bluuebunny/crossref_metadata_2025 huggingface dataset:
Squeeze Cast Co-Continuous AlN/Al Composites
Authors: Lu Yuan , Li Jing Long , Yang Jian Feng , Jing Qiang Zheng , Li Jing Jing , Li Peng
Published: April 2014

The co-continuous AlN composites with different Al contents were fabricated through the squeeze casting of porous AlN preform with varied porosities obtained by carbothermal reduction. The effects of volume fraction of Al phase and the heat treatment temperature on the mechanical properties of composites were investigated. The change of the mechanical properties of composites with the Al content was in line with the mixed rule. With an increase in the Al content, the fracture toughness increased, the Vickers hardness and the flexural strength decreased. The toughen mechanism of composites included ductile rupture and microcrack toughening. The avoiding of excessive interface reaction between AlN and Al was beneficial to the mechanical properties of composites. With an increase in the heat treatment temperature, the stress and the dislocation due to mismatch in the coefficients of thermal expansion increased, the fracture toughness decreased, the vickers hardness and the flexural strength increased.
Preparation and Thermal Stability Properties of Epoxy Matrix/Nano-SiO2 Composites
Authors: Lin Qin , Song Zhen Jiang , Xie Jian Liang
Published: April 2014

The addition of nanoparticles has been proven to a high potential application for improving polymer thermal stability properties. In this paper, the nanocomposites based on epoxy matrix modified with different mass ratio of silica nanoparticles were investigated. In order to disperse and incorporate silica nanoparticles into epoxy matrix, silica nanoparticles were modified with coupling agent (Gamma-glycidoxy propyl trimethoxy silan, KH-560). FTIR spectra showed that KH-560 was absorbed on the surface of SiO2 nanoparticles. The thermo gravimetric traces indicated that the addition of silica nanoparticles has improved the thermal stability properties of epoxy matrix significantly. The decomposition temperature of nanocomposite increased with the addition of nanoSiO2, and the temperatures of the maximum rate of degradation of the unmodified nanocomposite with 0wt%, 1wt%, 3wt%, 5wt% nanoSiO2 were 401oC, 405oC, 411oC, 421oC, respectively. The temperatures for 50% weight loose of the modified nanocomposite with 1wt% and 3wt% nanoSiO2 were 389oC and 405oC, respectively.
Study of Ca and Ce Additions on Different Ignition Resistance Behavior of Magnesium Alloy
Authors: Ding Jian , Zhao Wei Min , Qin Lin , Li Yong Yan
Published: April 2014

In order to develop ignition resistant magnesium alloy, Ca and Ce elements were selected alloying elements to fabricate Mg alloy. Different content of Ce (0,0.5,0.8,1.2,1.5wt%) and Ca (0, 0.6,0.8,1.0wt%) were added into pure magnesium to analyze their ignition-proof effect. The concentration of Ce and Ca elements on the melt surface was believed to be key factor for ignition resistance, which caused the change of interfacial tensions. It was indicated that the ignition resistance could be improved with increase of Ce and Ca addition. This could be attributed to a protective surface oxide owing to the diffuse of Ce and Ca to surface.
Effect of Re Addition on the Ignition Resistance of Pure Magnesium
Authors: Ding Jian , Fang Zheng , Qin Lin , Zhao Wei Min
Published: April 2014

This paper focus on the effect of rare earth elements addition on the oxidation resistance of pure magnesium. The results show that the ignition points of the Mg-RE alloys vary like “V” along with the increase of the rare earth elements. When the content of Y reaches 10wt%, the ignition point of magnesium alloy is 890K, about 40K higher than the ignition point of pure magnesium. After the addition of rare earth elements, dense oxide film forms on the surface of Mg-RE alloys. The outer oxidation film mainly consists of rare earth oxide.
Preparation and Properties of Cotton Fiber/Poly(lactic acid) Composites
Authors: Qian Jin , Yu Min Min , Ge Zhao , Xu Ming Jie , Zhang Hui Hui , Yang Ge Sheng , Shao Hui Li
Published: April 2014

In order to improve the mechanical properties of poly (lactic acid) (PLA), cotton fiber/PLA composites were prepared by melting compounding and injection molding. The effects of cotton fiber content and coupling agent on mechanical properties, crystalline behavior and interface morphology of the composites were studied by universal testing machine, DSC and SEM, respectively. The results showed that the crystallinity of the composites increased gradually with the increase of cotton fiber content, whereas the mechanical properties of the composites increased firstly and then decreased with further addition of cotter fiber. The composite with 20wt% cotton fiber had an optimal mechanical performance. In addition, with the incorporation of 1wt% coupling agent, the interfacial adhesion between cotton fiber and PLA improved obviously, and the mechanical properties of the composites increased accordingly. Compared with the neat PLA, the tensile strength, flexural strength, flexural modulus and impact strength of the resultant composites were increased by 66.0%, 27.4%, 45.8% and 60.4%, respectively.
Effect of Two-Step Treatments on Interfacial and Mechanical Properties of Sugarcane Rind Fiber/Natural Latex Biodegradable Composites
Authors: Chen Shi Yan , Chen Shi Yan , Xin Hai Xia , Wang Hua Ping
Published: April 2014

