bluuebunny/crossref_metadata_2025 huggingface dataset:
The problematic restoration of a conceptual light artwork
Authors: Steib Olivier
Published: February 2019

L’œuvre Erlauf de Jenny Holzer est un panneau lumineux faisant partie d’une série, réalisée en 1998. Une étude préalable a été menée en vue de sa restauration, qui a soulevé les difficultés relatives à ce type d’objet. Ce cas a permis une collaboration internationale entre l’atelier de l’artiste, des techniciens et des musées, dont le Conservateur-Restaurateur a la charge de la coordination et de la gestion des points de vue parfois opposés de chacun.
Conservation et matérialité des œuvres numériques
Authors: Michaan Alexandre
Published: February 2019

L'idée d’une absence de matérialité de l’œuvre numérique peut constituer un écueil pour la conservation. Elle occulte une forme de matérialité spécifique et sur laquelle il est possible d’agir pour les restaurateurs et les acteurs de la conservation. À travers l’étude de plusieurs cas d’œuvres audiovisuelles numériques aujourd’hui technologiquement obsolètes, nous tenterons de montrer de quelle manière les mécanismes d’altération de ces œuvres sont intimement liés à une forme de matérialité tout autant assujettie au passage du temps que celle des œuvres issues d'autres domaines de création.
Droit d’auteur et restauration des œuvres à caractère technologique
Authors: Moya-Plana Anne-Laure
Published: February 2019

Comment concilier les règles du droit d’auteur avec les principes de la restauration et, plus précisément, comment articuler les droits de l’artiste et de ses ayants droit avec ceux du musée qui a acquis l’œuvre ? L’objectif est d’instaurer dès l’acquisition de l’œuvre un dialogue ou, à tout le moins, rétablir une bonne communication une fois la question des modalités de conservation-restauration posée. Il faut anticiper en amont les conflits entre l’artiste ou ses ayants droit d’une part, et l’acquéreur de l’œuvre d’autre part, par la voie contractuelle et, en tout état de cause, concilier les intérêts en présence une fois le conflit ouvert. Le colloque a permis d’explorer quelques pistes de réflexion à partir d’exemples concrets d’œuvres à caractère technologique.
Influence of the Riser Boost Line on the Thermal Stress of Riser in Deepwater Drilling
Authors: Luo Kui Dong , Li Jun , Yang Hong Wei , Wang Jiang Shuai , Zhang Xin
Published: February 2019

In deep water drilling, the existence of boost line makes the wellbore temperature change violently, and the thermal stress caused by it has a great influence on the strength of the riser. The paper considers the variable mass flow caused by the boost line fluid entering the wellbore during deepwater drilling. Based on the principle of conservation of mass and energy, the paper establishes a mathematical model for transient heat transfer in different regions of the wellbore and formation, analyzes the effect of the displacement of boost line on the temperature field of the wellbore, and calculates the transient stress of the casing under thermal effect. The results show that with the increase of cycle time, the temperature of the inner wall of the riser above the critical well depth first decreases and then increases. The thermal stress of the inner wall of the riser first increases and then decreases to zero, and then gradually increases, and the final thermal stress remains unchanged. With the increase of cycle time, the thermal stress of the inner wall of the riser increases with the increase of the circulating temperature of the inner wall of the riser below the critical well depth, and the rate of increase decreases gradually, and the final thermal stress remains unchanged. As the displacement of the riser increases, the circulating temperature of the inner wall of the riser increases, and the thermal stress on the inner wall of the riser increases. The research results can provide reference for the analysis of the factors affecting the riser stress in deep water drilling.
Influence of the Characteristics of Cement Plug on well Integrity for Offshore Abandonment
Authors: Zhang Xin , Li Jun , Zhao Chao Jie , Luo Kui Dong , Zhang Di
Published: February 2019

With the development of offshore oil fields into the middle and late stages, more and more oil wells are facing the problem of disposal. The reliability of the plugging between the cement plug and the wellbore is directly related to the safety of offshore operations and the problem of marine ecological damage caused by oil and gas leakage. Starting from the cement failure mechanism between the cement plug and the casing, consider the heterogeneity of the formation and the magnitude of the ground stress. The finite element software is used to simulate the interaction between the cement plug and the casing with different characteristics, and then judge the risk of sealing failure. Furthermore, the influence of cement plug properties on casing stress and cementation strength is obtained. Study show that the use of high strength, low modulus of elasticity, low Poisson's ratio cement is conducive to prevent cement plug tensile failure. When the local layer is hard, the method of reducing the elastic modulus of the cement plug can be adopted; and when the local layer is soft, the method of appropriately increasing the elastic modulus of the cement plug should be adopted. It has certain guidance and reference significance for the safe disposal of offshore wellbore.
Corrosion Behavior Research of Aluminized N80 Tubing in Water Injection Well
Authors: Lu Cai Hong , Feng Chun , Han Li Hong , Feng Jie , Zhu Li Juan , Jiang Long , Feng Yao Rong
Published: February 2019

