bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterojunction Properties of p-CuO/n-CdS Diode
Authors: Gaewdang Thitinai , Wongcharoen Ngamnit
Published: April 2015

In this paper, p-CuO/n-CdS heterojunction was prepared by thermal evaporating CdS thin films on CuO 1 mm thick ceramic pellet substrate. The electrical properties of p-CuO/n-CdS heterojunction were investigated by forward current–voltage–temperature (I–V–T) characteristics in the temperature range of 100-300 K. The junction barrier height, ideality factor, and the series resistance values of the diode evaluated by using thermionic emission (TE) theory and Cheung’s method are 0.566 eV, 5.535 and 618.24 Ω at 300 K, respectively. The junction barrier height, ideality factor and series resistance were found to be strong temperature dependence. In part of C-V measurements at room temperature, the obtained built-in potential value being 0.538 V is well consistent with the junction barrier height value evaluated from I-V measurements
Effect of CW-CO2 Laser Evaporation Parameters on Structural and Physical Properties of ZnSe Film
Authors: Phae-Ngam Wuttichai , Sansomboon Arthit , Kumpeerapun Taswal , Kosalathip Voravit
Published: April 2015

ZnSe thin films were deposited onto glass substrates by CW-CO2 laser evaporation with the various evaporation times and laser power. SEM studies showed that the thicknesses of deposited films were varied from 176 nm to 1824 nm. AFM studies showed that the surface roughnesses were varied from 2.4 nm to 5.1 nm. The structure of deposited films were indicated by XRD technique which the result showed the cubic structure. The average crystallite sizes were calculated from the XRD pattern with ranged between 23.8 nm and 31.7 nm. The transmission spectates were ranged from 250 nm to 900 nm. The values of the optical bandgap energies determined from the absorption spectra were ranged between 2.61 eV and 2.88 eV. This paper presents the simple and low cost technique for ZnSe film deposition. Another advantage of this research is the high-precision control of thickness by the variation of the evaporation time and laser power.
Technological Processes Automation of Chemical Heat Treatment at Industrial Enterprises
Authors: Ostroukh Andrey , Mavrin Andrey , Surkova Nataliya
Published: April 2015

This paper presents analysis of chemical and thermal processing (CTP) methods to support multi-component gas atmosphere processes and their mathematical models as objects in the automated process control system (APCS). CTP mathematical models, algorithms, interaction structures and concepts of APCS components based on a specialized electronic controller have been proposed and implemented. The system provides a time control of all the necessary gas atmosphere parameters – its composition, temperature, pressure, with the possibility of using saturating medium of up to four components. Implementation of the system will improve the service properties of processed products, reduce the rate of spoilage and the psychophysical stress of the production staff, as well as reduce the overall CTP time.
Compatibility of Elastomers in Biodiesel-Diesel-Bioethanol Blend (BDE)
Authors: Thangavelu S.K. , Piraiarasi C. , Ahmed A.S. , Ani Farid Nasir
Published: April 2015

The present study aims to investigate the impact of biodiesel-diesel-bioethanol (BDE) blended fuel on the degradation behavior of elastomers such as nitrile rubber (NBR) and polytetrafluroethylene (PTFE). Static immersion test in B20D75E5 blends (20% biodiesel, 75% diesel and 5% bioethanol) at 50°C for 200 h was carried out. At the end of immersion test, degradation behaviour of elastomers was investigated by measuring mass, volume and hardness. The exposed surface of elastomers was studied using optical microscope (OM). Fourier Transform Infrared (FTIR) spectroscopy was carried out to identify the chemical and structural changes in the elastomers. Moreover, physical and chemical characteristics of the fuel blend after the immersion test such as total acid number (TAN), density and colour change were also investigated. Results showed that the degradation of NBR was high compared to PTFE.
Preparation and Properties of Yttrium Doped Barium Cerate (BaCe1-xYxO3-δ)
Authors: Magdaluyo Eduardo R. , Gapasin Jomyr E.
Published: April 2015

Yttrium doped barium cerate is considered a promising electrolyte material for solid oxide fuel cell applications due to its excellent proton conductivity. The proton conductivity characteristics of the ceramic material can be influenced by the different synthesis processing parameters. This study aimed to obtain yttrium doped barium cerate BaCe1-xYxO3-δ (x = 0.15, 0.20) using a sol-gel modified Pechini method. The phase formation and surface morphology of the yttrium doped barium cerate were investigated using x-ray diffraction and scanning electron microscopy. The thermal decomposition of the calcined ceramic material was examined using thermogravimetric analysis. Diffraction analysis confirmed the formation of perovskite crystalline structure with the presence of secondary phase yttrium doped ceria. Larger grain size with homogeneous distribution and coalescence was observed in the sintered BaCe0.80Y0.20O3-δ.
Synthesis of Yttrium-Doped Barium Zirconate/Barium Cerate (BZY20/BCY20) Core-Shell Structured Proton-Conducting Solid Electrolyte via Modified Pechini Method
Authors: Balanay Mary Jozen , Cervera Rinlee Butch M.
Published: April 2015

