated P110 steel to SSC in deaerated stagnant and flowing solution containing 0.01 M Na2S2O3 (as a source for H2S) and 3.5 w% NaCl at room temperature. The experimental results show the heat treated P110 steel was susceptible to SSC in stagnant solution, while it was not susceptible in flowing fluid.
The application of broken expanded polystyrene particles in thermal insulation coating material
Authors: Zhang Y , Li S Y
Published: March 2020

Thermal insulation coating material is a kind of green thermal insulation material with high efficiency, which is used in the exterior wall of buildings and has many advantages such as strong sticking strength, low heat conductivity, flame retardancy and water resistance. The aggregates, main insulation components, play an important role in the thermal insulation coating material. Expanded polystyrene (EPS) particle is a good material, which can be used as an aggregate for its low thermal conductivity coefficient of 0.029 W/(m·K). Accordingly, by using the broken particles prepared from wasted expanded polystyrene, (EPS), the abandoned resources can be recycled and used again, resulting to the reduction of “white pollution” and cost. In the environment of establishing an economical social, it has huge significance and broad market prospects. Studies have shown that the broken expanded polystyrene particles and expanded perlite have the lowest thermal conductivity according to the weight ratio of 1:2.96. By using wasted expanded polystyrene particles and expanded perlite as aggregates, the thermal insulation coating material has good crack resistance, thermal insulation and compressive strength.
Acceptability analysis for determining the average grain size by ASTM E112 standard
Authors: Bi Geping , Guan Yong , Chen Xiaoyu , Tan Wenhua , Huang Wenniu , Gao Yuqing , Wang Meimei
Published: March 2020

In this paper, the ASTM grain size number of aluminium alloy specimen was determined by the Abrams three-circle procedure and planimetric procedure, according to ASTM E112-13 standard, and the measurement uncertainty was evaluated. Based on the test data and theoretical analysis, the %RA limit for acceptability of ASTM E112 grain size measurement was discussed. The following two corrections are made: when G is determined via the Abrams three-circle and planimetric procedures, the %RA limit should not exceed 8.4% and 16.1%, respectively, instead of earlier regulated value of 10%.
Influence of additives on polycarbonate/acrylonitrile-butadiene -styrene blending for fused deposition modeling
Authors: Chen Y W , Yin Y , Feng L , Ling X , He J K , Lai W W , Wang Y
Published: March 2020

This study aimed to investigate the use of polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS), PC/ABS/maleinized acrylonitrile-butadiene-styrene copolymer (ABS-g-MAH) composite, PC/ABS/methyl methacrylate-butadiene-styrene (MBS) composite, and PC/ABS/organic montmorillonite composite for fused deposition modeling experiments and compare their mechanical properties. The tensile test results of specimens printed with different orientations revealed that PC/ABS compatibilized by 7% MBS exhibited the highest tensile elongation of the samples built in a horizontal orientation. Moreover, PC/ABS compatibilized by 6% ABS-g-MAH showed the greatest tensile strength between the three composite specimens printed with horizontal orientations. The notch impact test results revealed that PC/ABS/ABS-g-MAH and PC/ABS/MBS composite specimens printed with horizontal and vertical orientations were much stronger than the other systems.
Application of GeTe phase-change films in the directly heated two-port switch design
Authors: Qu S , Zhang J H , Gao L B , Chen H W , Li X , Wang J M
Published: March 2020

Phase-change (PC) materials offer the property of thermally induced reversible change and exhibit different resistance values due to the structure changes between crystalline and amorphous phases. In this work, GeTe films with a thickness of 100 nm were deposited on the glass substrates by radio-frequency magnetron sputtering and annealed at different temperatures. The XRD analysis showed diffraction peaks corresponding to the rhombohedral structure of c-GeTe (021), (200), (202), and (220), respectively. Upon annealing at 300 and 340°C, the rhombohedral structure would transform into a rock salt structure. The Raman analysis revealed that a-Ge-Te covalent bond is the mixed structure of tetrahedron and defective octahedron changing into tetrahedral cells. The resistivity declined sharply from 0.72 to 3.8× 10−6 Ω-m, whereas the Hall mobility of holes sharply rose to 300 m2/Vs. Based on the above films, a two-port directly heated switch device was designed and fabricated in sandwich structure to verify its phase-change characteristics. Low-resistance state was converted from crystallization with a 20ns 9V voltage pulse, while high-resistance state was by passing a 2 μs 2V voltage pulse. The on/off resistance ratio of switch could reach five orders of magnitude, while the switch state remained stable after the process termination. The results obtained strongly suggest that GeTe is a promising material for RF switches.
Formulation of EPDM heat-resistant V-ribbed belt
Authors: Ling X , Hu Y L , Lai W W , Wang Y
Published: March 2020

