bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface/Subsurface Damage of Yttria Partially Stabilized Zirconia in Grinding Using Monolayer Brazed Diamond Wheel
Authors: Li Shu Sheng , Xu Jiu Hua , Fu Yu Can , Su Hong Hua
Published: March 2010

A new brazed monolayer diamond grinding wheel is developed with the same continuous cutting edge distance on the wheel surface. Surface/subsurface damage of yttria partially stabilized zirconia (Y-PSZ) in grinding using monolayer brazed diamond wheel is analyzed. In this investigation, the influence of the maximum undeformed chip thickness (hm) on material removal mechanism is analyzed. The experiment results show that the ground surface is almost in ductile material removal mode when hm is below the critical value for Y-PSZ, otherwise it will be the combined removal modes of brittle and ductile when hm is above the critical value.
Effect of Anisotropy on Chemical Mechanical Polishing of LBO Crystal
Authors: Li Jun , Zhu Yong Wei , Zuo Dun Wen , Zhu Yong , Chen Chuang Tian
Published: March 2010

The anisotropy of LBO crystal leads to the different properties of different crystal faces, such as thermal expansion coefficient, which results in trouble of ultra-precision machining. Chemical mechanical polishing of a face (001), b face (010) and c face (001) of LBO crystal by adopting Logitech PM5 Precision Lapping & Polishing Machine in the same process conditions was investigated. The effect of anisotropy on MRR and surface roughness was studied. In the same CMP process conditions, c face of LBO crystal is the highest MRR, b face is inferior to and a face is the lowest. And surface roughness of c face is the best, b face is followed and a face is the worst. The results also show that the anisotropy leads to the different MRR and surface roughness on different crystal faces. In CMP of LBO crystal, the higher MRR is, and the better surface roughness is in the scope of experiment.
Path Segmentation Algorithm for Automatic Guided Vehicle Based on Machine Vision
Authors: Zhang Yuan , Wang Peng , Li Ji Xiang , Yin Shi Wei , Xin Jing Lei
Published: March 2010

A novel path segmentation algorithm for automatic guided vehicle is designed by machine vision technology. Firstly, wiener filter based on parameter estimate is used to restore path image in HIS model. Secondly, mutivariate stepwise fitted regression method is adopted to smooth guide line edge of path image. It can be concluded that path guide line of automatic guided vehicle under industry surrounding may be recognized accurately through this way.
Analysis of Cutting-Press Compound Shaping Fin Structure
Authors: Li Yan , Yuan Qi Long , Yang Ming Shun , Zheng Jian Ming
Published: March 2010

The cutting-press compound shaping technique is a green technology for manufacturing some functional surfaces such as fin-tubes. In practical application, different fin parameters and fin structures are required. Aiming to obtain different fin structures, the determination of the geometric parameters of the fins is discussed; according to the affects of the side cutting edge on the fin shapes, different fin structures under different side cutting edges are analyzed; which can provide guidance to obtain different fin structures under different applications.
Surface Roughness Model for Helical Milling of Die-Steel Based on Response Surface Methodology
Authors: Qin Xu Da , Hua Song , Ji Xiao Lai , Chen Shi Mao , Ni Wang Yang
Published: March 2010

Holes making process is widely applied in die steel machining, Helical milling a hole, also called orbital drill, is hole making process by milling in which the center of end mill orbits around the center of the hole while spinning on its axis and moving in the axial direction. The paper presents the secondary regression prediction model of the holes surface roughness for helical milling of die-steel. To minimize the number of experiments for the design parameters, response surface methodology (RSM) with orthogonal rotatable central composite design is used. By means of variance analyses and additional cutting experiments, the adequacy of this model is confirmed. The model will be helpful in selecting cutting conditions to meet surface finish requirements in helical milling operation.
Research of Gyroscopic Effects on the Stability of High Speed Milling
Authors: Xu Xi Qing , Tang Wei Xiao , Sun Shan Shan
Published: March 2010

High-speed milling (HSM) which is characterized as high productivity and low power consumption can be widely used in the manufacture industry. However, while the speed of spindle-tool reach the high speed range, the prediction of its stable milling faces more difficulties, as the gyroscopic effects become prominent. In this paper, a dynamics model of HSM system was set up considering the influence of gyroscopic moment due to high rotating speed of spindle-tool. Then a method was proposed by transforming time-varying stiffness system into fixed-step time invariant one. Finally the stability lobes diagrams (SLD) was elaborated. The results shows that the gyroscopic effects due to high rotating speed have non-negligible impact on the stability limitation, which must be considered for the predicting of stability limit in the high speed milling.
Research on High-Speed Preparation of Micro-Nanocrystalline Diamond Film
Authors: Xiang Bing Kun , Zuo Dun Wen , Li Duo Sheng , Chen Rong Fa , Wang Ming
Published: March 2010

Micro-nanocrystalline diamond (M-NCD) Film may be successfully prepared on Mo substrate with DC arc plasmas jet deposition device. This paper studies the influences of carbon source concentration on the shape of M-NCD Film particles under circumstances of stable electric arc, and characterizes the grain size and quality of samples through SEM, AFM and Raman spectrum. The research result shows that, in the state of stable electric arc, relatively low carbon source concentration (1%) could deposit high-quality microcrystalline diamond film on the substrate, with a growth rate of up to 8.3μm/h and grain size of about 2～4μm; relatively high carbon source concentration (10% or 15%) could deposit high-quality nanocrystalline diamond(NCD) film on the microcrystalline diamond film at high speed, with a growth rate of up to above 12.6μm/h or 19.7μm/h, grain size of about 4～80nm and average grain size of 27.4nm.
A Knowledge Management Method Based on Ontology for AP1000 Nuclear
Authors: Lin Lin , Zhang Yong Jian , Yin Lu
Published: March 2010