Intermediate temperature solid oxide fuel cells (IT-SOFCs) operating at 400-700°C utilizes proton conducting electrolytes and are now being one of the focus of many research studies with regards to efficient, clean power sources and energy conversion. Potential electrolyte materials include acceptor-doped barium zirconates and barium cerates. In this study, preparation of a core-shell structured proton-conducting solid electrolytes of 20 vol% BaZr0.8Y0.2O3-δ (20BZY20) for the core and 80 vol% BaCe0.8Y0.2O3-δ (80BCY20) for the shell is done by wet chemistry route. The synthesized core-shell structured material (20BZY20/80BCY20) is developed to possibly address the problem of high grain boundary impedance of Y-doped BaZrO3 and low chemical stability of Y-doped BaCeO3. The obtained samples were characterized for its structure, thermal stability, morphology and elemental distribution of the material. At a lower sintering temperature of 1150°C, a densified pellet was obtained as observed by SEM analysis. The diffraction pattern of 20BZY20/80BCY20 powder shows two distinct phases corresponding to BZY20 and BCY20 suggesting a successful synthesis of the core-shell solid electrolyte.
Fatigue Behavior of Aerospace Al-Cu, Al-Li and Al-Mg-Si Sheet Alloys
Authors: Alexopoulos Nikolaos D. , Migklis Vangelis , Kourkoulis Stavros K. , Marioli-Riga Zaira
Published: April 2015

In the present work, an experimental study was performed to characterize and analyze the tensile and constant amplitude fatigue mechanical behavior of several aluminum alloys, namely 2024 (Al-Cu), 2198 (Al-Li) and 6156 (Al-Mg-Si). Al-Li alloy was found to be superior of 2024 in the high cycle fatigue and fatigue endurance limit regimes, especially when considering specific mechanical properties. Alloy 6156 was found to have superior constant amplitude fatigue performance that the respective 6xxx series alloys; more than 15% higher endurance limit was noticed against 6061 and almost 30% higher than 6082. Alloy 6156 presented only a marginal increase in fatigue life for the HCF regime.
Hybrid Evolutionary Optimization Algorithm for Structures
Authors: El Hami Norelislam , Itmi Mhamed , El Hami Abdelkhalak
Published: April 2015

In the structure problems, the randomness and the uncertainties of the distribution of the structural parameters are a crucial problem. In the case of optimization of structure, the objective is to play a dominant role in the structural optimization problem introducing the reliability concept. The optimization of the initial structural cost under constraints imposed on the values of elemental reliability indices corresponding to various limit states. In this paper we use a new optimization method for a modified particle swarm optimization algorithm (MPSO) combined with a simulated annealing algorithm (SA). MPSO is known as an efficient approach with a high performance of solving optimization problems in many research fields. It is a population intelligence algorithm inspired by social behavior simulations of bird flocking. Numerical results show the robustness of the MPSO-SA algorithm.
Simulation and Optimization of an Actuator
Authors: El Hami Norelislam , Itmi Mhamed , El Hami A.
Published: April 2015

This paper presents a new methodology for the Reliability Based Particle Swarm Optimization with Simulated Annealing. The reliability analysis procedure couple traditional and modified first and second order reliability methods, in rectangular plates modelled by an Assumed Modes approach. Both reliability methods are applicable to the implicit limit state functions through numerical models, like those based on the Assumed Mode Method. In modified approaches, the algorithms are based on heuristic optimization methods such as Particle Swarm Optimization and Simulated Annealing Optimization. Numerical applications in static, dynamic and stability problems are used to illustrate the applicability and effectiveness of proposed methodology. The results of example show that the predicted reliability levels are accurate to evaluate simultaneously various implicit limit state functions with respect to static, dynamic and stability criterions.
3D Remeshing Simulation of Aluminum Foams Behavior under Static Load
Authors: Zhu Shi Jie , Cherouat Abel , Borouchaki Houman , Gong Xiao Lu
Published: April 2015

The compression characteristics of open-cell aluminum foams were experimentally and numerically investigated. It is found that the mechanical parameters, such as collapse stress and absorbed energy, are dependent on the porosity of aluminum foams. Three macroscopic models were chose to predict the compression behavior of open-cell foams. During simulation of metal foam compression, the finite elements distort severely at the local regions with high gradient of physical field such as stress, strain due to these problems. The procedure integrates Explicit solver of ABAQUS, OPTIFORM mesher and python script program transfer to execute step by step the incremental deformation process. At each step, the meshes are refined and coarsened automatically based on geometrical and physical error estimations; the physical fields are transferred from old to the new one using advanced algorithm.
Analysis of the Hydroforming Process Using Metamodels
Authors: El Hami Abdelkhalak , Radi Bouchaib
Published: April 2015

In this paper, an original method is presented for evaluating the probability of failure in a precise manner in the tube hydroforming process (THP). This process consists to apply an inner pressure combined to an axial displacement to manufacture the part. During the manufacturing phase, inappropriate choice of the load paths can lead to failure. Our approach is to determine the space failure probability for each item in the area is critical. It is defined by identifying the critical element, and then a patch is defined on this item that represents the area of the most probable failure. The identification of the critical element for each failure mode is done by reference the state of strain on the forming limit curve (FLC) of the material. Access to the probability of space failure allows to give an idea on the stability of the process and also to predict the most likely area where plastic instability can appear. The failure probability estimation based on a characterization probabilistic principal strains (major and minor) for each failure mode and for each element. Access to this probability of failure in a direct manner is impossible given the complexity of the treated problem and the huge number of calculations by finite elements necessary. To compensate for this problem, approximation techniques have been used to replace the real model by metamodel that enables to evaluate the response quickly and allows us to get an idea on the stability of the process.Keywords: Hydroforming process, metamodels, random, forming limit curve (FLC), failure mode, finite element.
Weldability of Superalloys Hastelloy X by Yb: YAG Laser
Authors: Graneix Jeremie , Beguin Jean Denis , Alexis Joël , Masri Talal
Published: April 2015

