bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of a Strong Magnetic Field on Dendritic Growth of Ti-Ni Alloy
Authors: Chang Hui , Huang Chun Li , Tang Bin , Hu Rui , Li Jin Shan , Zhong Hong
Published: March 2013

A phase field model has been developed to simulate the dendritic growth of Ti-Ni alloy subjected to a strong magnetic field. The influence of a strong magnetic field on the microstructure morphology and its evolution was successfully investigated by the model. The effect of the magnetic field intensity on the dendritic evolution has been further discussed. The simulating results revealed that with greater magnetic field intensity, the primary dendritic arms and the side branches were easier to coarsen. Besides, the dendritic tip growth rate increased with increasing magnetic field intensity, while the curvature radius had an opposite tendency. The microstructure evolution under a strong magnetic field was also studied combined with solidification thermodynamics theory. The results indicate that, the temperature of equilibrium solidification of Ti-Ni alloy changes with the presence of a strong magnetic field, and the morphology of dendritic grains will be affected eventually.
The Influence of Niobium on the Interdiffusion Coefficients in α2 and γ of TiAl Alloys
Authors: Han Dong Dong , Xu Xiang Jun , Zhang Lai Qi , Liang Yong Feng , Lin Jun Pin
Published: March 2013

nterdiffusion coefficients in α2-Ti3Al and γ-TiAl of conventional TiAl and TiAl-8Nb alloy were measured at the temperature ranging from 1273K to 1523K. Single-phase diffusion couples were employed, and the concentration profiles of Al after annealing were measured by an electron probe microanalyzer (EPMA), and the interdiffusion coefficients were calculated according to the Boltzmann-Matano method. The results showed that there was no significant concentration dependence of interdiffusion coefficients for all the alloys with various phases, and the values of interdiffusion coefficients covered three orders of magnitude (E-17-E-14) with the increase of temperature according to Arrhenius law. In α2-Ti3Al and γ-TiAl phase of conventional TiAl alloys, the pre-exponential factor and activation enthalpy were D0=3.95×10-5m2s-1,Q=276KJmol-1 ;D0=7.26×10-5m2s-1,Q=275KJmol-1 respectively. The pre-exponential factor and activation enthalpy were D0=4.54×10-6m2s-1, Q=244KJmol-1 in γ-TiAl phase of TiAl-8Nb alloys. However, the temperature dependence of interdiffusion coefficients in α2-Ti3Al of TiAl-8Nb alloys did not follow Arrhenius laws very well. With the addition of Nb, the interdiffusion coefficients increased significantly in α2-Ti3Al, but changed slightly in γ-TiAl at high temperature.
Effect of Nb on the Properties of Ti-Nb Random Alloys from First-Principles
Authors: Lai Min Jie , Xue Xiang Yi , Meng Cai Si , Kou Hong Chao , Tang Bin , Chang Hui , Li Jin Shan
Published: March 2013

The effect of Nb on the equilibrium lattice parameters and relative stability between β and ω phases of Ti1-xNbx (0 < x 0.4) random alloys as well as their mechanical properties in body-centered-cubic crystallographic phase was investigated using the exact muffin-tin orbitals method in combination with the coherent potential approximation. It has been found that the calculated lattice parameters of the β phase agree well with the experimental data. For ω phase, the value of a increases almost linearly with increasing Nb concentration, while the opposite situation presented for c/a. Both Nb addition and increasing temperature enhanced the stability of β phase relative to ω phase. The critical Nb concentration for the complete stabilization of β phase at 300 K, 673 K and 1273 K was 22 at.%, 17 at.% and 9 at.%, respectively. The polycrystalline bulk modulus B, Youngs modulus E and shear modulus G increased monotonously with Nb addition and reducing the Nb concentration below 30 at.% resulted in lower E compared to that of Ti-6Al-4V. The calculated G/B values demonstrate that the bcc Ti1-xNbx (0 < x 0.4) random alloys should be intrinsically ductile.
Lattice Structures of AlSc and their Effect on Interdiffusion
Authors: Li Juan , Ye Feng , Huang Li , Liang Yong Feng
Published: March 2013

The structures of AlSc with 50at.% and 55at.% Sc were investigated. It was shown that orthorhombic AlSc is formed at Sc 50at.%, and B2 AlSc at Sc 55at.%. After anealing above 1100 °C, the orthorhombic AlSc transited into B2 structure, which indicated that B2 AlSc can also be a metalstable phase in the alloy with Sc less than 50at.%. The effects of these two structures on the phases formation via inter-diffusion were also studied using diffusion couple with titanium and γ-TiAl. It was found that the interdiffusion coefficients are the main factors for Ti/AlSc and structures are the main factors for γ-TiAl/AlSc.
Microstructural Evolution and Precipitation Mechanism of α-Phase in Ti-55531 Alloy Aged at High Temperature
Authors: Zhang Xue , Chen Yi , Zhang Feng Shou , Yang Jun Ting , Lai Yun Jin , Kou Hong Chao , Li Jin Shan , Zhou Lian
Published: March 2013