In this paper, in view of the problem of tubing corrosion in the water injection well, it is proposed to use the aluminizing N80 tubing to improve the corrosion problem. An aluminized layer with a thickness of about 150 μm was prepared on the surface of commonly used N80 tubing. The electrochemical polarization test at room temperature and the high temperature autoclave test for simulated water injection well environment were carried out on both of the aluminized and non-aluminized N80 tubing. It is intended to provide a feasibility test basis for the application of aluminized tubing in water injection wells by comparing the corrosion resistance performance of the aluminized and non-aluminized N80 tubing. The results showed that the aluminized layer on the surface of N80 tubing had good adhesion due to the mutual diffusion layer, and the thickness of the aluminized layer can reach 150μm. Compared with the non-aluminized N80 tubing, the self-corrosion current density of the aluminized N80 tubing polarization curve decreased obviously in the water injection well environment, and the corrosion rate in the high temperature autoclave test was also reduced to one quarter of that of the non-aluminized N80 tubing.
Analytical Method to Evaluate Casing Stress during Multi-Fracturing for Shale Gas Wells
Authors: Guo Xue Li , Li Jun , Zeng Yi Jin , Ding Shi Dong , Zhang Xu
Published: February 2019

An analysis model of casing stress distribution and its variation regularities presents several challenges during hydraulic fracturing of shale gas wells. In this paper, an analytical mechanical - thermal coupling method was provided to evaluate casing stress. In the model, the casing, cement sheath, and formation (CCF) system was divided into four stress field induced by uniform stress, deviator stress, shear stress, and thermal stress,. Based on this analytical model, the parametric sensitivity analyses of casing stress such as mechanical properties, operation parameters, and geo-stress were conducted during multi-fracturing. The results indicated the casing stress increased first, then decreased with the increase of cement sheath modulus. However, it always decreased with the increase of cement sheath Poisson's ratio and the injection fluid temperature. The casing stress increased dramatically with the increase of δ. However, it decreased first, then increased with the increase of fracturing pressure. Higher fluid temperature, cement with small modulus and large Poisson’s ratio were effective to decrease the casing stress. In conclusion, the analytical model can accurately predict casing stress and become an alternative method of casing integrity evaluation for shale gas wells. It is a useful and efficient method for a preliminary design, being capable of simulation the actual situations in order to assess the casing stresses and integrity.
Erosion Law of Inner Drill Pipe in Reelwell Reverse Circulation Directional Drilling
Authors: Li Jun , Huang Tao , Gao De Wei , Wang Chao , Song Xue Feng , Ren Kai
Published: February 2019

In the process of ReelWell reverse circulation directional drilling, the drilling fluid returns through the inner drill pipe, and the debris particles continuously eroded and wear the drill pipe in the inclined section, which easily causes the failure of the inner drill pipe erosion. Analysis, through the Fluent software to simulate the flow field in the inner drill pipe, to study the impact of different drilling fluid displacement, different mechanical drilling speed, different cuttings particle size on the drill pipe erosion. The results show that: (1) The larger the drilling fluid displacement, the higher the return velocity of the drilling fluid, the greater the number of cuttings, the larger the maximum erosion rate of the curved pipe section, and the larger the erosion area; (2) The higher the drilling rate High, the higher the concentration of cuttings particles, the higher the probability of particles hitting the pipe wall, the greater the maximum erosion rate of the curved pipe section, and the larger the erosion area. When the mechanical drilling rate is higher than 10m/h, the maximum erosion rate increases significantly; (3) the smaller the cuttings particle size, the larger the number of cuttings particles, and the greater the maximum erosion rate of the curved pipe section. It is recommended that the drilling fluid displacement and the mechanical drilling rate should not be too large during the reverse circulation drilling process. At the same time, the cuttings particle size should be controlled, the drilling tool management should be strengthened, and the reasonable use standard after the drill pipe erosion is established. The research results have a certain guiding significance for revealing the failure of the inner drill pipe erosion in ReelWell reverse circulation directional drilling and the scientific use of the wear drill pipe.
Fabrication of 1D Nanometer Tungsten Trioxide under Different Solvent System
Authors: Zhao Lin Yan , Shen Yue Gang , Fan You Shu , Ma Li Wen , Xi Xiao Li
Published: February 2019

As a cheap and stable transition metal oxide, tungsten trioxide (WO3) has received extensive attentions due to superior physical and chemical properties that could be used in electronic devices, lithium-ion batteries, gas sensors, dye sensitized solar cells, catalysts. In this study, the well-designed 1D architecture of nanowires and nanorods was successfully synthesized via a simple and facile solvethermal method with no template or additives. It is found that both solvent type and concentration of W raw material can affect the size and morphology of WO3significantly in a regular way. Different products showed distinct photocatalytic activities during the processing of degradation methylene blue under visible light, and the underlying reasons for the different photocatalytic activities were discussed.
Effect of Chelating Additive on Pore Structure and Mechanical Property of Mortar under Different Curing Conditions
Authors: He Peng , Wang Rui Yang , Zha Ya Gang , Yu Jian Ying
Published: February 2019