Hastelloy X is a commercially available nickel-chromium-molybdenum superalloy with a good oxidation resistance, a good mechanical properties at high temperature and a significant formability; sine qua criteria for the choice of materials for the production of chambers turbojet combustion which is part of this study [1]. Arc welding technique is commonly used for the manufacturing of parts but the aeronautical requirements becoming increasingly severe especially in terms of reproducibility of geometry and metallurgical grade fillet weld. Laser welding is a viable method of assembly to meet these new demands by its automation to replace longer term the manual TIG welding. The high power CO2laser is extensively used for practical applications such as cutting and welding laser welding. The CO2laser is very used in the industry with regard to Yb:YAG laser which until now was not rather powerful but this changes. The aim of this study was to evaluate the effect of Yb:YAG laser beam parameters on the microstructure and mechanical properties of the laser beam welded superalloys Hastelloy X to define a field of weldability. The implementation of an experimental design approach is required due to the multitude of input parameters and the complexity of the phenomena involved [2-3].
The Influence of Formula and Process on Physical Properties and the Release Profile of PVA/BSA Nanofibers Formed by Electrospinning Technique
Authors: Risdian Chandra , Nasir Muhamad , Rahma Annisa , Rachmawati Heni
Published: April 2015

Electrospinning is a simple versatile process to produce nanofibers. However, it requires careful approach to form appropriates fibers for different purposes. This report describes aspects influencing successful development of nanofiber containing BSA using electrospinning method. Optical and scanning electron microscopy, energy dispersive X-Ray and Fourier transformed infrared spectroscopy, differential scanning calorimetric, and X-Ray diffraction analysis of nanofiber were performed. Modification of PVA/BSA nanofiber with Eudragit L-100 was conducted by dip coating method. The presence of BSA increased the diameter of the fibers. Modification of PVA/BSA nanofiber with Eudragit L-100 delayed the release of BSA in acidic medium but promoting its release in intestinal mimicking medium.
Effect of Carrier Gas Flow Rate on In2O3 Nanostructure Morphology and Growth Mechanism
Authors: Zhang Li , Xia Huan , Qiu Chen , Jiang Jian Jun , Bie Shao Wei
Published: April 2015

The effect of carrier gas flow rate on the morphologies of In2O3 nanostructures was studied in a horizontal tube furnace via chemical vapor deposition method. Under low carrier gas flow rate, there appeared randomly oriented nanorods on the substrate, while the high carrier gas flow rate resulted in the nanocubes growth. The insufficient understanding of the role of the argon carrier gas flow rate motivated us to systematically research the transportation of the grown species during the growth processes and its effect on the nanostructure growth. COMSOL simulations were applied to evaluate the distribution of the growth species in the reactor versus the carrier gas flow rate, based on the geometry of our chemical vapor deposition system and a variety of actual growth conditions. The vapor species partial along with different carrier gas rate could cause the different super saturation condition, which is mainly to be responsible for the structural transformation. A combined VLS–VS mechanism was proposed to describe the growth of the Au-catalyzed In2O3 nanorods, while the nanocubes were governed by catalyst free VS growth mechanism.
Unsupervised Gabor Filter-Bank Method for Characterization of the Self-Assembled Hexagonal Lattice
Authors: Pourfard Mohammadreza , Faez Karim , Tabaian S. Hadi
Published: April 2015

In this paper a new robust and precise ordering criterion for the characterization of self-assembled hexagonal lattice like Anodic aluminum Oxide (AAO) has been proposed. In order to unveil the mechanism for the self-organization process and deposition techniques in AAO, it is necessary to be able to have a quantitative objective criterion to evaluate the amount of order through every SEM sample of a material. Most of methods in the literature are only able to characterize the extreme case of highly ordered or lowly ordered texture well. But the real challenge is in characterizing the order of medium-ordered texture which is the dual concept of near-regular texture analysis in image processing. Our method based on more advanced image processing techniques, Gabor filter-bank, are able to characterize medium-ordered AAO textures more precisely. Our idea is also able to define the domain's place of the AAO image.
The Role of the Deformation Conditions in the Evolution of the Microstructure of the Ti-6Al-2Sn-4Zr-6Mo Alloy
Authors: Krawczyk Janusz , Łukaszek-Sołek Aneta , Dąbrowski Robert
Published: April 2015

