Table of Content

25 July 2018, Volume 46 Issue 7

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Materials Science & Technology

Effect of Composite Thermal Insulation System on High Temperature Insulation Performance of Cement-Based Coatings

ZHANG Zhijie CHENG Congmi GAN Wei Lü Hang WEI Ronghui ZHANG Qiuhua

2018, 46(7):  1-6.  doi:10.3969/j.issn.1000-565X.2018.07.001

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The thermal insulation components of cement-based non-intumescent fireproof coating are the key to its high temperature insulation performance． In this paper，ternary composite thermal insulation system of aerogel powder，hollow resin ball，and sealed pores are used． The effect of variation of three thermal insulation components volume fraction on the high temperature thermal insulation performance of cement-based coatings is investigated in the condition of constant volume of all thermal insulation components． The change law of ternary composite thermal insulation system is analyzed by concentration triangle． The result shows that the high temperature insulation performance of aerogel powder is significantly better than that of hollow resin ball and sealed pores． In the two binary composite thermal insulation systems of aerogel and hollow resin ball，aerogel and sealed pore，as the volume fraction of aerogel powder increases，the high temperature thermal insulation performance of the sample increases significantly． In the ternary composite thermal insulation system of aerogel，hollow resin ball and sealed pore，the specimens have a high temperature insulation performance when the volume fraction of aerogel powder is between 0. 33 and 0. 78 and the volume fractions of hollow resin ball and sealed pores are close to each other．

Simulation of Liquid Infiltration Process for Ｒeparation of Composite Materials by Multi-Component Pseudopotential LBM

LI Peisheng WANG Zhaotai ZHAO Wandong ZHONG Yuan ZHANG Ying

2018, 46(7):  7-15.  doi:10.3969/j.issn.1000-565X.2018.07.002

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In this paper，the infiltration process of liquid preparation of composite materials has been simulated in porous media by a modified multi-component pseudopotential model ( EFM) ． A study has been conducted of the effects of viscosity ratio ( M) ，wall wettability，Ｒeynolds number ( Ｒe) ，porosity and different fractal structures on the infiltration process． It is shown that the larger the viscosity ratio is，the smaller the infiltration saturation ( S) and infiltration time ( t) will be; meanwhile the effect of viscosity ratio on infiltration saturation and time is negligible when M ＞ 90． At this time the influence of contact angle is very small; the smaller the Ｒe is，the greater the infiltration saturation and infiltration time are，and the greater the effect of wall wettability will be． When the Ｒe of inlet is consistent，the smaller the porosity is，the lower the permeability of the fractal porous will be． Due to the uneven pore distribution，the fluid preferentially infiltrates in local area，leading to the decrease of the infiltration time and the saturation． For different fractal porous media，the influence of wall wettability is obviously different． For Type A ( standard fractal) and Type C ( right deviation of solid matrix) porous media，the larger the contact angle ( θ) is，the saturation and the infiltration time is smaller． The fractal porosity of type B ( upward deviation of solid matrix) and D ( left deviation of solid matrix) fractal porous，the larger the contact angle is，the saturation and the infiltration time tend to increase firstly and decrease lately，and the extreme value appears in the contact angle which is less than 90°．

