bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the Austenitic Grain Growth by Thermoelectric Power Measurements
Authors: Capdevila Carlos , De Cock Tommy , Caballero Francisca García , García-Mateo Carlos , García de Andrés Carlos
Published: March 2009

The influence of the deformation grade on the recrystallised grain size has been studied in the AISI 304 stainless steel. Therefore, cold rolled samples of this material with reductions varying between 30% and 80% were annealed at different temperatures and subsequently quenched. The mean austenitic grain sizes were measured and compared. Moreover, the correlation between the variation of the thermoelectric power and the grain growth was investigated for each degree of prior
deformation.
Effect of Copper Addition on Grain Growth Behavior of Austenite in Low Carbon Steels
Authors: Nakashima Koichi , Imakawa K. , Futamura Y. , Tsuchiyama Toshihiro , Takaki Setsuo
Published: March 2009

The effect of copper (Cu) addition on the grain growth behavior of austenite was
investigated in a low carbon steel and a Cu bearing low carbon steel. Cu addition to the steel does not affect the nucleation rate of reversed austenite on heating in the martensitic structure but markedly retards the grain growth of the austenite during holding at 1173K (austenitization). As a result, the grain size of austenite in the Cu bearing steel becomes about one-third times smaller than that in the base steel after austenitization for 14.4ks. TEM observations in the Cu bearing steel revealed that Cu particles precipitated during aging treatment had completely dissolved in 1.2ks of austenitization. Therefore, the retardation of grain growth of austenite can not be explained by the grain boundary pinning effect of Cu particles but by the dragging effect of Cu atoms in the austenitic solid solution.
3D Atom Probe Analysis on Nb and Mo Segregation during Recrystallisation of α-Fe
Authors: Maruyama Naoki , Smith George D.W.
Published: March 2009

Atomic-scale interface segregation behaviour of Nb and Mo during different stages of recrystallisation of a-Fe has been investigated using a three-dimensional atom probe (3DAP). Experimental procedures to analyse a specific region of interest in the specimens and to determine an orientation relationship between analysed contiguous grains are briefly described, and then analytical artefacts which may affect the measured solute distribution are discussed. Atom probe analysis reveals that Gibbs free energy of segregation of Nb is larger than that of Mo in a-Fe, implying that a stronger solute Nb-interface interaction can be a reason for the larger retardation effect of recrystallisation by Nb addition. The comparison of measured solute profiles at migrating recrystallisation interfaces with calculated solute profiles show that Cahn’s solute drag model gives a reasonable fit to solute profiles for migrating interfaces.
Measurement of Impurity Concentration at Grain Boundaries after Recrystallization
Authors: Cornen Marilyne , Le Gall René
Published: March 2009

Impurity segregation at grain boundaries in polycrystalline alloys is known to have a
tremendous impact on the material properties such as grain boundary mobility, cohesion... But direct measurement of grain boundary chemistry is quite complex and there are few results concerning polycrystals. In this paper we present an indirect method to measure segregationmisorientation dependence on polycrystalline Ni-S alloys using 3D reconstruction of etch grooves. Samples of Ni-S alloy (1 ppm at) have been cold rolled at respectively 0.3 and 0.9 Von Mises
equivalent strain and then annealed at 455°C to promote recrystallization. Then they have been etched near the transpassive potential to form etch grooves, whose geometry depends on the sulfur segregation level. It is found that the sulfur concentration at grain boundary decreases significantly when the driving force for grain boundary migration (i.e. the initial strain) increases, as predicted by solute drag theory.
Modeling of Grinding Force in Constant-Depth-of-Cut Ultrasonically Assisted Grinding
Authors: Wu Yong Bo , Nomura Mitsuyoshi , Zhi Jing Feng , Kato M.
Published: March 2009

This paper discusses the mechanism behind the grinding force decrease associated with ultrasonication of the grinding wheel in constant-depth-of-cut ultrasonically assisted grinding (UAG). By introducing a grinding model describing the cutting trace of an abrasive grain, an equation relating the grinding
force decrease to such process parameters as the amplitude and frequency of vibration and the grinding wheel speed, is established. Experiments are conducted to confirm the theoretical prediction. Theoretical and empirical results both indicate that the decrease in grinding force is due to the grinding chips becoming smaller and fracturing more easily under ultrasonication. The results also suggest that the grinding force decrease is greater at higher vibration amplitudes and at lower grinding wheel speeds.
Effect of Hot Pressing Temperature on Mechanical Properties and Microstructure of Si3N4-TiCnano Composites
Authors: Zhao Jun , Ai Xing , Huang Xin Ping , Lü Z.J.
Published: March 2009

Si3N4 ceramic matrix composites toughened with TiC nanoparticles were fabricated by using hot pressing technique with Al2O3 and Y2O3 as sintering aids. The effects of hot pressing temperature on the densification, mechanical properties and microstructure of Si3N4-TiCnano composites were investigated. The experimental results showed that optimum mechanical properties were achieved for Si3N4-30vol. % TiCnano composite hot pressed at 1750°C for 60min, under 30MPa pressure in N2, with the flexural strength, fracture toughness and hardness being 850MPa,
6.7MPa×m1/2 and 16.5GPa respectively. The microstructure and phase composition of the composites were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The analysis results indicated that fine, elongated b-Si3N4 grains and the reinforcements of both intergranular and intragranular TiC nano particles as well as the sub grain boundaries inside the b-Si3N4 grains contributed to the optimum properties of the composite hot pressed at 1750°C.
Research of Intelligent Tool Condition Monitoring Technology Based on Multi-Information Fusion
Authors: Ji Shi Ming , Zhang Li , Wan Y.H. , Zhang X. , Yuan Ju Long , Zhang L.B.
Published: March 2009