This work discusses the influence of the processing temperature, time and processing strain on the microstructure of the Ti6Al2Sn4Zr6Mo alloy. The Ti6Al2Sn4Zr6Mo alloy belongs to the two-phase (α+β) type of titanium alloys. The samples were compressed with the use of the Gleeble thermo-mechanical simulator at the temperatures of: 800, 900, 950, 1000 and 1100°C and at the strain rates of: 0.01; 0.1; 1; 10 and 100 s-1 to a total true strain of 1. The occurrence of the primary α phase in the Ti6Al2Sn4Zr6Mo alloy was investigated. The diagram showing the influence of the processing temperature and the strain rate on the dynamic recrystallization of the β phase was presented.The occurrence of the primary α phase precipitates blocks the grain growth. Therefore, the plastic deformation of this alloy should be carried out at a temperature at which the separation of the primary α phase occurs to finally obtain a material with a fine grain.
Influence of Process Parameters on Cooling Conditions in Nickel Base Superalloy Investment Casting
Authors: Nawrocki Jacek , Szeliga Dariusz , Kubiak Krzysztof , Matysiak Hubert , Motyka Maciej , Ziaja Waldemar
Published: April 2015

The published results of the research on crystallization process of nickel base superalloy castings rarely take into account the effect of the wall thickness of the casting. Current study presents a comprehensive assessment of the impact of molten alloy temperature, mould temperature, mould thermal insulation and casting diameter on crystallization process of polycrystalline nickel base superalloy. Research was designed and conducted as an factorial experiment at two levels. Different diameter samples were designed and optimised by the numerical simulation of solidification process using ProCAST software. Inconel 713C nickel based superalloy was cast into alumina-silicate moulds produced by lost wax technique. Casting temperature during solidification was measured using thermocouples installed in sections having a diameter of 10 and 20 mm. Statistical analysis of the influence of the main process parameters and casting diameter on cooling rate, total freezing temperature range and critical temperature range was performed. Cooling rates in the range from 0.21 to 1.24°C/s were obtained. It was found that diameter of the casting, mould temperature and the thermal insulation of the mould had significant effect on the cooling rate.
The Influence of Microstructure of Medium Carbon Heat-Treatable Steel on its Tribological Properties
Authors: Dziurka Rafal , Madej Marcin , Kopyściański Mateusz , Malyszko Mateusz , Dziadosz Magdalena
Published: April 2015

The hereby work presents the influence of microstructure on the tribological properties of medium carbon heat-treatable steel. These steel is used for various elements of which in addition to high wear resistance a high plasticity is required. For tested steel there different heat treatments were performed in order to obtain the different microstructure and properties. Each sample was hardened from the same temperature, which has been selected on the basis of standards for these steel and it was equal 890 °C. Two samples were quenched after austenitising in water. After quenching one of the samples was cooled in liquid nitrogen for 30 minutes (sub-zero treatment). After that these two samples were tempered in the preheated furnace at 200 °C for 2 hours. The third sample immediately after austenitising was quenched in mixture of molten salts heated to 200 °C (fused salt quenching). After these three carried out heat treatments the various microstructures were obtained with preserved high hardness. After heat treatment samples for the tribological test were prepared. The test was performed using the T-05 type roll-block test machine. This type of test machine is used to obtain the resistance to friction wear of metals and others. Thanks to these tribological tests and mass loss measurements the best heat treatment, which significantly increase of the wear resistance for tested steels was indicated.
Processing Maps of the Ti-6Al-4V Alloy in a Forging Process Design
Authors: Łukaszek-Sołek Aneta , Krawczyk Janusz
Published: April 2015

The paper presents the results of a complex study of the Ti-6Al-4V alloy, conducted with the application of the dynamic material modelling (DMM) method, in a wide range of temperatures, strain rates and strains. A compression test was carried out in a wide range of temperatures (800 – 1100°C) and strain rates (0.01 – 100 s-1), up to the constant final true strain value of 0.9. The obtained stress-strain curves were a basis for determining deformation activation energy with the use of an Arrhenius plot and a correlation between the Zener-Hollomon parameter and flow stress, for which the constitutive equation proposed by Sellars was used. The power dissipation efficiency parameter was calculated. The maps of power dissipation as the function of temperature and strain rate were plotted in the form of the isoclines of the power dissipation efficiency parameter expressed in %. The processing maps exhibited the range of occurrence and recrystallization of the primary α phase, the degree of the β phase recrystallization progress against the background of the process deformation windows and instability flow domain. An analysis of the influence of process parameters up on the microstructure and hardness changes was conducted.
Burnishing of Aluminium Alloy Surface Using Diamond Matrix Composite Tools
Authors: Szutkowska Magdalena , Toboła Daniel , Czechowski Kazimierz
Published: April 2015

To make the most of unique properties of diamond and to diminish an influence its disadvantageous properties new diamond tool composites with ceramic bonding phase (MAX) has been proposed. Ti3(Si,Ge)C2 and Ti3SiC2 were produced by self-propagating high temperature synthesis (SHS). 3-6 µm (MDA, De Beers) diamond powder was mechanically mixed with 10 wt% Ti3(Si,Ge)C2 or 30 wt% Ti3SiC2, pressed and the compacts were sintered at 1962 °C at 8.0 GPa in a Bridgman-type high pressure apparatus. These mechanical properties were determined: Vickers hardness HV1, Young’s modulus, tensile strength, fracture toughness and wear resistance.Microstructure and phase composition were studied by scanning and transmission electron microscopy and X-ray and electron diffraction techniques. To improve the final quality of the AlCu4MgSi(A) alloy, balls of diamond-new composites were incorporated into the burnishing tools. The influence of burnishing parameters, such as burnishing force and feed, on surface geometry parameters were measured and profilograms of the surface roughness recorded.
Research into the Impact of Magnesium Content in the AlSi7Mg Aluminum Cast Alloys on the Strength and Electrical Properties of the Material after Different Parameters of Heat Treatment Operations
Authors: Wiecheć Justyna , Uliasz Piotr , Knych Tadeusz , Tatarczuch Jakub
Published: April 2015

