bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Graphite Source and the Synthesis Method on the Properties of Graphene Oxide
Authors: Richtera Lukáš , Omelková Jiřina , Bálková Radka , Zmrzlý Martin , Másilko Jiří , Hermanová Soňa
Published: November 2013

The purpose of this study is to insight more thoroughly into the structural properties of graphene oxide (GO) in particular of the type generated by Hummer's method in relation with graphite precursor originating from different sources. The systematic study using elemental analysis (EA), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) was performed to reveal the changes of GO microstructure. The results revealed considerable influence of both the original graphite source and isolation procedure of GO by lyophilisation. Further, maintaining of GO in a form of aqueous colloidal dispersion is crucial for preservation of its unique properties. SEM results revealed the occurrence of associated GO blocks formed form identically oriented planes.
On the Micromechanisms of Fatigue Crack Propagation in Aluminum Cast Alloys
Authors: Krupp Ulrich , Giertler Alexander , Siegfanz Stefanie , Michels Wilhelm
Published: November 2013

Specimens of the common cast alloy Al-7Si-0.3Mg (A356) were solution heat treated at different temperatures and times to modify (i) the precipitation strengthening effect in the aluminum solid solution phase and (ii) to spheroidize the eutectic silicon. Just 15 minutes of solution heat treatment at a temperature of 540°C are sufficient to reach the desired effect. Cyclic loading experiments revealed an increase in fatigue life as compared to specimens heat treated at lower temperatures. In particular in the HCF regime, fatigue cracks that were originally initiated at pores follow crystallographic slip bands under shear control (mode II) as it was proven by automated EBSD (electron back scatter diffraction) measurements. The smoothly polished surface of the fatigue specimens was observed continuously by a long-distance microscope and discontinuously by SEM (scanning electron microscopy) to identify the fatigue crack propagation mechanisms. It was shown that da/dN decreases strongly when the crack tip interacts with the eutectic areas. Obviously, the blocking effect of the eutectic silicon particles makes the crack leaving the straight slip-band path.
Siliconizing in a Fluidized Bed Reactor
Authors: Anthymidis Konstantinos , David Kostas , Trakali Afroditi , Tsipas D.N.
Published: November 2013

Fluidized bed technology has been used for surface engineering applications in the deposition of hard and/or corrosion resistant layers e.g. aluminizing, chromizing, nitriding, carburizing, boronizing. In the present paper we used fluidized bed technology (FBT) to deposit silicide coatings on steels. The silicide coatings are well known for their excellent corrosion resistance. Siliconizing in fluidized bed is a promising method to improve the corrosion resistance of steel without altering its other properties. The asproduced silicide coatings are uniform all over the steel substrate, with good thickness, adequate adherence and consisted only from the phase FeSiC.
Microstructure-Based Life Prediction of Thermal Barrier Coatings
Authors: Eriksson Robert , Yuan Kang , Johansson Sten , Peng Ru Lin
Published: November 2013

The widespread use of thermal barrier coatings (TBC) in gas turbines stresses the importance of accurate life prediction models for TBCs. During service, the TBC may fail due to thermal fatigue or through the formation of thermally grown oxides (TGOs). The current paper presents a Thermo-Calc/Dictra-based approach to life prediction of isothermally oxidised atmospheric plasma sprayed (APS) TBCs. The β-phase depletion of the coating was predicted and compared to life prediction criteria based on TGO thickness and Al content in the coating. All tried life models underestimated the life of the coating where the β-depletion-based model was the most conservative.
Thermal Analysis of Halide Activator Used in Aluminizing of TiAl Intermetallics
Authors: Dychtoń Kamil , Przeliorz Roman , Góral Marek , Sieniawski Jan
Published: November 2013

A detailed study of thermal analysis of ZrCl4 was carried out to investigate the influence of the halide salt type activator on the growth behavior of coating formed in vapor phase aluminizing process and subsequently to identify the most suitable condition. The equilibrium partial pressures of vapor species generated at the decomposition temperature of ZrCl4 were calculated by using a procedure based on minimization of the whole Gibbs energy with Factsage 6.2 using Fact 53 and SGsold thermodynamic databases. The results were discussed and compared with literatures. With the aid of thermodynamic analytical tools, chloride salt activator was analysed and the decomposition temperature with related enthalpy change was evaluated.
Complex Metallic Alloys – Microstructure Characterization
Authors: Janovec Jozef , Černičková Ivona , Priputen Pavol
Published: November 2013

The recent findings related to binary and ternary structurally complex phases in selected complex metallic alloys coming under Al-Pd-Co, Al-Cu-Co, and Al-Mn-Fe systems are presented. The phases were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, high-angle annular dark-field imaging, X-ray diffraction, and differential thermal analysis. There are highlighted some unusual features of phases D, U, T, and ε-family from both structural and compositional points of view.
Microscopic Strain and Crystal Rotation Measurement within Metallurgical Grains
Authors: Bridier Florent , Stinville Jean Charles , Vanderesse Nicolas , Villechaise Patrick , Bocher Philippe
Published: November 2013

