bluuebunny/crossref_metadata_2025 huggingface dataset:
Solving Frictional Contact Problems within the Bipotential Framework
Authors: Boudaia El Hassan , Bousshine Lahbib , Chaaba Ali
Published: January 2012

The main objective of this paper is to present a theoretical and numerical analysis of frictional contact problems for large deformation elasto-plastic based on the finite element method (FEM) and the mathematical programming. The study is done on an elasto-plastic material obeying to the von Mises criterion. The Coulomb’s friction contact is used to implement the frictional boundary conditions and is formulated by the bipotential concept leading us to minimize only one variational principle of minimum in displacement. In order to follow up the sequences of large deformations, we have used the sequential analysis procedure; it consists in the updating of material properties and geometrical configuration after each sequence.
Finite Element Data Reduction Based Energy Release Rate for Delamination Tests
Authors: Choukri S. , Karama Moussa
Published: January 2012

This paper deals with the advantages of the finite element modeling and design, especially, of delamination test coupons involved in fracture analysis of laminated composite plates. This is shown through two relevant aspects in delamination toughness measuring, say: data reduction and Iso-G delamination front design. Many experimental data reductions are based on beam theories and thus assumes straight delamination front during propagation, which is not true when investigating laminates with general anisotropy. Another aspect is also emphasized, and concern test procedure simplification to avoid displacement measurements. This is done through a direct energy release rate calculations via the crack closure integral method.
Characterization and Comparison of Defects Detection Limits of Ultrasonic Non Destructive Techniques
Authors: Péronnet Elodie , Eyma Florent , Welemane Hélène , Mistou Sébastien
Published: January 2012

This work deals with the Liquid Resin Infusion (LRI) process developed within the research program “FUSelage COMPosite” of DAHER SOCATA. This manufacturing process enables the realization of complex composite structures or fuselage elements in a single phase (mono-material), which considerably reduce connections and relative difficulties. The concern here is the investigation of non destructive testing (NDT) methods that can be applied to LRI-structures in order to define their capacities for defect detection, and especially their associated critical defect size. In aviation industry, the AITM standards require the ultrasonic testing as NDT for composite materials. Therefore the aim of this work is to characterize and compare three different and complementary ultrasonic techniques on composite specimens. Such analysis allows to define the NDT application field of each method in term of defect detection.
Tribological Behaviour of Stellite Matrix Composites for High Temperatures Applications
Authors: Delbé Karl , Orozco Gomez Solisabel , Carrillo Mancuso Juan Manuel , Paris Jean Yves , Denape Jean
Published: January 2012

Extreme working conditions affect material used as friction components in transportation field: they rapidly reach their limits and critical parts require to be regularly replaced. Alternative solutions withstanding higher operating conditions imply to find innovative materials. Stellite matrix composites including various solid lubricants, WS2 and h-BN, able to admitextreme conditions were developed using a Spark Plasma Sintering technique, which makes possible the formation of new microstructures out of reach by conventional means. Sliding tests were conducted using a pin-on-disc tribometer in air at 450°C, with a velocity of 0,25 m/s and various normal load ranged from 2.5 to 40 N. Influence of solid lubricant content and sensitivity to test parameters were studied in terms of friction and wear responses of the contacting materials. Friction properties are equivalent to Stellite ones and sometimes lesseffective. A reduction of wear is quantified for many composites, and the best behavior is observed for those that contain WS2. In agreement with the third body approach, interpretations are proposed to describe the interphase dynamics within the contact.
Mechanical Properties of Al2O3-TiN Nanocomposite Ceramic Tool Materials
Authors: Fei Yu Huan , Huang Chuan Zhen , Liu Han Lian , Zou Bin
Published: January 2012

Al2O3-TiN nanocomposite ceramic tool materials were fabricated by hot-pressing technique and the mechanical properties were measured. Mechanical properties such as room temperature flexural strength, Vickers hardness and fracture toughness were measured through three-point bending test and Vickers indentation. The effects of the content of nano-scale TiN, sintering temperature and holding time on the mechanical properties were investigated. The results shows that the addition of nano-scale TiN can improve the mechanical properties of alumina ceramics. Both the flexural strength and the fracture toughness first increased then decreased with an increment in the content of nano-scale TiN. Both the Vickers hardness and the fracture toughness increased with an increment in the sintering temperature. The flexural strength increased with an increment in the holding time, while the fracture toughness decreased with an increment in the holding time. The composites with only nano-scale TiN have the highest Vickers hardness for the holding time of 30min, while the hardness of the composites with nano-scale TiN and micro-scale TiN decreased with an increment in the holding time.
Numerical Simulation on Temperature Field in Multi-Layers Inside-Beam Powder Feeding when Laser Cladding
Authors: Wang Ming Di , Shi Shi Hong , Liu X.B. , Song Cheng Fa , Sun Li Ning
Published: January 2012