A new intelligent tool condition monitoring technique for metal cutting process is proposed. Fiest, the frequency spectrum analysis of the audio signal during cutting process, the pixel space projection analysis and equal gray pace analysis of the images of machined workpiece surface are introduced. Then combined the results of the audio signal analysis and the workpiece surface image analysis with artificial neural network, we implemented the intelligent tool condition monitoring based on multi-information fusion. The experimental results indicate that this method can recognize the tool condition effectively and improve the dependability of tool condition monitoring.
Modeling of Computer-Controlled AC Servo Feed System
Authors: Xi Z.Y. , Lu Chang Hou , Zhang Jian Chuan
Published: March 2009

This paper will be devoted to build a mathematical model of this kind based on the
computer-controlled AC servo feed system of a common XY worktable. First, a practical AC servo worktable system is analyzed and its linear theoretical mathematical model is given. Second, the parameter in this model is identified in terms of the actual measured output data and reference signal by using an ARX model by using RLS identification method. Then, by using servo “simulation” techniques, a very accurate model of the servo drive can be constructed. Based on this model, it is possible to observe the effect on performance by changing the factors such as backlash, friction, servo-loop gains. Hence, a deep understanding of dynamics of the computer-controlled AC servo feed system of a common XY worktable is obtained. It is expected that this paper will lay reliable foundation for the further work—friction compensation, so that the precision of the system will be improved in the end.
A Study on the Microstructure of Nano-Scale Ceramic Tool Materials
Authors: Zou Bin , Huang Chuan Zhen , Liu Han Lian , Wang Sui Lian
Published: March 2009

Nano-scale ceramic materials are very suitable to be used as the high speed cutting tool owing to their excellent properties. The incorporation of nano-scale second phase, such as SiC and Ti(CxN1-x) particles, into a ceramic matrix can lead to an improvement in mechanical properties, which is contributed to a change in microstructure. However, the differences between nano-scale ceramic materials and monoclinic ceramic materials can be found through fabricating these two kinds of materials. Firstly the changes in microstructure that will affect the mechanical properties of the nano-scale ceramic materials are investigated as the nano-ceramic tools are compared with the monolithic ceramic tools. Secondly the effect of microstructure on the mechanical properties is discussed. Finally the microstructure formation mechanism of nano-ceramic materials is given on the bases of some hypotheses.
Microstructure and Mechanical Properties of Ti(C,N)-ZrO2-Ni-Mo Composite Cermet
Authors: He Lin , Huang Chuan Zhen , Sun Jing , Liu Han Lian
Published: March 2009

Ti(C0.7N0.3)-ZrO2-Ni-Mo cermet with 73.9%Ti(C0.7N0.3)-10%ZrO2-13%Ni-3.3%Mo(in mass) was fabricated by HP technology. The fabricated material possesses good mechanical properties with flexure strength (1264.4Mpa), fracture toughness (15 MPa.m1/2) and Vickers hardness (16.2GPa). The results of microstructure observation and analyses of the composite cermet by TEM, SEM and EDAX show that Mo2C nanoparticles are separated in the Ti(C,N) grains and the structure is similar to the “intragranular structure” in nanocomposite material. Smaller size t-ZrO2 and m-ZrO2 grains are distributed o n the boundaries of Ti(C,N) grains and the amount of m-ZrO2 is more than that of t-ZrO2.The growth of m-ZrO2 grain has an orientation on Ti(C,N) grain, which is propitious to the boundary bonding strength.
Research Status Quo of Simulation Design Methods for Ceramic Tool Materials
Authors: Xu Li Qiang , Huang Chuan Zhen , Wang Sui Lian , Liu Han Lian
Published: March 2009

The employment of ceramic material simulation design methods can eliminate the
disadvantage of traditional ceramic material developing methods of being time-consuming, laborious and high cost. Three simulation methods of artificial neural network, regression analysis and pattern recognition, and their application to ceramic material simulation design were presented in this paper. The problems existing in ceramic material simulation were proposed finally.
Wear Mechanism of Diamond Mills in Stone Cutting
Authors: Huang B. , Liu Zeng Wen , Li Jian Feng , Zhang Jin Sheng , Wang Z.
Published: March 2009

With the growing use of natural stone both in industrial field and in ornamental materials of building, Complex-shaped stone products are being dramatic increasing. It is necessary to machine it with flexible and automatic machines such as NC machining enters. Versatile tools such as shaped diamond mills are used. The wear mechanism of diamond mills in stone cutting is presented in this paper though experiments. The macro-geometries of diamond mills such as mill diameter, profile and weight are described. The changes of macro-geometries of shaped diamond mills can be used to express tool wears. The changes can therefore be used to forecast tool wears in stone machining.
Machine Vision and Data Reconstruction for Measuring Free Form Surface
Authors: Zhang Hong Wei , Zhang Guo Xiong , Shi Y.
Published: March 2009