This work describes an experimental procedure to measure the progressive strain localization and crystal lattice rotation within metallurgical grains. A digital image correlation software was implemented and associated with mechanical tests carried out inside a scanning electron microscope on specimens exhibiting nanometric grainy patterns. Cross-correlation analyzes between electron backscattering diffraction maps were also developed to quantify the corresponding local crystal rotation relative to the original structure. The microscale strain and rotation fields on the surface of a tensile-loaded specimen made of austenitic stainless steel 316L are presented as an illustration. Their direct spatial correlation between strain heterogeneities and the progressive activation of slip systems is put into evidence and discussed.
Advanced Microstructure Studies of an Austenitic Material Using EBSD in Elevated Temperature In Situ Tensile Testing in SEM
Authors: Calmunger Mattias , Peng Ru Lin , Chai Guo Cai , Johansson Sten , Moverare Johan
Published: November 2013

In this study an advanced method for investigation of the microstructure such as electron backscattering diffraction (EBSD) together with in-situ tensile test in a scanning electron microscope (SEM) has been used at room temperature and 300°C. EBSD analyses provide information about crystallographic orientation in the microstructure and dislocation structures caused by deformation. The in-situ tensile tests enabled the same area at different strain levels to be investigated. For the same macroscopic strain values lower mean misorientation angles of individual grains at the elevated temperature indicated that less residual strains at grain levels are gained compared with room temperature. The influence of grain size on plastic deformation on microscopic level, where larger grains tend to accumulate more strains, is discussed.
Experimental Study of Defect Induced Temperature Evolution in Polycrystalline Metals
Authors: Plekhov Oleg , Naimark Oleg
Published: November 2013

This work is devoted to theoretical and experimental study of energy dissipation and storage processes in titanium alloys under quasistatic loading. The specimen surface temperature was measured by infrared camera FLIR SC 5000 (a spectral range of 3-5 micron). Extending previous results of the research group in Perm, we coupled the experimental investigation of temperature evolution with a statistical description of the mesodefect ensemble. It allowed us to propose a thermodynamic internal variable model of heat dissipation in metals.
Influence of the Surface Treatment of Tubes on the Heat Transfer in Low Pressure Atmosphere
Authors: Šnajdárek Ladislav , Kracík Petr , Pospíšil Jiří
Published: November 2013

This paper presents the current research on heat transfer at a sprinkled tube bundle consisting of smooth tubes and located in a chamber inside of which a low pressure is created by a liquid vacuum pump. It also monitors the changes of the heat transfer coefficient in relation to the speed of sprinkled and sprinkling liquid flow, thermal gradient.
Comparing the Properties of Polypropylene Fibers Contained in Ordinary and Lightweight Concrete Using Three-Point Bending Tests with Stress Concentrator and Acoustic Emission Method
Authors: Trčka Tomas , Láník Jaromír , Macků Robert
Published: November 2013

The results of many bending tests of fiber reinforced concrete specimens did not produce a clear answer to the question whether the fibers are activated before the macro-crack. Our diagnostic method is based on the measurement of acoustic emission signals during three-point bending tests of concrete specimens with stress concentrator. Acoustic emission activity measurement could help us to answer the question if the fibers are activated before the macro-crack is able to seen by human eyes. Several groups of concrete samples with various concrete composition formulas have been prepared for our experiment. This contribution describes the prepared concrete composition, measurement system and also includes the experimental results of one concrete samples set.
Study of Initial Stages of Fatigue Process Using Non-Destructive Testing Methods
Authors: Vlasic František , Volák Josef , Nohál Libor , Mazal Pavel , Hort Filip
Published: November 2013

This paper deals with the basic research of cyclic damage during the initial stages of fatigue process using the non-destructive testing methods. The acoustic emission method was used for monitoring of the microstructure changes during fatigue loading. The electrical potential measurements of specimen and microscopic observation were used mainly to detect the first short cracks and their propagation. The fatigue tests at room temperature were conducted on titanium alloy and creep-resistant steel specimens under bending and tension loading. The aim of the study was to compare the acoustic emission signal at different types of loading until fracture and to analyze in detail the signal changes in initial stages of fatigue process. This analysis was primarily based on the waveform similarity and division into classes. The results show the high sensitivity of the acoustic emission technology in the transition from the stage of surface relief evolution to the stage of crack nucleation and propagation.
Advanced 3D Packaging of Chips and Materials Integrity: Stress-Induced Effects and Mechanical Properties of New Ultra Low-k Dielectrics for On-Chip Interconnect Stacks
Authors: Sander Christoph , Gall Martin , Yeap Kong Boon , Zschech Ehrenfried
Published: November 2013

Managing the emerging internal mechanical stress in chips particularly if they are 3D-tscked is a key task to maintain performance and reliability of microelectronic products. Hence, a strong need of a physics-based simulation methodology/flow emerges. This physics-based simulation, however, requires materials parameters with high accuracy. A full-chip analysis can then be performed, balancing the need for local resolution and computing time. Therefore, effective composite-type materials data for several regions of interest are needed. Advanced techniques to measure FEA-and design-relevant properties such as local and effective Youngs modulus and effective CTE values were developed and described in this paper. These data show a clear orientation dependence, caused by the chip design.
Influence of Morphology of Deformation Induced α´-Martensite on Stress-Strain Response in a Two Phase Austenitic-Martensitic-Steel
Authors: Skorupski Robert , Smaga Marek , Eifler Dietmar , Schmitt Regina , Müller Ralf
Published: November 2013