Numerical simulation of laser cladding is the main research topics for many universities and academes, but all researchers used the Gaussian laser light source. Due to using inside-beam powder feeding for laser cladding, the laser is dispersed by the cone-shaped mirror, and then be focused by the annular mirror, the laser can be assumed as the light source of uniform intensity.In this paper,the temperature of powder during landing selected as the initial conditions, and adopting the life-and-death unit method, the moving point heat source and the uniform heat source are realized. In the thickness direction, using the small melt layer stacking method, a finite element model has been established, and layer unit is acted layer by layer, then a virtual reality laser cladding manu-facturing process is simulated. Calculated results show that the surface temperature of the cladding layer depends on the laser scanning speed, powder feed rate, defocus distance. As cladding layers increases, due to the heat conduction into the base too late, bath temperature will gradually increase. The highest temperature is not at the laser beam, but at the later point of the laser beam. In the clad-ding process, the temperature cooling rate of the cladding layer in high temperature section is great, and in the low-temperature, cooling rate is relatively small. These conclusions are also similar with the normal laser cladding. Finally, some experiments validate the simulation results. The trends of simulating temperature are fit to the actual temperature, and the temperature gradient can also ex-plain the actual shape of cross-section.
Processing and Characterization of an Al2O3/TiCN Micro-Nano-Composite Graded Ceramic Tool Material
Authors: Gao Z.J. , Zhao Jun , Zheng Guang Ming
Published: January 2012

In this study, an Al2O3-based functionally graded ceramic tool material reinforced with TiCN micro-particles and nano-Al2O3 particles was fabricated by using hot-pressing technique. The experimental results showed that optimal mechanical properties were achieved for the composite with the addition of nano-Al2O3 particles increasing from 10vol.% in the surface to 20vol.% in the core, with the flexural strength, fracture toughness and Vicker’s hardness being 1073MPa, 5.99MPa.m1/2 and 21.78GPa, respectively. The microstructure and phase composition of the composites were characterized with SEM, TEM and XRD. It is believed that addition of nano-Al2O3 increasing from the surface to the core, which developed an nano-particles-rich tougher core and a hard Al2O3/TiCN-rich surface, improved the integrated mechanical properties of micro-nano-composite graded ceramic material.
Research of CBN Film and its Application Prospect on Cutting Tool
Authors: Qing Zhen Hua , Zuo Dun Wen , Zhang X.H. , Xu F. , Zheng L.
Published: January 2012

Tool material has been one of the focuses in tool research. Diamond and cubic boron nitride (c-BN) are materials of exceptional and very similar properties that make them extremely valuable not only for the aesthetics of diamond. C-BN is a material synthesized rather recently that has rapidly spurred technological and scientific interest. Presently, both materials have found commercial applications. There is still a long way for the practical application of cBN film. The main problems are such as adhesion, thickness, purity, nucleating, and growth mechanism. We will develop a new way of DC plasma jet CVD way to synthesis the cBN film. The deposition of cBN films can be performed in a DC jet plasma CVD reactor by using an Ar-N2-BF3-H2 gas mixture, on the basis of deposition of diamond has been achieved.
Study on Drilling Tools for Ti/Carbon Fibre Interlaminated Composites
Authors: Shi Run Ping , Wang Cheng Yong , Bai X.M. , Gao L.M.
Published: January 2012

There are some defects such as delamination and tools chipping etc. in drilling Ti/Carbon fibre interlaminated composites. To look for countermeasures, a special drill is developed considering tool material, geometry, coatings, cutting edge strengthening and drilling technology. The drill is comparable with imported tools as far as holes quality, efficiency and life are concerned. It is highly appreciated by customers.
Study on the Mechanism of Diamond Wear in Precision Cutting of Isotropic Pyrolytic Graphite
Authors: Wang M.H. , Wang W. , Huang S.T. , Sun Yue
Published: January 2012

Isotropic pyrolytic graphite is a kind of graphite material. Because of its excellent performance, it is gradually used in aero-engine turbine shaft seals. But this material is a kind of brittle material, and it wears seriously during the cutting process. Through analysis of the process of cutting this material with PCD insert, the main wear region and the wear pattern at different cutting time were obtained. Using the scanning electron microscopy to observe the wear regions, the wear mechanism of PCD was obtained. At the first stage of the wear mechanisms were mainly mechanical wear and abrasive wear, the main wear regions were rake face and the cutting edge. With the increase of cutting distance, about 32 min later, both the depth of the crater on the rake face and the depth of micro grooves on the flank face were increased. Abrasive wear on the cutting face and the micro grooves wear on the flank face were the main wear pattern at the stable wear stage. At rapid wear stage, cutting edge was transformed from micro chipping into tool tipping. This caused by erosion wear .Experimental results indicated that the wear pattern was typical mechanical wear, abrasive wear, cutting edge erosion wear and possible adhesive wear.
Surface Modification of Secondary Battery Separator by Hollow Cathode Remote Plasma Polymerization
Authors: Wen Yi Fang , Li Zhi Hu , Chen Xin , Li De Cheng , Rui Yan Nian , Wang Hong Wei
Published: January 2012