After two-stage annealing heat treatment process, the near β-Titanium alloys reveal a mixed microstructure containing lath-like α phase and finer acicular α phase in β matrix, leading to the improvement of strength-ductility balance. In this paper, the microstructural evolution and the behaviour of α precipitate during high temperature ageing process were investigated by SEM in a near β-Titanium alloy called Ti-55531.The relationship between α precipitates and the β grain orientation in high temperature was investigated by EBSD. The results show that the α-phase precipitated only at some places of the β grain boundaries at higher ageing temperature (~780 °C); the amount of grain boundary α increased with the decreased of the ageing temperature; after ageing at 720 °C for 45 min, we found that the α-phase precipitated not only at grain boundaries but also within the grains. It seems that the precipitation of grain boundary α is strongly influenced by β grain boundary energy which means that grain boundary α tends to form preferentially at high energy grain boundaries (high-angle grain boundaries); The α-phase precipitates more easily at the grain boundaries where the {110} plane of adjacent β grains have the same orientation.
Effects of Scandium on Corrosion Resistance and Mechanical Properties of Cellular Al-Based Foams
Authors: Huang Li , Yang Dong Hui , Wang Hui , Ye Feng , Lu Zhao Ping
Published: March 2013

Cellular Al-0.24wt.%Sc and Al-0.41wt.%Sc foams with a porosity ranging from 37 to 86% were successfully fabricated via the melt-foaming method with the calcium particles as the thickening agent and titanium hydride as blowing agent. The corrosion rate increased with the increasing of porosity for the cellular Al-0.24wt.%Sc, Al-0.41wt.%Sc and Al foams. Large size Al3Sc precipitates can accelerate the corrosion of the Al foams. However, T6-treatments could improve the corrosion resistance significantly. With T6-treatments, 0.24 wt.%Sc addition to Al foams exhibited unconspicuous decrease in the corrosion resistance but much improved strength.
Research on Precision Forming Technology of Titanium Alloy Sheet Metal Based on the Principle of the Stress Relaxation
Authors: Chen Ming He , Xie Lan Sheng , Liu Lei
Published: March 2013

In this paper, a series of relevant theoretical analyses and experimental researches have been carried out for precision forming of a typical aerospace revolver. By use of the material stress relaxation principle, the finite element numerical simulation and the preforming sizing process technology of stress relaxation, it have been revealed that the new process can be used for precision forming of titanium alloy sheet and its forming precision can meet the manufacturing requirements of aerospace sheet-metal parts. The precision forming technology of titanium alloy can also be used to improve the digital manufacturing technologies of aerocraft sheet-metal parts, and thus has potential application prospects.
Fabrication and Properties of Cu/MgB2 Composites by Vacuum Sintering
Authors: Yang Qing , Zou Jun Tao , Liu Zhao , Yu Xiao Jiang
Published: March 2013

Cu/MgB2 composites with different content of MgB2 (10, 20, 30 vol.%) were fabricated by vacuum sintering of copper and MgB2 powders. The effects of MgB2 content and sintering process on the properties of Cu/MgB2 composites including the microstructures, relative density, electrical conductivity and hardness were then investigated. The results showed that the distribution uniformity of MgB2 on copper matrix decreased obviously with the increase of MgB2 content, the hardness of Cu/MgB2 composites increased and the relative density decreased slightly though the electrical conductivity decreased greatly. The relative density and hardness of Cu/MgB2 composites increased after the repressing-resintering process, the electrical conductivity was also improved slightly.
Research Progress of Cold Working Die Steel
Authors: Ni Xin Lei , Zhang Guo Qing , Zhang Yong
Published: March 2013

Working conditions, failure forms and property requirements of cold working die steels were presented. This review attempted to introduce the development of cold working die steels, the ways to improve its quality, heat treatment and surface treatment technology at home and abroad. Meanwhile, the characteristic and application prospects of spray-formed cold working die steels were analyzed.
Effect of High Density Pulsing Current on Mechanical Properties of Fe-6.5wt.%Si Alloy Sheet
Authors: Zhou H.C. , Liang Yong Feng , Ye Feng , Tang Guo Yi , Lin Jun Pin
Published: March 2013

t is well known that excellent soft magnetic properties are obtained in electrical steel with Si content of 6.5wt.%, such as high permeability, low coercive force, near zero magnetostriction, etc. However due to its poor ambient temperature ductility it is very hard to fabricate this material by conventional hot-cold rolling process. Meanwhile, high-density electropulsing treatment (EPT) attracts widespread applications as a new heat treatment approach. In this paper, heat treatment effect of high-density pulsing current on microstructure, micro-hardness and mechanical properties of as rolled Fe-6.5wt.%Si alloy sheet were investigated. The results showed that the microstructure and mechanical properties were closely related to the parameters of the pulses. Refined and uniform recrystallized grains were obtained by optimizing parameters of the high density pulses. Compared with the conventional heat treatment method, the time and temperature for heat treatment can be reduced dramatically. Therefore, it is considered that EPT is an efficient heat treatment approach for this rolled sheet. Mechanism of the effect of high-density pulsing current has been discussed also in this investigation.
Effects of TIG Process on Corrosion Resistance of 321 Stainless Steel Welding Joint
Authors: Hu Dan , Li Shu Lin , Lu Sheng
Published: March 2013

In this paper, the effects of different TIG welding parameters on corrosion resistance of 321austenitic stainless steel welding joint were studied. Intergranular corrosion, stress-strain curves of SSRT and the fracture surface of the welding joint were investigated by means of intergranular corrosion test, SCC test and SEM. The results showed that the intergranular corrosion cracks did not occur for all joints welded in the range of TIG welding current of 130A~190A. In pure water at room temperature, strain rate at the range of 1×10-5 s-1~1×10-6 s-1 had little effect on the maximum tensile strength of the material under the same welding conditions and the time of joint fracture increased as the strain rate decreased. At strain rate of 1×10-6 s-1, the maximum tensile strength of the joint welded in the current of 130A and 150A decreased significantly in the dyeing assistant and presented stress corrosion sensitivity. Joints welded in the current of 170A and 190A, showed excellent resistance to stress corrosion. Through the analysis of the fracture surface of joints, the joint welded in current of 130A presented a tendency to brittle fracture, while the joints in the current of 170 A and190 A were characterized with ductile fracture.
Preparation and Mechanism of Cu/Nano-TiO2/PBO Composite Fibers by Photocatalysis Electroless Plating
Authors: Luan Yan Yan , Liu Xue Feng , Peng Zhan Nan , Xie Jian Xin
Published: March 2013