Effect of chelating additive on microstructure, hydration products and mechanical property of mortar under different curing conditions was investigated. The microstructure was tested by nuclear magnetic resonance and scanning electron microscope. And the chemical composition of hydration products was analyzed by X-ray diffraction. The compressive strength was measured under different curing conditions at different curing age, including standard curing, water immersion, seawater immersion and salt mist curing. After curing for 28 days in water, compared to control mortar, the reduction ratio of harmful pores whose size larger than 0.1μm in mortar with chelating additive (CA mortar) was 14.6%, followed by 8.9%, 9.2% and 2.9% which was under standard curing, seawater immersion and salt mist curing, respectively. From the scanning electron microscope image, there were more needle-like and bar-like crystals in CA mortar making it more compact, which was mainly calcium silicate hydrate through component analysis. Besides, the raising percentage of compressive strength of CA mortar under water immersion is 28.6% compared to control mortar at the age of 28 days, followed by 26.8%, 21.8% and 16.3% which was under standard curing, seawater immersion and salt mist curing, respectively. The results indicate that chelating additive can enhance compactness and compressive strength of cement-based materials especially under water immersion by promoting the formation of calcium silicate hydrate.
Fatigue Crack Growth Behaviors in Novel TC32 Titanium Alloy with Bimodal and Basket-Wave Microstructures
Authors: Li Ming Bing , Zhu Zhi Shou , Wang Xin Nan , Zhu Li Wei , Shang Guo Qiang , Li Jing , Liu Ge Chen
Published: February 2019

This article investigated the fatigue crack growth behaviors in the novel TC32 titanium alloy with bimodal and basket-weave microstructures, which were respectively obtained by the convectional (α+β) phase forging and quasi-β forging processing. Results showed that at the same level of tensile performance, the basket-weave microstructure had a lower fatigue crack growth rate than the bimodal microstructure, as the basket-weave microstructure had a more tortuous crack path, a rougher fracture surface and more secondary cracks. All these served to improve the fatigue crack growth resistance, which attributed largely to the effects of crack closure. Moreover, secondary cracks grew primarily along the α/β interfaces for the basket-weave microstructure but directly went across the colony-type lamellar (α+β) phase and the primary α phase without obvious regularity for the bimodal microstructure.
Investigation of Volatile Organic Compounds from the Manufacturing Process of Recycled PET Fibers Using TGA-DTA/MS Technique
Authors: Hu Ji Yue , Chen Ye , Liu Shan Shan , Ke Fu You , Gao Ling Ling , Wang Chao Sheng , Wang Hua Ping
Published: February 2019

Recycling is promising to dispose the wasted Poly (ethylene terephthalate) (PET) fibers currently. However, high temperature and oxygen in the recycling process may accelerate the degradation of PET and residual dyes, resulting in the volatile organic compounds (VOCs) emissions, which will do serious harm to the environment and human health. Exploring the source of VOCs is significant to remove VOCs and keep products safety. This study was carried out to investigate the influence of high temperature on the release of four VOCs (formaldehyde (CH2O), acetaldehyde (C2H4O), benzene (C6H6) and toluene (C7H8)) during the recycling process of PET fibers, utilizing thermogravimetric analysis and differential thermal analysis coupled with mass spectrometric (TGA-DTA/MS). The atmospheres and heating conditions of esterification, polycondensation and melt spinning were simulated by TGA with various atmospheres and programmed heating processes (heating from 50 °C to 240 °C in Ar, 280 °C in Ar and 280 °C in air, respectively, and then maintaining for 30min). Bis (2-hydroxyethyl) terephthalate (BHET) (esterification product) and virgin PET (VPET) were used to explore the thermal degradation of PET. White PET popcorn, black PET popcorn and dyes were used to explore the effect of dyes on the release of VOCs. The results indicated that: (1) Aldehydes including formaldehyde and acetaldehyde are generated during the manufacturing process of PET, mainly due to its thermal oxidation;(2) Aromatic compounds including benzene and toluene are originated from the disperse dyes. So the degree of dye removing has a great influence on the production safety; (3) Thermal oxidation causes more VOCs than nonoxidative thermal degradation. So in the stages of melt spinning and slightly alcoholysis, usually in O2 containing atmosphere, devolatilization should be developed further.
Effect of Warm Mix Agent on Physical and Aging Properties of Crumb Rubber Modified Bitumen
Authors: Zhuang Rong Hua , Yu Jian Ying , Chang Heng , Zeng Yan , Lan Xue Yong
Published: February 2019

The effects of modified natural zeolite warm mix agent (MNZWMA) and organic viscosity reducing warm mix agent (OVRWMA) on the physical properties, short term thermal oxidation aging, long term thermal oxidation aging and UV aging properties of the crumb rubber modified bitumen (CRMB) were investigated. The results showed that MNZWMA and OVRWMA could improve the high temperature stability and the low temperature crack resistance of CRMB, respectively. During the short term thermal oxidation aging, long term thermal oxidation aging and UV aging, OVRWMA increased softening point increment (SPI) and viscosity aging index (VAI) of CRMB, however, MNZWMA decreased its SPI and VAI. The analysis of FTIR spectra indicated that MNZWMA reduced the formation of carbonyl groups and sulfoxide groups, but OVRWMA accelerated the formation of carbonyl groups and sulfoxide groups to some extent during ultraviolet aging. Therefore, MNZWMA could improve the anti-aging properties, and OVRWMA was not conducive to the anti-aging properties of CRMB.
High Compressibility ZrTiHfV0.5Nb0.5CX Refractory High-Entropy Alloys
Authors: Chen Wen Kai , Li Yun Kai , Chen Yi Wen
Published: February 2019