In this paper, the surface of non-woven polypropylene secondary battery separator was modified by Hollow Cathode Remote Plasma. The effects of treating parameters on separator’s properties were studied. The IR and SEM were used to analyze the chemical composition and the surface morphology. Using electrical chemical property measurement, the electrical chemical property was measured and analyzed. The results show that the hydrophilic group was imported on the surface of polypropylene after Hollow Cathode Remote Plasma modification, so that the wettability of the non-woven polypropylene secondary battery separator and the property of secondary battery were greatly improved.
Wear Mechanisms of Coated Carbide Tools in Dry Boring of Titanium Alloys
Authors: Zhang Zong Yang , Liu Zhan Qiang , Ai Xing , Wang B.L.
Published: January 2012

This paper deals with an experimental research on the wear mechanism of coated carbide tools in dry boring of the titanium alloys TC11 which are commonly used for aero-engines. The wear mechanism of coated tool inserts was investigated at various combinations of cutting speed, feed rate, and depth of cut. Analysis carried out with the SEM suggests that adhesive wear and coating delamination are the dominant wear mechanisms under low speed and feed rate and depth of cut; while chipping and breakage are the dominant wear mechanisms for the combinations of high cutting speed, feed rate, and depth of cut. There was no observation of oxygen existing based on the analysis of SEM which indicated no oxidation wear generated during the boring machining. The excellent chemical stability of TiAlN coating and oxidation resistance performance made contribution to prevent oxidation wear. Another reason was that boring temperature was lower than oxidation temperature.
Comparative Study on Helical Milling and Drilling of Ti-6Al-4V
Authors: Qin Xu Da , Sun Xiao Tai , Wang Q. , Chen S.M. , Li H.
Published: January 2012

Helical milling is a 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 feeding in the axial direction. This paper makes a comparison between drilling and helical milling in cutting forces, hole quality and tool wear through a series of experiments. The results show that the axial cutting force of helical milling is far less than that of drilling and the holes quality is also better than traditional drilling. Cutting tools show excellent machinability in helical milling.
Cutting Forces and Tool Wear in Intermittent Turning Processes with Al2O3-Based Ceramic Tools
Authors: Cui Xiao Bing , Zhao Jun , Zhou Yong Hui , Pei Z.Q.
Published: January 2012

Orthogonal and single factor intermittent turning experiments of hardened AISI 1045 steel were conducted with two kinds of Al2O3-(W, Ti)C ceramic tools used, aiming to reveal the effects of cutting parameters on cutting forces, the influence of mechanical and thermal loads on tool wear mechanisms at different wear evolution stages. Empirical formulas for average cutting forces and tool lives (impact number of tools under two different flank wear limits 0.1 mm and 0.3 mm) were established respectively. The worn or fractured surfaces of the tools tested at different cutting speeds were analyzed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). It is found that feed rate and depth of cut had greater influence on the average cutting forces in cutting periods than cutting speed did. The amplitude of the vibration generated in the radial direction decreased with increasing cutting speed, while that of the vibration generated in the other two directions increased. The influences of mechanical and thermal loads on tool wear changed in different ways at different stages of tool wear evolution process. There existed critical cutting speeds above which adhesive wear of the ceramic cutting tools became less serious.
Effect of Milling Speed and Feed on Surface Residual Stress of 7050-T7451 Aluminum Alloy
Authors: Li C. , Wan Yi , Zhang R.R. , Liu Zhan Qiang
Published: January 2012

The residual stress in the milling of 7050-T7451 aluminum alloy was measured using X-ray diffraction method in which Psi-oscillation, Phi-oscillation and peak fit were adopted. Cutting speed and feed are main variables which were considered in this study. The results show that compressive residual stresses are generated in surface for the down milling generally, which is mainly due to burnishing effect between the tools flank face and the machined surface. In feed and its orthogonal direction, the effect of cutting speed and feed speed on residual stress is similar. Therefore, required residual stress can be achieved by controlling the cutting condition such as cutting speed, feed speed etc.
Experimental Investigation on Surface Roughness of KDP Crystal Pro-Cessed with Rotary Ultrasonic Face Milling
Authors: Zhang Cheng Long , Feng Ping Fa , Wu Z.J. , Yu Ding Wen
Published: January 2012

KDP crystal is a good nonlinear optical and electro-optical crystal material. However, KDP crystal is considered to be one of the most difficult machining materials due to its inherent properties. This paper presents a preliminary experimental study on surface roughness of KDP crystal processed with rotary ultrasonic face milling. The study shows that the process variables (spindle speed, feedrate, and milling depth) have significant influence on the surface roughness in processing KDP crystal. It discusses the effects of the mechanical properties of KDP crystal on the processing performance. The experimental investigation reveals that the rotary ultrasonic face milling method can obtain smoother surface, which means the method is available for processing KDP crystals with a proper machining conditions. This preliminary research affords a guiding significance for precision processing KDP crystals.
Manufacturing Process and Geometric Model of Porous Metal Fiber Sintered Felts
Authors: Zhou Wei , Song R. , Tang Y. , Wan Z.P. , Liu B.
Published: January 2012