Reverse engineering of free-form surfaces is one of the most challenging technologies in advanced manufacturing. With the development of industry more and more sculptured surfaces, such as molds and turbine blades, are required to measure quickly and accurately. Optical non-contact probes possess many advantages, such as high speed, no measuring force, in comparison with contact ones. The ability of stereovision probe with CCD cameras in gathering a large amount of information simultaneously makes it the most popularly used one in sculptured surface measurements. So based on the laser triangular principle, a measuring and testing device with two CCD cameras was designed, and its accuracy was analyzed. With a virtual 3D target in form of a grid plate, all the intrinsic and extrinsic parameters of CCD camera including the uncertainty of image scale factor and optical center of camera can be readily calibrated. In order to obtain all the required data with high accuracy in a short time, the curvature-based adaptive sampling strategy is presented. Due to huge amount of arbitrary scattered points, the Delaunay triangular division and Bezier interpolation and NURBS interpolation are applied to get a continuous surface.
The Study on the Dynamic Characteristic of High Speed Machine Tool and Experiment Validate
Authors: Zhang Yi Min , Lin Xiu Li , Wang Xiao Dong , Cai Guang Qi
Published: March 2009

One of the important factors resulting in the high-speed machinery performance is its
machine tool dynamic characteristic. It will directly influence the final manufacturing capability of the machinery and it is also the important criterion of evaluating machinery performances. Especially, the dynamic characteristic of spindle assembly has large effect on manufacturing capability of machinery. So it is very important both analyzing dynamic-static characteristic of the spindle assembly and machine tool of high-speed machinery and studying the effect to machinery function. Using Finite Element Analysis software did a Finite Element Analysis of spindle assembly of the high-speed machine tool, and some experiments are done to validate the result the Finite Element Analysis results.
Performance of Diamond Segments in Different Machining Processes
Authors: Xu Xi Peng , Hong Y.B. , Chen S.
Published: March 2009

An investigation is reported of the performance of diamond impregnated segments in three machining processes - circular sawing of granite with diamond segments, dressing of diamond segments with refractory bricks and surface grinding of diamond segments with an alumina wheel. Two kinds of segments were fabricated by incorporating diamonds (either coated or uncoated) into an iron-based bond matrix. Measurements were made of the horizontal and vertical force components in the machining processes. SEM was used to examine the diamond-matrix bonding states and the ground surfaces of the segments. The changes of forces and segment wear (weight loss and wear performance) were found to be basically consistent for the three machining processes.
Module Partition of Equipment for Working Special-Shaped Stones Based on Function Analysis
Authors: Wang Zhenya , Zhang Jin Sheng , Zhang C. , Yu F.Y. , Ren X.H. , Liu Zeng Wen
Published: March 2009

According to the structure characteristic of the existing equipment for working special-shaped stones, the function partition sketch map of equipment is established in the paper by means of function analysis on the basis of various module partition methods. The theory of function analysis is used to discuss the procedure and method of module partition. Qualitative analysis method based on function is put forward in the paper to divide the main parts with explicit function and structure, while quantitative analysis method is for those whose ascription is ambiguous. The module partition of equipment for working special-shaped stones is completed according to the principle of module partition, establishing the foundation for modularization design and manufacture of equipment.
Study on the Machining Technology of Composite Materials
Authors: Zhang Jing Ying , Yu Qi Xun , Pang Si Qin , Zhu Z.F.
Published: March 2009

The kinds and the properties of composite materials and superhard cutting-tool materials are introduced in this paper. By using five kinds of superhard cutting tools, such as polycrystal cubic boron nitride (PCBN), polycrystal diamond (PCD), thin film and thick film of chemical vapor deposition (CVD) diamond and carbon nitride (CxNy), two kinds of composite materials (fiber reinforced and particle reinforced) have been turned. Many experiment data have been gotten. It is
shown that the superhard cutting tool is the best for machining composite materials. Moreover, surface finish and cutting force in composite material machining are discussed.
Experimental Investigations of the Al 6082 Alloy Subjected to Equal-Channel Angular Pressing
Authors: Krállics György , Malgyn Dmitry , Fodor Arpad
Published: March 2009

The interest in bulk nanostructured materials (NSM), processed by methods of severe plastic deformation (SPD), is justified by their unique physical and mechanical properties. Equalchannel angular pressing (ECAP) is one of the methods of severe plastic deformation (SPD) that produces ultra fine-grained material. Due to the cyclic nature of the process, it is difficult to produce specimens with a high length to diameter ratio. Ratios of 6-7 have been reported in the literature to date. Longer specimens, however, are useful since the homogenous part is larger and the relative size of end effects is smaller. A new method was developed to obtain length to diameter ratios as high as 8-10. This new technique was developed using the multi-pass finite element simulation. The as-received alloy used in this study was the 6082 commercial Al-Mg-Si alloy. High strength and high ductility phenomenon that was found recently in materials after SPD were reached with the route C. The induced anisotropy of specimens after ECAP was monitored.
Wear of the Tungsten Electrode at the TIG Arc-Spot Welding of Dissimilar Metals
Authors: Dobránszky János , Bella Szabolcs , Kientzl Imre
Published: March 2009

Micro-TIG welding experiments have been used for the welding of the contacts of special lamps. Since the welded materials were different, the welded joint was a heterogeneous bound. For the joints a 0.6 mm Ni-Mn alloy or 0.4 mm Mo wire were inserted onto the hole of AISI 304 type austenitic stainless steel sheet, with a wall thickness of 0.35 mm. The micro-TIG welding was completed with a welding machine of which control characteristics corresponded to all the requirements
necessary for TIG arc-spot welding. The goal of the experiments was to find the optimum regarding the quality of the lamps’ welded joints that correspond with the needed production quality level. The problems that occurred throughout the welding process were due to the very high melting point of the Mo. Also, using optical microscopy and scanning electron microscopy have performed a proper testing in parallel with the experiments. The details, revealed that the geometry of the joint
and the resistance depend very much of the arc length, shielding gas velocity and especially of the tip geometry of the tungsten electrode and its wearing. Regarding to the electrode’s wearing, there have been determined the tip angle, the tapering and the effect of the electrode’s material composition. The latter parameter was investigated for unalloyed, thorium-oxide, cerium-oxide and lanthanum- oxide alloyed electrodes.
TEM Observation on Nano-Precipitation of Plain Low Carbon Steel by CSP
Authors: Zhang L.N. , Zhang X. , Ma Y. , Liu D.L.
Published: March 2009