Refractory high-entropy alloys (RHEAs) have outstanding characteristics such as high melting point, high temperature oxidation resistance and corrosion resistance, which shows very promising application in the high temperature field; but commonly the refractory high-entropy alloys have the disadvantages of high density and poor plasticity. In this work, ZrTiHfV0.5Nb0.5Cx(x=0, 0.06, 0.12, 0.2) alloys are prepared by vacuum non-consumable arc-melting with ZrTiHfV0.5Nb0.5based. The density of ZrTiHfV0.5Nb0.5C0.2alloy is reduced to 8.014g/cm3compared to ZrTiHfV0.5Nb0.5(8.135g/cm3). The microstructure, static and high-temperature compressive strength are investigated. XRD and EDS analysis show that the microstructure of ZrTiHf0.5Nb0.5Cxalloys consists of BCC phase and HfC phase. ZrTiHfV0.5Nb0.5Cxalloys have high compression plasticity with plastic strain> 40% at room temperature, no fracture occurred during compression and yield stress is closed to 1GPa.
Influence of Cold Rolling Reduction on Microstructure and Mechanical Properties in 204C2 Austenitic Stainless Steel
Authors: Wang Tian Yi , Song Ren Bo , Cai Heng Jun , Wen Jian , Su Yang
Published: February 2019

The present study investigated the effect of cold rolling reduction on microstructure and mechanical properties of a 204C2 Cr–Mn austenitic stainless steel which contained 16%Cr, 2%Ni, 9%Mn and 0.083 %C). The 204C2 austenitic stainless steels were cold rolled at multifarious thickness reductions of 10%, 20%, 30%,40% and 50%, which were compared with the solution-treated one. Microstructure of them was investigated by means of optical microscopy, X-ray diffraction technique and scanning electron microscopy. For mechanical properties investigations, hardness and tensile tests were carried out. Results shows that the cold rolling reduction induced the martensitic transformation (γ→α ́) in the structure of the austenitic stainless steel. With the increase of the rolling reduction, the amount of strain-induced martensite increased gradually. Hardness, ultimate tensile strength and yield strength increased with the incremental rolling reduction in 204C2 stainless steels, while the elongation decreased. At the thickness reduction of 50%, the specimen obtained best strength and hardness. Hardness of 204C2 stain steel reached 679HV. Ultimate tensile strength reached 1721 MPa. Yield strength reached 1496 MPa.
Effect of Annealing Treatment on Microstructure, Mechanical and Damping Properties of Ductile Iron
Authors: Zhang Yu , Guo Er Jun , Wang Li Ping , Feng Yi Cheng , Zhao Si Cong , Song Mei Hui
Published: February 2019

Ductile iron was prepared through Sandwich Process and annealing treatment was carried out. The effects of annealing treatment on the microstructure, mechanical and damping properties of ductile iron were studied by means of metallographic microscope, scanning electron microscope, transmission electron microscope, universal test machine and dynamic thermal mechanical analyzer. The results show that annealing treatment has little effect on the morphology and distribution of graphite cast iron, but it will lead to the decrease of pearlite content in the matrix, the increase of ferrite content and the disappearance of cementite. Annealing transforms the fracture form of ductile iron from cleavage fracture to quasi-cleavage fracture, which greatly increases the ductile fracture area of the matrix compared with the as-cast, and tends to develop ductile fracture. The annealing treatment results in a decrease in the tensile strength of the ductile iron, but it can increase the plasticity and increase the elongation after fracture to 7.5 times that of the as-cast state. The damping value of as-cast ductile iron increases first and then decreases with the increase of temperature, and peaks at 190 °C when Q-1 is 0.025. The damping value of annealing ductile iron decreases with increasing temperature. The damping value increases with increasing strain amplitude before and after annealing. Annealing treatment will reduce the sensitivity of the damping property of ductile iron to strain amplitude.
Hot Ductility Behavior of 9SiCr Alloy Tool Steel by Thin Slab Casting
Authors: Zhu Wan Jun , Wang Chun Feng , Qi Jiang Hua , Sun Yi Qang , Cai Zhen , Qiu Chen
Published: February 2019

In order to evaluate the feasibility of 9SiCr alloy tool steel produced by thin slab casting, the high temperature mechanical properties of 9SiCr alloy tool steel were investigated by Gleeb-1500 thermal simulator. The morphologies of the tensile fracture at different temperatures were observed by scanning electron microscope (SEM), together with analysis of fracture mechanisms in different regions. The results showed that there were two brittle zones in the temperature range from 600 °C to 1200 °C. A melting fracture was characterized in the high temperature brittle zone of above 1170 °C, whereas a typical cleavage fracture was exhibited in the low temperature brittle zone from 820 °C to 600 °C, Meanwhile, a good hot ductility behavior characterized by typical dimple fracture was demonstrate at the temperature range from 1170 °C to 820 °C.Thus, the 9SiCr alloy tool steel with the final gauge of 1.5mm was produced by CSP, based on the optimal process parameters.
Microstructure and Mechanical Properties of Ferritic Rolling Low Carbon Steel
Authors: Zhao Hu , Cheng Peng Fei , Zhou Xun
Published: February 2019