Using the designed multi-tooth tool, a novel porous metal fiber sintered felt (PMFSF) with three-dimensional reticulated structure has been produced by solid-state sintering of copper fibers. The copper fibers were fabricated using the cutting method. According to the SEM results, it was found that there were two kinds of sintering joints of surface contact and crossing fiber meshing among the fibers in the PMFSF. The coarser sintering joints will help to enhance the mechanical strength of PMFSF. Based on the structure characteristic, a three-dimensional model with the cubic pore cell structure was established to describe the structure of PMFSF. In addition, the effectiveness of geometric model was verified by the test results of specific surface area of PMFSF.
Research of Distribution and Dynamic Characteristic of Particle Group in the Structural Flow Passage
Authors: Ji Shi Ming , Zhong J.Q. , Tan Da Peng , Chi Y.W.
Published: January 2012

Because of the liquid phase’s driving action, particles would be collided the surface and impacted with each other in the flow passage, the surface will be machined though the continuous action of impact force and friction force. The finishing results of structural surface is related to the collision frequency and the pressure, abrasion situation in different area of the structural surface can be analyzed obviously by investigating dynamic characteristic and distribution of particle group. Based on coupled wave theory of liquid-solid two phases flow, using mixture model which belongs to Euler-Euler multiphase flow model and realizable turbulence model, turbulence effects of liquid-solid two-phase flow in the wall is numerical simulated and some parameters such as turbulent velocity and turbulent energy are calculated with different particles concentration in the flow passage which has V-shaped texture and semicircular cross-section. The simulation results show that the disorder degree of turbulence can be improved by assembling V-shaped constrained component, because V-shaped passage is benefit of eddy current’s generation. As the concentration of particles being enhanced, the velocity of particle would be increased in a certain range, turbulence energy reduces gradually, fluctuation margin of particle volume fraction is smaller and smaller, and curves of every kind of parameters change as continuous oscillation, area of surface corresponded with crest of the curve. The concentration of particles should be selected properly and different particles distribution and finishing performance would be obtained with different particles concentration.
Research Progress on Digital Design and Manufacturing for Solid Carbide End Mill
Authors: Ding Guo Fu , Cheng X.F. , Li R. , Liu J.J. , Mi R.
Published: January 2012

This paper summarizes the research progress of integral end milling cutter and series of common theories and methods: the construction in the reasoning machine of end milling cutter structure parameters, obtained structure parameter according to the type and the main design parameters of end milling cutter; General the mathematical model and the geometric modeling method of end milling cutter ,based on structure parameters that get from reasoning machine, get 3D parametric model which include all structure information and manufacturing characteristic of end milling cutter; the design technology of end milling cutter Based on manufacturing simulation, check the tool-position trajectory quickly by 2D curved shapes from 2D section Boolean operation, then validate the process rationality and manufacturability of end milling cutter via combine the 2D section simulation technology and the 3D manufacturing simulation. Present some research results finally, the detailed studies details will report in the subsequent articles.
Accuracy Synthesis of Redundant Parallel Kinematic Mechanism with Weighted Least Square Method
Authors: Li Xin You , Chen Wu Yi
Published: January 2012

In order to reduce manufacturing cost, a methodology of accuracy synthesis for machine tool was recommended by combining both machining cost and Least Square method. Weighted coefficients representing the machining difficulty of manufacturing processes were introduced. 3PRS/UPS redundant parallel kinematic mechanism (3PRS/UPS PKM) was taken as an example, and its component tolerances were derived by the proposed method. Comparing with conventional method, the component tolerances were allocated reasonably. A further tolerance allocation for spherical and rotational joints was studied in detail. And hence, the producibility of component was improved and the manufacturing cost was reduced. The results showed that the proposed method was capable of producing tolerance allocations economically and accurately.
Test Analysis of Milling Force of Titanium Alloy Base on MATLAB
Authors: Shi L. , Jiang Z.H.
Published: January 2012

Orthogonal experiments of milling titanium alloy TA12 were done on the lifting workbench milling machine. The milling force signals were acquired through PIC-1712 Data Acquired Board. The main frequencies and energy distribution were got through analysis in SPTOOL of MATLAB. The signals were decomposed and reconstructed based on the main frequency of the milling force with wavelet toolbox. The influence of the milling velocity, axial depth of cut and radial depth of cut on the component milling force was got through range analysis. Through analyzing known that three factors had different influence on the component milling force.
The Application of Swirling Cavitation in Wastewater Treatment Device
Authors: Shi Jin Ping , Guo Pei Quan , Zhao Hao Dong
Published: January 2012

The operation simulation of wastewater treatment device based on swirling cavitation degradation has been done by means of CFD software. The condition of swirling cavitation formation and the shape of cavitation distribution were analyzed. The validity of simulation and wastewater treatment device operation were verified according to the testing results of device’s working parameters and degradation for Rhodamine B. The criterion to judge cavitation formation or degradation efficiency has been established. The industrialized enlargement for mini wastewater treatment device has been analyzed by means of simulation. It is useful to establish industrial application foundation of this kind of wastewater treatment device.
The Effect of Tool Edge Preparation of Indexable Carbide Insert
Authors: Zou Xi Yue , Sun J.F. , Chen W.Y. , Xie J.X.
Published: January 2012