Preparation and Characterization of Polydopamine Films on Pure Magnesium Surface

QIAO Liying YAO Yan WANG Yong LAI Ning WANG Weilang

2018, 46(7):  16-23.  doi:10.3969/j.issn.1000-565X.2018.07.003

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In order to decrease the corrosion rate of the pure magnesium and improve cell affinity of magnesium materials，polydopamine ( PDA) films and Mg ( OH) 2-PDA composite films are deposited on the pure magnesium surface． The optimum process of two kinds of films is investigated by the single factor experiment． The effects of DA mass concentration and film-forming time on film morphology and corrosion resistance are analyzed by field emission scanning electron microscope and dynamic potential polarization method． The chemical structure of the two films is studied by Fourier transform infrared spectroscopy． The results show that the optimum technological conditions for the preparation of PDA films is DA mass concentration of 1. 0 g /L，and the film-forming of 12 h; the optimum technological conditions for the preparation of Mg ( OH) 2-PDA composite films are the DA mass concentration of 1. 5 g /L and the film-forming time of 20 h． The corrosion resistance of the substrate is significantly improved under the optimum process parameters，and the corrosion resistance of Mg ( OH) 2-PDA composite films is the best． The obtained PDA films on pure magnesium have obvious crack defects． The microstructure of Mg ( OH) 2 films obtained by water heat treatment can provide a better site for the binding of polydopamines，which results in a more uniform polydopamine film．

Error Study of the Shape Deviation for Multi-Point Flexible 3D Stretch Bending Rectangular Tube Part

LI Yi LIANG Ce YU Jiaqi LIANG Jicai CHEN Guangyi

2018, 46(7):  24-29.  doi:10.3969/j.issn.1000-565X.2018.07.004

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Ｒeferring to the section deformation problem of 3D stretch bending profile，the shape deviation and influential factors of section deformation for multi-point flexible 3D stretch bending profile is investigated on the basis of the independent developed equipment; and the effect of part axial length on part cross section height /width deformation is analyzed． The experiment result shows that，on the upper/lower surface of rectangular tube part，both the concave percentage and concave deformation of part emerged and rose with the increased length from the bending symmetric center point to two sides along with axial direction，the concave deformation value on upper surface is bigger than that of lower surface; both the convex percentage and convex deformation emerged on the inside and outside vertical surface，and the convex percentage and convex deformation value rose with the increased length from the bending symmetric central point to two sides along with axial direction．

Hydration Features of Calcium Sulfoaluminate Cement at Different Curing Temperature

WANG Zhongping ZHAO Yating XU Linglin

2018, 46(7):  30-38,46.  doi:10.3969/j.issn.1000-565X.2018.07.005

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A study has been performed on the setting time，compressive strength，drying shrinkage ratio and hydration products of calcium sulfoaluminate ( CSA) cements with different amounts of anhydrite at 5 ℃，20 ℃ and 40 ℃ ． Ｒesults reveal that the effect on the hydration of calcium sulfoaluminate cement clinker depends directly on the curing temperature，although anhydrite can promote the formation of ettringite． At 5℃，anhydrite dramatically delays the early hydration so that the setting time is greatly extended and the early strength is significantly reduced， which is different from the condition at 20 ℃ and 40 ℃ ． Because anhydrite can effectively inhibit the transition from ettringite to monosulfate at high curing temperature，the compressive strength of mortar with CSA cement cured at 40 ℃ is higher than that of CSA clinker．

Atmospheric Corrosion Behavior of Q235 Steel Exposed on Transmission Tower Sites of Guangdong Province

GAO Yan HUANG Yinhui ZHENG Zhijun MENG Xiaobo LIAO Yongli LI Ruihai

2018, 46(7):  39-46.  doi:10.3969/j.issn.1000-565X.2018.07.006

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: The atmospheric corrosion behavior of Q235 steel used as the transmission tower material was investigated systematically in the 10 representative transmission lines of four typical atmospheric environments ( urban，industrial，marine and rural) by field exposure in Guangdong Province for one year． The period for recapturing samples from the field station lasted 6 and 12 months respectively． Their corrosion weight losses in unit area were measured to investigate the corrosion rule of Q235 steel． X-ray diffraction ( XＲD) and scanning electron microscopy ( SEM) were applied to analyze the microstructure and morphology of the corrosion products respectively． Ｒesults suggested that the atmospheric corrosion grade of a large part of Guangdong Province belongs to C3 and other parts belong to C2，a moderate rank as a whole． The influence of different environments on the atmospheric corrosion is different as follows: the heavy industrial environment，the compound one of marine and light industry，the marine and urban one，the little city and rural one． The corrosion rate of Q235 in the previous 6 months is obviously higher than that in the latter stage from 6 to 12 months in one-year-field exposure． The corrosion products are mainly αFeOOH and γ-FeOOH with net-or needle-like micro morphology，and a small amount of β-FeOOH is observed in the marine environment