The microstructure and mechanical properties of ferritic rolling low carbon steel are investigated by metallurgical microscope, thermal simulation testing machine, electron backscattered diffraction (EBSD) and universal tensile test machine. The finishing temperature of the transition from austenite to ferrite changed from 680°C to740 °C with different cooling rates, which was obvious lower than that of the interstitial free steel. The deformation stress of low carbon steel was larger than that of interstitial free steel. In addition, the deformation stress of the low carbon steel was more sensitive to the deformation rate than that of the interstitial free steel. The microstructure at the surface layer of the hot rolling plate was composed of fully recrystallized grains while the microstructure in the center was composed of fibrous deformed grains. The ferritic rolling low carbon steel has lower yield ratio and higher elongation than that of normal rolling low carbon steel.
Effect of Process Parameters on Microstructure and Properties of 1500 MPa Grade Hot Formed Steel without Boron but Containing Niobium
Authors: Cui Zhen Nan , Kang Yong Lin , Zhu Guo Ming , Li Bao Shun , Qiu Quan Quan , Liu Ren Dong , Liu Hong Bo
Published: February 2019

In this paper, a new type of automotive 1500 MPa grade hot-formed steel without boron but containing niobium was subjected to thermoforming experiments. The phase transition point and Continuous Cooling Transformation (CCT) curve of the hot-formed steel were measured by thermal dilatometer, and then the best austenitizing parameters was determined. The microstructure of the cold-rolled sheet and the hot-formed steel sheet were observed by electron microscopy. The microstructure of the steel sheet after hot forming was studied by X-ray diffraction (XRD) method to determine whether the microstructure after hot forming had residual austenite. The influence of residence conditions on its mechanical properties was studied. The experimental results has shown that the microstructure of the original cold-rolled sheet is mainly composed of ferrite and pearlite. After thermoforming, the basic microstructure are martensite and a small amount of ferrite; When the hot forming parameters is that 900 °C of the heating temperature, 3 min of the holding time, 8 s of the residence time, quenching temperature is the room temperature, the new 1500 MPa grade hot formed steel has the best mechanical properties that the tensile strength is 1519 MPa, the yield strength is 1060 MPa, the yield ratio is 0.73, and the elongation reaches 10.52%. The result shows that the new 1500 MPa grade hot formed steel could obtain excellent mechanical properties through a reasonable process under the premise of ensuring hardenability.
Thermal Deformation Behavior and Critical Conditions of Dynamic Recrystallization of QCr0.8 Alloy
Authors: Yang Shu Yu , Wang Qiang Song , Xie Guo Liang , Liu Dong Mei , Liu Fang
Published: February 2019

In this paper, the flow stresses, the constitutive equation, processing map and the critical conditions of dynamic recrystallization (DRX) of the hot forged QCr0.8 alloy are studied by hot compressive test in the 750-900°C temperature and 0.01-10s-1 strain rate ranges using Gleeble-1500D thermo-mechanical simulator. The compression reduction of thermal compression deformation is 50%. The results show that the thermal deformation temperatures and strain rates have a significant effect on the high temperature deformation behavior of the alloy. The higher the temperature, the smaller the strain rate and the easier the DRX of the alloy is found.The peak stresses of the alloy decreases with the increase of temperature and increases with the increase of the strain rates.The flow stresses during hot deformation can be described by a hyperbolic sine function. The activation energy Q of the thermal compression deformation is determined to be 370.8KJ/mol. The constitutive equation and processing map of the alloy are established. Critical strains of DRX εc are studied by the inflection point characteristic of the lnθ-ε curve of the alloy and the corresponding minimum value of the ∂θ (∂θ)/∂ε-ε curve.
Service Temperature Evaluation of Cast K465 Superalloy Turbine Vane Based on Microstructural Evolution
Authors: Zheng Zhen , Zhou Jing Yi , Zhao Wen Xia , Zheng Yun Rong
Published: February 2019

The overtemperature in a vane made of cast K465 superalloy is investigated in this paper. The vane was taken from a K465 guide ring after the service for specific period of time. The relationship between the temperature and content of γ´ precipitates was established for the K465 superalloy, which was then used to make the microstructural evolution analysis on failed turbine vane associated with overtemperature. The content of γ´ precipitates in dendritic region and the volume fraction of melting zone in interdendritic region in K465 superalloy were used as the microstructural parameters to check the overtemperature. It is found that there is a sound relationship between the parameters and the temperature. On the basis of this relationship, the microstructural evolution along with temperature variation of the overtemperature K465 turbine vane can be analyzed and the overall service temperature which the K465 guide ring experienced can be evaluated.
Fractal Characterization of Relative Movement Modes in Simulated Friction and Wear Tests
Authors: Jiang Wei , Ji Cui Cui , Zhang Dan Dan , Xiao Hua Xing , Dai Yun Tian
Published: February 2019

