bluuebunny/crossref_metadata_2025 huggingface dataset:
Melt Flow Behavior of Metal Filled in Polymer Matrix for Fused Deposition Modeling (FDM) Filament
Authors: Sa'ude Nasuha , Ibrahim Mustaffa , Ibrahim Mohd Halim Irwan
Published: October 2014

This paper presents the melt flow behavior (MFB) of an acrylonitrile butadiene styrene (ABS), Polyproplene (PP), Polylactic Acid (PLA), ABS mix 10% Copper and ABS mix 10% Iron in the simulation. In this study, the effect MFB of ABS mix with 10% Iron and 10% Copper material was investigated based on the viscosity, density, thermal conductivity, melting temperature and specific heat of material properties. The MFB of metal filled in polymer matrix composite (PMC) through the FDM nozzle was investigated using Finite-Element Analysis (ANSYS CFX 12). Based on the result obtained, pressure outlet of mix ABS copper and ABS iron in extruder nozzle was higher value compared with others plastic material. The velocity was increased since the nozzle diameter is smaller than the entrance diameter. It can be observed that, the melt flow behavior of metal filled in PMC are affected on pressure drop, velocity and the nozzle size at the exit nozzle.
Experimental Investigation of Multiple Coils Magnetorheological Damper under Dynamic Loadings
Authors: Yazid Izyan Iryani Mohd , Mazlan Saiful Amri , Kikuchi Takehito , Zamzuri Hairi
Published: October 2014

This paper presents performance comparison of Magnetorheological (MR) damper with two different coil arrangements. Two coils at different location have been introduced that could enhance the activation areas in the MR damper. The experimental tests were conducted in three different conditions of coil; internal coils, external coils and the combination of coils. For each trial, the effect of the applied current and the condition of coils were analyzed and investigated. The results showed that the internal coil could produce higher damping force than the external coil, and the combination of internal and external coils could increase the damping force up to 125 N for the same experimental parameters.
Overcoming Limitation in DFM Using Layer Manufacturing
Authors: Abdul-Rani Ahmad Majdi , Zhariff Rasip Nasiruddin , Rao T.V.V.L.N. , Altaf Khurram
Published: October 2014

Design and fabrication of an object with parts embedded internally within the part has always been a difficult challenge to fabricate. This is mainly due to limitations in design for manufacturing (DFM). The objective of this work is to investigate improvements in overcoming limitations in DFM of non-metallic object with embedded part within a part through 3D printing technology and silicone rubber. 3D printing technology is a type of Rapid Prototyping (RP) method which has limitations in its material durability and product failure rate. This technology combined with silicone rubber is envisaged capable to overcome some of the limitations in DFM while increasing its durability. Layer manufacturing using 3D printing is used to construct scaffolding of the end product and silicone rubber used as material to fill the cavities. The end product is a unique “one-piece” outdoor water-feature cage that has no assembly of parts between its various internal and external components which entraps a free rotating ball feature inside the cage. Both limitations in DFM of a part within a part and improving prototype materials durability had been overcome.
Simplified MRP for Bench Vice Through Production Base Education (PBE) in POLMAN Bandung
Authors: Setiawan Albertus B. , Ananto Gamawan
Published: October 2014

Bandung State Polytechnic for Manufacturing (POLMAN), as a high education vocational institution, implements certain portion of practical program in its workshop that aimed to build students skill competencies. For those, product media are created from structured exercises and combined with external inquiries from collaboration with industrial parties, through a system called Production Based Education (PBE). Completing the ‘job shop’ products that students are doing daily, Bench Vice as one of standard product in Polman is treated as ‘batch product’ due to its appropriated characteristic. The idea of Material Requirements Planning (MRP) method for Bench Vice handling is implemented in order to get most beneficial either for students, lecturers and institution. Since the common MRP and other control functions influence each other related with capacity and schedule, simplified MRP for Bench Vice is developed as a learning media for all involved parties in organization.
Impact of RFID and Xbee Communication Network on Supply Chain Management
Authors: Ahmed Aftab , Hasnan Khalid , Aisham Badrul , Bakhsh Qadir
Published: October 2014