Cu/nanoTiO2/PBO composite fiber with low density, high strength, toughness and conductivity was prepared with a photocatalysis electroless plating method by reduction depositing Cu2+ on the surface of nanoTiO2/PBO composite fiber. The process parameters on the preparation of Cu/nanoTiO2/PBO composite fiber were optimized by the characterization of surface morphology, phase, composition, pull-out strength and resistivity of Cu/nanoTiO2/PBO composite fibers using SEM, XRD, EDS, electronic tester of tensile strength and multimeter, respectively. The mechanism of Cu coating nanoTiO2/PBO composite fiber was also discussed in this study. The results showed that Cu/nanoTiO2/PBO composite fibers were well prepared under the bath composition of CuSO45H2O 16gL-1, KNaC4H4O64H2O 15 gL-1, Na2EDTA2H2O 24 gL-1, HCHO 16 mlL-1, NaOH 14 gL-1, C10H8N2 24 mgL-1 and K4Fe (CN)6H2O 12 mgL-1 by the UV-light irradiated for 30 min. The diameter, pull-out strength and resistivity of Cu/nanoTiO2/PBO composite fiber were 20.2 μm, 2.25 GPa and 0.02864 Ωmm2m-1, respectively. Cu2+ ions on the surface of nanoTiO2/PBO composite fiber were reduced to Cu by photo-electrons which were generated of nanoTiO2 under the UV-light irradiated, and the primary Cu layer as a catalytic center promoted the reduction reactions of producing Cu/nanoTiO2/PBO composite fiber further.
Influence of Sulfur and Manganese Contents on Texture and Fish-Scale Resistance of DC03EK Cold-Rolled Enamel Steel
Authors: Dong Fu Tao , Du Lin Xiu , Liu Xiang Hua , Jiao Jing Min
Published: March 2013

In the this paper, the compositions design with low carbon and addition of sulfur and manganese which can enhance fish-scale resistance by MnS as hydrogen trap was adopted to produce DC03EK cold-rolled enamel steel. The effect of sulfur and manganese contents on formability and fish-scale resistance of DC03EK cold-rolled enamel steel was investigated. Results show that yield strength, ultimate tensile strength, elongation, work hardening exponent and average plastic strain ratio of the steel with sulfur content of 0.024wt% and manganese content of 0.22wt% is 133 MPa, 310 MPa, 36.8%, 0.22 and 1.46, respectively, showing the well formability. And its hydrogen penetration time and diffusion coefficient is higher than 12 min and lower than 9.26×10-7 cm2/s, respectively, showing excellent fish-scale resistance. However, for the steel with sulfur content of 0.012wt% and manganese content of 0.12wt%, even though better formability is obtained, the fish-scale resistance is poor with hydrogen penetration time of 4.7 min and hydrogen diffusion coefficient of 2.36×10-6 cm2/s which is far from the expectation of steel for enamel.
Effect of Alterative and Homogenization on the Microstructure of Cu-20Ni-5Sn Alloy
Authors: Cai Wei , Yang Sheng Li , Chen Liang , Lu Meng Meng , Liao Yu Min
Published: March 2013

The serious dendritic segregation occurs in Cu-20Ni-5Sn alloy. The microstructure of Cu-20Ni-5Sn alloy as-cast is composed of white light dendrite (Cu-Ni solid solution), Sn-rich solid solution (Cu2Ni3Sn3 phase) and block light precipitation (Ni17Sn3 phase). The microstructure of Cu-20Ni-5Sn alloy affected by alterative and homogenization temperature was studied. The results show that the alterative can refine the microstructures of the Cu-20Ni-5Sn alloy and reduce the segregation of Sn. The grains are quite fine with 0.9%Wt alterative in the alloy. The homogenization temperature of the Cu-20Ni-5Sn alloy decreases with increase of alterative content in the alloy. Grains enlarged with the increase of homogenization temperature, and the secondary phase distributes became more evenly. The optimization condition of homogenization treatment is at 800 in 24h.
The Kinetics of Reorientation of Multi-Variants under the Continuous Tensile Stress: Phase-Field Simulation
Authors: Wan Jian Feng , Zhang J.H. , Rong Y.H.
Published: March 2013

The kinetics of martensitic variant reorientation as well as the evolutional pathway under the continuous tensile stress in NiMnGa alloys has been investigated by using Phase field method. The simulated results revealed that the final structures and the pathway of evolutioncan be determined by the different external stress and there existed a critical stress to obtain the single variant. The related kinetics and the mechanism of the structural conversion were proposed to explain the inner physical nature. The pseudo-elasticity related to the structural conversion was also investigated. The mechanism of the motion for interfacial step associated with the nucleation and growth of one variant in another variant at the twin boundary was discussed.
Effect of Addition Zr on As-Homogenization Microstructures of 5182 Aluminum Alloy
Authors: Jin Bin Hui , Zhu Bao Hong , Li Xi Wu
Published: March 2013