A knowledge management method for AP1000 nuclear is proposed. Based on the modularization characteristic of AP1000, the set of AP1000 ontology is created. Because the first nuclear power based on AP1000 is still being developed, the ontology model of AP1000 is hard to construct now. The particle swarm optimization is adopted to extract the relatively independent instance models from the complexity AP1000 instance model, which map into the conception models called basis ontology. In order to implement the comparison between two conceptions, using the idea of the DNA inheritance in a family, a similarity measure model of the conception is developed. By means of the general-special relation between the conceptions, the similarity measure model and the basis ontology, the knowledge retrieval for AP1000 is implemented.
Influence of Feed on Spiral Inner Grooves Formation with Ploughing
Authors: Tang Yong , Yuan Dong , Lu Long Sheng , Deng Da Xiang , Pan Min Qiang
Published: March 2010

Ploughing technology has been applied in manufacturing micro grooves on the outer surface of copper tube. In order to study the formation of spiral grooves on the inner surface of tube, a FEM model operated on DEFORM is established. Two ploughing processes are simulated. At first, an initial groove is manufactured on the workpiece, and then a nearby groove, which will influence the initial groove's geometry, is manufactured with twelve feeds separately. The groove's geometries, including groove width, inclined angle and fin height, are detected. Geometry comparison between the two grooves show that different feed results in different groove shape. According to the geometry change tendency of grooves, the feed can be divided into three different intervals.
Study on the Coated Tool Disability and the Work-Piece Surface Quality in High Speed Cutting
Authors: Xu Jin
Published: March 2010

The results of the experimental researches show that the high speed cutting tool is disabled in two modes of gradual wear and rapid breakage as HSC proceeds. Tool breakage occurs in low speed cutting. In process of HSC, the tool disability is the combination of flank face wear, boundary wear and cutting edge slope-plane wear. Under the action of the tool cutting movement, the ridges and furrows and burntthrough speckles and the molten metal daub phenomena come into being on the machined surface. With cutting speed increasing, it is weakened that tool wear has adverse effects on the forming of machined surface, and the workpiece surface quality is improved to a certain extent.
Effect of Discharge Parameters on Micro-Surface Topography of NAK80 by Mirror-Like Surface EDM
Authors: Wang Hong Jun , Zuo Dun Wen , Miao Hong , Wang Hong Feng , Wang Min
Published: March 2010

The effects of discharge parameters on micro-surface topography in mirror-like surface electrical discharge machining (EDM) process were investigated, and the optimization scheme was obtained. The realization of the process parameters and their effects were analyzed by the Taguchi method. The surface roughness amd 2D micro-surface topography were measured. An L16 (44×23) Taguchi standard orthogonal array was chosen for the design of experiments. The level of importance of the parameters parameters on surface roughness was determined by using analysis of variance (ANOVA). The experimental results confirmed that peak current and open discharge voltage have more influence on the surface roughness on mirror-like surface EDMed workpiece in comparison with pulse duration and pulse off-time.
Comparative Studies on the Cutting Performance of CVD Diamond and DLC Coated Inserts in Turning GFRP Composite Materials
Authors: Zhang Dong Can , Shen Bin , Sun Fang Hong , Chen Ming , Zhang Zhi Ming
Published: March 2010

The diamond and diamond-like carbon (DLC) films were deposited on the cobalt cemented tungsten carbide (WC-Co) cutting tools respectively adopting the hot filament chemical vapor deposition (HFCVD) technique and the vacuum arc discharge with a graphite cathode. The scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD) and Raman spectroscopy were used to characterize the as-deposited diamond and DLC films. To evaluate their cutting performance, comparative turning tests were conducted using the uncoated WC-Co and as-fabricated CVD diamond and DLC coated inserts, with glass fiber reinforced plastics (GFRP) composite materials as the workpiece. The research results exhibited that diamond and DLC coated inserts had great advantages in cutting tests compared to uncoated insert. The flank wear of the CVD diamond coated insert maintained a very low value about 50μm before the cutting tool failure occurred. For the DLC coated insert, its flank wear always maintained a nearly constant value of 70~200μm during whole 45 minutes turning process. The flank wear of CVD diamond coated insert was lower than that of DLC coated insert before diamond films peeling off.
Comprehensive Evaluation Analysis and Optimization Methodology of Tool Geometric Parameters for High Speed Cutting
Authors: Feng Ping Fa , Xu Dao Chun , Wu Zhi Jun , Yu Ding Wen
Published: March 2010

Tool geometric parameters, which are key factors to be considered in tool design, have a direct effect on tool cutting performance. Based on the diversity and complexity of geometric parameters and technological goals, we select cutting force and temperature as initial input conditions to build a comprehensive dimensionless tool geometric parameters evaluation method. According to the multilevel weight relationships between the technological goals and the basic cutting characteristics, the evaluation factors for cutting force and temperature are determined. The comprehensive evaluation method (CEM) is then applied to analyze and optimize the key parameters of a saw milling tool. As shown by the research results, the parameters obtained by the CEM prove that some tool parameters from actual production were reasonable, while others had re-optimized space. The CEM is shown to be effective and feasible. Also, the analysis results have an explicit guiding function for production practice.
Experimental Study on Chip Shape and Tool Wear of High-Speed and Micro-Feed Cutting
Authors: Xu Dao Chun , Feng Ping Fa , Yu Ding Wen , Wu Zhi Jun
Published: March 2010