As a major pillar industry of the national industrial economy, the automobile industry has been greatly affected by the increasingly strict requirements of environmental protection in recent years. With the constant promotion of new energy vehicles, further compression of costs and improved performance will enable enterprises to occupy a place in international competition. In terms of the belt material of automobile engines, HNBR and EPDM, which are better in performance, are gradually replacing the traditional CR to adapt to the more demanding working environment. Compared with HNBR, EPDM is cheaper. In this paper, the effects of carbon black N330 and nylon staple fiber and their dosage on the properties of EPDM wedge rubber were studied by orthogonal test method to find the best formula. Studies have shown that the nylon fiber content has a great influence on the physical properties of EPDM wedge rubber, and comes to the influence of carbon black N330 content. The interaction between them is not obvious. When the content of the nylon fiber is 5phr and the content of the carbon black is 65 phr, the rubber wear rate after vulcanization is 15.5%, and the storage modulus at 120°C is about 60% at room temperature, its strength, heat resistance and aging resistance are excellent.
Mitigation of uncommon peel-off defects in galvanized steel sheets
Authors: Fang F , Zhang W H , Chen Y M , Zhou W Q
Published: March 2020

Galvanizing defects occurring in hot-and cold-rolling procedures were studied by scanning electron microscopy and focused ion beam, and analyzed via the JMP software. The results show that, among the 200 bright spots dispersed along the hot dipping steel plate, the defect may be misidentified as zinc slag by the representation of coating surface, but there exists a tiny peel off on the matrix without oxide particles under each spot. Upon partial removal of zinc coating, a tiny iron film outcropped from the coating was revealed. As some of iron films are not adhered to the matrix, such outcrops are not detected. The cross-sectional morphology shows the formation of inhibition layer, with no oxide between the peel off and matrix. The relative cold and hot rolling plates are also analyzed to trace the source, that the defect is inherited from hot rolling process according to the results. By using JMP to calculate the relationship of hot rolling parameters with the defect, slab heating temperature is concluded as a strong correlation condition. The high slab heating temperature ensures smooth rolling procedure, but the intergranular binding force is too low, which enhances the coating surface separation from the matrix. After reducing the slab heating temperature from 1350 to 1300°C or lower, and optimization of descale and pickling parameters, the occurrence ratio of bright spot defects caused by peel-off was significantly reduced.
Numerical simulation of force characteristics and contact loss of high-speed railway subgrade
Authors: Wang Y H , Xiao H , Lv Y X , Lv S
Published: March 2020

In order to explore the dynamic stress distribution, attenuation characteristics of subgrade under high-speed train load, a three-dimensional solid model was established by the ABAQUS finite element software, and the dynamic stress characteristics of subgrade of high-speed railway were calculated and analyzed. The research results show that: The distribution of additional dynamic stress on the surface of subgrade is close to elliptical, and the distribution on the cross section is similar to saddle-shaped; the peak value of stress appears below the rail. The additional dynamic stress of the subgrade has no superposition effect between the front rear bogie and the rear front bogie of the two trains. The additional dynamic stress distribution of the subgrade surface can be regarded as four stress waves that do not overlap each other. When the contact degradation shape of the subgrade gravel and the track structure concrete base is assumed to be rectangular, the aspect ratio is between 2 and 3.3. With the deterioration of the contact state, the maximum additional dynamic stress of the surface layer of the subgrade is 120 kPa.
Interfacial reactions and structural properties of explosively welded titanium/copper plates
Authors: Paul H , Chulist R , Miszczyk M M , Cios G , Galka A , Skuza W , Petrzak P , Mania I
Published: March 2020

In this study, the effect of post-processing heat treatment on the interface morphology and kinetics of intermetallic phase growth in titanium/copper bimetallic sheets were analyzed using a scanning electron microscopy and mechanical testing. Ti/Cu composite was fabricated by explosive welding. Then, clads were subjected to the post-welded annealing at 973 K for times ranging between 15 min and 100h. In the as-bonded state, the interface shows a wavy character with a limited number of melted zones, which are mostly composed of phases that are not observed in the Ti-Cu equilibrium phase diagram. Short-term annealing is shown to transform non-equilibrium phases into equilibrium ones, such as TiCu4 and Ti3Cu4. For longer annealing times, the growth of four intermetallic sublayers (Ti2Cu, TiCu, Ti3Cu4, and TiCu4) distributed along the entire interface is detected. However, the growth kinetics of particular sublayers was different. Volume fraction estimation of intermetallic phases at annealing times under study revealed the largest thickness for TiCu and TiCu4 phases. The nano-hardness of intermetallic sublayers was found to drop with the Ti content.
Analysis of factors influencing the steel sheet surface waviness in cold rolling process
Authors: Guo J , Meng Q G , Zuo H X
Published: March 2020