Every industry, organization or individual needs to be minimize their expenditure, time and fatigue and maximize their profit in supply chain. These goals can be achieved through automation by using Radio Frequency Identification (RFID) and Zigbee wireless communication technologies, which is easily available in the market. Basically RFID technology is used for automatically tracking, locating or identifying the entities. It can easily integrate with low cost low power consumption Xbee (Zigbee) device, which is used to increase the communication range by large number of node deployment. RFID-Xbee network integrates with Laboratory Virtual Instrument Engineering Workbench (LabVIEW) Graphical User Interface (GUI), which gives real time information of supply chain at single control panel. The integrated communication model proves the near field inductive coupling and can be used in supermarket for item pricing, office automation, security system, and car parking. This system confirms the concept of real-time locating system (RTLS) in an indoor environment. The impact of RFID and Xbee network communication model enhance the read range of RFID reader, so that out of range items can be tracked easily without additional RFID readers. The benefit of this system is to maximize profit, reduce human intervention and minimize waste.
The Preventive Maintenance Schedule: A Case Study at Aman Sales and Services Sdn. Bhd. and Ladang Sabah Palm Oil Mill.
Authors: Mohd Tahir Abdullah , Jasmin Jamrin , Sualin Alfero , Mohd-Lair Noor Ajian , bin Abdul Rahman Abdul Kadir
Published: October 2014

Maintenance is crucial to system performance and reliability of a machine for an industry. Machine maintenance system in small and medium industries in Malaysia usually consists of manual file management system, which records all the conducted maintenance works. However, a maintenance system should be more complex to include the scheduling of maintenance activities. This paper presents the findings of studies on the implementation of preventive maintenance schedule conducted at Aman Sales And Services Sdn. Bhd. and Ladang Sabah Palm Oil Mill both located in Sabah, Malaysia. In this study, data form previous maintenance works or activities were collected from both companies. The data were then analyzed. The analysis indicates that reduction in time can be obtained by combining similar or repetitive tasks guided by recommendation from the machines’ manuals. This analysis provides foundation for developing an improved preventive maintenance schedule for each company. The new preventive maintenance schedules are found to be able to reduce the breakdown time ranging from as low as 25% to as high as 50%. This reduction signifies the efficiency of the proposed maintenance schedule.
Selection of Mother Wavelet for Effective Wavelet Transform of Bearing Vibration Signals
Authors: Kumar H.S. , Srinivasa Pai P. , Sriram N.S. , Vijay G.S.
Published: October 2014

Condition monitoring (CM) and fault diagnosis of equipments has gained greater attention in recent years, due to the need to reduce the down time and enhance the life/ condition of the equipments. The rolling element bearings (REB) are the most critical components in rotary machines. Hence, bearing fault detection and diagnosis is an integral part of the preventive maintenance activity. Vibration signal analysis provides wide range of information for analysis. So in this paper, vibration signals for four conditions of a deep groove ball bearing namely Normal (N), bearing with defect on inner race (IR), bearing with defect on ball (B), and bearing with defect on outer race (OR) have been acquired from a customized bearing test rig under maximum speed and variable load conditions. Depending on the machinery operating conditions and the extent of bearing defect severity, the measured vibration signals are non-stationary in nature. Non-stationary signals are effectively analyzed by wavelet transform technique, which is a popular and widely used time-frequency technique. The focus of this paper is to select a best possible mother wavelet for applying WT on bearing vibration signals. The two selection criteria includes minimum Shannon entropycriteria(MSEC) and Maximum Energy to Shannon Entropy Ratio criteriaR(s). This helps in effective bearing CM using WT.
Helicopter Bearing Degradation Data Analysis Using Spectral Kurtosis and Time-Frequency Representation
Authors: Wan Hai Bo , Zhan Rui , Xin Xiong , Wang Xiao Jing
Published: October 2014