The continuous development of manufacturing processes and techniques in the production of cast aluminum alloy products is possible due to research into casting materials and technologies as well as analyses of the impact of technological factors on the operational parameters of products. A novelty of recent years are the aluminum casting alloys, which are used for carrying electric power in high-voltage Gas Insulated Switchgears - GIS and in elements of hardware for transmission and distribution lines. Casting aluminum alloys occurring in the European standardization are primarily intended for mechanical application and, for this reason, the value of their electrical conductivity is generally omitted or given only for indication. Therefore, there is a justification for undertaking research into the development requirements for the group of alloys, for which electrical properties will be the primary criterion for qualitative acceptance. Hence, the aim of this work is to determine optimal addition of magnesium and heat treatment parameters of AlSi7Mg aluminum cast alloys, in order to achieve the most favorable set of electrical and mechanical properties.
Corrosion Resistance and Tensile Property of Al-Coated Mg-Li Alloy Produced by Hot Extrusion
Authors: Tomita Kaho , Matsuura Kiyotaka , Ohno Munekazu , Tokunaga Toko , Wu Rui Zhi , Zhang Mi Lin
Published: April 2015

Al-coated Mg-Li alloy rods and plates having a homogeneous coating layer of 180μm in thickness have been produced by hot extrusion of Mg-Li alloy billets together with Al disks. The Al-coated Mg-Li alloy exhibits an excellent corrosion resistance in a weight-loss test with a 0.5 mass% HCl aqueous solution, and it has been revealed by a potentiometric corrosion test with a 3 mass% NaCl aqueous solution that the Al-coated Mg-Li alloy has the same electric potential as that of pure Al. Al-coated Mg-Li alloy sheets produced by hot forging of the extruded plates exhibits good elongation of 22 %, 40 % and 130 % at room temperature, 200 °C and 300 °C, respectively.
Thermal Effects of Mechanical Polishing and Conditioning on Polishing Pads
Authors: Tsai Hung Jung , Chuang Chia Hao
Published: April 2015

Polishing process is a primary technique for planarization of material surface in manufacture fabrication. The pad structure and its material properties are important to determine the polish rate and planarity that can be achieved by the polishing process. Besides, the pad conditioning is used to regenerate the surface of the polishing pad surface by breaking up the glazed areas. Because the polishing and pad conditioning mechanism is inadequately understood and because higher levels of pad polishing performance are desired, the investigation of experiment becomes more important.In this paper, a high precision polishing machine has established. With an improved design, a test rig can be easily used to simulate the polishing, pad conditioning process and acquire the signals of temperature. The temperature of test pads (i.e. Rodel IC1000A, Rodel IC 1000B and Opetech SB 660) is measured during polishing and pad conditioning process. For the self-design test rig, its surface temperature is measured by T-type thermocouples screwed behind the polishing (or conditioning) interface of the carrier. The experimental results provide a temperature index to end-point-detection and contribute to understanding of the mechanism on polishing pads.
Effect of Castor Oil and Biodiesel on Tribological Performance of Engine Oil
Authors: Lin Yuan Ching , Shen Tsung Yi , Hsieh Ming Jhe , Ku Yong Yuan , Lin Ke Wei
Published: April 2015

This study aims to investigate the effects of castor oil and biodiesel on the tribological performance of engine oil. Five mixed types of engine oils (B0, B5, B100, 5B-5% and 10B-5%) were used as the testing oils. Tribological performance of the test oil was evaluated under different temperature and duration by Cameron Plint TE77 reciprocating rig. SEM, EDS and AES/XPS were separately to characterize the morphology of worn surface and indentify the composition of the surface films. The results show that the anti-wear ability of the engine oil mixed with castor oil is better than that of the engine oil mixed with biodiesel oil. At room temperature, the anti-wear ability of engine oil is dominated by the physical adsorption capacity and hydrodynamic effects; while at high temperature, the anti-wear ability of engine oil is depend on the moment of decomposition of ZDDP additive and its chemical reaction rate.
Effects of Aluminum Content on Oxidation Behavior of W-Al Nanolayer Coatings
Authors: Yao Shun Hui , Hung Shang Hsien , Su Yen Liang , Kao Wen Hsien , Lin Yueh Feng
Published: April 2015

A series of W-Al nanolayer coatings were deposited with varying content of aluminum from 0 at.% to 65 at.% by a unbalanced magnetron (UBM) sputtering system. The as-deposited coatings were investigated first. Then, the coatings were oxidized aiming to study their oxidation behavior. SEM, TEM, XRD, GDOS and nanohardness tester were used. The results showed that the Al content had a significant effect on the performance of W-Al coatings. The hardness of as-deposited and oxidized coatings decreased with increasing Al content. The pure W coating was heavily oxidized. As the Al content increased, the oxidation decreased fast and then remained stable as the Al content was higher than 45at.%. The effects of formed oxides on hardness were discussed.
Tribological Properties and Nanomechanics of Cu-BTA Composite Nanooils
Authors: Kao Mu Jung , Hsu Fu Chun
Published: April 2015