In this research work specimens of the metastable austenitic steels AISI 304 and AISI 347 with one phase (fully austenitic) and two phase (austenitic-α ́-martensitic) microstructure were monotonically loaded at ambient temperature. Using stress-strain and temperature measurements the deformation behavior was characterized in detail. To study the influence of morphology of deformation induced α ́-martensite on the stress-strain response a phase field model for α ́-martensite transformations was developed. With this approach it was possible to model the two phase austenite-α ́-martensite microstructure and investigate the deformation behavior on the micro level. With optical microscopy, magnetic and x-ray measurements the microstructure characterization of fully austenitic and austenitic-α ́-martensitic steels was realized.
Extrapolation of Sigmoidal Creep Curve by Strain Acceleration Parameter
Authors: Sato Hiroyuki , Omote Kosuke , Sato Akira , Ueno Kouki
Published: November 2013

It has been widely accepted that the creep characteristics at high temperatures are mainly evaluated by a minimum creep rate and a time to fracture. Although, a shape of creep curve may vary depending on deformation conditions, the apparent minimum creep rates may become the same value. Thus, for detailed analysis and prediction of creep behavior, other values should be considered which reflects the shape of each creep curve. For the purpose, authors have proposed Satos Strain-Acceleration-Parameter (SAP) which reflects strain rate change during creep. Based on the concept of SAP, the whole creep curve can be represented by a set of small numbers of numerical parameters, and can be extrapolated from a part of creep curve [. It is also well accepted that the creep rates depend on microstructures, and microstructural changes cause strain rate change. The SAP would reflect stability and magnitude of microstructural change during deformation at high temperatures. In this paper, application of the concept of SAP to creep curves that show sigmoidal type primary creep is presented. The creep curve can be divided into two regime based on the SAP values. The sigmoidal creep curve is reasonably reproduced by the concept of Strain-Acceleration-Parameter, and reasonably agrees with experiment. Whole creep curve can be reasonably represented by a few numerical values which reflect shape of creep curve in each regime. The concept of SAP is applicable for quantitative evaluation of both normal and sigmoidal type of creep curves.
Acoustic Emission from Quasi-Brittle Failure of Cementitious Composites - Experimental Measurements and Cohesive Crack Model Simulations
Authors: Veselý Václav , Vodák Ondřej , Trčka Tomas , Sobek Jakub , Koktavý Pavel , Keršner Zbyněk , Koktavý Bohumil
Published: November 2013

Conducted loading tests of plain concrete specimens are briefly introduced in the paper together with description of the performed numerical simulations of these tests in ATENA 3D software. The simulation results of concrete failure are analysed in detail and compared with the experimental results recording failure processes with the help of acoustic emission. The simulation results are in good agreement with the recorded data.
Relations between Microstructure and Mechanical Properties in Laminated Ti-Intermetallic Composites Synthesized Using Ti and Al Foils
Authors: Konieczny Marek
Published: November 2013

Ti-(Al3Ti+Al) and Ti-Al3Ti laminated composites have been fabricated in vacuum using 50, 100, 150, 200, 400 and 600 μm thick titanium and 50 μm thick aluminum foils. The composites were synthesized with controlled temperature and treating time. Microstructural examinations showed that Al3Ti was the only phase formed during the reaction between Ti and Al. The initial foil thicknesses only affected the volume fraction of the resultant Ti, Al and Al3Ti layers. Treating time at 650 °C was a main factor determining microstructures and properties of the composites. After 20 minutes not all aluminum was consumed and therefore the composites consisted of alternating layers of Ti, Al and Al3Ti. After 60 minutes aluminum layers were completely consumed resulting in microstructures with Ti residual layers alternating with the Al3Ti layers. Mechanical tests were performed on the materials with different microstructures to establish their properties and fracture behavior. The results of investigations indicated that mechanical properties of the composites strongly depended on the thickness of individual Ti layers and the presence of residual Al layers at the intermetallic centerlines.
Role of Microstructure on Fracture Behavior of T91 Steel in Presence of Liquid Sodium
Authors: Hamdane Ouadie , Vogt Jean Bernard , Proriol-Serre Ingrid
Published: November 2013

The sensitivity to liquid sodium embrittlement (LME) of T91 martensitic steel, one of the selected structural materials for future sodium fast reactors has been investigated. The study took into account the role of microstructure. Small punch tests and three points bending tests were carried out in a purified and controlled atmosphere. Precipitation state and dislocations structure resulting from a tempering at 550° C provoked LME of the T91 steel between 200 and 550 °C. Secondary Ions Mass Spectroscopy investigation suggested that sodium penetration at prior austenitic grains boundaries promoted by plastic deformation occurred and caused brittle crack initiation. Brittle cracks propagated in sodium preferentially along martensitic laths-boundaries. J integral calculations confirmed a drop in toughness of T91 tempered at 550°C by liquid sodium up to 80 %.
Slip Activity of Persistent Slip Bands in early Stages of Fatigue Life of Austenitic 316L Steel
Authors: Man Jiří , Weidner Anja , Klapetek Petr , Polák Jaroslav
Published: November 2013