Sugarcane rind fiber/natural latex biodegradable composites were prepared by compounding natural latex with sugarcane rind fiber as reinforcing filler. We selected three chemical solvents, including sodium hydroxide (NaOH), silane (KH550) and acrylic acid (AA), and used one-step or two-step treatment method to improve the interfacial adhesion between sugarcane rind fiber and natural latex matrix. Fourier Transform Infrared spectroscopy (FTIR) was used to characterize the chemical composition change at the sugarcane rind fiber surface structure by the chemical treatments. Scanning Electron Microscopy (SEM) results showed that the interfacial adhesion and dispersion of the composites based on two-step treated fiber were improved. The mechanical properties of these biodegradable composites were evaluated, which showed an increase of the tensile strength and elongation at break of the composites based on two-step treated fiber compared to those based on untreated fiber.
Facile Fabrication of Super-Hydrophobic Surface on Aluminum and its Effects in Accelerating Underwater Bubble Bursting
Authors: Kang Chun Mao , Ji Jin Yan , Zhao Jun Li , Zhong Hong Peng , He Jiao , Ma Yu , Yu Mu Huo
Published: April 2014

Facile fabrication of bio-mimic super-hydrophobic surfaces has attracted attentions in both fundamental research and practical application. In this article, we developed a simple one step etching method to fabricate a super-hydrophobic surface on aluminum surface. The contact angel of water reaches 155.9° without coating any low energy materials. Surface morphology clearly demonstrates a combination of micro/nanohierarchical structures. Moreover, such surface remarkably shortens the bursting time of air bubbles under water. For a middle size bubble about 1mm, the bursting time at super-hydrophobic surface shortens to about 20%, comparing to freely bursting. This intriguing effect may contribute to future expand applications of super-hydrophobic surface in industrial field, such as fiber spinning.
Solid-State Synthesis and Thiophanate Methyl Visible Light Degradation of Magnesium Doped TiO2 Mesoporous Nanomaterial
Authors: Liu Shao You , Yang Hong Yun , Min Zong Yi , Luo Chen Yan , Zhang Yang , Jiang Tian Zhi
Published: April 2014

Mg-doped TiO2mesoporous nanomaterial with high-efficiency solar photoelectric conversion was successfully prepared by a solid-state reaction using cetyltrimethyl ammonium bromide as a template agent. As-prepared Mg-TiO2nanomaterials are characterized with XRD、SEM, UV-Vis, XPS, BET and Raman spectroscopy. It was found that magnesium as Mg2+incorporates into the framework of TiO2by isomorphous replacement with content of 2.36%. The Mg-TiO2nanoparticles are anatase phase with particle size of 10-24nm. The rod-like nanoparticles have specific surface area of 104.5m2/g and pore-diameter distribution centre of 5.1 nm. The surface of Mg-TiO2material with stretching vibrational peak at 1105cm−1is assignable to the Mg-O-Ti bond. Furthermore, the UV–vis displays that the absorption region of mesoporous Mg-TiO2powder shifts to 405nm, and the absorption intensity of the visible-light region is enhancement. At 20oC, pH = 6.8,c0= 50 mg/L, within 150 min, the rule of pseudo-second-order reaction and the degradation rate of thiophanate methyl of 57% and 91.8% corresponding visible-light irradiation and ultraviolet irradiation are obtained for the Mg-TiO2nanomaterial. But it is poor to photodegradation of thiophanate methyl for P25-TiO2, and it keeps to the rule of pseudo-first-order reaction.
A Novel Method for the Synthesis of Amphiphilic Copolymer: PHEMA-b-PDMS-b-PHEMA
Authors: Xu Jian Feng , Peng Xiao Quan , He Chun Ju
Published: April 2014

In this study, a novel amphiphilic copolymer based on the flexible polydimethylsiloxane (PDMS) macroinitiator was successfully prepared by atom transfer radical polymerization (ATRP). First, the high molecular weight bis (hydroxyalkyl)-terminated PDMS was prepared by hydrosilation reaction between hydrogen-terminated PDMS and 2-allyloxyethanol in the presence of Karstedt’s catalyst. The macroinitiator Br-PDMS-Br was prepared by the reaction between different molecular weight bis (hydroxyalkyl)-terminated PDMS and 2-bromoisobutyry bromide. Then the amphiphilic ABA-type block copolymers of poly [dimethylsiloxane-b-(hydroxylethyl methacrylate)] were initiated by bromide end-capped PDMS with HEMA, under an appropriate catalyst/ligand system of CuCl/bpy. The polymerization proceeded with first-order kinetics. It showed that the reaction system was a controlled/‘living’ polymerization. The triblock copolymers were characterized by FTIR, 1H-NMR, TGA and GPC techniques. GPC results showed the tribolck copolymer had narrow polydispersity of Mw/Mn (PDI<1.5). TGA results showed the good thermal stability of the triblock copolymer.
Study on Preparation and Property of High Thermal Oxidation Stability PPS/SiO2 Fiber
Authors: Meng Si , Hu Ze Xu , Xing Xue Yu , Lu Qiu Xu , Zhou Zhe , Zhu Mei Fang
Published: April 2014

PPS/SiO2 composite was studied to enhance the thermal oxidation stability of PPS. In order to improve the dispersity of SiO2 in PPS matrix, the SiO2 was modified by silane coupling agent, KH-570. The fractured surface morphologies, thermal properties and rheological property of PPS/SiO2 composite were researched. The high thermal oxidation stability PPS/SiO2 fibers were prepared by melt spinning. The thermal ageing treatment was carried out, and the strength and retention strength, before and after ageing treatment, of two kinds of fibers (PPS fibers and PPS/SiO2 fibers) were compared. The results of SEM showed the good dispersity of the modified SiO2 in PPS matrix. After adding modified SiO2, the initial decomposition temperature increased. At the same time, the fiber strength and retention strength were improved, which can be found by comparing. Compared with pure PPS, after adding 1.0 wt%, which was proved to be the optimum dosage by the research, modified SiO2 into PPS, the initial decomposition temperature was increased by 15.3°C, the retention strength was increased from 60.3% to 85.1% after ageing treat.
Study on Spinnability of UHMW/PAN Dope in DMSO
Authors: Du Wei Feng , Chen Hui Fang
Published: April 2014