Rolling element bearing is crucial for operation safety of modern mechanical equipment. Its poor damping and heavy load capacity usually makes it degrade faster than the shafts and the gear sets. In this paper, a recently proposed time-frequency (TF) representation tool, named the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), is introduced for the TF representation of helicopter bearing degradation data. Totally three sets of sequentially collected accelerometer data were included for the comparison study, with the first two data sets showing no signs of degradation and the third data set corresponds to totally scored bearing rollers. Facilitated by CEEMDAN method, no clear distinction can be observed on the TF plane as for the strong background noises. Thus we previously highlight the bearing signatures using spectral kurtosis (SK), a forth order statistics which is sensitive for impulsive components. Its fast algorithm, called the kurtogram, implements the detection of considerably weak bearing components and suppresses other background components, e.g., gear mesh components. With the preprocessing by kurtogram, the feature information on the TF plane can be easily characterized for the third data set.
Detection of Moving Objects Based on Mixture Gaussian Model
Authors: Chen Guang Hua , Sheng Gui Zhi
Published: October 2014

The paper proposes an improved adaptive Gaussian mixture model (GMM) approach with online EM algorithms for updating, which solves the video segmentation problems carried by busy environment and illumination change. Different learning rates are set for foreground district and background district respectively, which improves the convergence speed of background model. A shadow removal scheme is also introduced for extracting complete moving objects. It is based on brightness distortion and chromaticity distortion in RGB color space. Morphological filtering and connected components analysis algorithm are also introduced to process the result of background subtraction. The experiment results show that the improved GMM has good accuracy and high adaptability in video segmentation. It can extract a complete and clear moving object when it is incorporated with shadow removal.
Scheduling and Routing Optimization of Maintenance Fleet for Offshore Wind Farms Using Duo-ACO
Authors: Zhang Zhen You
Published: October 2014

Wind energy is one of the fast growing sources of renewable power production currently and there is a great demand to reduce the cost of operation and maintenance to achieve competitive energy price in the market especially for offshore wind farms. An offshore wind farm usually comprises a large number of turbines and thus needs a number of service vessels for maintenance. It is already a complicated task to plan the schedule and route for each of the vessels on a daily basis, dealing with several constraints, such as weather window and maintenance demand, at the same time. Even more challenging is to find an optimal solution. This paper propose a method, i.e. Duo Ant Colony Optimization (Duo-ACO), to improve the utilization of the maintenance resources, specifically the efficient scheduling and routing of the maintenance fleet and thus reduce the operation and maintenance (O&M) cost. The proposed metaheuristic method can help operator to avoid a time-consuming process of manually planning the scheduling and routing.
High Quality Velocity Detection of Incremental Encoder for Servo Drive
Authors: Jin Jie , Huang Su Rong
Published: October 2014

Considering the contradiction of detection speed and detection accuracy of incremental encoder, a novel digital velocity detection N/S algorithm is proposed in this paper. The algorithm of velocity detection mainly consists of two parts: the pulse sliding counting and velocity synchronous updating. In order to reduce the pulse-detection time delay, the pulse-sliding-counting method is used to count the encoder pulses during the sampling period, and the pulse-pattern sequences are obtained sequentially. In order to improve the accuracy of velocity detection, synchronization of velocity updating and pulse-mode alternation is applied, which reduces the calculation error caused by asynchronization of velocity updating. The experimental results are shown to demonstrate that the measurement speed and measurement accuracy are improved simultaneously by using of the proposed algorithm.
Reverse Engineering of Cam Design Based on BP NN
Authors: Zhao Yan , Lu Li Xin , Li Gui Qin , Li Zheng , Yuan Xiao , Li Hong Bo
Published: October 2014

A three layer BP NN is created to design the cam. The data of cam contour ,which can be measured by CMM, has been used for the training where back propagation method is used.Advantage of solving nonliner problems gives BP netwok the ability to make out a more demand curve of cam. Taking advantage of its learning ability,NN model fits the actual cam contour gradually until the error fulfil the demand.Cam contour is ploted by Matlab,the result of which is better than cubic curve fitting,especially in the aspects of precise and velocity.
Continuous Improvement and Benchmarking to Achieve Zero Defect Manufacturing
Authors: Myklebust Odd , Eleftheriadis Ragnhild , Capellan Alvaro
Published: October 2014