Flat specimen of 316L steel was cyclically pre-deformed with constant plastic strain amplitude to early stage of fatigue life relevant to the period of cyclic strain localization and fatigue crack initiation. To document slip activity and reversibility/irreversibility of persistent slip bands (PSBs) in situ experiments in the high-resolution SEMFEG under special imaging conditions were performed. The half-and full-cycle slip activity and distribution of plastic strain within PSBs in individual grains were investigated via slip steps generated in half-and full-cycle deformation after intermediate vibration polishing. After completion of in situ tests the surface topography in identical locations was quantitatively documented using atomic force microscopy (AFM).
Forming Limit Curves and Forming Limit Stress Curves for Advanced High Strength Steels
Authors: Panich Sansot , Barlat Frédéric , Uthaisangsuk Viton , Suranuntchai Surasak , Jirathearanat Suwat
Published: November 2013

Experimental and numerical investigations using Forming Limit Curve (FLC) and Forming Limit Stress Curve (FLSC) were carried out for two Advanced High Strength Steel (AHSS) grades DP780 and TRIP780. The forming limit curves were experimentally determined by means of Nakazima stretching test. Then, both FLC and FLSC were analytically calculated on the basis of the Marciniack-Kuczinsky (M-K) model. The yield criteria Barlat2000 (Yld2000-2d) were employed in combination with the Swift and modified Voce strain hardening laws to describe plastic flow behavior of the AHS steels. Hereby, influence of the constitutive models on the numerically determined FLCs and FLSCs were examined. Obviously, the forming limit curves predicted by the M-K model applying the Yld2000-2d yield criterion and Swift hardening law could fairly represent the experimental limit curves. The FLSCs resulted from the experimental data and theoretical model were also compared.
Effective Forming Processes of Hub Forging from Aluminum Alloy AlCu2SiMn
Authors: Gontarz Andrzej
Published: November 2013

This paper presents results of theoretical and experimental research works on metal forming process of a hub. A typical technology of forging on hammer of this part with flash was discussed. Two new processes of a hub forging were proposed, characterized by large material savings in comparison with typical technology. The first process is based on forming without flash of a forging with axial cavity. The second one is connected with forming of forging from pipe billet. The realization of these processes is possible at the application of a press with three movable working tools. Theoretical research works were done on the basis of simulations by means of finite element method. Simulations were made mainly in order to determine kinematics of material flow in forging processes and precision of shape and dimensions of obtained products. The first of the proposed processes was experimentally verified and a product of good quality was obtained. Material consumption of the analyzed processes and other factors acting on their effectiveness were also compared.
Strain Induced Martensite in Incremental Forming - Formation, Effect and Control
Authors: Katajarinne Tuomas , Kivivuori Seppo
Published: November 2013

Stainless steels are increasingly today applied in industrial use. The metastable structure of austenitic stainless steels enables strain induced martensite formation during plastic deformation. Thus, in order to effectively apply these steels in incremental sheet forming (ISF), it is essential to know their α-martensite transformation tendency in the process. For the four different austenitic stainless steels in the present study, the transformation was found to be very sensitive to the applied process parameters. The martensite formation was more profound with the unstable grades, however, with external heating the martensite formation could be diminished. By optimizing the ISF process, the amount of transformed martensite can be controlled and products with exceptional property combinations can be produced. The novelty of the present paper is to, first, provide information on the influence of strain induced martensite on the incremental forming process and product properties. In addition, based on the observations, propose means to control the transformation. Furthermore, the paper establishes that ISF favours a moderate rate of martensite transformation for extreme formability.
Experimental Studies and FEM Analysis on the Creep Age Forming for Aluminium Alloy 7050
Authors: Huang Xia , Zeng Yuan Song , Gai Pen Tao
Published: November 2013

Creep age forming (CAF) is a combined creep forming and age hardening treatment process. How to control the springback after forming is one of the key problems for the process. In this paper, Creep tests were conducted for different stress levels at 160°C for 25h, which is the suitable parameters for CAF process of aluminum alloy 7050T451. Based on experimental results, a set of mechanism-based creep constitutive equations was formulated. The six material constants of the constitutive equations were determined by non-linear least squares fitting methods. The creep age forming process for aluminum alloy 7050T451 plate was simulated by using FE software ABAQUS through the subroutine CREEP. The effects of the forming parameters on the springback were analyzed. Finally, experimental research was performed. It is found that the developed numerical simulation can be used to simulate the whole process of creep age forming process. The maximum relative error is 6.9%.
Grain Refinement in the Formability of Aluminium Thin Cup
Authors: Hadi Syamsul , Tieu A. Kiet , Lu Cheng , Su Li Hong , Yu Hai Liang
Published: November 2013

Refinement of the grain diameter of the micro structure of Aluminium foil with a thickness of 300μm has been done through the ARB process up to fourth cycles with 72 layers that are proven to increase formability in micro forming a cup. Grain size was measured from the full annealed condition, of the ARB process, and the results of ARB process followed by stress relieved. Formability of the formation of a cup which is expressed as the LDR has increased from 1.87 for the material conditions of full annealed to 2.00 for the ARB process followed by stress relieved in a single step process. In addition to improved formability obtained in a cup formation, grain refinement in the microstructure can also reduce cup earing and wrinkle on the cup wall.
Effects of Hot Extrusion on Microstructure, Texture and Mechanical Properties of Mg-5Li-3Al-2Zn Alloy
Authors: Hou Le Gan , Wu Rui Zhi , Li Ji Qing , Zhang Jing Huai , Zhang Mi Lin , Shang Yong Chen , Qu Zhi Kun
Published: November 2013