In order to study the influence factors of steel sheet surface waviness in cold rolling process, using coherence scanning interferometry, the surface waviness with different cold rolling processes had been investigated at room temperature, and without condensation according to relevant standard. The results show that the surface waviness of the typical steel was successfully evaluated, while the mill reduction rate, working roll cycle, and temper rolling elongation were found to be the most informative for surface waviness parameters Wa0.8
and Wsa1-5
It was found that the surface waviness parameters Wa0.8
and Wsa1-5
sharply increased with increasing rolling reduction rates in rolling process, and vice versa. Moreover, in the continuous annealing process, finish rolling temperature had almost no effect on the waviness. In temper rolling, the surface waviness parameters Wa0.8
and Wsa1-5
gradually increased with elongation and dropped with increasing working roll period. Ultimately, it was proved that the control measures to improve the surface waviness of steel plate in cold rolling process successfully improved the product surface quality.
Design and simulation analysis of an aerospace damper
Authors: Wang Q L , Wang Q X , Jiang H J , Lin Y H , Zhou X H
Published: March 2020

In this paper, viscoelastic materials are used to attenuate vibration for the optical remote sensor and satellite base. Flexible-base single-degree-of-freedom vibration attenuate system model is built considering that the satellite base is not rigid. The transfer ratio of the vibration damping system when the satellite platform foundation is non-rigid is obtained by using the four-terminal parameter method and the mechanical impedance method. Furthermore, the effects of mass ratio, fundamental frequency ratio, basic damping ratio and damper damping ratio on the vibration attenuate efficiency are discussed. According to the properties of integrated space optical remote sensor and satellite base, the optimum parameter combination between damping ratio and vibration attenuate efficiency is obtained. The design schemes of the viscoelastic material damper are refined using the simulation analysis results.
Low-frequency band gaps in Y-type phononic crystals
Authors: Ma X F , Xiang J W
Published: March 2020

In this paper, an Y-type of locally resonant phononic crystal (LRPC) material model is analyzed in detail. Some geometric parameters of the material model are investigated using FEM to assess the trends of band gaps (BGs). The BGs results show that the material model can open a low-frequency BG less than 200 Hz. When the lattice constant of the material model cell is determined, the geometrical parameters of scatterers are found to be the key to open BGs. The results show that the effect of the scatterer on BGs is studied by adjusting the two ratios (the ratio of the square bottom edge length to height of the scatterer composed of lead and the ratio of the square bottom edge length to height of the scatterer composed of aluminium), respectively. The changes of the two ratios have little effect on the upper edge of BGs. Similarly, the change of the ratio of the scatterer composed of aluminum has little effect on the lower edge of BGs. However, the variation of the ratio of the scatterer composed of lead can make the lower edge of BGs lower and increase BGs width. The vibration and noise reduction devices with different working frequencies can be designed by adjusting the geometric parameters of the scatterer.
Band gaps of a fan-like solid-fluid phononic crystal
Authors: Zhai H F , Xiang J W
Published: March 2020

The vibration problem has a serious impact on modern life. The phononic crystal (PHC) is a periodically arranged composite material, which has good vibration attenuation capability because of its band gap (BG) characteristics. Most of available PHCs are limited to solid structures and the application ranges are limited. In this paper, a new fan-like solid-fluid PHC structure is proposed to supress vibration in special environment. Firstly, the unit cell of fan-like PHC is built and the corresponding band structure is further calulauted by finite element method (FEM). The band structures reveal that this fan-like PHC structure has four BGs below 10000 Hz. In order to illustrate the functionality of the fan-like PHC structure for vibration attenuation, the frequency response function (FRF) of a finite fan-like PHC structure is calculated. The FRF shows that there are strong attenuations in the ranges of BGs. Finally by adjusting the side length of the square inclusion, the influence of the filling rate of the scatterer on BGs is studied. This new PHC provides new ideas for the vibration attenuation of builds at the riverside.
Electrochemical analysis of the inhibition performance of glucobiogen on low-carbon steel in neutral chloride solution
Authors: Loto R T , Fajobi M , Oluwole L , Loto C A
Published: March 2020