Plain low carbon steel produced by compact strip production (CSP) process was analyzed using TEM, EELS and XEDS. Nano-sized oxides and sulfides were observed in the steel. The nano-oxides are mainly ferrospinel of <20nm in size, and the nano-sulfides are MnS and FeS particles with size of 20-100 nm. They distributed both in grains and at grain boundaries. These nano precipitates could form in cast slab before heavy deformation by rolling process. It is proposed that besides the grain refinement, the nano-pricipitation plays an important role in yield strength enhancement. This mechanism may provide a new approach to strengthen plain low carbon steels.
Study on Dynamic Mechanic Properties of Thermosetting/Thermoplastic System Used as the Matrix of Advanced Composite
Authors: Tang Bang Ming , An Xuefeng , Yi Xiao Su
Published: March 2009

Resin matrixes for aeronautic advanced composites based on thermoplastic PEK-C
(modified polyetherketone) and blending epoxies of DGEBA (diglycidyl ether of bisphenol A) and TGMDA (tetraglycidyl methylenedianiline) are analyzed by DMTA in this paper. The effects of blending ratios and high-temperature post-curing processes on DMTA properties are investigated. The results show that epoxies exhibit different curing features with the existence of high viscous thermoplastic, by contrarily the neat epoxies systems cure according to a random copolymerization
rule. The primary peak of tangent delta of DMTA mainly attributes to segment motions of thermoplastic in a blend and the secondary peak mainly for those of the DGEBA cured networks. The higher the ratio of TGMDA to DGEBA is the more obviously the separation degree of tangent delta peaks adopt. Increasing the amount of TGMDA is helpful for separating of phases in the blends. High temperature post-curing promotes separating of phases. In a blend the continuous
phase mainly consists of a mass of thermoplastic and some TGMDA, DGEBA mainly collects in dispersed phases.
Photo-Oxidation of Polyethylene Composites with Different Interfacial Interactions
Authors: Yang Rui , Yu Jian , Wang Kun Hua
Published: March 2009

The photo-oxidation stability is crucial for the materials that are exposed to outdoor
application. For polyethylene, it has been investigated thoroughly and the auto-oxidation mechanism has been widely accepted. Nevertheless, the photo-oxidation of polyethylene composites, the most widely used materials, has not attracted enough attention yet. It is well known that the mechanical properties of composites are of great difference to that of matrix polymers, due to the introduction of the fillers and the different interfacial interactions between the matrices and the fillers. Also the oxidation behavior of composites have interesting characteristics owing to the various fillers and interfacial interactions, which always depend on the coupling agents. In the present work, the natural photo-oxidation of high-density polyethylene composites was studied. The results showed that the coupling agent had the most important but different influence on the oxidation stability of the composites, according to the different fillers.
Study on the Cure Kinetics of Middle Temperature Curing 3234 Epoxy Resin System
Authors: Liu Tian Shu , Chen Xiang Bao , Zhang Bao Yan
Published: March 2009

The cure kinetics of middle temperature curing 3234 epoxy resin was investigated under both isothermal and dynamic curing conditions by Differential Scanning Calorimetry (DSC) technique. The kinetic equations for isothermal and dynamic curing were established respectively by analyzing experimental data obtained from DSC . By following the temperature procedure of the standard cure cycle of the resin system, the validity of the cure kinetic equations was verified by means of determining the residual heat of reaction of samples from different stages of the cure cycle. Results showed that the cure kinetics under both isothermal and dynamic conditions could be described by the autocatalytic kinetic model. Predictions by the kinetic equation for dynamic curing agreed well with the experimental results.
Experimental Study on Dynamic Properties of High Strength Fiber Clusters
Authors: Huang Chen Guang , Chen Si Ying , Duan Zhu Ping
Published: March 2009

In this paper, the dynamic behaviors of several kinds of high strength fibers,
including Kevlar, UHMPE, glass fibers, carbon fibers etc., are investigated experimentally, with a Split Hopkinson Tension Bar（SHTB）. The effect of strain rate on the modulus, strength, failure strain and failure characteristics of fibers, under impact loading, is analyzed with the relative stress vs. strain curves. At the same time, the mechanism about the rate dependence of mechanical behaviors of various fibers is discussed based on the understanding on the microstructures and deformation models of materials. Some comments are also presented on the decentralization of experimental results, and a new method called traveling wave method is presented to increase the experimental accuracy. Research results
obtained in this paper will benefit to understand the energy absorption and to build up the constitutive law of protective materials reinforced by high strength fibers.
Strain-Induced Precipitation of Nb(CN) during Deformation of Undercooled Austenite in Nb-Microalloyed HSLA Steels
Authors: Chen Guoan , Yang Wang Yue , Guo Shou Zhen , Sun Zu Qing
Published: March 2009