With increasing spindle speed the cutting will be easy to enter into micro-feed cutting region. In the paper, the chip thickness and shape of high-speed and micro-feed cutting was researched in orthogonal milling. The cutting times in different fz was analyzed. We calculate the effective rake angle, friction angle and shear angle Furthermore, we measure cutting edge arc wear and tool flank wear of micro-feed cutting. Shown as the research results, the phenomenon of empty cutting and pure extrusion is very obvious as the feed rate per tooth is lower than 0.011mm/z. As the feed rate per tooth is lower than 0.005mm/z, the tool wear form is mainly cutting edge arc wear. As fz achieves 0.015mm/z, tool wear will decrease obviously and the tool appears the self-sharpening phenomenon.
Simulation Research on Elastic Constant and Natural Frequency of NCD Coated AFM Probes
Authors: Jiang Yan , Li Xiang Feng , Zuo Dun Wen , Yuan Jia Jing
Published: March 2010

In this work, the elastic constant and natural frequency of NCD and non-NCD coated AFM probes were simulated using ANSYS. The results indicated that after depositing 1～2μm thick NCD films on the silicon probes, the elastic constant and natural frequency were both increased, yet within the prescribed limit: when the cantilevers had the same total thicknesses (3μm, 3.5μm and 4μm), the elastic constant and the natural frequency of the NCD coated probes were increased by 96%～107% and 28%～30% respectively, compared with the silicon probes.
Study on Deposition of NCD on AFM Probe
Authors: Huang Ming Min , Zuo Dun Wen , Lu Wen Zhuang , Xu Feng , Wang Min
Published: March 2010

The performance of Atomic Force Microscope (AFM) is greatly determined by the quality of its probe. Nowadays, probes of diamond tips have become more and more popular than silicon ones, and have been widely used in industries. In this paper, research about the fabricating of nanocrystalline diamond (NCD) coated AFM probe has been done using Hot-Filament Chemical Vapour Deposition (HFCVD) technique. The results showed that NCD films have been grown on the probe. Problems about the growth of NCD on the tips have been discussed. The optimum parameters have also been proposed. This research can provide reference for the further experiments on the fabrication of NCD coated tips.
Microstructure and Mechanical Properties of Multi-Scale Titanium Diboride Matrix Nanocomposite Ceramic Tool Materials
Authors: Liu Han Lian , Huang Chuan Zhen , Xiao Shou Rong , Wang Hui , Hong Ming
Published: March 2010

Under the liquid-phase hot-pressing technique, the multi-scale titanium diboride matrix nanocomposite ceramic tool materials were fabricated by adding both micro-scale and nano-scale TiN particles into TiB2 with Ni and Mo as sintering aids. The effect of content of nano-scale TiN and sintering temperature on the microstructure and mechanical properties was studied. The result showed that flexural strength and fracture toughness of the composites increased first, and then decreased with an increase of the content of nano-scale TiN, while the Vickers hardness decreased with an increase of the content of nano-scale TiN. The optimal mechanical properties were flexural strength 742 MPa, fracture toughness 6.5 MPa•m1/2 and Vickers hardness 17GPa respectively. The intergranular and transgranular fracture mode were observed in the composites. The metal phase can cause ductility toughening and crack bridging, while crack deflection and transgranular fracture mode could be brought by micro-scale TiN and nano-scale TiN respectively.
Simulation of the Effect of Initial Grain Size of Matrix on Microstructure Evolution in Nano-Composite Ceramic Tool Material
Authors: Cheng Hong Mei , Huang Chuan Zhen , Liu Han Lian , Zou Bin , Li Y.
Published: March 2010

A new Monte Carlo Potts′ model for the sintering process of two-phase nano-composite ceramic materials with various grain size of initial matrix is set up. The grain growth process is successfully investigated assuming the green body is completely dense. The effect of the initial matrix grain size on microstructure evolution is observed and discussed quantitatively.
Fabrication and Characterization of NiCr/NiSi Functional Thin Films on Temperature Measurement of Cutter Sensor
Authors: Cui Yun Xian , Yang De Shun , Zeng Qi Yong , Sun Bao Yuan
Published: March 2010

NiCr/NiSi functional thin films of temperature measurement of cutter sensor were prepared by means of advanced Twinned microwave ECR plasma source enhanced Radio Frequency (RF) reaction non-balance magnetron sputtering technique. Fabrication technologies of NiCr/NiSi thin films were studied. The Compositions, micro-morphology, general structure and depth of NiCr/NiSi thin films were analyzed by means of Electron Probe, SEM, AFM, step profiler and stereo vision micro operation system. The results showed that NiCr/NiSi thin-films were small depth, uniform compact, smooth and good continuity, composition of which was close to target.
Milling Force Modeling for Ti-5Al-5Mo-5V-1Cr-1Fe Alloy
Authors: Zhang Guo Liang , Ming Wei Wei , Chen Ming , Han Bing , Rong Bin
Published: March 2010