The extensional rheological properties of the PAN/DMSO spinning solution using ultrahigh molecular weight (UHMW) PAN as additive were studied. The effects of the additive content on the extensional rheological curve, the extensional viscosity, as well as the spinnability of the PAN/DMSO spinning solution were investigated. The results revealed that the spinnability was related to such factors as solution concentration, additive content, temperature, apparent extensional viscosity and extensional strain rate. The effect of additive on the spinnability of the spinning solution turned out to be small when additive contents were set at a very low level. The spinnability of the spinning solution was optimized when the additive content was 0.5%wt, while the spinning solution adding 1%wt additive had a good spinnability only at a relatively higher temperature.
Preparation and Study on Nano-Ag/SnO2 Electrical Contact Material Doped Rare Earth Element
Authors: Zhu Yan Cai , Wang Jing Qin , Wang Hai Tao , An Li Qiang
Published: April 2014

As a new type of electrical contact material, Ag/SnO2 has poor processing performance and large contact resistance, which limits its application so far. In order to improve the machinability and electrical performance of the Ag/SnO2 electrical contact materials, a new kind of nanoAg/SnO2 electrical contact material doped rare earth element Ce was prepared by sol-gel-chemical plating method. The purity of the powders was analyzed by X-ray diffraction (XRD) and the crystallite size of the nanoparticle was calculated according to the Scherrer equation. The distribution of Ce-doped SnO2 powers were studied using scanning electron microscopy (SEM). In parallel, rated making and breaking experiments on nanoAg/SnO2 were conducted. The results of XRD and SEM show that the nanoSnO2 powders are small, uniform and with no obvious phenomenon of reunion, and thus significantly improve the density, strength and machinability of the sample. Furthermore, the results of arc erosion show that the nanoAg/SnO2 electricity contact materials doped element Ce have superior fusion welding resistance properties.
Effect of Brazing Flux Pb on Microstructure and Mechanical Property of CMT Weld-Brazed Lap Joint of 5052 Aluminum Alloy to Galvanized Q235 Steel
Authors: Lai Hua Qing , Lu Sheng
Published: April 2014

5052 aluminum alloy and galvanized Q235 steel sheets with thickness of 1mm were lap welded/brazed by cold metal transfer technology (CMT) with ER4043 as the filler wire and Pb foil as the brazing flux. Scanning electron microscope (SEM), microscope with super-depth, X-ray diffraction (XRD), electronic universal tensile testing machine and hardness tester were employed to study the microstructure and mechanical properties of the joint. The results indicate that Pb foil effectively improved the mechanical properties of the joint with tensile strength up to 160Mpa which is higher than that of the joint without the brazing flux of Pb foil. Intermetallic compound (IMC) layer in the brazing joint unequally distributed in the interface of aluminum alloy and galvanized steel. The thickness of IMC layer was about 1~3.5um. The main phases of the IMC layer were FeAl and AlFe6Si. Fine equiaxial crystals existed in the weld metal while columnar crystals existed in the fusion zone of aluminum alloy. The hardness of fusion zone was higher than base metal while the hardness of heat affected zone was lower than base metal. In most case, the lap joint was broken in the junction of base metal and fusion zone.
Effect of Deformation Ratio on Microstructures and Properties of High Nitrogen Martensitic Stainless Steel
Authors: Zhang Shan Ju , Yang Mao Sheng , Lei Ting
Published: April 2014

To reveal the effect of deformation ratio on high nitrogen martensitic stainless steel, the room temperature mechanical properties, microstructures and precipitates morphology were studied by using optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM) as well as mechanical tests. The results indicate that the tensile strength, yield strength and impact energy were raised 241MPa, 180MPa and 10.0J respectively, at a higher deformation ratio. While, the average original austenite grain size was refined from 14.93μm to 9.57μm when the deformation ratio was increased from 0.65 to 0.83 as well as the martensite lath width thinned from 400nm to 250nm. Furthermore, at various deformation ratios, the precipitates morphology was different in quantity, grain size and dispersion. There are more eutectic precipitates and secondary precipitates dispersed along the grain boundary as continuous chains with lower deformation ratio. On the contrary, the precipitates in specimen with higher deformation ratio were uniform and fine without chain or network. It can be inferred that the improvements on mechanical properties, microstructures and precipitates morphology are mainly due to the deformation ratio.
Fabrication of Microfibrous Patterns via Electrospinning
Authors: Huang Yuan Yuan , Liu Shu Liang , Sun Bin , Long Yun Ze
Published: April 2014

Using patterned conductive and insulating collection devices, fibrous patterns from polyvinyl pyrrolidone were fabricated by electrospinning. Considering that the electrospun fibers tend to deposit along the direction of electric field line, when conductive patterned template is used as collector during electrospinning, the as-spun fibers tend to assemble onto the conductive grids, whereas the dropping fibers prefer to avoid insulation grid by concentrating toward the surface of the Al foil when an insulating grid based on Al foil is used as collector.
Recrystallization and Precipitation of β-Mg17Al12 Phase of the Cold-Rolled Mg-9Al-1Zn Alloy Strip during Isothermal Annealing
Authors: Jiang Yan Bin , Zhang Zhi Hao , Guan Lei , Tang Guo Yi
Published: April 2014