The inhibition performance of glucobiogen (GBN) on low-carbon steel (LCS) corrosion in neutral chloride solution (3.5% NaCl in H2O) was evaluated by potentiodynamic polarization, metal weight loss measurement and optical microscopy characterization. Data obtained showed GBN effectively inhibited the LCS corrosion with inhibition efficiency exceeding 80 and 90% from potentiodynamic polarization test and weight loss measurement. GBN, at lowest concentration performed poorly with inhibition efficiency value below 50%. The inhibition performance of GBN showed mixed type inhibition effect with higher tendency for anodic inhibition from relative shift in corrosion potential. Inhibitor adsorption on LCS was determined to be physisorption with respect to the Langmuir and Frumkin adsorption isotherm. The optical microscopy characterization revealed that GBN hindered the formation of corrosion pits and general surface deterioration of LCS.
Analysis of nuclear radiation damage effect on typical materials
Authors: Sun S H , Xie X , Wu F
Published: March 2020

In order to evaluate the effects of nuclear radiation on several typical materials, the mathematical models of radiation damage characteristics of three materials are established based on the analysis of radiation environment and damage forms. In order to simplify the calculation, the principles and indexes of damage estimation are determined according to the radiation damage process of three typical materials: polymer materials, high-energy explosives, and metal materials. The results show that the pure nuclear radiation environment has no obvious effect on the properties of three typical materials. It lays a theoretical foundation for radiation hardening of devices.
Investigation of processing factors affecting flexible heating wire by coating polyester yarns with carbon nanotubes
Authors: Xiao Y , Zhang L R , Li L X
Published: March 2020

A method for preparing a flexible heating wire coated with carbon nanotubes on a surface of a polyester yarn is proposed in view of the problems of poor flexibility and water washing resistance of the existing heating wire. Based on the flexible heating wire forming system, the orthogonal test method was used to study the effects of process parameters such as solution concentration and polymer content on the formation of flexible heating wire; the prepared heating wire was subjected to resistance measurement, microscopic morphology observation, heating and washing resistance tests. The results show that the optimal parameter parameters for the preparation of flexible hot wire is A3B3C2D2. In this combination, the polymer content is 15 g/L and the heating wire resistance is 180.5 Ω/cm. Moreover, the photomicrograph shows that the surface has a conductive layer composed of polymer and carbon nanotubes, which has no obvious protrusions and breaks; the surface of the parallel mesh structure can obtain a heating temperature of 52.2°C at a voltage of 12 V; the resistance of heating wire does not increase with latter washing after the first washing.
Application of confocal 3D-MXRF technology to the 3D elemental analysis and surface topography imaging of samples
Authors: Xiang Z J , Meng Z Y , Liu Z G , Pan K , Zhao W G , Zhou P , Li Y
Published: March 2020

X-ray fluorescence analysis technology (XRF) is widely used in many fields. In this experiment, a three-dimensional confocal microbeam X-ray fluorescence analysis (3D-MXRF) spectrometer built by the laboratory is used to perform deep scanning on single element sample, surface coated sample, and ceramic sample, etc., the new spectrometer has deeper probing depth and better ability to resolve adjacent elements in the sample. The distribution of three-dimensional elements of samples is analyzed and explained. And the surface topography imaging of two samples is performed, and the newly constructed confocal 3D-MXRF was found to have a higher microscopic resolution, which plays a potential role in the popularization of surface inspection and 3D element analysis of industrial products.
Effect of SnO2 content on properties and microstructure of Ag/SnO2 electric contact materials
Authors: Wang J B , Qiu H H , Si F , You Y B , Liu S T , Matsumoto N H
Published: March 2020

In order to explore the effects of SnO2 content on the properties and microstructure of Ag/SnO2 electric contact materials with low silver content. A series of Ag/SnO2 electric contact materials with different SnO2 content were prepared and their arc erosion properties and physical properties were tested. The results show that with the decrease of Ag content, the hardness of Ag/SnO2 contact materials increases, and the conductivity and density decrease. When the Ag content is 88%, Ag and SnO2 enrichment zones are formed on the surface of the Ag/SnO2 contact material after arc erosion test. When the silver content is less than 82%, the surface microstructure of the Ag/SnO2 contact material after arc erosion is uniform, and no obvious Ag and SnO2 enrichment zones were formed, but cracks and pores increased.
Hardening and precipitation of a commercial 6061 Al alloy during natural and artificial ageing
Authors: Chen Y , Lu B Q , Zhang H A
Published: March 2020