The microstructure of 5182 alloys, standard and modified by Zr, before/after homogenizing heat treatment were investigated by optical microscope (OM), scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) and transmission electron microscope (TEM). The microstructures on optimum condition for homogenizing heat treatment and the effect of Zr were discussed. It is found that the intermetallic compounds formed on the grain boundaries are less in Zr modified 5182 than 5182 alloys for the as-cast structure. After the two alloys homogenized at 475 for 24h, the dendritic structure disappear and intermetallic compounds become discontinuous, Al2Mg3 phases are decomposed, and there are some precipitates of Al6(Mn,Fe) and Al6Mn in the grain interior. In addition, precipitates of Al3Zr distributed in the matrix of Zr modified 5182 alloys.
Atomic Modeling and Simulation of AlCoCrCuFeNi Multi-Principal-Element Alloy
Authors: Wang Shao Qing
Published: March 2013

Atomic structure model of bulk AlCoCrCuFeNi multi-principal-element alloy was build by following the principle of maximum entropy. Morse pair-potentials to describe the inter-atomic interaction among neighboring atoms in the alloy were generated directly from first-principles calculations within density-functional theory. Molecular statics simulation was carried out to achieve the optimized atomic configuration of AlCoCrCuFeNi alloy. The results show that the crystallographic behavior in lattice structure observed experimentally is just caused by the average of the disordered atomic position and composition in wide range since there is neither short-range nor long-range order in the local atomic arrangement of this kind of materials.
Influence of Deformation and Quenching Temperature on Structures and Properties of High Nitrogen Stainless Bearing Steel
Authors: Zhang Shan Ju , Yang Mao Sheng , Lei Ting
Published: March 2013

The influence of deformation and quenching temperature on microstructure and properties for high nitrogen stainless bearing steel was studied using the calculation of Thermo-Calc software and relevant Fe-based database and some experiments. The results showed that there was a small precipitation amount of carbide in the sample after a large deformation. The value of impact toughness (AKU) was increased from 2.0 J to 12.0 J with the deformation increasing from 71% to 83%. When the quenching temperature reached 1050, the value of the hardness was up to the tiptop. Additionally, according to the calculation, it was found that there was a linear functional relation between the precipitation of carbide M23C6(M) and quenching temperature (T). And the relational model could be expressed as:MM23C6=55.34 - 0.05T(T1000).
The Effect of Strain on the Impedance and Surface Potential of Austenite in 304 Stainless Steels
Authors: Xie Jin Peng , Luo Hong Yun , Lv Jin Long
Published: March 2013

Local electrochemical technique was used to measure the impedance of austenite in AISI 304 stainless steel under tensile strain of 0%, 10%, 20%, 30%, 40%. Scanning Kelvin probe (SKP) technique was used to measure the potential distribution of the surface. The results showed that the impedance of the austenite declined with the increase of the strain and declined sharply under the strain of 30%. Potential of austenite decreased non-monotonously with increase of the strain. The potential reached the minimum under strain of 30% and then increased. Through the transmission electron microscope (TEM) results, plane dislocation pile-ups were observed in the grain boundary under the strain of 30% and transformed to cellular substructure structure and cell wall under 40%. Combined with the results of local electrochemistry impedance spectroscopy (LEIS) and surface potential, it may be concluded that it was the dislocation density and dislocation structure influence the impedance spectroscopy significantly, while surface potential was sensitive to the dislocation structure.
Microstructure and Precipitates of High-Pure Ferritic Stainless Steels Stabilized by Niobium and Titanium
Authors: Wang Hong Po , Peng Bo , Sun Li Feng , Liu Cheng Jun , Jiang Mao Fa
Published: March 2013

As stabilization elements added into ferritic stainless steels, various kinds of precipitates of niobium and titanium will form and have great effect on their microstructure, which has great effect on the mechanical and corrosion properties of the final products. Combined with thermodynamic calculation by FactSage software, microstructure and precipitates of ferritic stainless steels containing different niobium and titanium were investigated by optical microscope, scanning electron microscope, transmission electron microscope and energy dispersive spectrometer. The results show that titanium mainly exists in form of TiN but niobium exists mainly in form of NbC. Moreover, a certain amount of NbN particles precipitate when there is not enough titanium to react with nitrogen. TiN particles with size of 2μm~8μm promote the recrystallization but Nb-rich precipitates with size of less than 500nm suppress the recrystallization in the process of annealing.
Effect of Annular Electromagnetic Stirring on Microstructure and Mechanical Property of 7075 Aluminium Alloy
Authors: Gao Zhi Hua , Xu Jun , Zhang Zhi Feng , Tang Meng Ou
Published: March 2013

Annular electromagnetic stirring (A-EMS) process, developed by General Research Institute for Non-Ferrous Metals, is an advanced processing technology for conditioning liquid metal prior to solidification processing. A-EMS can avoid skin effect effectively, impose a higher shear rate and a higher intensity of turbulence to the liquid metal, and increase the area of the melt heat dissipation by means of innovatively combining noncontact electromagnetic stirring and an annular chamber with specially designed profiles. The solidification structure, composition macro-segregation and property of 7075 alloy were investigated under the conditions of the conventional casting, the conventional electromagnetic stirring casting and A-EMS casting. The results indicated that A-EMS melt processing technology had significant effects on grain refinement, reduction of composition macro-segregation and improvement of mechanical properties.
Rheological Model for a Nanoporous-Elasto-Hydrodynamic Composite Material
Authors: Suciu Claudiu Valentin , Fukui Shuuhei
Published: March 2013