The paper focused on the effect of tool edge preparation of indexable carbide insert on cutting temperature, force and tool wear. The initial wear experiments were carried out to measure flank wear and two criteria to evaluate the effect of tool edge preparation were proposed. The cutting temperature measurement utilized tool-work thermocouple and revealed that the cutting temperature of honed insert was lower. The cutting force measurement with a strain gauge dynamometer showed that tangential cutting force Fz, feed force Fx would be increased and radius force Fy would be decreased after tool edge preparation.
Tool Wear Behavior in Turning Inconel 718 with Coated Inserts
Authors: Zhu Xiao Li , Zhang Song , Xu X.L. , Lv H.G.
Published: January 2012

In the present study, an experimental investigation has been carried out in an attempt to monitor tool wear progress in turning Inconel 718 with coated carbide inserts under the wet cutting condition. First, each experimental test was conducted with a new cutting edge and the turning process was stopped at a certain interval of time. Secondly, the indexable insert was removed from the tool holder and the flank wear of the insert was measured using a three-dimensional digital microscopy (VHX-600E); and then the insert was clamped into the tool holder for the next turning experiment. The final failure of tool wear surfaces were examined under a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). It is indicated that significant flank wear was the predominant failure mode, and the abrasive, adhesive and oxidation wear were the most dominant wear mechanisms which directly control the deterioration and final failure of the cutting tools.
Improvement on the Cutting Performance of CVD Diamond Coated Drills in Drilling CFRP
Authors: Zhang Jian Guo , Wang Ben , Sun Fang Hong , Gao Hang
Published: January 2012

Carbon fiber reinforced plastics (CFRP) is difficult to machine because of the extremely abrasive nature of the carbon fibers and its low thermal conductivity. CVD diamond films have many excellent properties such as wonderful wear resistance, high thermal conductivity and low friction coefficient, therefore depositing diamond films on the surface of drills is thought to be an effective way to elongate the lifetime of drills and improve the cutting performance. In this study, diamond films are deposited on the WC-Co drill using hot filament chemical vapor deposition (HFCVD) method. The results of characterization by the scanning electron microscope (SEM) and Raman spectrum indicate that the fabricated CVD diamond coated drill is covered with a layer of uniform and high-purity diamond films. The cutting performance of as-fabricated CVD diamond coated drill is evaluated in dry drilling CFRP, comparing with the uncoated WC-Co drill. The results demonstrate that the CVD diamond coated drill exhibits much stronger wear resistance. Its flank wear is about 50μm after drilling 30 holes, about one-third of that of WC-Co drill. Machining quality of the exit and internal wall of drilled holes shows better surface finish obtained by coated drill, which suggests that CVD diamond coated tool has great advantages in drilling CFRP.
Three-Dimensional Wheel Topography Measurement with Laser Triangulation
Authors: Liu Jia , Chen Wu Yi , Chen F.
Published: January 2012

Laser triangulation was used to measure the topography of vitrified CBN wheels and optimum sampling interval was obtained by comparing measuring results with different sampling intervals. Four evaluation indexes including the mean protrusion height of abrasive grains Hm, the standard deviation of grain protrusion height Hv, the standard deviation of the distance between two adjacent grains Dv and the number of micro cutting edges per square millimeter Nm were put forward to assess wheel topography and grinding performance. These indexes were verified to be effective by comparing 3D topography of newly manufactured wheel and dressed wheel.
Computer Simulation of AISI D2 Orthogonal Cutting Using Finite Element Method
Authors: Yan L. , Jiang Feng , Rong Y.M.
Published: January 2012

This paper presented a finite element simulation model for the analysis of AISI D2 orthogonal cutting process using TiAlN coated inserts. Firstly, AISI D2 material constitutive model was built based on power law model, which was used in the FEM codes to describe the effect of strain, strain rate and temperature on the material flow stress. In modeling the chip formation, a damage model was employed to predict the chip separation. Then cutting edge radius and thickness of TiAlN coating of cutting tool were measured by SEM. Friction coefficients of cutting tool against AISI D2 steel were obtained by ball-on-plate friction tests on UMT-2 high speed tribometer. Finally, finite element simulations of AISI D2 orthogonal cutting processes were performed using AdvantedgeTM software. The simulated results of cutting forces and chip morphology showed good agreement with the experimental results, which validated the reliability of the cutting process simulation method.
Deposition and Application of CVD Diamond Films on the Interior-Hole Surface of Silicon Carbide Compacting Dies
Authors: Wang Xin Chang , Shen Bin , Sun Fang Hong , Zhang Z.M. , Shen H.S. , Guo S.S.
Published: January 2012

Silicon carbide (SiC) is a promising material for fabricating wire compacting dies due to its advantages of light weight and even high wear resistance over the tungsten carbide, which currently is the most popular material used to produce compacting dies. In present study, a layer of CVD diamond film is deposited on the interior-hole surface of compacting dies using the hot filament chemical vapor deposition (HFCVD) method, following by a surface polish process, aiming at further elongating the lifetime of compacting dies and improving the surface quality of produced wires. The characterization of both as-deposited and polished CVD diamond films is employed by scanning electron microscopy (SEM), surface profiler, Raman spectroscopy and X-ray diffraction (XRD) spectroscopy. Furthermore, the performance of as-fabricated CVD diamond coated compacting dies is examined in the real production process. The results exhibit that the as-deposited CVD diamond films are homogeneous and their surface finish is significantly smoothened after the surface polish process. As compared with the conventional compacting dies, the working lifetime of the diamond coated SiC compacting dies can be increased by a factor of above 15 and in the course of processing, copper stranded wires with high surface quality and uniform sectional area can be obtained.
Effect of Drawing Parameters on Elongation of Micro Copper Tube with Straight Grooves
Authors: Ou D.S. , Tang Yong , Wan Zhen Ping , Lu L.S. , Lian B.
Published: January 2012