With the development of aerospace, biomedical and chemical industries, titanium alloy Ti-5Al-5Mo-5V-1Cr-1Fe (TC18) is becoming widespread used. TC18 has even better mechanical property than Ti-6Al-4V (TC4). For better cutting TC18, simulation model was set up. PVD and CVD coated carbide inserts were used to machine titanium alloy TC18. The cutting forces were measured. Milling model was set up for the extraction of the cutting force coefficients and chip flow angle. Results were compared. All the coefficients of CVD coated carbide insert were found to be larger than those of PVD coated carbide insert. The model was proved to be reasonable after validation.
An Investigation of the Wear Mechanism for Carbide Tools in Face Milling the Ti-5Al-4.75Mo-4.75V-1Cr-1Fe Alloy
Authors: Zhang H.Z. , Ming Wei Wei , Chen Ming , Han Bing , Rong Bin , Liu Gang , Zhang Yun Shan
Published: March 2010

The α+2βtype Ti-5Al-4.75Mo-4.75V-1Cr-1Fe (TC18) is a very difficult machine material for its low thermal conductivity, low elastic modulus, and high chemical activity. So how to improve the machining efficiency and prolong the tool life have got more and more attentions. In this paper, wear mechanism and wear types of coated (TiN+TiAlN) carbide tool and uncoated carbide tool are presented when face milling the Ti-18 alloy under the same machining condition. The results showed that wear types of PVD coated tool are mainly adhesive, diffusion and crater wear, while the mainly failure mode of uncoated carbide tool is tipping. So it is more appropriate to select the PVD coated tool than uncoated tool in the milling TC18 alloy process.
Force and Temperature in Dry Cutting of Hardened W18Cr4V with PCBN
Authors: Wu Hai Rong , Huang Guo Qin , Xu Xi Peng
Published: March 2010

An experimental study was carried out to investigate the effects of cutting parameters on cutting force and temperature in cutting of hardened W18Cr4V with PCBN cutter. Three components of cutting force were recorded by a strain-gauge dynamometer and the cutting temperature was measured by a nature thermocouple of tool-workpiece. The cutting parameters were arranged by orthogonal method. It is shown that the cutting temperature increased with each of the three cutting parameters and the main effecting factor is feeding speed. The three components of cutting force increased greatly with an increase in feeding speed and cutting depth. But the forces decreased a little as cutting speed increased. The main and axial cutting forces depend mainly on cutting depth whereas the radius force is mainly influenced by feeding speed.
On a Kind of Applied Model Oriented Mechanical Assembly Process Simulation
Authors: Yan Jing , Xie Jian , Li J.P. , Zhang Dan , Zuo Dun Wen
Published: March 2010

A kind of model oriented assembly process simulation in WTK environment has been proposed. In the model, firstly, the assembly hierarchy of mechanical products can be presented clearly. Secondly, the assembly constraints between parts can be added to the model easily. At last, the assembly process information such as assembly sequence and path for each part can be recorded at real time in the model. Then, the converted method from PRO/E system to WTK environment about the mechanical product’s design information including geometric models, product design hierarchies and constraints has been discussed, which makes for easier building the model in the virtual environment.
A Kinematic Approach to Locating Error Analysis for Fixture Design
Authors: Qin Guo Hua , Lu Dong , Sun Shi Ping , Ye Hai Chao
Published: March 2010

In order that the required manufacturing processes can be carried out, fixtures are developed to locate and hold a workpiece firmly in the accurate position. However, source errors of fixtures can change the accurate position and in turn, cause the locating error. It follows that the evaluation of locating error is important to fixture design. Therefore, a general approach to the locating error analysis is formulated for the first time. Firstly, a kinematic model and its algorithm of the locating error are proposed to analyzing the linear dimension based on the velocity composition law of particle movement. In addition, according to the relationship between the linear velocity and angular velocity, another kinematic model and its algorithm of the locating error are also formulated to verifying the angular dimension.
Study on Mixed Assembly Modeling of Rigid and Flexible Parts for Aerospace Product Virtual Assembly
Authors: Zhang Dan , Zuo Dun Wen , Jiao Guang Ming , Xie Jian , Zhou Hua Lin , Chen Yi Liang
Published: March 2010

According to the characteristics of aerospace product, the model representation and storage of the rigid part and cable harness is proposed. The Dendritic Correlative Model of Mixed Assembly of Rigid and Flexible Parts (DCMMA-RFP) is introduced based on the hierarchical model and graph model. The assembly model which realizes the lightweight storage can clearly represent the hierarchy relation and assembly process of aerospace products. The assembly modeling process in the virtual assembly environment is detailed described. Finally the effectiveness of DCMMA-RFP is verified by an example.
Application of Piezoelectric Materials for Monitoring the Growth of Defects in Structures
Authors: Morikawa Sergio Ricardo Kokay , Lannes Daniel Pontes , Gama Antonio Lopes
Published: March 2010

This paper presents the results of an experimental investigation on the use of piezoelectric materials as a technique for monitoring the growth of defects in structures. The method consists of exciting the structure with piezoelectric actuators while recording the electromechanical responses from sensors placed close to the defect. The piezoelectric sensors detect the damage growth or an incipient defect by monitoring changes in the dynamic strain field, induced by the piezoelectric actuator, near the defect. This technique was evaluated through experiments using an aluminum frame structure. Results show that the piezoelectric active method is capable of detecting small changes in defect depth.
Microstructural Analysis and Tensile Properties of Squeeze Cast Al-7%Mg Alloy
Authors: De Brito Crystopher Cardoso , Magalhães Fabrício Dias , Costa André Luiz de Morais , Siqueira Cláudio Alves
Published: March 2010