By using TEM strain-induced precipitation of Nb(CN) during deformation of undercooled austenite was investigated in Nb-microalloyed steel. The results showed that at 1200°C all of Nb were dissolved and there were no Nb(CN) precipitates formed during cooling until down to 760°C; During deformation enhanced ferrite transformation Nb(CN) of dynamic precipitation required an incubation
period, but compared with isothermal transformation it reduced significantly. Only when the strain increased to 0.69, Nb(CN) began to precipitate on dislocation nodes and grain boundaries. Furthermore the volume fraction of Nb(CN) precipitation increased with increasing strain but their coarsening wasn’t significant. Results showed that the measured grain size is in good agreement with
the calculated value.
Static Analysis of Thick Laminated Beams: Two-Dimensional Elasticity Solutions via Differential Quadrature
Authors: Lü Chaofeng , Gao Ying , Chen W.Q.
Published: March 2009

This paper intends to present two-dimensional elasticity solutions for static problem of thick laminated composite beams using a hybrid method of state-space-based differential quadrature. The technique of differential quadrature is employed to reduce the partial differential state equations into the ordinary differential ones at all arbitrary sampling points for each individual laminate. General solution to the assembled state equation is then obtained according to the matrix theory. Taking account of the continuity conditions at the interfaces of all the adjacent lamina, a
relationship between state variables at the top and bottom surfaces of the beam is established through a global transfer matrix. After incorporating the boundary conditions at these two surfaces, an eigenvalue equation for static problem is then derived. Numerical examples are presented, through which the accuracy and convergence characteristics of the present method are investigated. It is shown that the present method is of excellent efficiency for laminated composite thick beams subjected to arbitrary end supporting conditions.
Tensile and Bending Behavior of Melt Growth Al2O3/YAG Composite at Ultra High Temperatures (1773-2023K)
Authors: Ochiai Shojiro , Sakai Yuushi , Sato K. , Ueda T. , Morishita Kohei , Okuda Hiroshi , Tanaka Masashi , Hojo M. , Waku Y. , Nakagawa Narihito , Sakata Shinichi , Mitani Atsuyuki , Takahashi T.
Published: March 2009

The deformation and fracture behavior at 1773-2023K of the unidirectionally solidified
eutectic Al2O3/YAG (Yttrium-Aluminum Garnet with the composition of Y3Al5O13) ceramic composite was investigated. The stress-stain curve and strength of unnotched and notched specimens, measured by bending and tensile tests, showed that (a) both unnotched and notched specimens fractured in a brittle manner at low temperatures and at high displacement speeds, but in a ductile manner at high temperatures and at low displacement speeds, and (b) the notched strength increased, reaching maximum, and decreased with increasing temperature and decreasing displacement speed. The increase in the notched strength with increasing temperature and decreasing displacement speed up to the maximum value was accounted for by the increase in plastic zone size ahead of the notch,
and the decrease with further increasing temperature and decreasing displacement speed by the loss of the stress carrying capacity of the yielded ligament, based on the finite element analysis.
Effects of S-Doping and Subsequent Annealing on Photoluminescence around 1.54ųm from Er-Containing ZnO
Authors: Zhou Zhen , Sato N. , Komaki T. , Koizumi Atsushi , Komori T. , Morinaga Masahiko , Fujiwara Yasufumi , Takeda Yoshikazu
Published: March 2009

The wide band-gap semiconductor, ZnO, has been proposed as one of the good host for Er3+ ions. In this investigation S was doped into the Er-containing ZnO specimens through the heat treatment in a H2S gas atmosphere. After sulfurization, the photoluminescence (PL) peak centered at 675nm from the ZnO host became much weaker, and accordingly the absorption peaks of Er3+ at 526nm, 550nm, and 665 nm became weaker. Also, the PL intensity around 1.54µm decreased after
the sulfurization. However, when the sulfurized specimens were annealed at 1000oC in air, the PL intensity increased by about 3 times. The effects could be due to the modification of the local structure around the Er3+ ions in ZnO.
Effect of Excess PbO on the Kinetics of the Growth of PMNT Polycrystals by Templated Grain Growth Method
Authors: Zhao Lili , Gao Feng , Wang Wei Min , Tian Chang Sheng
Published: March 2009

The oriented 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMNT) polycrystals were prepared by the conventional ceramic technique and the templated grain growth method adding excess PbO in the matrix. Kinetics of the development of oriented structure was investigated systemically. In the presence of PbO liquid phase, the oriented PMNT polycrystals mainly grow by the dissolution-precipitation mechanism. The diffusion is determined by the sintering temperature and the PbO-excess content in the matrix. The thickness of oriented PMNT polycrystals displays a t1/3
dependence, which is characteristic of diffusion-controlled growth. For the thicker oriented structure, 20% excess PbO in the PMNT matrix and 1150oC for 10h are the proper experimental conditions. Moreover, the addition of PbO in the matrix hardly affects the final composition of ceramic matrix.
Effect of TiO2 on the Property of RuO2/γ-Al2O3 Catalyst
Authors: Yang Shao Xia , Feng Yu Jie , Wan Jiafeng , Zhu Wanpeng , Jiang Zhanpeng
Published: March 2009

A catalyst, as a kind of function material, plays important roles. In the paper
RuO2/g-Al2O3 and RuO2-TiO2/g-Al2O3 catalyst were prepared by the impregnation method. The structure o f two catalysts was studied with XRD, SEM and XPS. The addition of TiO2 promoted the dispersion of Ru particles, and made the amount of the chemisorbed oxygen increased on catalyst surface. The activity was investigated in WAO of phenol over RuO2/g-Al2O3 and RuO2-TiO2/g-Al2O3 catalysts. The results showed that two catalysts had good activity, and TiO2
effectively increased the activity of RuO2/g-Al2O3 catalyst in WAO of phenol. With
RuO2-TiO2/g-Al2O3 catalyst 96% phenol removal was observed at 150°C and 3MPa after 80min reaction in WAO of phenol.
Microstructure and Mechanical Properties of PMS-PZT Ceramics with Silica Additives
Authors: Zhu Zhi Gang , Li Bao Shan , Li Guo Rong , Jiang Xiang Ping , Yin Qing Rui
Published: March 2009