Effect of isothermal annealing on the microstructure evolution of the cold-rolled Mg-9Al-1Zn alloy strip was investigated. It is found that the competition between the precipitation of β-Mg17Al12 phase and recrystallization of α-Mg matrix occur under the conditions of various annealing temperature and time. At a low annealing temperature (523K), the β-Mg17Al12 particles precipitate preferentially at locally high deformation area and grow into the lamellar-cluster with an increase in the annealing time, retarding the recrystallization of α-Mg matrix. With raising the annealing temperature (573~623K), both the precipitation of β-Mg17Al12 particles and recrystallization of α-Mg matrix take place. Both recrystallization and grain growth are prone to proceed without precipitation of β-Mg17Al12 particles when the annealing temperature is 673K. A mechanism for the competitive behavior between the precipitation of β-Mg17Al12 phase and recrystallization of α-Mg matrix at various annealing conditions is discussed.
Sliding Wear Behavior of Forged, Uncoated and Laser Nitrided LMD TC18 Titanium Alloy
Authors: Liu Lin , Liu Cheng Chen , Han Hao , Shangguan Yun Jie , Wang Qi , Tang Hai Bo , Wang Hua Ming
Published: April 2014

Recently, laser melting deposition (LMD) undergoes rapid development since its fabricating advantages make it particularly suitable for the fabrication of titanium aerospace components. The dry sliding wear behavior of forged, uncoated and laser nitrided LMD TC18 titanium alloy sliding against the forged TA15 alloy were investigated. Then, reasons of their wear behavior were further studied. The specimens were tested on the M-200 tester, worn surface morphology and wear debris were carefully analyzed by means of SEM and EDS. The results show that in the case of forged and LMD TC18 titanium alloy sliding against TA15 alloy, wear mechanism are abrasive wear and adhesive wear. Because of the lubricious nature of TiO2 oxides produced during sliding which reduces the wear and consequently wear loss, the wear resistance of forged TC18 titanium alloy is superior to that of LMD TC18 titanium alloy. After using laser nitriding treatment on LMD TC18 alloy, the formation of a protective layer composed of dendritic TiN attributes to significant wear resistance improvement.
Physical Properties, Compatibility and Morphology of Hydrogenated Nitrile Rubber/Fluoroether Rubber Blends
Authors: Wang Zhen , Qian Huang Hai , Geng Xin Ling , Zhao Yan Fen , Liu Li Ping
Published: April 2014

The physical properties, compatibility, and morphology of blends of hydrogenated nitrile rubber (HNBR) with fluoroether rubber were investigated with reference to the blends ratio. The results show that the blends have excellent physical properties. Minimum torque (ML), maximum torque (MH), optimum curing time (t90), compression set, volume and mass change in fluid, and specific gravity are linear with the content of HNBR. On the other hand, MH-ML, hardness and 100% modulus show synergistic effect when the blend ratio is 50/50, indicating that there is some special morphology or interaction between the two polymers. There are two glass transition (Tg) peaks in Tanδ-T, Loss modulus (E")-T and Differential Scanning Caloricity (DSC) curves of the 50/50 blend and the Cole-Cole curve of the 50/50 blend shows two modified semicircles, suggesting the absence of segmental miscibility of the blends. The thermal gravimetric analysis (TGA) curves demonstrate that the 50/50 blend is thermo-stable to the highest temperature which may be due to the interaction between the two materials. Scanning electron microscope (SEM) was used to investigate the morphology of the blends. The micrographs of 75/25 and 25/75 HNBR/fluoroether rubber blends have phase separated structures with the Sea-Island morphology. For the 50/50 blend, the SEM micrographs show a co-continuous morphology, which is suggested to be the reason for the synergistic effects of MH-ML, hardness, and the 100% modulus at the given ratio. In conclusion, the physical properties, DSC, TGA, dynamical mechanical thermal analysis, and SEM micrographs agree in suggesting that the HNBR and fluoroether rubber are not thermodynamically miscible but mechanically compatible.
Hot Compression Deformation Behaviors and Microstructure Evolution for Brittle Au-20Sn Eutectic Alloy
Authors: Zhang Wei , Mao Yong , Song Jia Jia , Guo Jin Xin , Xu Si Yong
Published: April 2014

The hot compression test of Au-20Sn alloys with different solidification structures was carried out. The deformation behaviors and microstructure evolutions during hot compression were investigated. The results indicate that the fine fully lamellar eutectic structure without primary phase exhibited a very low yielding stress and a low stress platform, while the coarse lamellar with large primary Au5Sn phase showed rather high in that value. After compression, the lamellar eutectic tended to be equiaxed due to dynamic recrystallization, the large primary phase became separate dendrites or split into small dendrites, and the small roselike primary phase partly dissolved in the eutectic matrix. The rate of recrystallization also increased as the primary phase eliminated and lamellae was refined. It is suggested that refining eutectic lamellae and eliminating the primary Au5Sn phase in the as-cast microstructure by solidification optimization are an effective way to improve the workability greatly for brittle Au-20Sn eutectic alloy.
Magnetic Properties of Cyano-Bridged Compound Co [Fe(CN)5NO]·5H2O
Authors: Lei Cheng Long , Lin Qing , Huang Hai Fu , He Yun , Wang Rui Jun
Published: April 2014