Using high-speed oil-filled spinning and multi-pass drawing composite machining methods, a micro straight groove of copper tube(MSGCT) with an outer diameter about 3 mm~6 mm was obtained, and the forming mechanism of micro straight grooves was investigated. The key factors of process parameters influence the drawing were analyzed. The experimental results show that the values of drawing elongation increases with reduction and die angle increasing. However, drawing elongation increases firstly and then becomes smooth with drawing speed increasing. Stable-quality MSGCT can be achieved by controlling the drawing process parameters and the configurations of micro straight grooves were observed by scanning electron microscope(SEM). In addition, the high-speed oil-filled spinning and multi-pass drawing composite manufacturing can further improve the capillary force of the micro straight grooves of copper heat pipe.
Effect of Thermal Treatment on Composite Coatings of Electroless Ni-P/Nano-Diamond on Pure Aluminum Substrate
Authors: Liu Ping , Zhu C.H. , Zhu Yong Wie , Hui J.
Published: January 2012

Recently, researches of composite coatings deposited on the aluminum substrate have been increasing. The Ni-P/nano-diamond composite coating deposited by means of direct electroless deposition on pure aluminum substrate was investigated. The effects of thermal treatment on the surface morphology, microstructure, micro-hardness, and adhesion and elements diffusion of composite coating were examined. Results show that the structure transformation of composite coating from amorphous/microcrystalline into crystalline occurs after thermal treatment and that its micro-hardness increases with the heating temperature and its maximal hardness is 1254Hv after being treated at 350°C for 1h. A diffusion layer forms after thermal treatment due to the inter-diffusion of Al, Ni and P elements at the interface, which leads to the improvement of adhesion strength between the coating and the substrate.
Evaluation for Adhesion Strength of High Performance Coatings by Pressure-Pushing Method and Analysis of Finite Elements
Authors: Cheng X. , Yan J. , Wang H.Y. , Zuo Dun Wen
Published: January 2012

Pressure-pushing method of evaluation for adhesion strength of high performance coatings material and substrate is presented. This method, based on the pressure-testing device of high performance bond strength test sample patent, is one that the sample is cracking along the interface by putting the static load. According to the sample’s stress boundary conditions, the formula of the adhesion strength is given. The surface coating/substrate interface stress distribution is analyzed by using the finite element method, which provides the theory basis for the correct evaluation of coating/substrate strength. The experiments are conducted on the strength of common coating substrate materials as well. All the results show that pushed method can test the adhesion strength of high performance coatings and substrate, whose data is smaller than the international standard and A STMC633-79. And the experimental data of the pushed method are free from the influence of random factors.
Heat Transfer Analysis and Optimization for Wafer System of Laser Annealing Equipment
Authors: Rong Zi Guang , Wu Z.J. , Feng P.F. , Yu D.W.
Published: January 2012

This paper provides heat transfer modeling analysis and parameter optimization for wafer system of laser annealing equipment. Heat transfer models are established at axial and radial directions. With the help of programming calculation, the relation between heat flux of radiation and distance of adjacent layers can be analyzed. In order to minimize heat transfer interference on the motor system, optimized parameters are selected. Performance of certain selection is verified by FEA simulation and experiment data.
Hot Forming Springback and Control of 22MnB5 Boron and Magnesium Alloy Sheet
Authors: Guo You Dan
Published: January 2012

Starting with 22MnB5 boron and magnesium alloy sheet material forming temperature, cooling rate and phase deformation, the impact of cooling rate and temperature change on rebound during hot-stamping as well as the impact of factors such as sheet material thickness on high strength sheet material forming performance. The study shows that the initial conditions, temperature changes during thermal forming and phase deformation are the main factors affecting rebound. When the cooling rate is above the critical cooling rate, rebound increases dramatically. The sheet material thickness has important impact on rebound control and formulating parameters for thermal forming process.
Fine and Ultra-Fine Grained AZ61 and AZ91 Magnesium Alloys Obtained by Friction Stir Processing
Authors: Rey P. , Gesto D. , del Valle J.A. , Verdera D. , Ruano Oscar
Published: January 2012