Squeeze casting is one of the modern casting processes, which was invented to address these shortcomings and has a high potential to produce sound casting alloys. Magnesium Alloys are the lightest structural alloys commercially available and have great potential for applications in aerospace and automobile industries. In this article, the influence of pressure variation on the microstructure and defects formation in the Al-7%Mg alloy during squeeze casting process was studied. It was observed that a small external pressure of 20 MPa promoted structural refinement and a significant increasing in the ultimate tensile strength. This improvement in structure and properties is attributed to increasing in the cooling rate during squeezing.
Manufacture and Electro-Thermomechanical Characterization of a SMA Copper-Based Cylindrical Connector
Authors: Da Silva Niédson José , Silva Jobson Alberto , Dos Reis Rômulo Pierre Batista , Simões Jackson de Brito , de Araújo Carlos José
Published: March 2010

The relevant and unique thermomechanical properties of shape memory alloys (SMA) have motivated researches for applications in several fields of engineering. The pseudoelasticity and shape memory effect (SME) are some behaviors displayed by these functional materials. The aim of the current work is the manufacture, physical characterization and investigation of electro-thermomechanical response of a SMA copper-based cylindrical element aiming the development of a smart electrical connector. The cylindrical element was manufactured by plasma melting and injection molding of a CuAlNi based SMA. During thermal activation, the SMA cylindrical element presented satisfactory movement of closure through the recovery of its shape, demonstrating a strong potential to generate normal contact forces useful for electrical connections.
Characterization of 150mm in Diameter NiTi SMA Ingot Produced by Electron Beam Melting
Authors: Otubo Jorge , Antunes André da Silva
Published: March 2010

Earlier works showed that NiTi shape memory alloy production by electron beam melting (EBM) is a viable process in which its main characteristic is the low contamination by impurities such as carbon and oxygen. Some difficulties arise when compared to conventional vacuum induction melting (VIM) process such as composition control and complex machine operation. This work focus on the production of ever made large scale 150mm in diameter NiTi ingot produced by EBM showing its viability. The carbon contamination was only 0.016wt% compared to usual 0.05wt% of VIM process. The ingot radial composition homogeneity was proved by small variation presented by direct and reverse peak martensitic transformations temperatures which was around 2°C.
Precession Electron Diffraction Assisted Orientation Mapping in the Transmission Electron Microscope
Authors: Portillo Joaquim , Rauch Edgar F. , Nicolopoulos Stavros , Gemmi Mauro , Bultreys Daniel
Published: March 2010

Precession electron diffraction (PED) is a new promising technique for electron diffraction pattern collection under quasi-kinematical conditions (as in X-ray Diffraction), which enables “ab-initio” solving of crystalline structures of nanocrystals. The PED technique may be used in TEM instruments of voltages 100 to 400 kV and is an effective upgrade of the TEM instrument to a true electron diffractometer. The PED technique, when combined with fast electron diffraction acquisition and pattern matching software techniques, may also be used for the high magnification ultra-fast mapping of variable crystal orientations and phases, similarly to what is achieved with the Electron Backscattered Diffraction (EBSD) technique in Scanning Electron Microscopes (SEM) at lower magnifications and longer acquisition times.
Fe2O3 Thin Films Prepared by Ultrasonic Spray Pyrolysis
Authors: García-Lobato M.A. , Hernández-V A. , Hdz-García H.M. , Martinez Arturo I. , Pech-Canul M.I.
Published: March 2010

Fe2O3 thin films were obtained on glass substrates by the ultrasonic spray pyrolysis technique; additionally, a thermodynamic analysis on the Fe2O3 formation from different precursor salts was performed. In this work, the influence of the deposition temperature is related with the structural, optical, and morphological properties of the iron oxide films. The present results reveal that amorphous thin films are obtained at temperatures lower than 350° C, while polycrystalline films with the maghemite structure are formed at higher temperatures.
Structural and Morphological Properties of HfxZr1-xO2 Thin Films Prepared by Pechini Route
Authors: García-Cerda L.A. , Puente Urbina Bertha A. , Quevedo-López M.A. , Gnade B.E. , Baldenegro-Perez Leo A. , Alshareef Husam N. , Hernández-Landaverde Martin A.
Published: March 2010

In this study, HfxZr1-xO2 (0 < x < 1) thin films were deposited on silicon wafers using a dip-coating technique and by using a precursor solution prepared by the Pechini route. The effects of annealing temperature on the structure and morphological properties of the proposed films were investigated. HfxZr1-xO2 thin films with 1, 3 and 5 layers were annealed in air for 2 h at 600 and 800 °C and the structural and morphological properties studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results show that the films have monoclinic and tetragonal structure depending of the Hf and Zr concentration. SEM photographs show that all films consist of nanocrystalline grains with sizes in the range of 6 - 13 nm. The total film thickness is about 90 nm.
Extended Crystallographic Defects in Gallium Nitride
Authors: Rojas Dasilva Yadira Arroyo , Ruterana Piere , Lahourcade Lise , Monroy Eva , Nataf Gilles
Published: March 2010