The cyano-bridged complex Co [Fe (CN)5NO]·5H2O has been synthesized. According to the reaction of cyanide-based unsaturated ligand precursor (molecular fragments)[BLy(CN)x]n-with the metal ions or complex unsaturated ligand, it is easy to control the structure of molecular magnets and tune up the magnetic properties. Hetero binuclear complex Co [Fe (CN)5NO]∙5H2O was prepared through [Fe (CN)5NO]2- ion. The room temperature Mossbauer spectrum revealed a doublet with the isomer shift parameter (-0.44(7) mm/s) and quadrupole splitting (QS = 1.91(3) mm / s) characteristic for low-spin Fe (III) ions. The low-spin (S = 1/2) of the Fe (III) ion of valence electrons on the electric field gradient (EFG) was caused by non-zero contribution. DC and AC magnetic measurements showed that the complexes belonged to the anti-ferromagnetic material, with a magnetic phase transition temperature below 2K.
Effect of the Ce-TiO2/Diatomite on the Photo-Catalysis Degradation of MB
Authors: Liang Xiu Hong , Fu Xiao Ye
Published: April 2014

In this paper, TiO2/diatomite and Ce-TiO2/diatomite were prepared by sol-gel method in order to improve the spectrum responding range and its photocatalytic effect. The obtained samples were characterized by means of X-ray Diffractometer (XRD), Scanning Electron Microscope (SEM), Infrared Absorption Spectroscopy (FT-IR) and so on, and the photocatalytic activity was evaluated by methylene blue degradation. The heat stability of TiO2/diatomite was improved by Ce-doped; TiO2 was successfully loaded on diatomite through physical and chemical action. The de-coloring ratio of methylene blue of the two composite materials were similar under UV light, Ce-TiO2/diatomite was higher under visible light, it reached to 80%, and it kept 65% after the five times repeated using of Ce-TiO2/diatomite.
Microstructure, Mechanical and Tribological Properties of the Tialn Coatings after Nb and C Dual Ion Implantation
Authors: Deng Bin , Pei Jun Fei , Tao Ye
Published: April 2014

Ion implantation is an effective method to enhance hardness and wear resistance of the TiAlN coatings. In this paper, Nb and C ions are co-implanted into TiAlN coatings deposited by Magnetic Filter Arc Ion Plating (MFAIP), using a Metal Vacuum Vapor Arc (MEVVA) ion source implantor with doses of 1×1017and 5×1017ions/cm2. The microstructure, chemical composition, mechanical and tribological properties of Nb+C-implanted TiAlN coatings have been investigated by glancing incidence X-ray diffraction, X-ray photoelectron spectroscopy, nanoindentation test and SRV friction & wear tester, respectively. The results showed that the NbN and TiC phases could be detected both from the XRD and XPS profiles of as-prepared films. Nb and C ion implantation could improve the hardness, plastic deformation resistance and wear behavior of TiAlN coatings due to the energetic Nb and C ion bombardment and the formation of NbN and TiC phases.
Effect of CO2 on Anti-Corrosion Property of a Polyurea Coating Modified with Organosilicone
Authors: Shi Qing Hao , Wang Bing Ying , Zhao Bin
Published: April 2014

The corrosion mechanism of organic silicon modified polyurea composite coating under different CO2 partial pressures was studied using high-temperature autoclave, combined with scanning electron microscopy (SEM), adhesion tests and electrochemical impedance spectroscopy (EIS) technology. The experimental results showed that: there was no corrosion product formed on the surface of coating sample after high-temperature high-pressure corrosion test, and with the increasing of CO2 partial pressure, the coating adhesion and impedance values decline increases. Moreover CO2 partial pressure increases accelerated the failure process of polyurea composite coating system.
Progress in Novel Composite Thermal Barrier Coating
Authors: Yao Jun Qi , He Ye Dong , Chao Ren , Ma Xiao Xu , Gao Jun Guo
Published: April 2014

Improved structure design has been acknowledged as an effective approach to obtain thermal barrier coating (TBC) with excellent resistance to high-temperature oxidation and spallation. Since ceramic composites can effectively enhance the strength and durability of ceramic components and improve their fracture toughness, it is reasonable to propose that composite structure of TBC should possess improved mechanical properties than its traditional structure with single phase in bond coat and top coat. In this paper, the progress in novel composite TBC developed by the authors’ research group has been summarized, including TBCs with bond coat of ceramic/ceramic and ceramic/noble metal composite coatings which replace the traditional alloy bond coat, and also TBCs with novel composite structure have been studied. It has been investigated that these TBCs exhibit not only excellent high-temperature oxidation resistance, but also excellent resistance to cracking, spallation and buckling under thermal cycling. Such beneficial effects can be attributed to the sealing mechanism of these coatings on oxygen diffusion, the improvement of thermal expansion mismatch and the toughening effects of these composite structures. It would be a growing trend in introducing various composite modes into the traditional thermal barrier coating or developing new composite structure of thermal barrier coating.
Effect of Aging Temperature on Microstructure and Hardness of CoCrFeNiTi0.5 High Entropy Alloy
Authors: Dong Yong , Chen Qiu Shi , Lu Yi Ping , Zhang Peng Chao , Li Ting Ju
Published: April 2014

A bulk casting ingot (Ø70 × 150mm) of CoCrFeNiTi0.5 high entropy alloy was prepared by vacuum medium frequency induction melting. The samples from the ingot were aged for 12h in the temperature range of 900-1100°C and then quenched in water to investigate the effect of aging temperature on the microstructure and hardness of CoCrFeNiTi0.5 alloy. The crystalline structure of as-cast CoCrFeNiTi0.5 alloy consisted of the principal face-centered cubic (FCC) dendrite phase plus (Ni, Ti)-rich R phase, (Fe, Cr)-rich σ phase, (Co, Ti)-rich Laves phase within the inter-dendrite area. The dendrite contained approximately equivalent amount of Co, Cr, Fe, Ni and a smaller amount of Ti element. After aging treatment in the temperature range of 900-1000°C, the (Co, Ti)-rich phase disappeared while the amount of (Ni, Ti)-rich phase and (Fe, Cr)-rich phase increased. But the volume fraction of FCC dendrite phase increased and the intermetallic phases decreased after aging at 1100°C. The micro-hardness and the macro-hardness of the as-cast CoCrFeNiTi0.5 alloy were HV616.8 and HRC52, respectively. After heat treatment at 1000°C, the micro-hardness and macro-hardness decreased from HV616.8 to HV386.8 and from HRC52 to HRC42.7, respectively.
Electrochemical Impedance Spectroscopy (EIS) Study of Nano-Composite Polyurea Coating under the Wet-Dry Cyclic Conditions
Authors: Wang Bing Ying , Shi Qing Hao , Zhang Wen Long
Published: April 2014