Friction Stir Processing (FSP) has attracted much interest as a tool for refining grain size and achieving high angle boundary misorientation in magnesium alloys. These characteristics have a great influence in key engineered properties such as strength and ductility, which could be markedly improved by means of this technique. The main objective of this work is to study the microstructural modifications produced when FSP is applied to homogenized cast AZ91 and wrought AZ61 magnesium alloys. Several attempts were made for achieving a homogenous microstructure without defects and enhancing the refinement of the grain size in the stir zone. It was revealed that is of great importance to break the initial microstructure, of coarse grains unfavourably oriented for deformation, in order to facilitate the process, particularly in the case of cast AZ91 alloy. It is highlighted that, after breaking up the initial microstructure, is possible to process the material, in subsequent passes, Furthermore, the use of different backing materials as heat sink and a previous heating treatment of the sample were evaluated. Changing the backing plate can improve more the reduction of the grain size during a second pass. Using a copper plate instead of a steel one can promote a refinement up to 700 nm in AZ91 and 1 μm in AZ61. A coolant agent can be used for inhibiting the grain growth causing a little more reduction of the grain size.
Microstructural Modelling for Friction Stir Welding of High Strength Aluminum Alloys
Authors: Robson Joseph D. , Campbell L.
Published: January 2012

Friction stir welding is conceptually simple but metallurgically highly complex due to thecombination of severe deformation and high temperature. This is particularly true in the case ofprecipitation strengthened alloys, such as high strength aerospace aluminium alloys, where theheat and deformation of FSW lead to profound changes in both grain structure and precipitatedistribution that ultimately determine weld performance.
Amorphous Silicon-Coated Carbon Nanofibers Composite as Anode Material for Lithium-Ion Batteries
Authors: Ghanbari E. , Saatchi A.R. , Raeissi K. , Saatchi A. , Tavanai H.
Published: January 2012

Silicon can be considered one of the most promising anode materials for lithium ion batteries (LIBs) as it has a low charge/discharge voltage at room temperature and exhibits the highest known theoretical lithiation capacity in combination with good safety characteristics. However, the silicon anode experiences enormous volume changes during repeated lithium insertion/extraction processes in every charge/discharge cycle. This leads to severe particle pulverization and results in a quick electrode structure failure. Moreover, the Si has to be amorphous, as crystallized Si can hardly alloy with lithium at room temperature. Amorphous Si thin films are currently manufactured by techniques such as chemical vapor deposition, that usually, are quite expensive, have complex equipment design and have slow rate of deposition. Electrodeposition of Si can offer a suitable alternative method of producing a thin film of amorphous Si by much easier and lower cost means. In this study electrodeposited amorphous silicon on carbon nanofibers (CNFs) have been investigated as the anode material for LIBs. Electrically conductive CNFs are produced by electrospinning and later heat treating of polyacrylonitrile (PAN) precursor. It is shown that the macromorphology of electrospinning-derived CNFs template provides enough space to accommodate the silicon volume expansions. By controlling electrodeposition parameters, cycle-ability of the anode material was optimized. It is envisaged that exceptional characteristics of CNFs and the electrodeposited Si will make the composite material an ideal candidate for the anode material of high-power LIBs.
Tape Casting as a Multi Purpose Shaping Technology for Different Applications in Energy Issues
Authors: Schafbauer Wolfgang , Schulze-Küppers Falk , Baumann Stefan , Meulenberg Wilhelm A. , Menzler Norbert H. , Buchkremer Hans Peter , Stöver D.
Published: January 2012

Tape casting is widely used in industrial scale for production of multilayer ceramic capacitors or substrates for different applications. In 2009, it was successfully introduced as standard shaping technology for 3 (BSCF) are shown. The entire scope from the preparation of the used powders, the different manufacturing steps and their optimization potential up to the final tape-cast product will be discussed. The influence of the use of pore forming agents, heat treatment or other parameters during processing will be described in detail. Finally, the option of sequential tape casting of different materials for graded structures as a future step in shaping technology will be presented for different applications.
Sintered Stainless Steel for Interconnectors for PEM Fuel Cell
Authors: Włodarczyk Renata
Published: January 2012

Polymer electrolyte membrane fuel cell performance strongly depends on properties of the fuel cell stack bipolar plates (BPs). Bipolar plates are a key component of fuel cells. Functions of materials used for fuel cells include even distribution of gas fuel and air, conduction of electricity between the adjacent cells, heat transfer from the cell as well as prevention of gas leakage and cooldown. Due to multifunctionality of fuel cell plates, choice of materials used for plates is immensely difficult. This paper presents opportunities of application of a new technology of powder sintering for creation of parts for electricity and heat generators. Sintered stainless steel 316LHD was investigated as a candidate material for bipolar plate materials. 316L powders were compacted with the following load: 700MPa, 550MPa, and 200MPa, and then sintered at the temperature of 1250 °C in hydrogen medium. The main criterion for selection of a particular material for components of fuel cells is their corrosion resistance in operating conditions of hydrogen fuel cells. In order to determine resistance to corrosion in the environment of operation of fuel cells, potentiokinetic curves (as a function of temperature) were registered in synthetic solution 0.1M H2SO4 + 2 ppmF- at 80°C. The investigations also covered measurements of mechanical properties and microstructural testing of sinters with austenitic structure.
Characterization of a Biomedical Titanium Alloy Using Various Surface Modifications to Enhance its Corrosion Resistance and Biocompatibility
Authors: Bhola Rahul , Mishra Brajendra
Published: January 2012