This paper presents methods for continuous improvement to achieve Zero Defect Manufacturing (ZDM) with focus on the shop floor and machine level. Benchmarking and best practices a part of Total Quality Management (TQM). To make a good product or production processes system it is important to focus on the working performance efficiency. Best practice or Benchmarking are then methods to focus on the best possible method to understand working processes, systems and performance ability. The EU-Project IFaCOM (Intelligent Fault Correction and Self-Optimizing Manufacturing systems) has five end-user demonstrators where Zero Defect Manufacturing (ZDM) solutions are to be implemented. The main goal for the project IFaCOM is to reach near ZDM. The ZDM framework is a quality controlled process system. The added value of the quality improvement is both a part of the continuous flow process; and the continuous improvement of value to the costumer. It is here where the usage of Benchmarking and Best practice methods will be considered for the project industry demonstrator implementations.
A Confidence Interval Estimation Method for Process Capability Index with Bias
Authors: Zhang Zai Fang , Wu Xiao Song , Miao Rui , Xia Bei Xin
Published: October 2014

Process capability index (PCI) has been widely applied in manufacturing industry as an effective management tool for quality evaluation and improvement, whose calculation in most existing research work is premised on the assumption that there exists no bias. In this paper, the bias of gauge which exerts an effect on the calculation of PCI is indicated inevitable. The influence on PCI caused by the bias is analyzed by constructing a comparative ratio R between the empirical process capability index and the PCI. A confidence interval estimation method is proposed to solve the underestimation problem of PCI.
Manufacturing of Porous Ceramic Spheres Using Calcium Phosphates, by a Mechanical Method without Additives or Binders
Authors: Violin Kalan Bastos , Goia Tamiye Simone , Ishikawa Kunio , Bressiani José Carlos , Bressiani Ana Helena de Almeida
Published: October 2014

The processing of porous ceramics spheres (PCS) has been developed for biphasic calcium phosphates (BCP), hydroxyapatite (HAp) and beta tricalcium phosphate (β-TCP) in order to be used mostly as bone fillers and drug delivery systems. The importance of the PCS is due to better accommodation of them in order to fill empty spaces and also because is more friendly to cells and bone tissue growth. Also is important to obtain a surface roughness to increase the surface area in contact with the living tissue and their fluids. There are several methods used to achieve the PCS form and most of them use suspensions based on liquids immiscibility effect or additives. The aim of this work was to achieve PCS of BCP, HAp and β-TCP with rough surface and varying size without using solutions or additives. The method developed is based on a mechanical continuous movement of the particles, relying on the normal ability of the ceramic powders to aggregate themselves while rolling in a cylindrical container for long periods. The physical forces involved in the process, gravity, particle attraction, centripetal force and shocking make the ceramic rounds with golf ball appearance on its surface. With this method it was possible obtain PCS with 30% of porosity with rough surface and size between 1 to 4 mm in diameter.
In Situ Platelet Reinforcement of Alumina and Zirconia Matrix Nanocomposites – One Concept, Different Reinforcement Mechanisms
Authors: Kern Frank , Gadow Rainer
Published: October 2014

Zirconia-alumina composites are structural ceramics which due to their high strength and toughness are interesting in biomedical and engineering applications. Reinforcement of such materials with in situ formed platelets can improve fracture toughness and reliability, the mechanisms are however not yet fully understood. In this study alumina and zirconia based composites (ZTA and ATZ) reinforced with various hexaaluminates were investigated. In ZTA materials the main effect of platelets is the improvement of toughness as the the grain size distribution of the microstructure is broadened and transformability of the zirconia dispersion is improved. Crack deflection by platelets is unimportant, toughening is commonly achieved at the expense of strength and hardness. In case of zirconia based composites results are strongly depending on the type of stabilizer (Y-TZP or Ce-TZP) used and the type of hexaaluminates formed in situ. Here platelets can cause crack deflection and crack bridging. By variation of the composite recipes a multitude of compositions can be produced which have mechanical properties tailored for individual applications.
Structural and Electrical Properties of (1-x)Pb (Zry Ti1-y)O3-xSm(Fe3+0.5, Nb5+0.5)O3 Ceramics Prepared by Conventional Solid State Synthesis and Sintered at Low Temperature
Authors: Kahoul Fares , Hamzioui Louanes , Boutarfaia Ahmed
Published: October 2014