The use of lead zirconate titanate ceramics for high power application must have superior mechanical properties, the composition Pb0.98Sr0.02(Mn1/3Sb2/3)0.05Zro.48Ti0.47O3 + x wt% SiO2 (x = 0-1.0) have been studied for this purpose. The microstructures were observed to study the improvement of mechanical properties by SEM and TEM. The nano-scale secondary phase of SiO2
and PbSiO3 were observed on the grain boundary and the twinned ZrO2 was found surrounded by PMS-PZT perovskite phase. The mechanism to the occurrence of twinned ZrO2 and its content increased with increasing Si concentration are discussed in the paper. The occurrence of the nonferroelectric phase such as ZrO2, SiO2 and PbSiO3 on the grain boundary should be the main reason for great improvement of fracture strength.
Fabrication of NiO-SDC Composite Anodes Using Gel-Casting for Low-Temperature SOFCs
Authors: Yin Yan Hong , Xia Chang Rong , Zhu Wei , Yong Guo , Meng Guang Yao
Published: March 2009

NiO-SDC(Ce0.8Sm0.2O1.9) cermet anodes for solid oxide fuel cells (SOFCs) were fabricated by sintering NiO-SDC composite particles derived from gel-casting. The influence of Ni content and sintering temperature on the electrode polarization using humidified CH4 as fuel was investigated in order to optimize the fabrication conditions. The lowest anodic polarization was obtained for an anode sintered at 1350 oC and consisting of equal volume of Ni and SDC. The anodic polarization at 600 oC was about 37mV at a current density of 300mA/cm2. Maximum power density of 352 mW/cm2 was achieved at 600oC for a single cell based on the optimized anode, inferring high catalytic activity of the gel-cast Ni-SDC anode. This high performance seems to be attributed to the microstructure in which Ni and SDC are uniformly distributed.
Stabilization Effect in BaTiO3 Single Crystal during Aging below Tc
Authors: Sun Da Zhi , Ren Xiao Bing , Yang Shi Ping , Luo Hao Su , Otsuka Kazuhiro
Published: March 2009

High purity BaTiO3 single crystal was aged below its Curie temperature for different
times. The reverse transformation (from tetragonal to cubic) temperature was measured precisely by differential scanning calorimetry (DSC). It was observed that the reverse transformation temperature increased with increasing aging time, indicating ferroelectric phase became stable with aging. This behavior is the same as found in ferroelastic alloys. The origin of the stabilization effect in ferroelectric single crystals was discussed with respect to the distribution of point defects.
Subsurface Microstructure Evolution of Hadfield Steel under High Impact Energy
Authors: Xu Yun Hua , Fang Liang , Cen Qihong , Zhu Jin Hua
Published: March 2009

It has been well known that Hadfield steel behaviors excellent wear resistance under high impact energy. Up to now there exist many theories to explain the wear mechanism of Hadfield steel. In this research subsurface microstructure evolution process of Hadfield steel was investigated after high energy impact experiments. It was shown from high resolution electron microscope (HRTEM) examination of subsurface microstructure that nanocrystallized austenite grains have been formed in the procedure of the reaction and rearrangement of high density dislocations under the heavy plastic deformation, sub-grains as a transitional structure and, finally, the formation of nano austenite grains. On the other side, the interactions of twins and stack faults or dislocations and stack faults make austenite crystals transform to amorphous solid. With increasing impact cycles the sizes of nano-grains were decreased and the amorphous volumes were increased further. A
large amount of nano-sized grains embedded in bulk amorphous matrix were fully developed, which will dominate the wear of the steel. In the subsurface no martensitic transformation was observed.
Study of the Weak Ferromagnetism in Ca1-xLaxB6 Ceramics
Authors: Cao Ming He , Yuan Jun , Jiang Jun
Published: March 2009

Ferromagnetism in La-doped single crystal CaB6 is interesting because it has no partially filled d- or f- orbits in CaB6. In this paper, we have investigated the relationship between the ferromagnetic properties with the La content in CaB6 polycrystalline ceramics prepared by redox method. Contrary to the single crystal results, we found that there is no direct correlation with the level of La substitution in ceramics samples Ca1-xLaxB6 (0 £ x £ 0.03). Instead we have shown that it is related to Fe impurities. Our results show it is important to consider the magnetic impurities in discussing the weak ferromagnetism in borides.
The Interface and Grain Growth in Cofired Ferroelectric / Ferrite Multilayer Composites
Authors: Gao Feng , Zhang Chang Song , Liu Xiangchun , Tian Chang Sheng
Published: March 2009

The multilayer composites were prepared by cofiring Pb(Ni1/3Nb2/3)O3-based
ferroelectrics and NiCuZn ferrite using tape casting processes. The interface and grain growth of the composites were investigated. The results show that the sintered interface of composites is solid, continuous with no delamination and cracks, which should be attributed to the chemical compatible of the two materials. The grain growth of ferroelectrics adjacent to the interface is different from
that far from the interface. It should attribute to Fe3+ diffused from the ferrite to ferroelectrics and soluted into the perovskite lattice. The difference factor dD is proposed to describe the microstructure difference between the interface and the inner parts.
The Structure and Optical Properties of Dy3+ Doped PLZT Ceramics
Authors: Zhang Yong , Ding Ai Li , Yin Qing Rui
Published: March 2009