The polyurea was modified by adding different amounts of nanometer ZnO. The corrosion behavior of polyurea/primer composite coating system in wet-dry cyclic environment of 3.5% NaCl solution was studied by using the Electrochemical Impedance Spectroscopy (EIS) measurement and adhesion test technology. The experimental result showed that, different mass fractions of nanometer ZnO had different influences on the corrosion resistance property of coating. When the mass fraction of nanometer ZnO was 5%, the composite coating had the largest protective action. The corrosion resistance property of nanometer ZnO can be improved by increasing the density of polyurea coating, however, the corrosion resistance property of polyurea coating will be weakened in case of exceeding the critical adding amount.
Anti-Ablation Property of MoSi2 Coatings Deposited by APS
Authors: Liu Yan Bo , Wang Quan Sheng , Ma Kang Zhi , Liu Jun Liang , Wei Si Hao , Fan Wen Chao
Published: April 2014

Carbon fiber reinforced carbon matrix composites (C/C) have received much attention due to their excellent high-temperature strength, high thermal conductivity, low coefficient of thermal expansion (CTE), good thermal shock resistance. However, the poor ablation resistance of the C/C restricts its high temperature ablating applications. Making a thin anti-ablation coating on the C/C has been proved to improve the performance effectively. In order to improve the anti-ablation property of the composite, MoSi2 coatings were deposited by Atmosphere Plasma Spraying (APS) on the SiC covered C/C matrix. The SiC coatings were prepared by pack cementation. Oxyacetylene flame torch was selected to simulate the ablation situation. The ablation temperature was 1800°C. XRD and SEM were employed to discover the diversification of the coatings structure and composition. And the mechanism of anti-ablation of the MoSi2 coatings system was investigated in this paper.
Microscopic Phase Field Study on the Kinetics of Order-Disorder Transition of APDBs Formed between DO22 Phases during Stress Aging
Authors: Zhang Ming Yi , Yue Guang Quan , Zhang Jia Zhen , Yang Kun , Chen Zheng
Published: April 2014

Kinetics of order-disorder transition at antiphase domain boundary (APDB) formed between DO22 (Ni3V) phases during stress aging was investigated using microscopic phase field model. The results demonstrated that whether order-disorder transition happens or not depends on the atomic structure of the APDB. Accompanied with the depletion of V and enrichment of Ni and Al, order-disorder transition happened at the APDB (001)//(002). Whereas at the APDB {100}·1⁄2[100], which remains ordered with temporal evolution, Ni and Al enrich and V depletes. Composition evolution of APDB with order-disorder transition favors the nucleation of the L12 and disordered phase. Some of the grains grew bigger while the others disappeared, accompanying the formation of disordered phase layer during order-disorder transition of APDBs, and the order-disorder transition of APDBs can be considered as accompanying process of coarsening of ordered domain phases and growth of disordered phases.
FEM Analysis of the Deformation Behavior at Thickness Direction in Laboratory Plate Hot Rolling
Authors: Liu Ji Yuan , Luo Zong An , Zhu Fu Xian , Tian Chao
Published: April 2014

As significant theory evidence in thick plate or heavy gauge plate hot rolling, the deformation behavior at the thickness direction was investigated. In the present work, multi and single pass rolling processes were studied by 2D explicit dynamic finite element method (FEM) simulation and verified by laboratory hot rolling experiment. The value of stress and strain could be obtained in any passes and time in the hot rolling process accurately. The verified FEM model could be used as an important reference factor for other hot rolling processes. Strain and stress distribution data was obtained from four portions at the thickness direction. A cooper rod was knocked into the hot rolling specimen, as a reference substance to observe the deformation after the hot rolling experiment. In the multi-pass simulation with nearly 10% per-pass reduction, the core metal yield when the total reduction was 40%. The same performance could be achieved when the first pass reduction larger than 20%. However, extremely first pass reduction would cause an instability deformation result in a confusion of microstructure. Finally, the relation between the reduction and the number of rolling passes was discussed.
Application of Dynamic Deadband Eccentricity Filter in GM-AGC System
Authors: Li Dong , Song Wei Xing , Zhang Cai Jin , Liu Jian Chang , Tan Shu Bin , Hou Shuai , Li Jian Ming , Xu Jun Yan
Published: April 2014

The problem of roll eccentricity has become one of important factors to affect the quality of strips as downstream industries require improvement of the strip quality. Reducing thickness control precision as little as possible is incompatible with restraining roll eccentricity perturbations on the requirement of the deadband size for the deadband drift method (DDM) with fixed deadband width. Therefore, the GM-AGC system in hot finishing mill of an aluminum plant uses the dynamic deadband eccentricity filter (DDEF) whose deadband width varies with the amplitude of the roll eccentricity signal. The operating principle of DDEF was introduced according to the characteristic of roll eccentricity signal. Based on the theory of DDEF, simulation was carried out. Comparing with DDM, the simulation result shows that DDEF can keep a balance between less lowering thickness control precision and restraining roll eccentricity perturbations on the requirement of the deadband size. Moreover, the deadband width of DDEF is capable to fit the variations in the frequency and amplitude of the synthetic roll eccentricity signal to restrain the misoperation of GM-AGC system.
Stability of Nanofluids for Heat Pipe
Authors: Liu Jian , Lu Sheng , Chen Qi , Zhang Jun Hao , Yao Shou Guang
Published: April 2014