Ti6Al4V titanium alloy has been characterized for its prospective applications as an implant material. The surface treatments performed have brought about enhanced surface properties of these alloys and have produced corrosion resistant oxide films with increased bioactive properties. Characterization of the alloy surface has revealed the presence of a duplex oxide structure over the surface treated specimens, composed of an inner barrier layer and an outer porous layer. The inner barrier layer has imparted a high corrosion resistance to the alloy while the outer porous layer which is responsible for the increased roughness of the surface treated alloy specimens, has encouraged formation and deposition of apatite into the oxide pores and further resulted in an increase in cell adhesion over the alloy surface. Anodization and heat treatment procedures have proved advantageous to titanium alloys in terms of producing oxide films that can offer these alloys an improved biological performance.
Catalytic Properties of Ni3Fe Foil for Hydrogen Production from Methanol
Authors: Xu Ya , Demura Masahiko , Hirano Toshiyuki , Kaneno Yasuyuki , Takasugi Takayuki
Published: January 2012

The objective of this study is to investigate the catalytic properties of intermetallic Ni3Fe foil. We fabricated Ni3Fe foil of 30 µm in thickness by a metallurgical process, and examined the catalytic activity of the Ni3Fe foil for methanol decomposition from 513 to 973 K. The Ni3Fe foil showed activity for methanol decomposition above 623 K. The activity increased with the increase of reaction temperature. Surface analysis revealed that a surface structure of fine Ni-Fe particles dispersed on carbon nanofibers was formed on the foil during the reaction. The activity is attributed to the formation of this fine structure.
Optimization of the Fluorine Effect for Improving the Oxidation Resistance of Tial-Alloys
Authors: Donchev Alexander , Schütze Michael , Kolitsch Andreas , Yankov Rossen
Published: January 2012

The oxidation resistance of TiAl-alloys can be improved drastically by treating the surface of the components with small amounts of fluorine. The oxidation mechanism is changed. Hence, the formation of a fast growing mixed oxide scale on untreated alloys is suppressed. Instead a thin protective alumina scale is formed on samples after fluorine treatment. The different methods only influence the surface region of the components so that the bulk properties are not affected. Recent results achieved with F-containing inorganic compounds showed that the fluorine effect can be improved even further. TiAl-specimens were treated only with fluorine and with F-containing compounds in several ways and their performance during high temperature oxidation tests in air was investigated. Results of isothermal and thermocyclic oxidation tests are presented. The results are discussed in terms of a later use of the fluorine effect for technical applications.
High-Temperature Tensile Properties of Ti-Al-X (X=Cr,W) Consisting of α2, β and γ in Three Phases
Authors: Hashimoto Keizo
Published: January 2012

Gamma titanium aluminides (γ-TiAl) have been investigated extensively for more than 25 years, since they are considered to be candidate materials for advanced jet engine components, automobile exhaust valves, turbo-chargers, and so on. Many researchers have reported that the mechanical properties of γ-TiAl have been improved by micro-alloying and thermo-mechanical microstructure control. Recently, γ-TiAl entered a new era by being applied to low-pressure turbine blades in newly developed commercial jet engines. In order to spread their applications further, material durability and affordability have become key issues. The tensile properties of the Ti-Al-X (X=Cr or W) have been studied intensively at various strain rates and test temperatures in a vacuum atmosphere. It has been demonstrated that the additions of a few atomic percent of Cr or W to γ-TiAl shifts the phase stability drastically and creates relatively fine-grain microstructures consisting of α2+β+γ in three phases. Although the microstructures of Ti-46at%Al-2.7at%Cr and Ti-45at%Al-1.9at%W show similar morphology, the high-temperature mechanical properties of each indicate distinguishable properties. The former specimens have demonstrated the capability of super-plastic deformation at temperatures above 1323K; the latter specimens, however, have showed relatively higher tensile strength than those of the other specimens having ternary compositions (Ti-Al-X). The differences in the tensile properties of Ti-Al-X (X=Cr or W) have been discussed in conjunction with microstructures and the effects of solid-solution hardening due to W atoms.
Surface Effects on the Mechanical Properties of Gamma Titanium Aluminides
Authors: Lindemann Janny , Glavatskikh Maria , Leyens Christoph
Published: January 2012

Surface conditions are of significant importance for the fatigue performance of rotating components for aircraft and automotive applications. Compared to the electropolished reference state the fatigue performance of gamma titanium aluminides at ambient temperature can be significantly improved by shot peening, while the fatigue strength after roller burnishing is hardly affected. Fatigue strength improvements after shot peening are mainly caused by cyclically stable residual compressive stresses in the near-surface region. Notably, also conventional turning operations generate high dislocation densities and residual compressive stresses in the near-surface region resulting in fatigue strength improvements similar to shot peening. Surface strengthening by shot peening or machining leads to subsurface fatigue crack nucleation and overcompensates the detrimental influence of the high surface roughness on fatigue. However, for temperatures above 650 °C, residual compressive stresses induced by shot peening and machining quickly relax. This indicates that, at elevated temperatures, surface roughness and dislocation strengthening become increasingly important for the fatigue performance of components.