This project investigated the tribological properties and nanomechanics of Cu-benzotriazole (BTA) composite nanooils. Cu-BTA nanoparticles were synthesized by a thermal decomposition process. Cu-BTA nanoparticles were added into paraffin oil to form the nanooils. Cu-BTA explores the nanomechanics of sphere geometry functions as a rolling medium for friction lower. BTA nanoparticles functions as a protector from oxidation of the Cu nanoparticles in various test circumstances. Tribological experiments were conducted using a pin-on-disk (ASTM G99) test for the wear scar diameter, friction coefficient, and morphology of worn surfaces. The experiment results revealed the dispersion capability of the benzotriazole-capped Cu nanoparticles and indicated the dispersing stability in liquid paraffin oil for the BTA-capped surface of Cu nanoparticles. The testing results show that the Cu-BTA nanoparticle used as an additive in paraffin oil at an appropriate concentration exhibits better tribological properties than those of pure paraffin oil. Cu-BTA functioning as an additives have different anti-wear abilities due to its small size effect and a high absolute viscosity given high Herser number, corresponds to relatively thick lubricant film and an larged elastohydrodynamic lubrication area. A thin film or powder consisting of spherical Cu-BTA nanoparticles on pin-on-disk (ASTM G99) test iron surface protests against damage from relative rolling movement, which reduces friction and wear.
Mechanical and Tribological Properties of W(100-x)%Cx% Coatings Deposited by DC Magnetron Sputtering
Authors: Su Yean Liang , Lin Yueh Feng
Published: April 2015

W(100-x)%Cx% coatings with different tungsten and carbon contents were deposited by unbalanced magnetron sputtering. The microstructures and mechanical properties of the W(100-x)%C x% coatings was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), nanoindentation and adhesion testing techniques. The tribological performance of the coatings was investigated using a pin-on-disc trobometer under dry conditions. Experimental results indicated that coating microstructure, mechanical properties and wear resistance varied according to the tungsten and carbon contents of the coatings. The W72%C28% coating had the highest hardness/elastic modulus (H/E) ratio. In the ball-on-disc wear tests, it was found that the W72%C28% coating exhibited the best wear resistance.
Study of Friction and Wear Behavior of C/C Composite under Electrical Sliding
Authors: Bao Shang Guan , Wang Yi Fan , Yang Zhen Hai , Zhang Yong Zhen , Chen Yue , Jia Li Xiao
Published: April 2015

Using C/C composite and chrome bronze as a friction couple, the frictional wear properties of C/C composite with electric current is studied in this paper. The results have shown that current, velocity and load are important factors to affect the frictional wear properties of C/C composite with electric current. Wear rate of C/C composite increases with the increase of arc energy .The coefficient of friction and the wear rate increase with the increase of velocity when the electric current is constant of 100A. The coefficient of friction increases but the wear rate decreases with the increase of load when the electric current is constant at 100A. The coefficient of friction decreases but the wear rate increases with the increase of current when the load is constant of 80N. Comparing with no electric current, the coefficient of friction of C/C composite with electric current decreases but the wear rate of that increases obviously. The wear mechanism of C/C composite is mainly of electric wear caused by arc erosion under the condition of current-carrying.
Analysis of Sliding Friction for Surface with Micro-Scale Circumferential Grooves
Authors: Wang Hsin Chih , Tsai Jhy Cherng
Published: April 2015

Friction is a crucial issue for the performance of a machine with sliding mechanism. While the sliding surface is often manually scraped to improve its tribological properties, the quality is not stable nor the efficiency of the scraping process. This study investigated the influences of micro-scale circumferential grooves on the frictional characteristics of a sliding surface through theoretical analysis and numeric simulations. The study found that sliding surface with micro grooves can reduce the friction, compared to plain surface. An in-depth analysis indicated that the slider with micro-scale grooves was uplifted when it slides, thus reduced the sliding friction. Moreover, as the amount of lubricant collected on the grooves increased, the friction force decreased with time and approached a stable condition.
The Study of Band Sawing Vibration and Cutting Performance
Authors: Wei Chin Chung , Chung Hsiao Yen , Zhang Jian Bin
Published: April 2015

Band saws machine is the most efficient metal cutting machine. By losing less material, material qualitative, having big saw range and having low cutting costs are superiority of band saws. Band saws are acting with most long route and more limited support point in all cutting tools. In band sawing machine, band saws and structure are easy to produce vibration. Affect cutting life, costs of band saws and material surface topography. So this study focuses on analyzing what is vibration cause of band saws by vibration source and establishes the relationship between band saws natural frequency along and change cutting condition. In this research use the C-430GNC band saws machine, and use S45C material for cutting test. Accelerometers are used with a measurement system to capture sawing vibration data. By the fast Fourier transform to analyze spectrogram transform in order to identified characteristic spectrums, and find out vibration feature with band sawing operating conditions and unusual evens came from wear of blade. Minimum cutting vibration and best surface topography were compared to find out the best cutting condition.
Effects of Tungsten Addition on Mechanical and Tribological Properties of Carbon Nitride Prepared by DC Magnetron Sputtering
Authors: Su Yean Liang , Lin Yueh Feng , Yao Shun Hui , Hsu Chia Jui
Published: April 2015