The phase structure, microstructure and electrical properties of (1-x)Pb (Zry Ti1-y)O3-xSm(Fe3+0.5, Nb5+0.5)O3 (PZT–SFN) (with x = 2 %, 41%≤ y ≤57 %) piezoelectric ceramics were prepared by the conventional solid state method, and effects of SFN and the Zr/Ti ratio content on the piezoelectric properties of PZT ceramics were mainly investigated. A stable solid solution has been formed between PZT and SFN, and a morphotropic phase boundary of PZT–SFN ceramics is identified in the range of 51% ≤ y ≤55 %. The Curie temperature of PZT–SFN ceramics decreases with increasing at Zr/Ti ratio content. A higher εr value and a lower tanδ value are demonstrated for the PZT–SFN ceramics with y = 53 %. The PZT–SFN ceramics with y = 53 % has an enhanced electrical behavior of kp ~ 61.2 %, Qm ~ 104, εr ~ 566, tanδ ~ 2.02 % and TC ~ 370 OC. As a result, PZT–SFN ceramics are promising candidate materials for the field of lead piezoelectric materials and piezoelectric device.
Effect of Different Sintering Processes on Microstructure of Alumina Ceramics
Authors: Chinelatto Adriana Scoton Antonio , Lago Ojaime Christiane , Gelfuso Maria Virgínia , Thomazini Daniel , Chinelatto Adilson Luiz
Published: October 2014

Structural ceramics, such as alumina, are widely used in industrial applications due to their properties such as hardness, chemical resistance and thermal stability in high temperatures. However, low fracture toughness has limited applications of these materials. One way to overcome the low fracture toughness is to control the microstructure, seeking a refined and homogeneous microstructure. In this way, the aim of this study was to investigate the effect of unconventional methods sintering based on two steps and microwaves sintering methods on the microstructure of a commercial alumina ceramic. From two-steps sintering method, the samples are first heated to a high temperature and then cooled down to a lower than one temperature to suppress grain-boundary migration. Ceramics obtained by microwave sintering method were produced after 1100, 1300 and 1350°C for 1 hour. The microwave heating method reduces the time and temperature processing, which results in energy saving. The sintered samples were characterized by apparent density, scanning electron microscopy and measurements of grain size. The results showed that two-steps sintering and microwave were effective to control the microstructure of alumina and that in two steps sintering it is essential to control the sintering steps to inhibit grain growth.
Mechanical Characterization of Conventional and Non-Conventional Sintering Methods of Commercial and Lab-Synthesized Y-TZP Zirconia for Dental Applications
Authors: Presenda Alvaro , Salvador María Dolores , Peñaranda-Foix Felipe , Catalá José Manuel , Borrell Amparo
Published: October 2014

Ceramics for dental applications have become increasingly important in the last decades. Particularly, the introduction of yttria-stabilized zirconia tetragonal polycrystalline (Y-TZP) materials as an alternative to the manufacturing of dental implants and prosthesis has provided a powerful tool to meet the demands required for these replacements in terms of biocompatibility, toughness, hardness and optical properties. Several commercial Y-TZP materials are currently available on the market and strong efforts in research and development facilities are being carried out to improve processing of Y-TZP to fully consolidate odontological pieces. Novel processing methods for ceramic powder sintering, including Y-TZP, aim to reduce processing times and production costs significantly, while maintaining or even improving the resulting microstructure and mechanical properties of the material. One of these methods includes microwave sintering. The purpose of this study is to characterize and compare the resulting properties of Y-TZP materials after conventional sintering and the non-conventional method of microwave heating. In this work one commercial material and one laboratory-synthesized Y-TZP powder are considered. The results suggest that microwave sintering results, generally, in better mechanical properties of the material in terms of hardness and fracture toughness than conventional sintering.
Ultradispersed Powdery Y2O3-Bi2O3-ZnO Composition with High Chemical Homogeneity for Fine-Grained Ceramics
Authors: Trusova Elena A. , Vokhmintcev Kirill V. , Kirichenko Aleksey N.
Published: October 2014