In this study, the precipitation and hardening of a commercial 6061 Al alloy during the combined natural and artificial ageing are analyzed, in order to maximize the alloy hardness by adjusting ageing time and temperature. The samples were solution-treated at 540°C for 2 hours, followed by water quenching. An artificial ageing was performed at 180, 200, and 220°C during a period from 2 min to 12 h. Natural ageing at room temperature during 12 h was performed simultaneously with the artificial one at different elevated temperatures. The Vickers hardness values of solution-treated and aged samples were measured. Precipitates were characterized via the X-ray diffraction and scanning transmission electron microscopy equipped with the energy dispersive X-ray spectroscopy. The highest hardness values were exhibited by samples that were naturally aged for 12 hours and artificially aged for 24 hours at 200 and 220°C. The hardness improvement was found to be controlled by the formation of β” phases before the peak ageing.
State-of-the-art applied research on conductive composites
Authors: Hu C Q , Huang Y M , Yang J S , Yu Q , Sun M
Published: March 2020

The article introduces the types of conductive composites and analyzes several kinds of their conductive mechanisms based on the percolation theory, quantum tunneling effect, effective medium, and field emission theory. The current research progress concerning the effects of conductive materials’ matrix, conductive fillers, and doping on them is discussed in detail. Available preparation methods and applications of conductive composite materials are summarized. A future research direction on the refinement of conductive composites is outlined, which implies the development of new matrix systems and conductive fillers with higher and more stable electrical conductivity.
Construction and application of a micro-area polarized energy dispersive X-ray fluorescence spectrometer with polycapillary X-ray lens in a conventional laboratory
Authors: Zhou M , Li Y D , Wang X Y , Duan J Y , Luo H , Ye L , Lin X Y
Published: March 2020

The polarized energy dispersive X-ray fluorescence analysis method can effectively reduce detection limits by improving the signal-to-noise ratio. However, the lack of high-power density and small analysis area of the polarized X-ray beam has hindered more accurate analysis of samples in conventional laboratory. A polycapillary X-ray lens can be applied to micro-area analysis. Therefore, a micro-area polarized energy dispersive X-ray fluorescence spectrometer based on a bent highly oriented pyrolytic graphite and a polycapillary X-ray lens is proposed. The polarization degree of the polarized X-ray beam is 99.76% and its focal spot size is 338.8 μm × 404.5 μm. The new spectrometer feasibility was proved by effective production of high-resolution element distribution maps of a holly (Ilex chinensis Sims) leaf sample.
Corrosion evolution of electric power equipment metal materials under industrial pollution environment with high heat and high humidity
Authors: Ren X , Zhong Y , Hao J , Wu G L , Wang Q
Published: March 2020

To investigate the atmospheric corrosion characteristics of metal materials of electric equipment in the atmospheric environment with high humidity and high chlorine industrial pollution, atmospheric accelerated corrosion tests of a typical power metal Q235 carbon steel and galvanized steel were carried out by the salt spray method. The corrosion kinetics, corrosion products, and morphology of both materials were investigated by the weight loss method, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The corrosion rate of carbon steel is larger than that of galvanized steel, and both drop with time. NaHSO3 promotes the formation of α-FeOOH in the corrosion process of carbon steel. The high-humidity and high-chlorine environment is not conducive to the formation of Fe3O4. The interaction of NaHSO3 and NaCl promotes the generation of corrosion products, mainly NaZn4SO4(OH)6Cl·6H2O, in galvanized steel by pitting corrosion.
Study on microstructure and texture of high-strength plastic cold-rolled dual-phase DP980 steel
Authors: Wang W W , Liu L , Li G Y
Published: March 2020

In order to improve the strength and plasticity of cold-rolled dual-phase DP980 steel, the relationship between process structure and properties were systematically studied by adjusting continuous annealing process parameters. The microstructure, recrystallized grains, phase distribution, and texture of different phases at different annealing temperatures were analyzed by OM, SEM, and EBSD. At the same time, the effect of continuous annealing temperature on the strength and plasticity were studied by mechanical tensile tests. The results obtained show that by optimizing and adjusting the continuous annealing process, not only a small amount of residual austenite can be obtained on the structure of cold rolled ferrite and martensite dual phase steel, but also recrystallized grains can be refined. Finally, cold-rolled DP980 steel with YS/TS < 0.5 and high elongation A50 < 15% can be obtained, and its strength/plasticity balance can be increased to 15-20 GPa%, which is also favorable for its formability.
Geometric accuracy of rapid prototyping technologies using laser scanner and coordinate measurement machine
Authors: Dardzinska A , Fiedorczuk K
Published: March 2020