This work mainly studied the effects of hot extrusion on microstructure, texture and mechanical properties of Mg-5Li-3Al-2Zn alloy. The results show that the microstructures of as-cast and as-extruded alloys both consist of α-Mg matrix and lamellar eutectic structure (α-Mg and AlLi phases). During the hot extrusion, the large eutectic structure of as-cast alloy was crushed into small eutectic structure and the grains were effectively refined. A {0002} basal texture was formed after hot extrusion. The as-extruded alloy exhibits remarkably improved tensile properties, which is mainly attributed to the grain refinement and the formation of texture.
Production of Mg-Based Bulk Metallic Glass Composites with High Magnesium Content
Authors: Biletska Olga , Laws Kevin J. , Gibson Mark , Ferry Michael
Published: November 2013

In this work, in-situ BMG composites based on the Mg-Ni-Gd system with high Mg content (>80 at. %) were produced by copper mould gravity and injection casting methods. The morphology, distribution and volume fraction of the crystalline phases that form in the amorphous matrix was shown to be influenced by cooling rate, composition and casting parameters. Hence, the mechanical properties and deformation behaviour of Mg-Ni-RE BMG composites can be tailored by controlling the microstructure generated during casting.
Microstructures and Mechanical Properties of Mg-6Li-6.5Gd-1Dy-2Zn Alloys
Authors: Niu Zhong Yi , Leng Zhe , Zhang Jing Huai , Wu Rui Zhi , Zhang Mi Lin
Published: November 2013

Extrusion Mg-6Li-6.5Gd-1Dy-2Zn alloy was prepared successfully by vacuum melting. The microstructures and mechanical properties of as-cast and as-extruded Mg-6Li-6.5Gd-1Dy-2Zn alloys were investigated. Extruding process refines the α (Mg) phase and β (Li) phase, and makes the Mg3X phase crushed and dispersed well. After heat treatment, Mg3X phase particles became finer and much more RE enriched phase particles formed in the matrix. These effects result in the improvement of mechanical properties of the alloys. In this study, after solution treated at 510°C for 3h and aged at 215°C for 99h, the as-extruded alloy exhibits the best mechanical properties, and the microhardness, ultimate tensile and elongation reach 103.0, 249 MPa and 34.8%, respectively.
Deformation Behaviour of a Commercial Pure Titanium Alloy during Hot Compression Testing
Authors: Chao Qi , Beladi Hossein , Sabirov Ilchat , Hodgson Peter
Published: November 2013

The flow curve behavior and microstructure evolution of commercially pure titanium (CP-Ti) through uniaxial hot compression was investigated at 850 °C and a strain rate of 0.1/s. Electron back scattered diffraction (EBSD) was employed to characterize the microstructure and crystallographic texture development for different thermomechanical conditions. The stress-strain curves of CP-Ti alloy under hot compression displayed a typical flow behavior of metals undergoing dynamic recrystallization (DRX), which resulted in grain refinement. The critical strain for the onset of DRX was 0.13 using the double differentiation analysis technique. It was also revealed that the texture was markably altered during hot deformation.
Effect of the Bias Voltage on the Structure, Mechanical, Electronic and Optical Properties of the Low Temperature ZnO Thin Films Deposited by Using Cathodic Vacuum Arc Deposition System on Plastic Substrates
Authors: Yang Ru Yuan , Pan Cheng Tang , Huang Chien Wei
Published: November 2013

The un-doped zinc oxide (ZnO) ﬁlms on the polyethylene terephthalate (PET) substrate at a low temperature (<75°C) by using cathode vacuum arc deposition (CVAD) system with different negative substrate bias voltage applied between 0 and -100 V. The material, mechanical, optical and electrical properties were investigated and discussed. The results show that all ZnO thin films have (002) preferred orientation, an average transmittance was over than 70 % in the visible region. Calculated band gap values are all around 3.2 eV with the different substrate bias voltages. The ZnO thin films with resistivities as low as 10-3 Ω*cm have been obtained by adjusting the substrate bias voltage on the plastic substrates.
A Study on Grade 1000MPa High Performance Steel Plate Processing by Direct Quenching
Authors: Hu Shu E , Sun Wei Hua , Liu Xiao Dong , Xiao Feng Qiang , Hou Deng Yi , Hou Dong Hua , Wang Guo Dong
Published: November 2013

A 1000MPa grade steel plate for coal mining machinery equipment was studied in this paper. The ultra-high strength steel plate is processed by direct quenching after hot rolling plus tempering (DQ-T) to obtain high toughness and ductility. It has found that the tempering temperature has an important influence on the steel microstructure, precipitation behavior and the plate mechanical properties. At the lower tempering temperatures from 400 °C to 450 °C, the steel plate has a low toughness. When the tempering temperature is higher than 450 °C, the higher mechanical properties can be obtained due to the carbides precipitation, dislocation dissolution and carbide decomposition from residual austenite after quenching. The steel microstructure is comprised of tempered sorbite and bainite, in which sorbite plays an important role in obtaining premium microstructure.
MCDM Model for Selection of Optimum Machining Process
Authors: Srinivasan Sriram , Srivatsan Lakshmikanthan , Sathyanarayan Rajaram , Vijaya Ramnath B.
Published: November 2013