The selection of the relative movement mode between the friction pairs in simulated friction and wear tests is a crucial factor for the characterization and evaluation of metallic material properties. In this study, two kinds of commonly used metal materials (stainless steel 0Cr18Ni9 and aluminum alloy 2A12) were applied for the simulated friction and wear tests with four different modes of relative motion, including unidirectional, reciprocating, circular and multi-directional cross-shear. The corresponding surface topography and statistical parameters such as surface roughness Ra were obtained via OLYMPUS ultra-depth microscope. Based on the fractal theory, fractal dimension D was calculated to characterize the surface topography and the results indicate that, the fractal dimension D of the unidirectional and multi-directional cross-shear simulated friction and wear tests is the minimum and maximum respectively, which reflects that the fractal dimension D is able to characterize the complexity of the surface morphology. The fractal dimension D may be related to the intrinsic physical properties of metal materials, such as hardness and toughness, which needs to be further studied.
Numerical Simulation of Electromagnetic Phenomena and Solidification under a Pulsed Magnetic Field
Authors: Chen Qi Peng , Oguma Hidetaka , Shen Hou Fa
Published: February 2019

The transient electromagnetic phenomena and solidification of Al-Cu alloy under a typical pulsed magnetic field (PMF) are numerically studied by a two-dimensional (2D) axisymmetric model. The results show that the magnetic flux density, eddy current density, Lorentz force and Joule heat all inherit the instantaneous and intermittent feature of the PMF, and their amplitudes and phases decrease with the increasing distance to the side surface of the ingot. The Lorentz force appears alternatively as pressure force and pull force mainly in the radial direction. Forced convection is induced in the liquid metal, and the flow field is composed of a clockwise vortex and a counter-clockwise vortex in the meridian plane of the ingot. The melt velocity is accompanied with a dramatic periodic oscillation. The temperature field in the ingot with the PMF tends uniform due to the mixing effect of the melt flow. However, the convection is damped soon after the solidification starts due to the increasing penetration resistance, and the temperature field gradually approximates that in the case without the PMF.
Tough Hydrogels Based on Macromicelles as Crosslinkers with pH and Ion Sensitive Properties
Authors: Yan Rui Jia , Yan Yan Zi , Ma Jing Hong , Gong Jing Hua
Published: February 2019

Stimuli-sensitive hydrogels crosslinked by macromolecular micelles usually present good mechanical properties. In this paper, a novel kind of pH and ion sensitive hydrogels with high toughness and strength were prepared using Pluronic F127 diacrylate (F127DA) as crosslinking centers for the free radical copolymerization of acrylamide (AM) and methacrylate (MA) monomers. These hydrogels showed high strength and tensibility with elongation at break of 1208%, fracture stress of 328 kPa and toughness of 1.80 MJ/m-3. The hydrogels not only exhibited enhancement of mechanical performance, but also achieved sensitive response to changes of pH and ionic strength, making an approach for the development of applications in drug delivery and sensors.
The Bending Behavior of Porous Titanium Manufactured Using a Novel Spherical Space Holder
Authors: Li Bo Qiong , Li Xiao Ming , Lu Xing
Published: February 2019

Porous titanium of 10-65% porosity and 100-400 μm macro-pore size manufactured by adding spherical polymethyl methacrylate (PMMA) powders as pore makers. The bending strength of 21-453 MPa and shear modulus of 1.9-43 GPa were obtained. Increasing in porosity and macro-pore size, the bending strength and shear modulus reduced as described by theoretical model, and the macro-pores of porous titanium yielded a smaller deformation under bending.
Preparation of High Sphericity Li2TiO3 Tritium Breeder by Polymer Assisted Sedimentation Method
Authors: Chen Zhi Peng , Lu Wei , Chu De Lin , Wang Wei Hua , Pu Wen Jing , Jiang Hai Yan , Pan Zi Hao , Ma Shu Bing , Deng Hai Fei , Qi Jun Li
Published: February 2019

The tritium breeder materials used in solid tritium breeding blanket of fusion reactor are lithium-based ceramics, like lithium titanate (Li2TiO3), lithium orthosilicate (Li4SiO4), lithium aluminate（LiA1O2) and lithium zirconate (Li8ZrO6). Among them, Li2TiO3 has the advantages of stable chemical property, high mechanical strength and high lithium content, so it has become one of the preferred materials. Based on the design of solid blanket and tritium extraction process, breeder materials need to be made into a certain shape of pebbles. B Spherical breeder is widely used in the design of fusion reactor for the larger specific surface area, more channels between the pebbles to diffuse and release tritium, and easier loading or unloading. However, due to the high requirements of the breeder pebbles, the production control are not complete. In this paper, a new preparation method of ceramic pellets with high sphericity, polymer assisted sedimentation method, was used to prepare ceramic pebbles. The slurry consists of micro-scaled ceramic powder and organic monomers. Spherical droplets of ceramic slurry were obtained by sedimentation method in viscous liquids. The organic monomer contained in the droplets was heated to polymerize into small pellet preforms during the sedimentation process. By optimizing the sintering process, the fabricated pebbles could perform high compressive load (>18 N), spherical shape (0.95~1.02), uniform particle size (0.8~1.2mm) and porosity (15~20 %). The main advantages of this method is the mild preparation conditions (50~110 °C), the simplified transfer and purification process and convenient industrialization.. The obtained product has high spherical shape, uniform particle size, high compactness and mechanical strength.
Effect of Fluorine-Containing Additive on the Electrochemical Properties of Silicon Anode for Lithium-Ion Batteries
Authors: Wang Jing , Yang Xiao Hang , Su Yue Feng , Chen Shi , Wu Feng
Published: February 2019