This work proposes a rheological model for a nanoporous-elasto-hydrodynamic composite material (NPEHDCM), which can be obtained by mixing a colloid, consisted of water and water-repellent nanoporous silica micro-particles, with an adequate jellification agent. Hydrogel is modeled as a biphasic mixture consisted of a nanoporous hydrophilic isotropic and linear elastic solid matrix, and a liquid phase (water). At dynamic pressurization, water molecules exude from the hydrogel matrix and forcedly penetrate the nanopores of hydrophobic silica particles. Based on the proposed rheological model, the NPEHDCM can be suitably designed.
Influence of Glass Coating Thickness on Interfacial Heat Transfer Coefficient during Forming of Nickel Based Superalloys
Authors: Busuttil Markus , Lin Yu Pei , Gebelin Jean Christophe , Reed Roger C.
Published: March 2013

The influence of glass coating thickness on the interfacial heat transfer coefficient has been examined using numerical modeling. Temperature and heat flux during working of a Inconel 718 work-piece and colder H13 dies have been simulated. The thickness of the glass coating is found to have a significant influence on the forming characteristic.
Fabrication of Photo-Polymerized PCL Tissue Engineering Scaffolds by Dynamic Masking Rapid Prototyping System
Authors: Cheng Yih Lin , Hsueh Chin Jen , Hsiang Su Hai
Published: March 2013

PCL is one of the popular biomaterials used in tissue engineering scaffolds, but it is seldom shaped by photo-polymerization. Layered manufacturing techniques, also known as Rapid Prototyping (RP) processes, provide a great opportunity to fabricate 3D scaffolds without problems such as limited control of pore-size and restricted geometric shapes in traditional methods. In our previous researches, the Biomedical Dynamic Masking Rapid Prototyping System was developed to photo-cure biodegradable materials through visible light. In this research, the Dynamic Masking RP System was modified to photo-polymerize cross-linkable PCL to form tissue engineering scaffolds. The cross-linkable PCL was synthesized by reacting PCL and acryloyl chloride, and dissolved in acetone mixing with photo-initiator. The tensile test and degradation test were performed on the cured PCL samples. Fabrication of single-layer pattern was first tested to understand the system’s capability and showed the errors were within 7%. Two types of scaffold design concepts were adopted—one took square, hexagon, or triangle as a basic element to create 2D grid patterns, and the interconnected pore were produced by offsetting the 2D pattern in alternating layers; the other took a double-sided trapezoid as a unit and arrayed it into tube shape with interconnected pore network. Various PCL porous tube scaffolds have been successfully fabricated in this study. In the future, they can be utilized to cell growth or mass cell duplication applications.
Improvement of Thermoelectric Properties of CuAlO2 by Excess Oxygen Doping in Annealing
Authors: Lu Yun , Maeda Kazunari , Sagara Katsuhiro , Hao Liang , Jin Ying Rong
Published: March 2013

The reaction behavior of CuAlO2during the annealing at high temperatures was investigated. The relationship between thermoelectric properties including electrical resistivity, excess oxygen doping and decomposition of CuAlO2was discussed. The evolution of CuAlO2compact during the annealing mainly included excess oxygen doping, decomposition of CuAlO2into CuAl2O4and CuO and complete decomposition of CuAlO2as following pattern : CuAlO2→ CuAlO2+x→ CuAlO2+CuO+ CuAl2O4→ CuAl2O4+CuO. Electrical resistivity of the compacts was decreased with excess oxygen doping, but increased when CuO and CuAl2O4were formed. Thermoelectric performance of the compacts was improved due to the excess oxygen doping.
Detection of Delamination in GFRP and CFRP by Microwaves with Focusing Mirror Sensor
Authors: Hosoi Atsushi , Yamaguchi Yuhei , Ju Yang , Sato Yasumoto , Kitayama Tsunaji
Published: March 2013

A technique to detect delamination in composite materials by noncontact, rapid and high sensitive microwave reflectometry with a focusing mirror sensor was proposed. The focusing mirror sensor, which has high sensitivity and resolution, is expected to detect delamination sensitively. In this paper, the ability of microwave inspection to detect delamination in glass fiber reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP) was verified. As the results, the existences of 100 μm thick delamination in 3 mm thick GFRP laminate and 2 mm thick CFRP laminate were detected.
A Study on the Rust Removal and Retard on the Surface of the Wear Water Screw-Thread Steel Using Flame Hot Melting
Authors: Xing Gui Ju , Xu Hai Jiang , Li Xue Ke , Chang Ling , Wu Xuan Nan
Published: March 2013

Screw-thread steel, which is produced using the quenching process through wear water controlled rolling system, would prone to generate red rust on its surface. For this reason a combustion apparatus with a smoke backflow area containing partly unburnt combustible fuel is designed to study the rusted 20MnSi wear water screw-thread steel under high temperature flame hot melting. With SEM/EDS and XRD analysis we could affirm that the main composition of the red rust is Fe2O3It assumes loose, porous branches and leaves, therefore makes the absorption of water and gas easier and intensified the sprawling of corrosion. While the steel surface after hot melting treatment form a tight passivation layer made of Fe3O4and FeO, which would isolate outer circumstance thereby protects the metal body. In the article we analyzed two main reasons that cause the red rust and point out contents that requires further studies. Compared with using chemical addition agent, this high temperature flame hot melting reaction technique is beneficial to the environment while of lower cost.
A Pseudo-Binary Diagram of the (Bi,Pb)-Sr-Ca-Cu-O System
Authors: Lu X.Y. , Yi D. , Chen H.
Published: March 2013