The work of manufacturing engineers is to utilize the minimum amount of energy or resources in bringing out a product without compromising on quality. Hence, to achieve this, the engineers must figure out the optimum or the best possible method to fabricate a product. This paper uses a multi criteria decision making (MCDM) model namely Analytical Hierarchical Process (AHP) to determine the best possible machining process to achieve the optimum results for an engraving operation on gear face in an automobile industry which uses five nontraditional machining processes viz; Laser Beam Machining (LBM), Ultrasonic Machining (USM), Electric Discharge Machining (EDM), Electrochemical Machining (ECM) and Electron Beam Machining (EBM). The five criteria considered in this paper are Material Removal Rate (MRR), Surface Finish, Depth Damage, Tolerance and Toxicity. The AHP result shows that ECM is the most suitable machining process as compared to others.
Development of Data Acquisition System for Examination of Grinding Performance
Authors: Liu Yung Tien , Li Bo Jheng , Chiu Neng Hsin , Huang Han Ju
Published: November 2013

In this paper, a data acquisition system was constructed for examining grinding performance of a plunge grinding machine. The system is capable of simultaneously recording power assumption of main spindle, grinding normal force, and material removal of a workpiece. Through grinding experiments for cylindrical workpieces, parameters of grinding process including normal force, power consumption, and time history of diametric error were obtained. With the obtained parameters, the stiffness and time constant of the grinding system were being derived such that the performance of the grinding machine was well evaluated. The configured system described in this paper can be applied to improve grinding performance through further online compensation process.
Running Behavior of a High-Speed Spindle Using a Micro-Mist Lubrication System
Authors: Lin Shen Yung , Li Jheng Hua
Published: November 2013

This work investigates the effect of lubrication parameter on the operation performance of a high-speed spindle using a micro-mist lubrication system. Experiments are conducted through a long-time spindle test under different combinations of oil-supply parameter and rotating speed for a micro-mist lubricated spindle. The correspondent relationships among temperature rise, vibration, oil-supply parameter and rotating speed are established through the experiments under moderate oil-supply. The results show that the better oil-supply parameter combinations exist under different spindle rotating speeds, which could ensure the sufficient and adequate lubricating oil film to be formed and a stable elasto-hydro-dynamic lubrication could be further created during the operation period. The minimization of the temperature rise in bearings may be attained. Increasing air pressure contributed to the reduction in bearing temperature, but saturation might be appeared after the pressure level reached to a certain extent. The dynamic response measurement shows that this prototype spindle has an overly large vibration and rotation unbalance on the radial plane, which highlights the unstable operation problem of the spindle. Therefore, it is necessary to improve the constructed procedures, such as design, manufacture, and assembly for further use, to enhance the operation performance of the spindle. The analysis, measurement and diagnosis procedures established in this study could be helpful to uplift the related techniques for precision machinery industry.
Machinability of Aluminum Nitride Ceramic Using TiAlN and TiN Coated Carbide Tool Insert
Authors: Reddy Moola Mohan , Gorin Alexander , Khaled Abou Ei Hossein A. , Sujan D.
Published: November 2013

This research presents the performance of Aluminum nitride ceramic in end milling using using TiAlN and TiN coated carbide tool insert under dry machining. The surface roughness of the work piece and tool wear was analyzed in this. The design of experiments (DOE) approach using Response surface methodology was implemented to optimize the cutting parameters of a computer numerical control (CNC) end milling machine. The analysis of variance (ANOVA) was adapted to identify the most influential factors on the CNC end milling process. The mathematical predictive model developed for surface roughness and tool wear in terms of cutting speed, feed rate, and depth of cut. The cutting speed is found to be the most significant factor affecting the surface roughness of work piece and tool wear in end milling process.
A Highly Efficient Activated Carbon by Chemical Activation Method for Adsorption of Paraquat (Toxin)
Authors: Rahman Md Mokhlesur , Awang Mohamed , Bintey Shajahan Mohosina , Razak Tariq Abdul , Yunus Kamaruzzaman
Published: November 2013

The optimum condition for preparing a highly efficient activated carbon has been investigated in this work. The effects of different activation temperatures on the pore structure and surface morphology of highly efficient activated carbon (AC) derived from waste palm shell by chemical activation method using phosphoric acid as activating agent were studied. For activation, different activation temperatures in the range of 550 °C-650 °C were carried out. Activated carbon with well developed pore size were produced at activation temperature of 600 °C for 2 hours. At this temperature the Brunauer , Emmett and Teller (BET) surface areas are 1287 m2g-1, the total pore volume for adsorption and desorption are 0.742 cm3 g-1. Scanning Electron Microscope also confirmed the porosity of the highly efficient activated carbon. Finally it was tested in vitro to determine its adsorbing capacity for paraquat as a toxin. For optimum adsorption ability of activated carbon for paraquat, 0.9% NaCl solution is the most suitable solvent. The paraquat preferentially adsorbed onto the activated carbon in NaCl solution. The adsorption ability of the activated carbon (the amount adsorbed) for paraquat observed to be 99.9 mg g-1.
Processing of CuZr Based Shape Memory Alloys
Authors: Biffi Carlo Alberto , Bassani Paola , Casati Riccardo , Vedani Maurizio , Tuissi Ausonio
Published: November 2013