The polycrystalline Dy3+ doped PLZT ceramics with compositional formula [Pb0.88
(La1-xDyx)0.12](Zr0.40Ti0.60)O3, were prepared by hot-pressed method. Effects of Dy3+ substitution on structural and optical properties were report here. All the samples have single phase with tetragonal structure, and the tetragonality was increased with content increased. As Dy3+ content increased, the optical transmission was found to decrease, and the refractive index was raised slightly.
Comparative Study on Microstructure of Pb(Mg1/3Nb2/3)O3-PbTiO3 Ceramics
Authors: Li Chun Hong , Li Qiang , Song Feng Bing
Published: March 2009

(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 ((1-x)PMN-xPT, PMN-PT) with composition near the morphotropic phase boundary (MPB) were prepared by the columbite precursor method and the rutile precursor method respectively. Attention has been focused on the influence of process on microstructure of PMN-PT ceramics. The results show that the average grain size of ceramics is insensitive to composition for both above processes. The refinement and homogeneity on grain size in the rutile precursor method is better than that in the columbite precursor method.
Evolution of Microstructures in a Low Carbon Bainitic Steel during Reheating
Authors: Wu Hui Bin , Yang Shan Wu , Yuan S.Q. , Shang Cheng Jia , Wang Xue Min , He Xin Lai
Published: March 2009

Cooled in water after isothermal relaxation of deformed austenite for different time, a
Nb-bearing microalloyed steel always exhibited synthetic microstructures of bainitic ferrite, granular bainite and acicular ferrite. When these samples were reheated to and held at 650°C or 700 °C, the non-equilibrious microstructures tended to evolve into equilibrious ones, accompanied by obvious change of hardness. The rate of microstructures evolution was closely related to relaxation time of deformed austenite. The sample relaxed for 60s displayed the highest thermal stability, while microstructure evolution was quickest in the sample relaxed for 1000s even though it was softest before reheating. By hardness measurement, it was found that softening was not only process occurring during reheating, in which hardness fluctuated with time. There were two peaks in hardness-time curve of each sample having undergone relaxation, while single peak occurred in the curve of the sample not being relaxed. These results indicate that thermal stability of microstructures is determined by their history of formation.
A Study on the Preparation of TiO2-xNx Films by Reactive Deposition and Their Absorption Properties in Visible Region
Authors: Zhao Ming , Zhuang Da Ming , Zhang Gong , Fang Ling , Wu Min Sheng
Published: March 2009

The nitrogen-doped TiO2 thin films were prepared by mid-frequency alternative reactive magnetron sputtering technique. The N concentration of the nitrogen-doped TiO2 thin films was analyzed by XPS. And the absorption spectra of the films in ultraviolet and visible region were also investigated. The results show that the mid-frequency alternative reactive magnetron sputtering technique is a convenient method for growing TiO2-xNx. Annealing the nitrogen-doped TiO2 thin film in nitrogen atmosphere under 380°C is helpful for increase the concentration of nitrogen in the film, but the ratio of N2 in reactive gas is mainly influence the concentration of nitrogen in the Ti-N bond in the TiO2 film. The increase of the thickness of nitrogen-doped TiO2 films will enhance the absorbability of the film in the ultraviolet and visible region. The wavelength of the absorption edge of TiO2-xNx film with 1.5% nitrogen shift to 441nm from 387nm, which is the absorption edge for undoped TiO2 films.
Fabrication of Ti3AlC2 Powder with High-Purity by Pressureless Sintering
Authors: Peng Chun Qing , Wang Chang An , Qi Liang , Huang Yong
Published: March 2009

In this work, a new method to fabricate high-purity Ti3AlC2 powder by pressureless
sintering (PLS) was reported through adding a little amount of B2O3 as a low-temperature aid. The elemental Ti, Al, and active carbon powders were used as raw materials with the molar ratio of 3 : 1.2 : 2. The effect of sintering temperature on the purity of Ti3AlC2 was investigated at the range of 800°C to 1400°C. The results showed that high-purity Ti3AlC2 powders, in which almost no TiC phase could be found, were stably fabricated by pressureless synthesis at 1400°C for 5 mins in flow
Ar atmosphere. The roles of B2O3 addition were discussed in the paper.
Joining of SiC Ceramic with Ternary Carbide Ti3SiC2
Authors: Dong Hongying , Han Wen Bo , Li Shu Jie
Published: March 2009

The investigation on joining of SiC to SiC has been conducted for some years. It is essential that the mechanical and thermal properties of the joints should meet the requirements of engineering. In view of the fact that the ternary carbide Ti3SiC2 has shown unique mechanical and thermal properties, it is promising to join SiC to SiC using ternary carbide Ti3SiC2 as filler (welding compound), and this is the subject to deal with in this paper. The joining of SiC to SiC has been successfully realized by hot pressing reaction joining process using Ti3SiC2 powder as filler. The
optimized technological parameters have been obtained by orthogonal experiments, under which the achieved weld strength is higher than that of the welding base material SiC ceramic. Ti3SiC2 is stable up to 1200oC in Ar atmosphere with an external pressure. At the joining temperatures of 1300～ 1600oC the main phases of the interface are Ti3SiC2, TiC and TiSi2. The mechanism of bonding at the interface is interdiffusion and chemical reaction.
Laminated Fabrication Ceramics by Aqueous Tape Casting Technology
Authors: Cui Xue Min , Zhou Ji , Huang Yong , Wang Chang An , Ouyang Shi Xi
Published: March 2009