In this paper we present a prototyping method used in medical data. 3D printing technology is extremely important, especially in medical area. Using 3D printing in preoperative treatment planning seems to be a proper solution in personalized medicine, contributing to improving healthcare system quality. Medical measurements methods on living bones, with respect to their natural environment are still unknown, the basic research includes mainly the measurement of landmarks using a digital caliper, where the linear measurement is taken between the marked points. Another way is to use a coordinate measuring machine. Most often, the accuracy measurement methods are based on marking landmarks on the object, which are collected by a machine, and then performs coordinate measurements of points. In our research we focus not on individual points of the model but on the measurement of whole objects, we prepared materials, and printed the model in 3D technology in different technologies and on different devices: FDM, PJ, SLM. On the basis of our work we conclude there is no best RP technique for making medical models. Due to the criterion of model accuracy, PolyJet is one of the most suitable technologies for medical modelling. The CJP method is the most appropriate for the cost of making a model. Due to the type of material the FDM method is the most suitable for medical applications. 3D printing technologies provide physicians, engineers and scientists with the ability to create customized solutions for a variety of conditions.
Gold nanoparticle-enhanced amplified spontaneous emission of laser dye molecules in diode-pumped organic solid-state lasers
Authors: Lin W J , Li Y L , Lan W X , Liu K P , Wei B
Published: March 2020

Gold nanoparticles (AuNPs) were introduced to enhance surface-amplified spontaneous emission of laser dye molecules, 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped N,N’-bis-(1-naphthyl)-N,N’-diphenyl-1,1’-biphenyl-4,4’-diamine (NPB), taking advantage of localized surface plasmonresonance (LSPR) effect and scattering effect. With emission received from the back surface of the substrate, the optically pumped gain medium with AuNPs, exhibits higher peak intensity, lower threshold, and better Q-factor of when compared with the neat gain medium without AuNPs. Moreover, to realize an organic solid-state laser pumped by electroluminescence emission in an integrated organic light emitting diode (OLED), NPB: DCJTB was embedded as color conversion-hole transport layer (CC-HTL). The AuNPs deposited on the ITO glass substrate of the OLED were also employed to enhance the photoluminescence of the CC-HTL. The maximum luminance, current efficiency and power efficiency improved by 21.55%, 21.90% and 42.11% at 150 mA/cm2 of AuNPs-OLED, respectively, compared to the OLED without AuNPs. These results were attributed to the enhanced hole injection caused by AuNPs as well as LSPR and scattering effects. The introduction of AuNPs provides a simple and promising method to realize diode-pumped organic solid-state lasers.
Experimental study and statistical analysis on corroded steel bars
Authors: Chang Y , Zhang L F , Gao P W , Tian Y L
Published: March 2020

Bearing capacity and durability of corroded steel bars is strongly deteriorated, and the degradation of mechanical properties versus corrosion ratio is topical. Given the random nature of corrosion process, stochastic method can be used to describe mechanical performance of corroded steel bars. In this paper, to simulate marine tidal zone environment, steel bars corroded by chloride solution under dry-wet cycling are studied experimentally, while mechanical performance deterioration of corroded steel bars is analyzed statistically. The corrosion ratios of specimens are found to increase over time for several phases, while their strength dropped with corrosion ratio. The residual nominal strength to corrosion ratio of steel bars is found to be well fitted with the Gumbel distribution, which parameters are calculated and discussed in detail.
Study on microstructure and mechanical properties of as-cast Mg-Zn-Sn-xCu(x=0,0.5,1.0,1.5wt.%) alloys
Authors: Liu Y H , Ma M L , Zhang K , Li X G , Li Y J , Shi G L , Yuan J W
Published: March 2020

In this paper, with the help of optical microscope, X-ray diffraction, scanning electron microscope and mechanical testing machine, the microstructures of ZT63-xCu (x=0,0.5,1.0,1.5wt.%) magnesium alloys were investigated and their mechanical properties were explored. It was found that the structure of as-cast alloys presented a typical dendrite morphology. The eutectic structure was refined by the addition of a certain amount of Cu, When Cu content continued to increase, the volume fraction of the eutectic structure increased and its continuity enhanced. The alloy without Cu addition was composed of α -Mg, MgZn2 and Mg2Sn phases. With the addition of Cu elements, MgZnCu phase was formed in the alloy, in addition to α-Mg, MgZn2 and Mg2Sn phases. With the increase of Cu content, the volume fraction of MgZnCu phase increased, and the proportion of MgZn2 phase gradually decreased. ZT63 alloy had the best matching of mechanical properties, its tensile strength and yield strength were 231Mpa and 80Mpa respectively, and the elongation reached 14.5%. With the increase of Cu, the mechanical properties of the alloys declined. When the Cu content is 1.5wt.%, tensile strength of the alloy decreased to 174Mpa, and the elongation was only 7%. The reduction of mechanical properties was related to the increase of MgZnCu phase.
Effect of Al content on the microstructure and mechanical properties of Mg-5wt%Sn-xAl as-cast alloys
Authors: Sun Z Q , Li Y J , Zhang K , Li X G , Ma M L , Shi G L , Yuan J W
Published: March 2020