Chemistry & Chemical Engineering

Microwave-Assisted Extraction Process of Tannins from Walnut Green Husk

ZHANG Lijuan ZHONG Manli HUANG Yuelong XU Jianren

2018, 46(7):  47-53,145.  doi:10.3969/j.issn.1000-565X.2018.07.007

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The extraction of natural pigments from walnut green husks can not only develop its application value but also reduce the environmental pollution． The main component of walnut green husk pigment is tannins． The tannins in walnut green husk are extracted by microwave-assisted ethanol extraction． Firstly，this article studies the effects of solid-liquid ratio，ethanol volume fraction，extraction temperature，extraction time and microwave power on the extraction yield of tannins，and then optimizes the extraction process by response surface methodology ( ＲSM) ． The optimal conditions are: ethanol volume fraction of 45% ，solid-liquid ratio of 1∶ 20 ( g /mL) ，temperature of 61℃，microwave power of 612 W，and a time of 10 min． Under these conditions，the extraction yield of tannins in walnut green husk is 20. 36 mg /g． The results provides the basic data and theoretical guidance for the extraction of tannins from walnut green husk

Preparation of Xylan-Based Catalyst and its Catalytic Synthesis of Benzoxanthene Derivatives

MA Jiliang XIANG Zhihua LIN Yuyang PENG Xinwen SUN Runcang

2018, 46(7):  54-61.  doi:10.3969/j.issn.1000-565X.2018.07.008

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Preparation has been made for the xylan-based solid acid catalyst was used in the two steps of carbonization and sulfonation． The catalyst was applied to the synthesis of benzoxanthenes． A study was conducted of the effects of the reaction temperature，time and dosage of the catalyst on the transversion． Furthermore，the universality and reusability of xylan-based solid acid catalyst were also investigated． Meanwhile，the xylan-based solid acid catalyst was characterized by scanning electron microscope ( SEM) ，Fourier transform infrared spectra ( FT-IＲ) and elemental analysis ( EA) ． The results showed that the catalyst exhibited high catalytic performance in the synthesis of benzoxanthene and their derivatives with good yields at 90 ℃ for 2 h in the presence of xylan-based solid acid ( 40 mg) ． The catalyst could be reused for several times without significant loss in its catalytic activity，indicating that the catalyst possessed excellent stability and recyclability

Adsorption Properties of Graphene Oxide on Chlortetracycline and Methylene Blue in Water

LI Zhili HUANG Wenxing GE Yuanyuan

2018, 46(7):  62-69,78.  doi:10.3969/j.issn.1000-565X.2018.07.009

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A modified Hummers method is adopted in the study of the graphene oxide ( GO) ． Morphological and structural characterization are performed by means of scanning electron microscopy，UV-visible spectrophotometer， Fourier transform infrared spectroscopy and X-ray diffraction scan analyses． Meanwhile，the effects of GO addition，solution pH，contact time，solution temperature，the initial mass concentration of chlortetracycline ( CTC) and methylene blue ( MB) are investigated into the adsorption of chlortetracycline and methylene blue by GO; The adsorption kinetic equations and adsorption isotherms are fitted． The results show that the adsorption removal rate of MB by GO is much higher than that of CTC; the CTC and MB adsorption onto GO fit well with the pseudo-second-order kinetic model and the Langmuir isotherm model respectively; the maximum adsorption capacity for CTC and MB are 265. 25 mg /g and 1095. 70 mg /g at 303 K respectively; the adsorption of CTC and MB onto GO is a spontaneous endothermic reaction，and the elevated temperature is favorable for the adsorption reaction． 

Tribological Properties of Nitrogen-Containing Lubricant Additives

LIAO Junxu LU Hao DAI Kangxu CAO Hua ZHAO Hongbin HAN Lifen XU Yongjun FANG Yutang