In the present work an investigation on primary processing of CuZr based shape memory alloys is proposed. In particular, the study addresses the effect of hot rolling process on the properties of CuZr shape memory alloys, in which the addition of some elements, such as Cr, Co and Ni, is taken into account. These alloys are produced by means of vacuum arc melting furnace under non contaminating conditions. Considering the high reactivity of these alloys, due to Zr element, hot working was undertaken after sealing the ingot cigars in a stainless steel protective can. The characterization of the rolled alloys is performed using DSC in terms of evolution of martensitic transfor-mation temperatures. The analysis is completed with mechanical and the microstructure investigations by means of microhardness and scanning electron microscopy (SEM) observations, respectively. The main result of this work is the evaluation of hot workability property of this system, which can be improved by adding metallic elements to the binary CuZr intermetallic system. Moreover, interesting characteristics, such as high transformation temperatures, thermal stability and reduced thermal hysteresis, can be also improved by means of the addition of Ni and Co at the same time.
Effect of Copper on Tensile Strength Improvement of Al-Cu-SiCP New Composite
Authors: Maleque Md Abdul , Arifutzzaman A.
Published: November 2013

The composite materials with 2, 4 and 6 % Cu were developed using a noble stir casting method. Tensile test was conducted using universal tensile test machine according to ASTM-2002 (E8M-01) standard and the fracture surface was analysed using scanning electron microscope (SEM). The result showed that the ultimate tensile strength (UTS) was increased due to the percentage increment of Cu in the Al-Cu matrix. A significant change in UTS was observed from 2 to 4 % Cu whereas slight improvement was seen from 4 to 6 % Cu addition. The SEM micrograph of the fracture surface reveals that the cracks were propagated in the fibrous zone resulting from the initiation of micro voids between the matrix and particle interfaces. The number and size of dimples for 2% Cu were considerably lower and the facet features were noticeably higher than higher Cu content composition, whereas, the dimple and facet size and number for the 4% Cu are very close to the 6% Cu content composite which may play important role in the improvement of tensile strength. These findings tinted for the potential application of SiCp reinforced Cu influenced Al-Cu-SiCp composite for automotive engine components and other similar applications as well.
A Taguchi Design Study for Optimisation of Plasma Sprayed Hydroxyapatite Coatings
Authors: Hasan Md Fahad , Wang James , Berndt Christopher C.
Published: November 2013

Plasma sprayed hydroxyapatite coatings were deposited onto mild steel substrates. A Taguchi L9 design of experiment protocol was used to optimise the coating process parameters. The effect of three factors: (i) power and secondary gas flow rate (X1), (ii) powder feed rate and carrier gas flow rate (X2), and (iii) stand-off distance (X3) on the coating responses was studied. The responses of the plasma sprayed hydroxyapatite coatings were evaluated in terms of porosity, deposition efficiency, microhardness, crystallinity, and surface roughness. A regression analysis established relationships between process parameters and responses. Higher power, lower powder feed rate and the middle stand-off distance of 11 cm lead to optimum attributes of low porosity, high deposition efficiency, high microhardness, high crystallinity, and high surface roughness.
Hydroxyapatite and Titanium Composite Coatings on Austenitic Stainless Steel Substrates Using Direct Material Deposition
Authors: Mansur Muhammad Rakib , Wang James , Berndt Christopher C.
Published: November 2013

Hydroxyapatite (HA) and titanium composite coatings, which demonstrate good biocompatibility and load bearing capacity, are important in the topical area of prosthetics. In this study, hydroxyapatite and titanium composite coatings were deposited on austenitic stainless steel (316L) substrates using the Direct Material Deposition (DMD) technique. The microstructures were characterized using optical microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Surface topography and roughness were assessed by SEM and profilometry, while Raman microscopy was employed to determine the nature of HA in the feedstock. The results indicate that average roughness increases with traverse speed and depends significantly on the power level. The crack orientation was found to be sensitive to traverse speed, while the number of cracks was related to the power level. Porosity decreased as the power level increased.
AFM and Ellipsometry Studies of Ultra Thin Ti Film Deposited on a Silicon Wafer
Authors: Lin Bing Jing , Zhu Hong Tao , Tieu A. Kiet , Triani Gerry
Published: November 2013

An ultra- thin Ti film with a thickness of less than 30 nm was deposited on the surface of a silicon wafer by the filtered arc deposition system. A novel technique was adopted to create a height step between the coated area and non-coated area (silicon wafer) during deposition. The surface morphology and thickness of the film was detected by atomic force microscopy (AFM). The AFM results showed that the deposited film formed a smooth structure on the silicon wafer and the height step between the coating and silicon wafer was clear enough to give the thickness of the deposited film. The composition of the deposited film was detected by a combined use of Ellipsometry and AFM. Natural oxidisation of Ti (TiO2) was found on the top of the Ti film after deposition, and the thickness of TiO2 was determined by ellipsometry to be about 0.6 nm.
Compaction Effect of Granular System with Parameters Changed
Authors: Li Xiao Peng , Zhao Guang Hui , Liang Ya Min , Ju Xing , Wang Quan Bin , Xin Li Li
Published: November 2013