Microstructure and mechanical properties of Mg-5wt.% Sn-xAl as-cast alloys were studied, for the Al content ranged from 0.5 to 3.0wt.%. It was found that Al element was mainly distributed in Mg17Al12 phase in as-cast alloys, and its increase rose the Mg17Al12 phase share. There were no ternary phases in these alloys. Only two forms of Mg2Sn and Mg17Al12 phases were detected, namely (i) Mg17Al12 phase attached to the end of Mg2Sn phase and (ii) Mg2Sn phase enclosed by Mg17Al12 phases. The grain sizes of these alloys got refined with the growing content of Al element, and 1.5wt% Al content corresponded to the grain size of 33.5um. As for the mechanical properties, the ultimate tensile and yield strengths of the alloys were improved at larger contents of Al. The Mg-5wt.%Sn-3.0wt% alloy had the highest ultimate tensile and yield strengths of 212 and 167MPa, respectively, while Mg-5wt.%Sn-1.5wt%Al alloy had the best elongation of 16.5%.
Effect of heat treatment on the electrical conductivity of ZM51 magnesium alloy
Authors: Yuan J W , Mu T , Zhang K , Li X G , Zhang K , Li Y J , Ma M L , Shi G L
Published: March 2020

The microstructures and electrical conductivity of extruded Mg-5.38 wt.%Zn-0.88 wt.%Mn (ZM51) magnesium alloys under four different heat treatments (T5: single aging, two-stage aging; T6:T4+single aging, T4+two-stage aging) were investigated by optical microscopy (OM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and conductivity test. The results show that the electrical conductivity of alloys after different heat treatments was increased with the aging time increasing identically. The conductivity of T6 ZM51 alloy is lower than that of T5 treatment alloy, and the conductivity of alloy with two-stage aging is higher than that of alloys with single-stage aging. In the two-stage aging, the time of pre-aging at low temperature formed dense GP zones which can serve as the nucleation core of the β1’ phases, and the formed β1’ phases are more diffuse and fine, and the scattering of free electrons are lower. The electrical conductivity of the alloy increased first and then reduced with the increase of the pre-aging time, and the reason is that the alloys form a more diffuse GP zones after pre-aging for 32h, which can be used as the heterogeneous nucleation core of β1’ phases, so that the precipitation of the β1’ phases are more finely dispersed, thereby increasing the scattering capacity of free electrons.
An explicit simulation of arbitrarily-shaped pseudo-elastic hysteresis loops in shape-memory alloys
Authors: Wang S Y , Zhan L , Xu Z H , Xi H F , Xiao H
Published: March 2020

A new and explicit approach is proposed for accurately simulating pseudo-elastic hysteresis loops of any shape in shape-memory alloys (SMAs). For this purpose, new finite strain elastoplastic J2-flow equations are established for modeling finite strain behavior of SMAs. A stress-strain loop of any given shape in each uniaxial loading-unloading cycle is derived exactly from these equations. Then, a new technique is further introduced toward integrating usual piecewise linear splines into a single smooth interpolating function in a unified form. With the proposed equations and technique, test data for SMA hysteresis loops of any shape may be automatically fitted with high accuracy based on a single-parameter identification.
Explicit and accurate characterization of hardening- softening behavior of metals up to failure
Authors: Xu Z H , Wang S Y , Zhan L , Xi H F , Xiao H
Published: March 2020

Full and accurate characterization of metal hardening-softening effects till failure is carried out with a new explicit approach. To this purpose, a new expression for the plastic work is presented explicitly in terms of the uniaxial stress-strain function of any given form. Accordingly, the yield strength as function of the plastic work can be determined jointly from the above functions with the axial logarithmic strain as parametric variable. Using the proposed approach, any test data obtained within the entire stress-strain range with hardening and softening portions up to failure can be fitted by directly treating a suitable form of the uniaxial stress-strain function. This allows one to bypass usual tedious trial-and-error numerical procedures in dealing with nonlinear elastoplastic rate equations for identifying numerous unknown parameters. Accurate simulation results are shown with numerical examples.
A unified simulation of low-to-high cycle fatigue failure effects for metals with efficient algorithm
Authors: Zhan L , Wang S , Xu Z H , Xi H F , Xiao H
Published: March 2020