Different mass concentrations of Al2O3, SiO2, CuO nanofluids were made by using two-step method with the three types of base fluids deionized water, ethanol and ethylene glyco. The suspension stability of nanofluids and its effect by adding anion and cation surfactants through sedimentation method were studied. The results show that ehylene glycol is as the base fluid, the suspension stability of nanofluids with DW as the base fluid is worst. The suspension stability of Al2O3, SiO2, CuO nanofluids is significantly improved by addition of appropriate dosage of adding anion and cation surfactants for different base fluids. The effect of HTAB is better than that of SDBS.
Compression Property of C/SiC and Inconel X-750 Springs from Room Temperature to 1000°C
Authors: Chen Si’an , Zhang Yu Di , Zhang Chang Rui , Xiong Xin , Hu Hai Feng
Published: April 2014

The compression properties of C/SiC composite and Inconel X-750 helical springs were investigated from room temperature (RT) to 1000°C in air. The density of C/SiC spring is 1.74 g/cm3, only ~1/5 of X-750 value (8.17 g/cm3) and the spring constants of C/SiC and X-750 springs at RT are 3.47 and 5.61 N/mm, respectively. The spring constants of X-750 spring decreased with increase of temperature. X-750 spring could keep excellent property below 600°C, but its spring constant was only 36.7% of RT value at 800°C and permanent deformation appeared. At 1000°C, it could not restore and was destroyed. The spring constants of C/SiC spring at 400°C and 600°C were appreciably higher than the RT value, and then decreased with temperature elevating. Above 800°C, the spring constant decreased with test progressing because of the oxidation of carbon fibers and SiC matrix. But it has a spring constant of 2.40 N/mm (69.2% of the RT value) at 1000°C and can revert to its original dimensions.
Aneurysmal Lesions of Patients with Abdominal Aortic Aneurysm Contain Clonally Expanded T Cells
Authors: Lu Song , White John V. , Lin Wan Lu , Zhang Xiaoying , Solomides Charalambos , Evans Kyle , Ntaoula Nectaria , Nwaneshiudu Ifeyinwa , Gaughan John , Monos Dimitri S. , Oleszak Emilia L. , Platsoucas Chris D.
Published: April 2014

Abdominal aortic aneurysm (AAA) is a common disease with often life-threatening consequences. This vascular disorder is responsible for 1–2% of all deaths in men aged 65 years or older. Autoimmunity may be responsible for the pathogenesis of AAA. Although it is well documented that infiltrating T cells are essentially always present in AAA lesions, little is known about their role in the initiation and/or progression of the disease. To determine whether T cells infiltrating AAA lesions contain clonally expanded populations of T cells, we amplified β-chain TCR transcripts by the nonpalindromic adaptor–PCR/Vβ-specific PCR and/or Vβ-specific PCR, followed by cloning and sequencing. We report in this article that aortic abdominal aneurysmal lesions from 8 of 10 patients with AAA contained oligoclonal populations of T cells. Multiple identical copies of β-chain TCR transcripts were identified in these patients. These clonal expansions are statistically significant. These results demonstrate that αβ TCR+ T lymphocytes infiltrating aneurysmal lesions of patients with AAA have undergone proliferation and clonal expansion in vivo at the site of the aneurysmal lesion, in response to unidentified self- or nonself Ags. This evidence supports the hypothesis that AAA is a specific Ag–driven T cell disease.
Murine B-1 B Cell Progenitors Initiate B-Acute Lymphoblastic Leukemia with Features of High-Risk Disease
Authors: Montecino-Rodriguez Encarnacion , Li Katy , Fice Michael , Dorshkind Kenneth
Published: April 2014

B-1 and B-2 B cells derive from distinct progenitors that emerge in overlapping waves of development. The number of murine B-1 progenitors peaks during fetal development whereas B-2 B cell production predominates in adult bone marrow. Many genetic mutations that underlie B-acute lymphoblastic leukemia (B-ALL) occur in the fetus, at which time B-1 progenitor numbers are high. However, whether B-ALL can initiate in B-1 progenitors is unknown. In the present study, we report that BCR-ABL–transformed murine B-1 progenitors can be B-ALL cells of origin and demonstrate that they initiate disease more rapidly than do oncogene-expressing B-2 progenitors. We further demonstrate that B-1 progenitors exhibit relative resistance to apoptosis and undergo significant growth following oncogene expression, and we propose that these properties underlie the accelerated kinetics with which they initiate leukemia. These results provide a developmental perspective on the origin of B-ALL and indicate B cell lineage as a factor influencing disease progression.
Cutting Edge: Differential Constitutive Expression of Functional Receptors for Lysophosphatidic Acid by Human Blood Lymphocytes
Authors: Goetzl Edward J. , Kong Yvonne , Voice Julia K.
Published: April 2014