A pseudo-binary phase diagram of the (Bi,Pb)-Sr-Ca-Cu-O system along the Bi1.6Pb0.4Sr2Can-1CunOx line is constructed. This resulting phase diagram shows three kinds of peritectic reactions, one eutectic reaction and one peritectoid reaction. The equilibrium solid phases in this diagram are the 2201 (n=1), 2212 (n=2), 2223 (n=3) and (Sr,Ca)CuO2 (n→∝) phases. The 2201 phase is solid solution which is stable at 1≤n≤1.2. The eutectic composition point is close to the maximum solid solution composition of the 2201 phase. The temperature interval between the peritectic reaction of L + (Sr,Ca)2CuO3 + (Sr,Ca)CuO2 → 2212 and the eutectic reaction of L → 2201 + 2212 is only about 3°C. For the composition of n=3, CaO and the liquid phase are stable at temperatures above 940°C. During the cooling, these two phases react peritectically to (Sr,Ca)2CuO3. At around 890°C, (Sr,Ca)2CuO3 reacts with the liquid to produce (Sr,Ca)CuO2. At around 865°C, (Sr,Ca)2CuO3 and (Sr,Ca)CuO2 react with the liquid to produce the 2212. The 2223 phase is transformed by a peritectoid reaction of the 2212 phase and residual (Sr,Ca)2CuO3, (Sr,Ca)CuO2.
Morphology and Residual Stress of Ultrathin Al Films Confined by AlN Layers
Authors: Rifai Abdulloh , Shi Ji , Nakamura Yoshio
Published: March 2013

Ultrathin Al films have been prepared in modulated Al/AlN multilayer structures by DC magnetron sputtering. The surface morphology was observed by scanning probe microscopy (SPM). SPM images show that ultrathin Al films consist of equiaxial in-plane grains. The surface roughness for 20 nm-thick Al film which is more than 1 nm is quite large. Full (2θ, ψ)-scan by 2 dimensional XRD (2D - XRD) confirms that ultrathin Al film has highly (111) texture. Residual stress of ultrathin Al films was observed by applying sin2Ψ method. It is found that 5 nm-thick and 10 nm-thick Al films are subjected to compressive stress due to the influence of Volmer-Weber growth mechanism during sputtering. All samples are subjected to tensile stress after annealing. The unstrained interplanar spacing of Al films expands when the thickness is reduced below 10 nm and contracts with increasing annealing temperature.
A High Sensitivity 3-D Measurement Method of Minute Specimen Based on Microscope and Laser Projection
Authors: Zhang Xue Li , Lu Cun Wei
Published: March 2013

The aim of our research is to realize a high-sensitivity three-dimensional (3-D) shape measurement of target with an optical microscope. On the conventional method – shape from focus, it’s to regulate focal length of microscope to obtain 3-D shape information of the specimen. However, the method is used the vertical stratification method to obtain 3-D shape information of total surface of target, and the variable focal length of zoom lens is limited therefore the measurement accurate is confined on the vertical direction. In order to solve these problems, we propose a high-sensitivity 3-D shape measurement method based on microscope and laser projection. The method is based on the slit pattern projection technique and 3-D image processing technique. The proposal method can be used for medicine, pharmacy, life science, and material science.
Ti-Based Bulk Metallic Glass Composites Produced by Spark Plasma Sintering
Authors: Xie Guo Qiang , Zhu Sheng Li , Qin Feng Xiang
Published: March 2013

Using gas-atomized Ti-based metallic glassy powder, or the mixed powder blended with hydroxyapatite (HA) powder, we produced Ti-based bulk metallic glasses (BMGs) and the composites with high strength and satisfying large size requirements by a spark plasma sintering (SPS) process. The Ti-based BMGs and the composites with excellent properties and without toxic elements make it possible to apply as biomedical materials.
Dynamic Strain Ageing in a Twin-Induced Plasticity Steel
Authors: Meng Jiang Ying , Qian Li He , Guo Peng Cheng , Zhang Fu Cheng
Published: March 2013

This work was to clarify the characteristics of serrated flow in an austenitic FeMnC twin-induced plasticity (TWIP) steel at room temperature (RT) using both strain- and crosshead displacement-controlled tensile tests. Three types of serrations were observed in strain-controlled but not in displacement-controlled tests, indicating that strain-controlled tensile tests provide more deformation details. The occurrence of the different types of serrations depends on both strain rate and strain level. Type C serrations were observed in TWIP steels at RT for the first time. The critical strain for the onset of serrations exhibits a positive strain rate dependence at higher strain rates, whereas an “inverse” critical strain behavior was observed in the lower strain rate region.
Predictor Equations for Estimating Crater Dimensions in PMEDM Process Using Fem Simulation and Experimental Validation
Authors: Bhattacharya Anirban , Batish Ajay
Published: March 2013

In the present study, the powder mixed EDM (PMEDM) process was simulated using FE approach to obtain simulated temperature profiles for estimating the crater dimensions and volume removed during formation of each crater. The craters formed in PMEDM process had higher diameter and shallow depth resulting in improved MRR and better surface finish. The addition of powder increased the amount of heat available at the workpiece between 20-25% as compared to conventional EDM process. The results were subsequently validated experimentally to compare the actual measurements with the simulation output. Predictor equations for crater radius and depth incorporating the significant factors were developed and also validated with the experimental results.
Electrokinetic and Impedimetric Dynamics of FeCo-Nanoparticles on Glassy Carbon Electrode
Authors: Ikpo Chinwe O. , Njomo Njagi , Ozoemena Kenneth I. , Waryo Tesfaye , Olowu Rasaq A. , Masikini Milua , Baleg Abd Almonam , Jahed Nazeem , Baker Priscilla G.L. , Iwuoha Emmanuel Iheanyechukwu
Published: March 2013