2018, 46(7):  70-78.  doi:10.3969/j.issn.1000-565X.2018.07.010

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Four environment friendly lubricant additives，namely N1，N2，N3 and N4，have been designed， synthesized and characterized． The thermal stability，oil solubility and corrosion resistance of these additives have been systematically studied． Tribological behaviors of the lubricant additives in liquid paraffin ( LP) were investigated． The surfaces morphology and elementary composition of the worn scar was recorded and analyzed by scanning electron microscopy ( SEM) and energy dispersive spectroscopy ( EDS) ． The reaction mechanism was initially discussed． It was found that the synthesized additives showed high thermal stability，excellent oil solubility and strong corrosion resistance． Among the four additives，N2 exhibited the best tribological property． For example， the maximum non-seizure load ( PB ) value of LP with 1. 0wt% N2 was 74% higher than that of LP，the sintered load ( PD) value was twice as large as that of LP． The wear scar diameter ( WSD) of 1. 0% N2 + LP system was 54% lower than that of LP，and the friction coefficient was 28% lower than that of LP． The addition of four additives significantly reduced WSD and surface abrasions of LP． The additive participated in tribo-chemical reaction in the friction process，which effectively improved the extreme pressure，anti-wear and anti-friction performance of LP．

Mechanical Engineering

A Mechanism Study of the Entrance Chipping Formation in the Drilling of BK7 Glass

Lü Dongxi ZHANG Yuanming SHEN Shengcheng

2018, 46(7):  79-84.  doi:10.3969/j.issn.1000-565X.2018.07.011

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: To investigate the entrance damaged formation mechanism in the process of drilling of BK7 glass，the dynamic characteristics of single abrasive and the distribution characteristics of abrasives on the tool end-face were analyzed． The morphological characteristics of the chipping and the formation mechanisms of the scattered surface stripes were explored，and the depths/widths of the chippings were measured． The results showed that the joint scratches of different abrasives on the end face of cutting tools caused the lateral cracking extending beyond the boundary of the hole，leading to the uneven distribution at the entrance of hole． In the formation process of the lateral cracks，the variation of the force state of the material resulted in the formation of the scattered stripes on the chipping surface． The correctness of the relationship between damaged depth and width was verified by experiments，and the nonlinear damaged depth increased with its width monotonically．

Structural Representation and Charpy Impact Properties of Sintered Stainless Steel Wire Mesh Porous Plates

DUAN Liuyang ZHOU Zhaoyao YAO Bibo

2018, 46(7):  85-93.  doi:10.3969/j.issn.1000-565X.2018.07.012

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Sintered stainless steel wire mesh porous plates have been prepared by winding，rolling and subsequently vacuum sintering． This paper investigates the pore size and size distribution，and the charpy impact properties of the stainless steel porous plates． Further studies of the effects on the impact properties by porosities，wire diameters and sintering parameters are performed． The results indicate that for the stainless steel porous plates prepared by the wire mesh，the pore structures are inerratic rectangles and the pore size distributes uniformly; as for the stainless steel porous plates prepared by wire mesh and powder，the pore structures are irregular; porosity of the stainless steel porous plates produces a major effect on their impact property，the impact toughness decreases from 26. 32 J/cm2 to 8. 02 J/cm2 along with the porosity increasing from 10. 64% to 29. 18% ; the impact toughness increases with the sintering temperature being raised and the wire diameter becoming thick． On the basis of macro and micro fracture morphology，the fracture of the specimens under impact load can be inducted as follows: densification，crack initiation，crack propagation，metallurgical joints broken and finally fracture． According to the fracture styles，the wires endure the tensile stress and shear stress before they rupture． 