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) from platelets and macrophages mediate T cell functions. Endothelial differentiation gene-encoded G protein-coupled receptors (Edg Rs) are specific for S1P (Edg-1, -3, -5, and -8 Rs) and LPA (Edg-2, -4, and -7 Rs). Human T cell tumors express many Edg Rs for both LPA and S1P. In contrast, human blood CD4+ T cells express predominantly Edg-4, and CD8+ T cells show only traces of Edg-2 and -5, by quantification of mRNA and Edg R Ags. LPA at 10−10–10−6 M suppressed significantly the secretion of IL-2 from anti-CD3 plus anti-CD28 Ab-challenged CD4+ T cells, but not CD8+ T cells. Monoclonal anti-Edg-4 R Ab, like LPA, suppressed stimulated IL-2 secretion from CD4+ T cells, but not CD8+ T cells. Constitutive expression of Edg-4 by CD4+, but not CD8+, human T cells accounts for differential functional responsiveness of the T cell subsets to LPA.
Cutting Edge: The Tumor Counterattack Hypothesis Revisited: Colon Cancer Cells Do Not Induce T Cell Apoptosis Via the Fas (CD95, APO-1) Pathway
Authors: Favre-Felix Nathalie , Fromentin Annie , Hammann Arlette , Solary Eric , Martin François , Bonnotte Bernard
Published: April 2014

The counterattack hypothesis, suggesting that cancer cells express Fas ligand (FasL) and are able to kill Fas-expressing tumor-infiltrating activated T cells, was supported by reports of the killing of Jurkat cells by FasL-expressing human colon cancer cell lines. Through the use of an improved cytotoxic assay in which soluble FasL and FasL-transfected KFL9 cells were used as positive controls, we show that none of seven human colon cancer cell lines induce apoptosis of two Fas-expressing target cell lines, Jurkat and L1210-Fas cells. Moreover, in coculture experiments, cancer cell monolayers do not inhibit the growth of Fas-expressing lymphoid cells. Although FasL mRNA and protein were detected in the extracts of the colon cancer cell lines, flow cytometry and confocal microscopy failed to detect the protein on the surface of tumor cells. These results suggest that the counterattack of tumor-infiltrating T lymphocytes by cancer cells may not account for immune tolerance toward tumor cells.
Human Intestinal Epithelial Cells Express a Novel Receptor for IgA
Authors: Kitamura Tetsuro , Garofalo Roberto P. , Kamijo Atsushi , Hammond Dianne K. , Oka Janet A. , Caflisch Carlton R. , Shenoy Mohan , Casola Antonella , Weigel Paul H. , Goldblum Randall M.
Published: April 2014

Binding and transport of polymeric Igs (pIgA and IgM) across epithelia is mediated by the polymeric Ig receptor (pIgR), which is expressed on the basolateral surface of secretory epithelial cells. Although an Fc receptor for IgA (FcαR) has been identified on myeloid cells and some cultured mesangial cells, the expression of an FcαR on epithelial cells has not been described. In this study, binding of IgA to a human epithelial line, HT-29/19A, with features of differentiated colonic epithelial cells, was examined. Radiolabeled monomeric IgA (mIgA) showed a dose-dependent, saturable, and cation-independent binding to confluent monolayers of HT-29/19A cells. Excess of unlabeled mIgA, but not IgG or IgM, competed for the mIgA binding, indicating that the binding was IgA isotype-specific and was not mediated by the pIgR. The lack of competition by asialoorosomucoid and the lack of requirement for divalent cations excluded the possibility that IgA binding to HT-29/19A cells was due to the asialoglycoprotein receptor or β-1,4-galactosyltransferase, previously described on HT-29 cells. Moreover, the FcαR (CD89) protein and message were undetectable in HT-29/19A cells. FACS analysis of IgA binding demonstrated two discrete populations of HT-29/19 cells, which bound different amounts of mIgA. IgA binding to other colon carcinoma cell lines was also demonstrated by FACS analysis, suggesting that an IgA receptor, distinct from the pIgR, asialoglycoprotein receptor, galactosyltransferase, and CD89 is constitutively expressed on cultured human enterocytes. The function of this novel IgA receptor in mucosal immunity remains to be elucidated.
Effects of Continuous Exposure to Stromal Cell-Derived Factor-1α on T Cell Rolling and Tight Adhesion to Monolayers of Activated Endothelial Cells
Authors: Kantele Jussi M. , Kurk Sandy , Jutila Mark A.
Published: April 2014

Immobilized stromal cell-derived factor-1α (SDF-1α) has been shown to induce tight adhesion of T cells to purified ICAM-1 in assays done under flow conditions. In this study, we show that soluble SDF-1α induced a rapid (within 20 s) cessation of rolling and tight adhesion of >90% of the rolling T cells on monolayers of activated endothelial cells under similar flow. Within 4 min, the T cells had either started to migrate between the endothelial cells or re-entered the rolling and circulating lymphocyte pool. This deadherence of the firmly bound cells, with either ensuing transmigration or continued rolling, was most likely due to desensitization of lymphocytes to the continuously present SDF-1α. The released rolling lymphocytes could still respond to other activating signals by a second round of tight adhesion. Pretreating the lymphocytes with pertussis toxin almost completely blocked the effect of the chemokine, confirming that the induction of firm adhesion was due to the function of the chemokine on the lymphocytes and not the endothelial cells. Pretreating the endothelium with SDF-1α did not lead to firm adhesion of subsequently added lymphocytes, also indicating that the effect was due to soluble, not endothelially bound, chemokine. Blocking experiments showed that the same molecules mediated rolling before and after SDF-1α-induced tight adhesion. This is the first study to demonstrate the effect of soluble SDF-1α on T cell rolling on an endothelial cell monolayer. The data broaden our understanding of the stimulatory factors directing the firm adhesion and ensuing transmigration of leukocytes into tissues through activated endothelium.