Silicon anode is a promising candidate as an alternative to the conventional graphitic anode in lithium-ion batteries. In this work, silicon anode is modified by NH4F using a facile method in air. The concentration of NH4F on the electrochemical performance is systematically checked. The 5wt%NH4F-modified silicon anode exhibits enhanced cycle and rate performances, the first discharge specific capacity is 3958 mAh·g-1 with 86.45% as the coulombic efficiency at 0.4A·g-1. The capacity can maintain at 703.3 mAh·g-1 after 50 cycles, exhibiting a much better cycle stability than pristine silicon anode (329.9 mAh·g-1 after 50 cycles). SEM images confirm that NH4F can alleviate the volume expansion of silicon since LiF can be generated at the surface which is beneficial to the stability of solid-electrolyte interphase (SEI).
Effects of Hot-Rolled Process and Heat Treatment on Microstructure and Mechanical Properties of Ti-6Al-4V ELI Alloy
Authors: Dong En Tao , Yu Wei , Cai Qing Wu , Shi Jia Xin , Ning Zhen , Zhang Ze Yu
Published: February 2019

The properties of titanium alloys significantly depend on the microstructure, which are correspond to the deformation conditions. However, because of its low thermal conductivity, sensitive to deformation temperature, narrow stable regions for hot working and structural heterogeneity, it does not achieve cosmically industrial production and application. In this paper, the effects of hot rolling deformation in single-phase (β) region, cross-phase region and heat treatment on the microstructure and mechanical properties of Ti-6Al-4V ELI alloy were systematically investigated. The relationship between microstructure and properties of alloy was also analyzed in order to a theoretical basis for the development of the rolling technology for the manufacture. The results indicated that hot rolling deformation in different region had significant effects on microstructure heterogeneity (the size and colony of α phase, lamellar microstructure of β transformed). It has been shown that fine and coarse lamellar α structure within grains and visible grain boundary α were characterized after the deformation above the β transformation temperature, which made high impact toughness. But in order to ensure in single phase region, the heat preservation method after passes of rolling may cause β grain coarsening (widmanstatten structure), leading to mechanical properties worsen. The fine crisscross substructures of α phase was obtained after deformation in cross-phase region, improving good mechanical properties. After solution treatment followed aging, the uniform type of microstructure was reached, which mainly displayed the change of contents and sizes of lamellar α phase.
Research on the Springback of Square TA18 Titanium Alloy Tube on the Numerical Simulation
Authors: Liu Cong , Yan Xiao Dong , Yang Yin , Ye Wei
Published: February 2019

This paper focuses on how bending and springback process of the titanium tubes with different bending radius and bending angle affect the springback rate after unloading and analyses tube distributions and variations of stress and strain by establishing a three-dimensional elastic-plastic finite element model of square TA18 titanium alloy tube based on ABAQUS/explicit and ABAQUS/standard. It is shown that under the same process parameters, the sprignback rate obtained by numerical simulation is in good agreement with that measured in the experiments. The springback rate after unloading increases with the increase of the bending radius linearly, and it increases nonlinearly with the decrease of bending angle. The distribution of the tube-roundness and the relationship between its roundness and springback rate under different process parameters could be obtained by comparing the variation of the absolute value of its outer wall unit at the maximum principal strain before and after unloading.
A Phase-Field Model for Multilayered Heterostructure Morphology
Authors: Wu Ping Ping , Wang Guan , Pang Shu Min
Published: February 2019

Heteroepitaxially grown multilayered thin film structures have been attracted of great interest due to its potential applications in photovoltaic/light emitting/electronics devices. The thin film morphology plays an important role in enhancing its related physical properties. It is not easy to simulate the multi-layered thin film structures due to the influence of the interface/surface fluctuation. However, the phase field method, based on thermodynamics and Cahn-Hilliard diffusion model, can predict the thin film morphologies without tracking the interfaces. In this paper, a new phase field model was developed for predicting multi-layer structures with multi-order parameters. The morphologies with strain distributions of the quantum wells, quantum dots and buffer layers structures were investigated in the current study. We found that the strain distribution has a strong effect on the suface/interface morphologies in the multilayered structures. Some simulation results are consistent with experimental observations.
Corrosion Behavior of P110S Oil Pipe in Simulated Working Condition
Authors: Fang Xiao Jun , Liu Li , Yang Zhi Gang , Zhang Yong Qiang
Published: February 2019