In the fabrication GaN-based devices, several growth orientations are currently under investigation in order to exploit material properties which are inaccessible using layers grown along the c-axis. However, such procedures rely on foreign substrates with large misfits. Therefore, complex crystallographic defects form in the epitaxial layers and have been the subject of extensive studies. They include threading dislocations and stacking faults, which can be within basal or prismatic planes. Out of the c-axis, depending on the growth orientation, the glide planes of perfect dislocations may be no longer available, complicating the relaxation processes.
Electron and Atomic Force Microscopy of Electrochromic WO3 and Molybdenum Doped WO3 Thin Films Deposited by Pulsed Spray Pyrolysis
Authors: Acosta Dwight R. , Ortega Jesús  M. , Magaña Carlos R.
Published: March 2010

WO3/FTO/Glass and WO3:Mo/FTO/Glass thin films were deposited using the pulsed spray pyrolysis technique. The Molybdenum doped thin films were deposited using 2,4,6,8 and 10 % at . concentration in the starting solution. The influence of molybdenum concentration on the structural, electrical, optical and electrochromic properties of WO3:Mo thin films have been systematically studied using Scanning Electron Microscopy (SEM), Selected Area Diffraction Patterns (SAED) in Conventional Transmission Electron Microscopy (CTEM), High Resolution Electron Microscopy (HREM) and Atomic Force Microscopy (AFM). The electrochemical behavior of our materials was studied using cyclic voltammetry both to induce electrochromic behavior and to characterize the electric charge injection and extraction processes. It was found that samples with 2% at. of molybdenum concentration in the starting solution, show the best electrochromic behavior with the highest efficiency and durability. The influence of structural details in our films and their evolution with the molybdenum incorporation, for a fixed substrate temperature on the electrochromic properties of our WO3:Mo thin films has been followed wherever possible.
Morphologic Modification in ABS by the Incorporation “in Situ” of Nano-ZnO: Study of the Effect on Characteristics and Final Properties
Authors: Díaz de León Ramón , Betancourt-Galindo Rebeca , Puente Urbina Bertha A. , Acuña Pablo , Falcón Luís
Published: March 2010

The synthesis of poly(acrylonitrile-butadiene-styrene) (ABS) was carried out using the mass-suspension process, high cis polybutadiene (PB), benzoyl peroxide (BPO) as the initiator and modified and unmodified nanoparticles of zinc oxide (nano-ZnO). X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were used to characterize the ZnO nanoparticles. A Universal tensiometer, Brokfield viscosimeter and transmission electronic microscopy (TEM) were used to characterize ABS. The employment of nano-ZnO induced an impressive morphologic modification and transformed the highly occluded salame morphology of poly(styrene-acrylonitrile) (SAN) to a highly dispersed one in its matrix. During the reaction, a decrease in the total production of SAN was observed due to the interaction between radicals produced by the initiator and nano-ZnO, causing a molecular weight increase of SAN. The nano-ZnO also induced a decline in the phase inversion and extended the period of occurrence. ABS without nano-ZnO yielded higher mechanical properties than one without any nanoparticles.
Synthesis and Characterization of Magnetic Polyurethane Nanocomposite Foams
Authors: Cámara-Hinojosa Alma , Bueno-Baqués Darío , Rodríguez-Fernández Oliverio S. , Ziolo Ronald F.
Published: March 2010

New magnetic polyurethane nanocomposite foams have been synthesized by the one-shot method. The opened-cell soft foams contain a dispersion of uniformly sized nanocrystalline iron oxide prepared ex situ by the high temperature thermal decomposition of iron acetylacetonate in phenyl ether in the presence of oleic acid. The magnetic particles were dispersed in polyol by sonication prior to the reaction of the latter with isocyanate to produce the magnetic foams. A 7 wt% loading of iron oxide yielded a soft, flexible foam with a room temperature magnetization of 3.5 emu/g at one Tesla. Higher loadings of iron oxide are possible without destruction of the soft open-cell polyurethane structure. Physicochemical characterization of the foams will be presented along with magnetic and mechanical properties. Potential applications include smart materials such as magnetic shape memory foams, adhesive-free metal to foam seals, inductively coupled thermal foams and applications for conformable foams having a magnetic component such as healthcare products.
Iron Oxide Nanoparticles Obtained from a Fe(II) - Chitosan Polymer Film
Authors: Luna Martínez Juan Fco , Reyes-Melo E. , González-González Virgilio , Torres-Castro A. , Guerrero-Salazar Carlos , Sepúlveda-Guzmán Selene
Published: March 2010

In this work, iron oxide nanoparticles (~5 nm) embedded in a chitosan polymer film, were synthesized. In order to obtain this nanostructured material, firstly a homogenous film of Fe(II)-chitosan was prepared. The resulting composite film has a thickness of ~140μm. Iron oxide nanoparticles were in-situ synthesized by treating the composite film with H2O2 under alkaline conditions. The morphological analysis by Transmission Electron Microscopy (TEM) shows the nanoparticles were embedded and stabilized in chitosan polymer film. The magnetic behavior was studied by magnetization measurements. The magnetization curves at room temperature showed that iron oxide nanoparticles have a superparamagnetic behavior.
Surface Modification of ZnO Nanoparticles
Authors: Betancourt-Galindo Rebeca , Berlanga Duarte M.L. , Puente Urbina Bertha A. , Rodríguez-Fernández Oliverio S. , Sánchez-Valdés Saul
Published: March 2010