The technologically acceptable modified sol-gel technique was developed for obtaining the ultradispersed powdery composition Y2O3-Bi2O3-ZnO, which is promising new generation material for photocatalysts and solar cells. The solution for preparing a sintering composition with a high chemical homogeneity was proposed to provide using ultradispersed powders consisting of ZnO nanoparticles (40-70 nm), decorating with Bi2O3 and Y2O3 particles with average size of 4-20 nm. All synthesized powders were characterized by XRD and TEM methods. It was found that ZnO surface differently affects the dispersity of Bi2O3 and Y2O3 in the composites. TEM microphotographs show that the Bi2O3 particles uniformly distributed over ZnO surface. The Bi2O3 particle size on ZnO surface was 5-11 nm, which is significantly less than in the single powder of Bi2O3 (110-130 nm). However, in the case of Y2O3 similar effect was not observed, and average size of its crystallites was 5-12 nm, which agrees well with particle sizes in single powder.
High Energy Milling of Zirconia: A Systematic Critical Review on the Phase Transformation
Authors: Gorodylova Nataliia , Dohnalová Žaneta , Šulcová Petra
Published: October 2014

The phase transformation of zirconia from monoclinic to tetragonal polymorph at room temperature under mechanical processing has been a subject of a great interest due to technological importance of this material. Mechanism of this transformation has been widely investigated and plenty of explanation theories of zirconia stabilisation have been developed as well. This article critically reviews the systematic development regarding this transformation under mechanical processing and includes the summarised results of key-publications on this topic.
Composition – Property Relations in Shear Thickening Fluids
Authors: Wierzbicki Łukasz , Leonowicz Marcin
Published: October 2014

It was shown that fumed silica particles (FS), dispersed in polypropylene glycol (PPG), form shear thickening fluids (STF). PPGs with different molar mass were tested. The best combination of the properties (high viscosity, obtained at high shear rate) present the fluids composed of 7 nm FS and PPG 425. The highest volume fraction of FS, which was possible to disperse in PPG 425, was 25%. This fluid exhibited the highest viscosity. The highest magnitude of shear thickening effect was obtained, however, for 17.5 vol.% of the solid phase. Dynamic oscillatory shear experiments were conducted at either a constant amplitude or frequency. The constant strain amplitude tests showed, that for the frequency sweep, the systems showed viscous properties, except that of 25 vol.% of FS in PPG 425, which exhibited elastic properties in almost entire range of the frequency investigated. For the constant strain sweep, for low strains, the elastic modulus and loss modulus were hardly dependent on the strain, but for relatively high strain, this dependency was increasing. Also the complex viscosity was also growing for high strain values.
SiOC Composite Structures for Intermediate Service Temperatures with Increased Friction Properties
Authors: Gadow Rainer , Weichand Patrick
Published: October 2014