Within the framework of a recently established elastoplasticity model incorporating fatigue failure effects into inherent response features, a new and efficient algorithm is proposed to simultaneously treat fatigue failure effects from low to high cycle cases. From the new model it is possible to derive an explicit algorithm with which the accumulated plastic work is directly calculated by means of a recursive scheme, thus bypassing very time-consuming procedures in carrying out numerical integrations of the elastoplastic rate equations for a large number of loading-unloading cycles. Comparisons of simulation results with fatigue failure data from low to high cycle cases are presented to demonstrate the efficacy of the new algorithm.
A unified and explicit approach for accurately characterizing the hardening-softening behavior of metals with a tension-compression strength asymmetry
Authors: Xi H F , Zhan L , Wang S Y , Xu Z H , Xiao H
Published: March 2020

A unified and explicit approach is proposed for accurately characterizing a complex hardening-softening behavior of metals with a tension-compression strength asymmetry. The proposed approach provides an explicit determining of the yield strength as plastic work function and contains the following three procedures: (i) a mode invariant is introduced to express the yield strength as a sum of two uncoupled parts for the tension and the compression case; (ii) a new expression for the plastic work is derived explicitly in terms of the uniaxial stress-strain function and, then, the yield strength function can be determined jointly from the just-mentioned two functions with the axial strain as parametric variable; and, finally, (iii) the axial stress-strain function is presented for representing the hardening-softening features. With these procedures, test data over the entire hardening-softening range can be fitted independently for the tension and the compression cases by directly treating the uniaxial stress-strain function. As such, tedious trial-and-error procedures are bypassed in identifying numerous unknown parameters. Numerical examples show that accurate simulations may be achieved with the proposed approach.
A flexible tactile sensor using seedless hydrothermal growth of ZnO nanorods on fabrics
Authors: Hong Gwang-Wook , Kim Jihyun , Lee Jun-Soo , Shin Kyeongho , Jung Dongsoo , Kim Joo-Hyung
Published: March 2020

A flexible and cost-effective electromechanical device for tactile sensing based on ZnO nanorods (ZnO NRs) grown on fabrics is developed. Sensing performance and the electromechanical properties of ethylcellulose/polyurethane-coated ZnO NRs on fabric substrates were tested by the LCR meter, force transducer, vibrator, and pulse analyzer. The peak-to-peak output voltage at an applied force of 21.5 N dropped considerably for the wool-, nylon-, and PP substrates and reached to the order of 3.84 mV, 1.8 mV and 4.1 mV, respectively. Furthermore, the frequency dependency of the dissipation factors revealed abrupt changes at low frequencies, while these changes were negligible at high frequencies.
Synthesis of graphene-like carbon from agricultural side stream with magnesiothermic reduction coupled with atmospheric pressure induction annealing
Authors: Lähde Anna , Haluska Ondrej , Alatalo Sara-Maaria , Sippula Olli , Meščeriakovas Arūnas , Lappalainen Reijo , Nissinen Tuomo , Riikonen Joakim , Lehto Vesa-Pekka
Published: March 2020

Generally, large-scale production of graphene is currently not commercially viable due to expensive raw materials, complexity and the high-energy consumption of the processes currently used in the production. The use of biomass precursors and energy efficient procedures for carbonization have been proposed to reduce the cost of the graphene materials. However, low-cost graphene production has not been accomplished yet. Herein, we present a sustainable procedure and renewable starting materials to synthesize carbon nanostructures with graphene-like features. First, a SiC/C composite was synthesized from phytoliths and sucrose through magnesiothermic reduction. The phytoliths were obtained from barley husk that is an abundant side stream of agricultural industry. Second, graphene-like structures were achieved by the graphitization of SiC/C composite with high temperature induction annealing at 2400 °C under atmospheric pressure. The formation of graphene-like carbon was initiated by vaporization of silicon from the pre-ceramic SiC/C. Complete transformation of SiC/C to hollow, spherical graphene-like carbon structures and sheets were verified with thermogravimetry, x-ray diffraction, energy dispersive spectroscopy, electron microscopy and Raman spectroscopy. Also, the theoretical thermodynamic consideration of the phase separation of silicon carbide and the role of free carbon in the process has been discussed.