The synthesis and surface modification of ZnO nanoparticles, achieved through a controlled precipitation reaction using NaOH as precipitating agent with a 0.2 molar ratio were studied. The surface modification was carried out through a chemical hydrolysis reaction at 80°C for 6 h, in order to promote better adhesion between inorganic particles and a polymer matrix when they were used in composite materials. Both 3-aminopropyltrimethoxysilane (APTMS) and difunctional alcohol spiroorthocarbonate (SOC DIOL) were used as modifying agents in a 0.5:1 ratio with respect to ZnO nanoparticles. According to x-ray diffraction (XRD), electron transmission microscopy with scanning modulus (STEM) and infrared spectroscopy (FTIR), the ZnO crystalline structure did not change after treatment. Surface modification was performed in order to subsequently use ZnO nanoparticles in medical antimicrobial devices.
Topographical Characterization of Electrodeposited Nickel Nanoparticles on an Indium Tin Oxide on Glass Thin Film
Authors: Martinez Gerardo T. , Zavala Genaro , Videa Marcelo
Published: March 2010

Topographical characterization of electrodeposited nickel nanoparticles was carried out by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The particles showed a hemispherical growth, typical from a Volmer-Weber growth mechanism. However, they presented different morphology and crystallization types under similar electrochemical conditions. Preferential growth on determined sites on the substrate surface at different electrochemical conditions was also studied, showing that the particle growth strongly depends on the competition of different electrochemical processes, such as Hydrogen Evolution Reaction (HER), which are promoted preferably by the pulse intensity.
Analysis of Nanocrystalline Intermetallic Compounds from their X-Ray Diffraction Patterns
Authors: Rojas-Chávez H. , Reyes-Carmona Fidel , Plascencia Gabriel , Jaramillo-Vigueras D.
Published: March 2010

Synthesis of intermetallic PbSe induced by high-energy ball milling has been studied.
Systematic analysis of transformation in the resulting phases of milling from 0 to 10 h has been traced by characterizing the microstructures in terms of morphology, crystallite size, and percentages of phases formed as a function of milling time. Results reveal the formation of two phases. Where the system of PbO-Se transforms gradually to PbSe. Complete transformation is achieved after 10 h of milling time. Study of particle structure by the Rietveld Method further corroborates the value of the nano-order crystallite diameters as evaluated from the microscopic studies.
Study on the Microstructure and Electrical Properties of Pb(Zr0.53 Ti0.47)O3 Thin-Films
Authors: Baldenegro-Perez Leo A. , Debray-Mechtaly Wardia , Fuentes-Fernandez E. , Quevedo-López M.A. , Alshareef Husam N. , Shah Pradeep , Gnade B.E.
Published: March 2010

In the present study a complete analysis of the morphological and electrical properties of PZT layers with composition 53Zr-47Ti is presented. Three different samples composed of 3, 6, and 9 PZT layers were analyzed on a substrate consisting of ZrO2-SiO2-Si structures. The PZT and ZrO2 layers were deposited via Sol-Gel, whereas the SiO2 layer, on every sample, was deposited via PECVD. SEM results showed morphology of very small granules on the 3 layered thin-film samples (12 nm), on the 6 layered thin-film samples a mixture of small and large size (100-300 nm) granule formation was observed, with the 9 layered thin-film samples exhibiting very large granule sizes (bigger than 300 nm). XRD results showed that increasing the number of deposited layers caused an incremental increase on the detected peak intensities, aided in the promotion of the perovskite phase, and diminished the presence of the pyrochlore phase. It was also observed, during electrical measurements, that increasing the number deposited layers directly increased the overall capacitance of the thin-film structure. This effect was attributed primarily to the large amount of perovskite and large size of grains presented on thick samples.
Search for Ultrahard Materials and Recent Progress in the Understanding of Hardness Enhancement and Properties of Nanocomposites
Authors: Veprek Stan , Zhang Rui Feng , Veprek-Heijman Maritza G. J. , Sheng Shu Hong , Argon Ali S.
Published: March 2010

The recent attempts to design new super- and ultrahard materials concentrate predominantly on those with high elastic moduli. This approach neglects the fact that elastic moduli describe the reversible, elastic response to small strain near equilibrium, whereas hardness is related to plastic deformation, the measurement of which involves substantial plastic strain, where the electronic structure becomes strongly distorted and can often result in structural transformations to softer phases. In the superhard nanocomposites consisting of 3-4 nm size randomly oriented nanocrystals of hard transition metal nitrides joined together by about one monolayer of silicon nitride variant, which is strengthened by negative charge transfer, the nanocrystals are free of defects and therefore reach ideal strength. Because of the strengthening of the interface and of the random orientation of the nanocrystals, these nanocomposites reach hardness of more than 100 GPa as shown experimentally. We provide a simple theoretical explanation why these materials can exceed the hardness of diamond, and outline a possible way how to design new nanocomposites with even higher hardness when reduction of Friedel oscillations of the valence charge density, which weaken the strength of the transition metal nitride, can be accomplished.
Mathematical Modelling the Power Supply-Load System for Electro-Discharge Polishing Process
Authors: Parshuta A. , Chitanov V. , Kolaklieva Lilyana , Kakanakov Roumen
Published: March 2010

The real electro-discharge polishing (EDP) system has been presented by an equivalent electrical scheme and described by a corresponded equation system. The Runge-Kutta-Merson method with automatically changed step is used for the numerical solution the equation system. The current through the resistor equivalent to the steam gas wrapper is defined with an I-V characteristic obtained by the method of multi-interval quadratic interpolation-approximation. A mathematical model of the power supply-load system has been realized in Basic and Matlab® languages. On the base of the developed modelling conditions limiting the current and voltage overload in the EDP system have been determined depending on the maximum polished area and the electrolyte temperature.
The Influence of Quartz Resonator Design and Thin Metal Oxide Layers on QCM Parameters
Authors: Raicheva Z. , Georgieva V. , Spassov L. , Gadjanova V. , Vergov L. , Angelov T. , Atanassov M. , Lazarov Y.
Published: March 2010