The corrosion resistance of P110S steel in CO2 and H2S coexistence corrosion environment under different temperature and PCO2/PH2S was investigated by high temperature and high pressure (HTHP) reaction kettle combined with SEM, EDS and XRD analysis methods. The stress corrosion cracking (SCC) resistance of P110S steel was studied under loading pressure of 682.2MPa (758MPa×90%) in simulated conditions after 720 hours test. The results show that the P110S steel has serious corrosion in the range of simulative temperature and H2S partial pressure. With the increase of temperature, the corrosion rate decreases first and then increases. With the increase of H2S partial pressure, the corrosion rate increases first and then decreases. The P110S steel has the highest corrosion rate when the temperature is 50 °C and H2S partial pressure is 0.1%. After the anti-SCC test, the specimens did not fracture, and cracks perpendicular to the tensile stress were not found on the surface. That is, P110S has good SCC resistance in the corrosive environment.
Microscopic Study on Mechanical Properties of Different Microregions during In-Service Welding
Authors: Qiao Ling , Han Tao , Wang Hong Tao , Han Lai Hui , Gu Shi Wei
Published: February 2019

In-service welding has been gaining considerable attentions due to its significant economic benefits. At high temperature, several technical difficulties exist during repair process and burn-through has been one of the critical issues. To reveal the physical nature of burn-through, finite element simulation and molecular dynamics simulation are combined to investigate the micro dynamic properties of different micro regions in welded joint and the effect of crack on the microdynamic behavior in the process of material failure. The results indicate that burn-through is a failure process under the effect of tensile stress and high temperature. The performance near fusion line is the worst and a burn-through tends to occur at the regions behind maximum melting depth. The failure process of welded joints experience the initiation and development of micro defects. Continuous expansion of micro holes and micro cracks causes the structural fracture. Furthermore, the micro crack would decrease the structural strength and the failure mode differs for cracks in different direction. Failure process of crack structure has experienced the crack tip passivation and dislocation emission. And the formation of stacking fault is carried out in failure process. This paper reveals the microscopic mechanism of burn-through at the atomic level and provides a scientific basis for the continuous and safe operation of gas pipelines.
Pressure Capacity Study of Φ100 Reinforced Thermoplastic Pipe
Authors: Wang Lin , Fan Yu Ran , Song Peng
Published: February 2019

The pressure capacity of reinforced thermoplastic pipe was studied by the finite element analysis and experimental study using Φ100 reinforced thermoplastic pipes. The simulation results illustrated that the failure mode of reinforced thermoplastic pipe under internal pressure was the break of glass fiber belt in structural layer. Moreover, the simulated burst pressure fitted well with the experimental result, the small deviation between two results may be resulted from the process defects of RTP.
Development of Characterization and Analysis Methods for Graphene Modified Coatings for Tubing
Authors: Cao Ya Qiong , Feng Chun , Zhu Li Juan , Li Rui Zhe
Published: February 2019

With the further deterioration of the oil and gas exploitation environment, the corrosion of tubing becomes an intractable problem. Therefore, choosing suitable anticorrosive coating is of great significance to the safe operation life of tubing and reduce economic cost. Effect addition of appropriate graphene in coatings can significantly improve its corrosion resistance of the coating. However, most of the applied research are focus on marine heavy corrosion condition; the relationship between the corrosion mechanism and performance of graphene coating for tubing is not clear, probably due to difficulty in the characterization of the organizational structure characterization of the graphene modified coating. In the present work, Typical methods of the graphene coating characterization: Scanning Electron Microscope (SEM) with EDS, Transmission Electron Microscope (TEM), Atomic Force Microscope (AFM), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) will be introduced, and the application prospect of the coating will be discussed. It indicated that the single characteristic method cannot analysis the structure and morphology information of graphene anticorrosion coating comprehensively. Flexibly use of a variety of characterization methods to study the anticorrosion mechanism and performance of the graphene modified coating for tubing is a better choice. The graphene modified anticorrosive coating for tubing is with the potential of wide applications.
Failure Analysis on Leakage of the Circumferential Weld of Steel 20 Buried Pipeline
Authors: Qu Ting Ting , Tong Ke , Zhu Li Xia , Cong Shen , Lu Cai Hong
Published: February 2019

Nowadays, the welding quality of circumferntial welds is the main influencing factor of the service behaviors of long-distance transport pipeline, and the accidents caused by the circumferential welding defects have get extensive attention. To figure out the leaking reason of circumferential weld of the steel 20 buried pipeline, with macro inspection, nondestructive testing, physical and chemical properties, methods of medium leakage and fracture analysis, we found that the welding defects in the weld toe are mainly responsible for pipeline leaking. The welding defects of circumferential weld destroy the continuity of welding, which result in the stress concentration and cracks. Under the combined action of corrosion, erosion, working stress and welding residual stress, the cracks extend along the welding weak areas and penetrates the welding metal, finally leading to the leakage failure of the welds, also some suggestions are given to prevent similar accidents.
Fracture Toughness and Application of X80 Pipeline Steel
Authors: Zhang Hua , Zhang Hong , Lu Cai Hong
Published: February 2019

The fracture toughness of X80 pipeline steel, which has been widely used in China, plays a key role in pipeline safety insurance. In order to know the accurate fracture toughness of X80, the methods of acoustic emission and high K ratio have been carried out to judge the initiation of crack propagation and improve flatness of fatigue pre-crack front. By this method, fracture toughness of base metal, weld and heat affect zone of X80 pipeline steel have been tested, and failure assessment curves of X80 have been established and fitting equations has been provided. The results suggested that different failure assessment curves should be established according to different crack sizes and material parameters.