The electrochemical dynamics of a film of FeCo nanoparticles were studied on a glassy carbon electrode (GCE). The film was found to be electroactive in 1 M LiClO4 containing 1:1 v/v ethylene carbonate dimethyl carbonate electrolyte system. Cyclic voltammetric experiments revealed a diffusion-controlled electron transfer process on the GCE/FeCo electrode surface. Further interrogation on the electrochemical properties of the FeCo nanoelectrode in an oxygen saturated 1 M LiClO4 containing 1:1 v/v ethylene-carbonate-dimethyl carbonate revealed that the nanoelectrode showed good response towards the electro-catalytic reduction of molecular oxygen with a Tafel slope of about 120 mV which is close to the theoretical 118 mV for a single electron transfer process in the rate limiting step; and a transfer coefficient (α) of 0.49. The heterogeneous rate constant of electron transfer (ket), exchange current density (io) and time constant (τ) were calculated from data obtained from electrochemical impedance spectroscopy and found to have values of 2.3 x 10-5 cm s-1, 1.6 x 10-4 A cm-2 and 2.4 x 10-4 s rad-1, respectively.
Study on Use of Nanosized Alpha Alumina from Schedule Waste as Formulation in Thermal Insulation Paint
Authors: Meor Yusoff M.S. , Nur Aqilah Sapiee , Mahdi E.M. , Wilfred Paulus , Masliana Muslimin
Published: March 2013

Schedule waste used in this study is white aluminium dross produce from an aluminium smelting plant. It has a gibbsite crystal form, and was calcined at high temperature and transformed into α-alumina. nanosized powder with 76 nm primary particle size was produced by top-down method via high velocity wet milling. Comparative thermal insulation study was then performed in paints made from 15 wt% of these nanosize and micron-size alumina. The results from this study shows that the nanosize α-alumina is the best insulator, with a temperature reduction of 57 and 41% less, compared to micron-size α-alumina respectively for ceramic and steel plate.
Fabrication of p-Type Double Gate and Single Gate Junctionless Silicon Nanowire Transistor by Atomic Force Microscopy Nanolithography
Authors: Dehzangi Arash , Larki Farhad , Hassan Jumiah , Hutagalung Sabar D. , Saion Elias B. , Hamidon Mohd N. , Abdullah A. Makarimi , Kharazmi Alireza , Mohammadi Sanaz , Majlis Burhanoddin Y.
Published: March 2013

In this work, we have investigated the fabrication of Double gate and Single gate Junctionless silicon nanowire transistor using silicon nanowire patterned on lightly doped (105 cm-3) p-type Silicon on insulator wafer fabricated by Atomic force microscopy nanolithography technique. Local anodic oxidation followed by two wet etching steps, Potassium hydroxide etching for Silicon removal and Hydrofluoric acid etching for oxide removal, were implemented to reach the structures. Writing speed and applied tip voltage were held in 0.6 µm/s and 8 volt respectively for Cr/Pt tip. Scan speed was held in 1.0 µm/s. The etching processes were elaborately performed and optimized by 30%wt. Potassium hydroxide + 10%vol. Isopropyl alcohol in appropriate time, temperature and humidity. The structure is a gated resistor turned off based on a pinch-off effect principle, when essential positive gate voltage is applied. Negative gate voltage was unable to make significant effect on drain current to drive the device into accumulation mode.
Dynamics and Control of a Gyroscope-Stabilized Platform in a Ship Anti-Aircraft Rocket Missile Launcher
Authors: Koruba Zbigniew
Published: March 2013

The paper presents the ways of stabilising and controlling a Ship Anti-Aircraft Rocket Missile Launcher (SAARML) with the use of a Three-Axis Gyroscope-Stabilized Platform (TAGSP). The analysis of the dynamics of the SAARML and TAGSP systems is conducted for the case of searching and tracking a manoeuvring air target in the conditions of interferences and the influence of kinematic forces from the base (ship's deck). Some research results are presented in a graphical form.
Application of Correlation and Coherence Functions in Diagnostic Systems
Authors: Dziurdź Jacek
Published: March 2013

Main problem in operation of diagnostic systems of power transmission systems is analysis of the energy of these harmonic components of the signal, which could be considered as diagnostic symptoms. Measured values can be affected i.a. by energy of random effects or other, less important components of the signal. Coherence and correlation functions are ones of classical methods of signal analysis being applied to analyze deterministic signals affected by random noise. In time domain autocorrelation function allows to determine time cohesion between adjacent fragments of analyzed process, shifted by different time values. In the paper author describes the method of minimization the impact of disturbances on signals being analyzed using basic properties of autocorrelation function. For the analysis of deterministic phenomena (including nonlinear) ordinary coherence function was applied. Showed examples were implemented and solved in MATLAB environment. The method was verified by analysis of model signals and signals (vibration accelerations) recorded on real object.
Stereological and Statistical Evaluation of Grain Size in Experimental Ni-Based and Conventional Supercoarse Sintered Carbides
Authors: Richter Janusz , Maliński Marian
Published: March 2013