A new method, which allowed lamination at room temperature without any additional
adhesive, was described in this paper. A low Tg styrene-acrylic latex binder was used to forming the green tape via a water-based slurry. The green tapes could adhere to each other at room temperature under low or slight pressure. The density and deformation of laminated green parts depended significantly on lamination pressure, but the density of green parts did not increase after the lamination pressure exceeded a specific value of 4MPa. The interface between the tapes had been investigated in the green and sintered state by SEM. The experimental results showed that the microstructure of interface and density of lamination ceramics was a function of fraction of binder, plasticizer, and laminated pressure.
Study on the Oxidation Behavior of Ca-α-SiAlON in an Air Stream
Authors: Dong Li Min , Wang Chen , Zan Qing Feng , Tian Jie Mo
Published: March 2009

The oxidation behavior of Ca-α-Sialon composites prepared by using the powders of
α-Si3N4, AlN, Al2O3 and CaCO3 as the starting materials has been studied, for the composition Ca0.8Si8.8Al3.2O16N14.4 in the temperature range of 1200 to 1400°C for 24 to 96h in an air stream. The bending strength and weight gain of the samples before and after oxidation experiment were measured, and the phases of surfaces of the samples were examined by XRD, the microstructures of sections and surfaces of the samples were observed by SEM. The results show that the weight gain increased and the bending strength decreased as the oxidation time increased, and the oxidation layers contained bar cristobalite and glass phase at 1200°C, bubbles and glass phase at 1300°C, transparent glassy film and the pores at 1400°C, the phases of oxidation layers consisted of cristobalite, CaAl2Si2O8, and glass phase.
High-Temperature Strength of Directionally Solidified Al2O3/YAG/ZrO2 Eutectic Composite
Authors: Murayama Yonosuke , Hanada Shuji , Lee Jong Ho , Yoshikawa Akira , Shimizu Kazutoshi , Nakagawa Narihito , Waku Yoshikawa , Fukuda Tsuguo
Published: March 2009

A2O3/YAG/ZrO2 eutectic Melt-Growth-Composites (MGCs) were unidirectionally solidified by the modified-pulling-down method (MPD) and the Bridgman type method, in which a crucible was brought down at different speeds. The microstructures and crystallographic textures were studied by field emission scanning electron microscopy (FE-SEM) and electron backscattered pattern (EBSP) method. The high-temperature strength was investigated by compression tests. All MGC rods show strong preferred growing orientation, although the structural size of eutectic microstructure among MGC rods was different. The high-temperature strength of MGC rods is dependent on orientation, compression temperature and strain rate. The high-temperature strength of MGC rods is controlled by the anisotropic strength of constituent Al2O3, as well as the structural size of eutectic microstructure.
Origin, Transformation and Control of the Inner Stress in the Green Bodies Prepared by Ceramic Colloidal Forming Processing
Authors: Zhang Li Ming , Ma Li Guo , Ma Tian , Yang Jin Long , Huang Yong
Published: March 2009

The origin of the inner stress in the ceramics green bodies prepared by colloidal forming was studied. The results show that the inner stress originates from the nonuniform shrinkage during the solidification of the precursor suspension and the drying of the green bodies, and the gradients of temperature, initiator concentration and moisture are the important original factors causing the inner stress. The inner stress could result in cracks in the green bodies during debinding.
Studies of Damage Accumulation in 4H Silicon Carbide by Ion-Channeling Techniques
Authors: Zhang Y. , Gao Fei , Jiang Weilin , McCready D.E. , Weber William J.
Published: March 2009

Single crystal 4H-SiC was irradiated with 2 MeV Au ions at 165 K. Ion-induced defect
configurations and damage accumulation were studied by ion-channeling techniques along the <0001>, > < 3 40 4 and > < 1 20 2 directions. A nonlinear dependence of damage accumulation is observed for both the Si and C sublattices along all three directions, and the relative disorder observed along the > < 3 40 4 and > < 1 20 2 directions is much higher than that along the <0001> direction. The damage accumulation can be described by a disorder accumulation model, which indicates that defect-stimulated amorphization is the primary amorphization mechanism in SiC, and the high disorder level for the large off-axis angles is attributed to particular defect configurations. Molecular dynamics (MD) simulations demonstrate that most single interstitial configurations are shielded by Si and C atoms on the lattice sites along the <0001> direction, which significantly reduces their contribution to the backscattering/reaction yield along the <0001> direction.
Defects and Ion-Solid Interactions in Silicon Carbide
Authors: Weber William J. , Gao Fei , Devanathan Ram , Jiang Weilin , Zhang Y.
Published: March 2009

Atomic-level simulations are used to determine defect production, cascade-overlap
effects, and defect migration energies in SiC. Energetic C and Si collision cascades primarily produce single interstitials, mono-vacancies, antisite defects, and small defect clusters, while amorphous clusters are produced within 25% of Au cascades. Cascade overlap results in defect stimulated cluster growth that drives the amorphization process. The good agreement of disordering behavior and changes in volume and elastic modulus obtained computationally and experimentally
provides atomic-level interpretation of experimentally observed features. Simulations indicate that close-pair recombination activation energies range from 0.24 to 0.38 eV, and long-range migration energies for interstitials and vacancies are determined.