Design of 3D Multi-Path Model for Transit-Time Ultrasonic Flow-meter

CHEN Guoyu LIU Guixiong

2018, 46(7):  94-99,108.  doi:10.3969/j.issn.1000-565X.2018.07.013

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Focusing on the problems such as low track coverage and weak adaptability to the irregular flow field in the current symmetrical track model of transit-time ultrasonic flow-meter，the design theory of 3D multi-path model is explored． Firstly，the formula for calculating the minimum number of paths satisfying the expected coverage is deduced． The distance between each path and the center of the pipeline is solved． The number of paths and the number of 2D track model are calculated． The angle between adjacent path segments of a 2D track model of a single path is calculated． Then，the coordinates of multi-path topology node are solved． Finally，multi-path topology is designed． The example calculation and application show that the design method of transit-time ultrasonic flow-meter 3D multi-path model is feasible，advanced and practicable．

A 3D Die Compensation Method Based on Interpolation Solution and FE Simulation

ZHANG Xueguang LIU Chunguo LIANG Jiye

2018, 46(7):  100-108.  doi:10.3969/j.issn.1000-565X.2018.07.014

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Die compensation is the major method to suppress springback for sheet metal forming． Aiming at the limitations of iterative correction method，a die surface compensation method based on interpolation solution and finite element ( FE) simulation is proposed． By defining the functional relation between work-piece shape error and die surface deviation，the ideal die compensation quantity is solved in the work-piece forming process． In FE simulation，the grid nodes are reversely adjusted along the node connection direction，and the compensated node group is reversely processed to realize die compensation surface reconstruction． This method simplifies the 3D die surface compensation process，realizes the independent and inhomogeneous compensation in different positions， and ensures the die smoothness． The roof covering skin of railway train is chosen as the research object，the springback and shape error with different die compensation surfaces are compared． The obtained ideal die surface is utilized to guide the forming experiment，and the result shows that the formed work-piece meets the requirement of precision．

Optimization of Multi-Organism Cooperative Propulsion Efficiency of Bionic Thunniform Fish Robot

ZHANG Kaisheng LIU Haotian WANG Qiang ZHANG Baocheng

2018, 46(7):  109-115,122.  doi:10.3969/j.issn.1000-565X.2018.07.015

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Propulsion efficiency is the core point of underwater vehicle，which produces effects on the practical application of machine equipment． In this paper，through kinematic character of the thunniform mode fish with undulatory movement，the fish robot was developed as a multi-rigid body system which could be divided into body，pectoral fin and caudal fin，combined with the external force of fish robot，the dynamic model was established with Newton-Euler method． Based on this dynamic model，with the goal of propulsion efficiency，the genetic algorithm was selected to optimize the kinematic parameters． By optimizing the multi-body coordination between fish body， tail fin and pectoral fin，the propulsion efficiency of the robot fish was improved． In connection with optimization results，the kinematics numerical simulation of robotic fish was further carried out． The results showed that at the speed of 1. 415 times of the body length，the efficiency of the robot-fish was 49. 9% ．

Fatigue Test and Fatigue Reliability Evaluation of Wheel Loader Drive Axle

LIANG Jia SONG Xuding Lü Pengmin WEI Yongxiang Lü Chang

2018, 46(7):  116-122.  doi:10.3969/j.issn.1000-565X.2018.07.016

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: In order to design anti-fatigue and evaluate fatigue reliability of the wheel loading drive axle，the actual load torque spectrum and rotational speed statistics of the input axle of the ZL50G wheel loader drive axle have been obtained． Loading spectrum of intensified fatigue test，positive and reverse loading fatigue test and fatigue reliability evaluation of the wheel loading drive axle have been carried out． The results show that the fatigue failure of the driving axle occurs mainly in the spiral bevel gear of the main reducer，bending fatigue failure is the main form of spiral bevel gear and contact fatigue failure is the main form of wheel planetary gear． Under the condition of given working life，the relationship curve between the working time and reliability of the drive axle is obtained on the basis of very small sample fatigue reliability evaluation of the fatigue life test results．