Chemical composition and technology of experimental Ni based binder-tungsten carbide particles composite have been worked out to increase corrosion resistance of conventional supercoarse WC-Co type sintered carbides. All the sintered WC cermets, both with Co and Ni-based binding phase have been manufactured using identical supercoarse WC powder. Grain size evaluation was performed using light microscope images and grain chord length measurements, samples of commercial WC-Co coarse and supercoarse grades being included into analysis for comparison purposes. The obtained statistical and geometrical distributions of the chord length revealed certain differences. The performed statistical analysis allowed to state that the investigated experimental grades of Ni-based sintered WC carbides are materials of microstructure significantly more coarse than the reference coarse commercial grade (i.e. they can be classified into supercoarse group of sintered carbides).
Thermal Gradients Behaviour during the C-E Transition within Solidifying Massive Roll
Authors: Wołczyński Waldemar , Wajda Wojciech , Guzik Edward
Published: March 2013

Columnar or equiaxed structure selection and particularly the C→E transition in the solidifying massive rolls is shown as the result of changes in heat transfer. The numerical treatment of heat transfer allows to separate the temperature field for columnar structure formation from equiaxed structure formation. An area where transition from columnar into equiaxed structure occurs, C→E≡CET is also distinguished. The current model requires the transformation of the calculated temperature field into the thermal gradients’ field. Thermal gradients are approximately constant during the examined C→E transition according to the numerical simulation. This result is in accordance with the Hunt’s theoretical predictions. The localization of the structural transition (CET) in space and in time is also shown within the map which yields from the temperature field.
Effect of Material and Technological Conditions on Quality of Metal Matrix Composite Castings
Authors: Gawdzińska Katarzyna , Nagolska Dorota , Wojnar Leszek
Published: March 2013

The paper presents a proof, which has been made by analyzing technological process of tested materials, that a set of quality characteristics of metal composite castings has to be different from the set of quality characteristics of castings produced out of traditional materials. However, some characteristics are similar for both material groups. These characteristics (pertaining to a set of quality characteristics of composite castings) that have been named as specific, have not been determined before. The set of characteristics has been determined on the basis of material and technological conditions as well as on methodology of diagnosing the castings quality. Basing on the Ishikawa diagram, weights of individual quality characteristics have been set along with values for particular material and technological causal groups, i.e. management, human impact, methods of manufacturing and material of composite castings and manufacturing workstation.
Analysis of Intermetallic Phases in 2024 Aluminium Alloy
Authors: Mrówka-Nowotnik Grazyna , Sieniawski Jan
Published: March 2013

The main objective of this study was to analyze the evolution of the microstructure (morphology, composition and distribution of intermetallic phases) in the 2024 aluminium alloy cooled with different cooling rates after solidification process. A few techniques: optical light microscopy (LM), scanning (SEM) electron microscopy combined with an energy dispersive X-ray microanalysis (EDS), X-ray diffraction (XRD) were used to identify intermetallics in the examined alloy. The results show that the microstructure of 2024 aluminum alloys in as-cast condition consisted following intermetallic phases: Al2Cu, Al2CuMg, Al7Cu2Fe, Al4Cu2Mg8Si7, AlCuFeMnSi and Mg2Si.
Application of Convex Hull Algorithm for Defect Detection in Selected Biological Materials
Authors: Petryniak Rafał
Published: March 2013

Conventional convex hull algorithm determines the smallest convex polygon that contains the analyzed shape. The article presents a modification of this algorithm, which allows us to select the concavity to detect. In contrast to the typical convex hull algorithm, the data are analyzed in portions. This paper proposes the use of this modified algorithm for the defects detection on medical images. Two types of images were used: micro-computer tomography images of dental root canals filled with sealer and magnetic resonance images of a patient hand with rheumatoid arthritis. Those images contained some defects that needed to be measured. Prepared algorithm greatly facilitated this process by supporting the user in the segmentation process. The achieved results were positively evaluated by experts - doctors: rheumatologists and endodontists.
Intermetallic Phases Formation in Hot Dip Galvanizing Process
Authors: Kopyciński Dariusz , Guzik Edward
Published: March 2013

The study describes the mechanism of structure formation in protective coating, growing on iron surface during hot-dip galvanizing. As a first stage of the galvanizing process, immediately after the iron sample has been dipped in galvanizing bath, a layer of frozen zinc is crystallizing on the sample surface. Next, as a result of isothermal solidification, an alloyed layer of the coating; composed of the sub-layers of intermetallic Fe-Zn phases, is formed. At the initial stage of the existence of the alloyed layer, another layer, that of undercooled liquid, is formed on the surface of iron dipped in liquid zinc. As a result of peritectic reactions under metastable conditions, the individual phases are born, forming sub-layers in the expected sequence of Γ1, δ and ζ.
Influence of Coatings Deposition Parameters on Microstructure of Aluminide Coatings Deposited by CVD Method on Ni-Superalloys
Authors: Nowotnik Andrzej , Góral Marek , Pytel Maciej , Dychtoń Kamil
Published: March 2013

The paper presents the preliminary results of technological tests of aluminizing using a new BPX Pro 325 S CVD equipment. Nickel based cast superalloys: IN 738 and MAR M200+Hf were used as a substrate material. The aluminizing processes with different parameters - pressure, HCl flow and time - were conducted. Microstructure analysis showed coatings whose thickness didn't exceed 20 µm. The authors showed that the changes of parameters values in the analyzed range weakly influenced the coating thickness (about 1-2 µm). It was proven, that it was necessary to decrease the flow of hydrogen chloride and perform the thermodynamic analysis.