Quartz resonators and thin metal oxide sorption layers are the main elements of quartz crystal microbalances (QCM). Quartz resonators, AT cut with basic frequency of 16 MHz, dynamic resistivity below 20 Ω and quality factor around 50 000 have been developed. Thin layers of SnO2 and MoO3 are used as sensing films. The influence of sorption layers on quartz resonator parameters with different electrode configurations is studied. The change of the spectral characteristics and dynamic parameters is traced. Quartz resonators with SnO2 and MoO3 (200 nm) sensitive layers are investigated at NH3 concentrations from 10 ppm to 1000 ppm. Quartz resonators with Au electrodes (with a diameter 3, 4 and 5 mm) are compared. At both sorption layers the highest sensitivity corresponds to quartz resonators with Au electrodes with a diameter of 4 mm. The fabricated structures can be used as sensor elements in QCM.
Thickness Dependence of Surface and Interface Phonon-Polariton Modes in InN/AlN Nanolayers
Authors: Valcheva Evgenia , Baleva Mitra , Zlateva G.
Published: March 2010

We study the conditions for appearance and observation of surface and interface phonon-polariton (SPP and IPP) modes in thin InN layers grown on sapphire using AlN buffer. Theoretical dispersion relations of the IPP modes in the system air/InN/AlN/sapphire for different thickness of the InN layer are obtained. Features in the experimentally measured infrared reflectance were associated with the appearance of interface phonon-polariton excitations at wave-numbers between the TO and LO modes.
Texture/Stress Characteristics of Microstructure Used in Interpreting Deformation Effects of Ti Subjected to ECAP Process
Authors: Bonarski Jan T. , Alexandrov Igor V. , Sitdikov Vil D. , Tarkowski Leszek , Grzonka J. , Bieda-Niemiec M.
Published: March 2010

The common feature of the technologies, such as the equal channel angular pressing (ECAP) is the use of a changeable deformation path, which changes the configuration (value and direction) of the acting forces that impose various directions of plastic flow. The changes destabilize a temporary dislocation structure as well as the spatial distribution of the areas with elevated elastic energy cumulated in deformed lattice.
The application of that technique results in a potentially large deformation (up to several hundred percent) and plasticity of materials considered to be brittle at ambient temperature. The microstructure effects accompanied with intensive and large deformation are reflected in the space orientation of grains (crystallographic texture) as well as in the configuration of the residual stresses existing in deformed material.
The presented results based on experimental data registered by X-ray diffraction and TEM techniques are helpful in interpreting deformation mechanisms operating in the bend-zone of the ECAP tool during processing Ti-ingot by the mentioned method of severe plastic deformation.
Influence of the Cold Rolling Reduction on the Texture Development and r-Value Anisotropy in Ti-Stabilized 18% Cr Ferritic Stainless Steel
Authors: Jung I. , Chae D. , De Cooman Bruno C.
Published: March 2010

Ti stabilized AISI 439 type 18% Cr ferritic stainless steel offers an attractive alternative for replacing Ni-containing austenitic steels. The influence of the cold rolling reduction on texture development and the planar anisotropy of Ti-stabilized 18% Cr ferritic stainless steel have been studied in order to find an optimized processing route to obtain improved formability properties. In the present study, both annealed and un-annealed hot strips were given different cold rolling reductions up to 86%, and recrystallization annealed. The recrystallization texture was analyzed by means of XRD. Tensile tests were carried out on cold rolled and annealed samples oriented in seven different directions to the rolling direction to evaluate the planar anisotropy in detail. The mean normal anisotropy rm increased with increasing cold reduction for both annealed hot band and un-annealed hot band. The planar anisotropy revealed a behavior related to the development of the recrystallization texture component in the annealed hot band and the texture component in the un-annealed hot band, with increasing cold reduction.
Texture Gradients in Shot Peened Ti-2.5Cu
Authors: Maawad Emad , Brokmeier Heinz Günter , Wagner Lothar
Published: March 2010

Shot peening is a mechanical surface treatment having a deep impact on the materials which generates beneficial near-surface plastic deformation resulting in changes in peening texture characteristics. The present study aims to investigate the texture gradients in the solution treated (SHT) Ti-2.5Cu after shot peening with Almen intensity of 0.20 mmA. Due to a high transmission and a large beam cross-section of neutrons, texture analysis by neutron diffraction has become the standard method to investigate bulk textures. In contrary, the penetration depth of conventional X-rays is a relatively smaller than that of neutrons. Therefore, it is able to measure texture gradients in some hundred microns from the surface.
Improved Plastic Anisotropy in Asymmetrically Rolled 6xxx Alloy
Authors: Sidor Jurij J. , Petrov Roumen H. , Kestens Leo
Published: March 2010

Formability, which is the property that characterizes the ability of a material to be deformed without fracture or necking, is strongly correlated to the crystallographic texture. Al alloys from the 6xxx series with non-conventional textures were produced by hot and cold asymmetric rolling processes. The plastic responses i.e. the formability of differently textured samples are characterized based on crystal plasticity modeling.