Architecture & Civil Engineering

Calibration Technology of Three-Dimension Sound Intensity Method

WANG Hongwei YANG Yajie ZHANG Long

2018, 46(7):  123-127,136.  doi:10.3969/j.issn.1000-565X.2018.07.017

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The development of Three-dimension sound intensity technology is of significance to the field of acoustic measurement． The three-dimension sound intensity calibration technology is to ensure the accuracy of three-dimension sound intensity measurement． This paper is mainly about the transfer function method to calibrate the three-dimension sound intensity measurement system，and to measure the amplitude error and directional error of the system in the whole anechoic chamber． Under the premise of ensuring accuracy，the measurement environment can be approximated as a planar sound field to simplify the calculation． It can be known from the actual measurement results that the adoption of the three-dimension sound intensity calibration system described in the text can ensure that the sound intensity probe has a high measurement accuracy． when f = 1 000 Hz，the difference between the amplitude error simulation and the value measured is less than 1. 4dB，and the difference between the directional error simulation and the value measured is less than 10°． Three-dimension sound intensity calibration system is to ensure that the sound intensity probe with a high accuracy．

Mechanical Behavior of Segmental Precast Prestressed Composite Box Girder with Corrugated Steel Webs

DENG Wenqin ZHANG Jiandong ZHANG Hong ZHANG Yongtao

2018, 46(7):  128-136.  doi:10.3969/j.issn.1000-565X.2018.07.018

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In order to explore the mechanical behavior of segmental precast prestressed composite box girder with corrugated steel webs，under the premise of considering the influence of construction technology and tendon ratios， three scaled model test beams were designed and manufactured for the experiment of mechanical behavior． The similarities and differences were compared and analyzed of the mechanical behavior between the integrally poured prestressed composite box girder with corrugated steel webs and the segmental precast prestressed composite box girder with corrugated steel webs． A calculation formula was presented of flexural bearing capacity of segmental precast prestressed composite box girder with corrugated steel webs． The results show that the stiffness degradation of the segmental precast beam is significantly greater than that of the integral beam after the concrete cracking，especially the segmental beam with only external tendons． The bending contribution of corrugated steel webs of segmental beam is significantly greater than that of the integral beam，particularly evident in the segment joints． The stress increment of external tendon of segmental beam is greater than that of the integral beam with a fast growth speed． Compared with the calculation formula of flexural bearing capacity of integral beam，the calculation formula of flexural bearing capacity of segmental precast beam presented in this paper is better in congruity with the test results

A Numerical Study of the Effect of Corrosion and Breakage of Wires on Mechanical Properties of Cable

SUN Huahuai CHEN Weizhen YANG Jianxi

2018, 46(7):  137-144.  doi:10.3969/j.issn.1000-565X.2018.07.019

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Corrosion and breakage of steel wires are main factors affecting the mechanical properties of the cable． Firstly，corrosion distribution model of cable wires along radial and cable directions is established． Then，on the basis of corroded wire fractured forms，the breakage law of wire under the combined action of corrosion and load was analyzed． A fracture mechanics criterion of corroded wire based on stress intensity factor is established． Finally，by taking friction of wires into consideration，this paper numerically simulates corrosion and fracture process of cable wires，and studies the effect of corrosion and breakage of each layer wires on mechanical properties of cable． Ｒesults show that stress redistribution of wire happens after corrosion and fracture of cable steel wires． The effect of wire breakage on the stress decreases gradually in the radial direction． Stress increase of the corroded wires next to the fractured wires layer is the biggest，and stress increase of the inner layer wire is the smallest． Due to the friction between wires，stresses of fractured wires synchronously recover in the recovery length in form of logarithmic． The recovery length increases with the percentage of broken wires，and it has two quadratic parabola relations with the percentage of broken wires，and it will converge to 3. 3 m． Cable force loss rate increases with the rise of the percentage of broken wire． The impact of corrosion and breakage of wire is small on cable force． When the percentage of wire breakage is less than 10% ，the cable force loss rate is less than 4% ．