Carbon nitride coatings doped with tungsten were deposited on high speed steel disks by unbalanced DC magnetron sputtering using nitrogen-argon mixture gas. The coatings were deposited on three different types of interlayer (Ti, Ti/TiN and Ti/TiC), and the tungsten target current was varied from 0 to 0.9 A. Surface morphology of the coatings were measured by roughness testing and scanning electron microscopy (SEM). In addition, the chemical composition and depth profile were analyzed by X-ray Diffraction (XRD) analysis, Raman spectroscopy, and glow discharge spectroscopy (GDS). Finally, the hardness (H) and elasticity (E) were measured by nanoindentation and a Rockwell indentation test, while the tribological properties were tested using a pin-on-disk tribometer. After all, the coatings were measured by cutting testing of tuning inserts and micro-drillers. It is found that all of the coatings are amorphous and have a thickness of approximately 1.5 μm. Moreover, the nitrogen content is around 30 at%, while the tungsten content varies in the range of 0-9 at%. In addition, the hardness values are in the range of 15-20 GPa and the elasticity varies from 236 to 274 GPa. A good correlation is observed between the wear resistance and the indentation adhesion level. Furthermore, it is found that the hardness is not significantly correlated to the tungsten content and the coatings deposited on the Ti/TiC interlayer have greater adhesion. Finally, the coatings generally have a very low coefficient of friction (0.01-0.3) and a wear coefficient as low as 10-6 mm3/Nm, and the CN/TiC coating reduced 41% and 43% of flank wear in the cutting testing of turning inserts and micro-drillers respectively.
Surface Roughness and Magnetic Effect of Magnetized Journal Bearings Lubricated with Ferrofluid
Authors: Hsu Tze Chi , Chen Jing Hong , Chou Tsu Liang , Chiang Hsiu Lu
Published: April 2015

This study investigated the combined influence of stochastic surface roughness patterns and a magnetic field produced by an infinitely long wire on the distribution of hydrodynamic pressure in journal bearings lubricated with ferrofluids. According to our results, the magnetic field can raise the dimensionless pressure, improve the dimensionless load capacity and reduce the modified friction coefficient, especially at high eccentricity ratio. However, these bearing Characteristics are also influenced by surface roughness pattern depend on the length to diameter ratio λ, and the critical value of λ equal to 0.6, 0.95 and 1.8 in this study.
Elastic-Plastic Analysis of Fretting Contacts
Authors: Kuo Chang Hung
Published: April 2015

A finite element procedure is implemented for the elastic-plastic analysis of carbon steels subjected to reciprocating fretting contacts. The nonlinear kinematic hardening rule based on Chaboche model is used to model the cyclic plastic behavior in fretting contacts. The results show that accumulation of plastic strains, i.e. ratchetting, may occur near the contact edge while elastic shakedown is likely to take place in substrate.
Observation of the Tribo-Film Formation Derived from ZnDTP by Using FT-IR
Authors: Watanabe Hirotomo , Tadokoro Chiharu , Sasaki Shinya
Published: April 2015

To understand the effects of tribo-film formation derived from ZnDTP (zinc dialkyl ditio phosphate) on friction behavior, friction tests were carried out with varying sliding time. The sliding surfaces were analyzed using Fourier transform infrared spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). On the basis of the surface analytical results of the tribo-film, the absorption bands in the region of 1300-1000 cm-1 assigned as polyphosphate appeared in all IR spectra after the sliding. The friction behavior of ZnDTP was related to the intensity change of the IR spectra peak at 1200 cm-1.
Tribological Study of PCL-PEG-PCL Polymer on SiNxHy Base
Authors: Hsu Chih Yueh , Wei Chin Chung , Jiang Cho Pei
Published: April 2015

Tribological behaviour of polymer and hard coating films is complicated with bio-lubricant. Contacting and kinematic conditions of a knee joint when a person in running was simulated in the study. Substrates of specimens are Ti6Al4V and 316LVM stainless steel. Two kinds of polymer films, PCL-PEG-PCL and mPEG-PCL-mPEG, were used to simulate the tissue of cartilage. The silicon nitride film, SiNxHy prepared by PECVD, was used as a protecting film, and it’s thickness about 1000 nm under the polymer film. The testing device was developed, upper specimen is rotated reversely and the lower one is moved linearly forward and backward for 6 mm. A frequency vibration is applied under the lower specimen to simulate the vibration caused from walking, which is sated 2 Hz. Two torque meters are used for friction measurement in rotational and sliding directions. Experiments simulated vertical vibration, rotary and reciprocating motion. Comparing friction coefficient with different substrates with SiNxHy film, mixture of PCL-PEG-PCL and bovine serum can effectively decrease friction but useless for mPEG-PCL-mPEG. If adhesion of PCL-PEG-PCL polymer can be improved, it has potential in the application of artificial joint.
Analysis of Stress and Strain for Multiply Asperity Sliding Contact Surface
Authors: Chern S.Y. , Lin Y.C. , Hsu P.W. , Lee C.L. , Tsai C.H.
Published: April 2015