In this work, the numerical equation has been established to simulate the vibratory compaction system based on the hysteresis loop of Davidenkov and with the gap ignored between the piston and the materials, and the dynamical characteristics and influence of parameters on the vibration compaction effect were analyzed with different stiffness, damping, amplitude and mass. Two types of experiments were carried out to study the dynamical characteristics and validate the numerical analysis and simulation. The first type of experiments was done with the different exciting vibration amplitude. The second type of experiments was done with the different water saturation instead of the stiffness and damping. The numerical and experimental results show that the equivalent natural frequency and vibration amplitude of the system increased with the stiffness, exciting amplitude increased and damping decreased. The experimental results agree well with results from a theoretical model in general. The research results will be used in intelligent granular compaction in the future.
Finite Element Analysis and Mold Design of Forging Process of Highway Bicycle Pedal
Authors: Chen Dyi Cheng , Chen Wen Jong , Hong Tai Lin , Chen Sheng Han , Lin Yi Xiang , Tsai Ming Jer
Published: November 2013

Forging is a simple and low-cost mass production process. Metallic materials can be processed using plastic deformation. This research analyzes an innovative forging mold design for the highway bicycle pedal. A series of simulation analyses in which the variables depend on various temperatures of forging billet and mold, friction factors, and forging speed show effective stress, effective strain, and die radial load distribution for a forging process and mold design of a highway bicycle pedal. Finally, we identify the results of simulation analyses with the design of an experimental forging mold to lower deformation behavior of a highway bicycle pedal. The analysis results provide highway bicycle pedal forming mold references to identify whether it is suitable with the finite element results for high-strength mold design.
Residual Stress Characterization of Electroformed Ni-Base Alloy for μ-Gear Mold
Authors: Son Seong Ho , Park Sung Cheol , Kim Hyeong Mi , Lee Won Sik , Lee Hong Kee
Published: November 2013

The micro gear molds for powder injection molding were fabricated by electroforming process of Ni-Fe alloys. The residual stress at interface between electrodeposit and substrate was important for micro electroforming. Addition of 6 g/L saccharin lowered residual stress from 466.3 MPa up to 32.8 MPa and increase of Fe content resulted in increase of residual stress. Electrodeposition by pulse current decreased residual stress in deposit although Fe content was increased. These results reveal clearly that decrease of residual stress due to pulse current is larger than increase of residual stress due to higher Fe content. The micro electroformed gear molds with 550 μm and 2,525 μm in outer diameter and 400 μm in height were fabricated by micro electroforming and 316L feedstock was injection-molded into micro molds. As a result, it is suggested strongly that micro electroforming is very useful process to manufacture micro mold with high dimensional accuracy for micro PIM.
Circular Cup Drawing of Magnesium Alloy Sheet under Cold Condition Using Rubber Tool and Improvement of Surface Appearance
Authors: Yamashita Minoru , Hattori Toshio , Kuwahara Koji
Published: November 2013

In order to accomplish the circular cup drawing of the sheet material whose ductility is extremely poor under the cold forming condition, the Maslennikov's technique was applied. A deformable rubber ring was used instead of the hard punch. Test material was magnesium alloy AZ31-O sheet. Small die profile radius was applied, which was twice or 4 times of the sheet thickness. A semisolid lubricant was used for the lubrication of the blank - die interface, on the other hand, the rubber - blank interface was degreased to increase friction. The limiting drawing ratio of 1.31 was attained. A peculiar fracture mode arises, where the material suddenly fractured with crack evolution emanating from the flange periphery. The fracture strain is found approximately equal to the work hardening exponent n-value in plastic property. Another kind of crack arose in the circumferential direction of the cup during unbending process with smaller die profile radius. To decrease the scratched lines of the cup surface caused by very high sliding contact pressure to the die, high-speed drawing was tested using a drop-weight. The surface was improved, because the material - tool contact was successfully prevented by the hydrodynamic lubrication film.
Thin Strip Profile Control Capability of Roll Crossing and Shifting in Cold Rolling Mill
Authors: Aljabri Abdulrahman , Jiang Zheng Yi , Wei Dong Bin , Wang Xiao Dong , Tibar Hasan
Published: November 2013

Controlling cold strip profile is a difficult and significant problem has been found in industry during thin strip rolling. At present choosing the new type of strip rolling mill is the one of main methods to control the strip shape quality in cold rolling. The influences of rolling process parameters such as the work roll cross angle and work roll shifting on the strip shape and profile of thin strip are recognised throughout this study. The results show that the roll crossing and shifting is efficient way to control the strip shape. The increase of the work roll crossing angle would lead to improve the strip profile significantly by decreasing the exit strip crown and edge drop. The strip profile would be enhanced if the axial roll shifting was increased. Moreover, the total rolling force was analysed in detail by changing the roll cross angle and axial shifting roll.