The Finite Element Method (FEM) is used to analysis multiply asperity sliding contact surface. The various distributions of stress and strain along the asperity contact profile are shown for various pressure, roughness, sliding velocity, friction coefficient, and thermal conductivity. The results show that equivalent strain increases as the friction coefficient decreases. Similar results are found for the shear stress. However, the maxima equivalent stress at the center peak increases as the roughness, thermal conductivity, or loading force increases. Instead of the peak point, maxima equivalent stress and strain can be found at the contact/non-contact interchange point of the contact profile. The equivalent stress and strain increase as the loading force increases. In addition, the normal stress increases as the friction coefficient and loading force increase. The maxima normal stress can be found at the center peak point.
An Experimental Investigation of the Torque Efficiency in Small Supr Gears
Authors: Lee Jian Shing , Horng Jeng Haur , Chiu Ming Yuan
Published: April 2015

In present study, a gear transmission system was used to evaluate the effects of oil viscosity, speed, oil temperature as well as the applied load on torque efficiency. The experimental results reveal that the efficiency is increased with the increasing oil temperature and/or applied load whether the multigrade or singlegrade oil was employed. Under a constant torgue, the power loss is increased with the increasing pitch line velocity. The above characteristic resulting from the use of high-viscosity oil yields the substantial variations. However, as the oil film thickness is quite small, the viscosity speed, oil temperature and applied load produces the limited effect on torque efficiency, It indicate that EP additives create an opposite effect on torque efficiency at poor lubrication.
Atomic Scale Friction in the Function of Modified Eyring Activation Energies
Authors: Chong William W.F. , Rahnejat Homer
Published: April 2015

At microscale, friction is better understood fundamentally through hydrodynamic and elastohydrodynamic lubrication. However, the mechanisms governing friction at nanoscale remains a subject of interest. With the emergence of small-scale devices such as Microelectromechanical Systems (MEMS) and Nanoelectromechanical Systems (NEMS), there is a need to improve on the fundamental understanding of friction at diminishing gaps. Therefore, the paper investigates the friction of a simple fluid (n-hexadecane 99%) using an atomic force microscope. The measurements are interpreted using modified Eyring’s thermal activation energy approach in order to examine the effect of molecular solvation at the assumed smooth summit of asperities. It is found out that solvation for a sliding contact could be observed through the shear stress activation volume due to generated thermal energy, which indicates the movement of the fluid molecules into and out of the contact.
Tribology Behavior of Graphene Containing Ni-Based Composite Coating under Room Temperature
Authors: Li Jian Liang , Chen Juan Juan , Xiong Dang Sheng , Zhang Yong Kang , Qin Yong Kun , He Yong
Published: April 2015

The graphene containing Ni-based composite coatings with different graphene addition amounts were prepared on 45 steel surface by using dipulse composite electrodeposition technology. The tribological behavior of composite coating was tested by against GCr15 steel pin under the dry condition. The friction coefficient of composite coating is 20-30% lower than pure Cr coating, their wear rates are almost in the same magnitude. Compared with 45 steel, the friction coefficient of composite coating decreases and wear rate falls over 50%.
Study of Thermal Expansion of a Vertical Motion Ball-Screw System Operated at High Rotational Speed
Authors: Hung Sheng Hao , Wei Chin Chung
Published: April 2015

A ball-screw system is widely used in high speed transmission platforms. High transmission speed brings high frictional force, heat and thermal expansion occurring on contact areas of ball, screw and nut. Positioning error of platform is affected by the thermal expansion during linear transmission. A vertical motion of ball-screw driving system was used for high speed transmission test. Thermal expansion of screw and positioning error were measured for discussion their effects. Cyclic vertical motion during a long transmission distance, 2 km, will integrate thermal heat to ball, screw and nut, thermal expansion of screw is also occurred. From experiments, temperature rising and thermal expansion of screw and nut were recorded and calculated for estimate elongation and positioning error of a vertical motion high speed ball-screw. Positioning error is not totally respected thermal elongation effects of screw and nut owing to contact forces caused by wear and thermal expansion at contact areas comparing to the heavy axial load is relative small in a vertical motion ball-screw system. Therefore, the structure stiffness is not affected significantly by thermal effect and wear.
Analysis of Hydrodynamic Porous Bearing with External Pressure Supply
Authors: Shaw Dein , Hsieh Hui An , Lo Chi Yu
Published: April 2015

For the need of high speed and load capacity of precision industry, a bearing used in a high speed spindle is studied. The hydrodynamic bearing composed a hydrodynamic bearing made of porous material and several hydrostatic chambers with an external oil system. The hydrodynamic bearing is pressurized with oil chamber and supports the spindle shaft both at rest and at rotation state. Because of the external pressure and the property of porous material, the load capacity of hydraulic bearing can be promoted without decreasing precision. To consider the relationship of parameters, we applied the Reynolds equation and Darcy’s law to describe the flow of the oil film between bearing and spindle shaft.
Contact Calculation for Rolling Bearings in Quarter-Spaces
Authors: Wang Zhi Jian , Shen Xue Jin , Chen Xiao Yang
Published: April 2015

An elastic contact solution considering the effect of free surface and code are developed using Hetenyi’s approach and semi-analytical method. Discrete convolution-fast Fourier transform (DC-FFT) is used to calculate elastic deformation. The modified conjugate gradient method is applied to solve surface contact pressure. By comparing with other literatures’ results, the program made by authors is proved valid.