Polymer Matrix Composites (PMC) are often used in lightweight applications due to their excellent mechanical properties combined with a low density. The manufacturing technologies are fully developed and raw materials are cheap. The limiting factor of these reinforced polymers is the maximum service temperature. Ceramic Matrix Composites (CMC) are suitable for service temperatures up to 1500 °C and more. These composites are composed of ceramic matrices combined with ceramic fibers based on alumina or silicon carbide. This class of composites is handicapped by the high cost of processing and raw materials and therefore only attractive for applications in astronautics and military aviation. Composite materials, bridging the gap between PMC and CMC, are manufactured by the use of polysiloxanes, carbon-and basalt fibers. Such competitive free formable Hybrid-composites are capable for service temperatures up to 800 °C in oxidative atmosphere. In order to make the material attractive also for series applications, manufacturing technologies like filament wet winding, Resin Transfer Moulding (RTM) or pressing techniques are employed. Beside the improved thermal resistivity in comparison to reinforced polymers and light metals, a major benefit of SiOC composites is investigated in the field of friction materials. The excellent properties in wear resistance and an adjustable coefficient of friction make it an interesting alternative for CFC and CMC.
Microwave Absorbency Change of Nitride Powders under Vacuum Heating
Authors: Sano Saburo , Takayama Sadatsugu , Kishimoto Akira
Published: October 2014

We measured the microwave and millimeter-wave behaviors of ceramics and metal powders as a basis for developing microwave and millimeter-wave heating technology. In this study, nitride powders were subjected to microwave absorption measurements at elevated temperature. These measurements were performed using a system comprising a vector network analyzer, a circular wave-guide fixture, and a vacuum furnace. The sample’s microwave absorbency was evaluated by the change in reflection power from the sample in the circular wave-guide fixture under vacuum heating. Measurements were performed at approximately 24 GHz and at temperature up to approximately 1100°C. Boron nitride (BN) exhibited almost no absorption of microwaves up to 1100°C, similar to the results of a low-loss oxide powder such as alumina. Dichromium mononitride (Cr2N) powder exhibited a rather high absorption of microwaves at room temperature. During vacuum heating, absorbency of Cr2N started to decrease at 300°C, and became almost zero at temperature greater than 600°C, similar to the behavior of iron powder. This result indicated that roughly packed Cr2N powder absorbs microwave radiation; however, during vacuum heating, the compact body was sintered and the whole sample body became a reflector of microwaves. This change was irreversible, and the sample maintained its reflection behavior upon the cooling. When a mixed powder of Cr2N (20 mass%) and Al2O3 was heated under vacuum, the compact sample exhibited microwave absorption that increased with increasing temperature. This change was reversible upon cooling. These results indicated that the mixed powder did not become reflector of microwaves; Cr2N particles were not electrically connected each other because the Al2O3 particles kept the Cr2N particles separate during the vacuum heating process.
Strong-Gravity Experiments on Perovskite-Type Oxides
Authors: Tokuda Makoto , Isram Khandaker Jahirul , Ogata Yudai , Mine Yoji , Nishiyama Tadao , Hayami Shinya , Yoshiasa Akira , Mashimo Tsutomu
Published: October 2014

Strong gravitational field causes the displacement or/and sedimentation of atoms in solids, by which we can changes the crystalline state or/and composition in multicomponent condensed matter. Perovskite-type doped manganite, La1-xSrxMnO3 (LSMO) has unique magnetoresistance effect which is called “colossal magnetoresistance (CMR)”. In this study, the strong gravity experiment (0.40x106G, 400°C, 20h) was performed on the LSMO oriented crystal to examine the change in composition or structure. The LSMO crystal whose growing crystal direction is normal to (214) plane was prepared by the floating zone method. The EPMA and XRD results of the gravity sample revealed that the La compositions decrease in the crystal grain, while the structure did not change much. The SQUID analysis showed that the magnetic property of the gravity sample had changed.
Tribological Behaviour of Ceramic Hip Replacements
Authors: Ciulli Enrico , Di Puccio Francesca , Mattei Lorenza , Battaglia Santina , Affatato Saverio
Published: October 2014

Since 1960, when the first hip prosthesis was introduced, up to now, several implant typologies have been proposed trying to meet the increasing clinical demands of more and more active and young patients. A substantial evolution of implant design has been occurring, both in terms of materials and geometry, basically driven by their tribological performances. Indeed, the main concern of hip implants consists in the release of wear debris, which can lead to implant loosening and failure. Thus, many studies on wear and lubrication of hip prostheses have been published in the last 15 years, mainly focused on experimental researches but also on numerical/modeling approaches. The aim of this work is to review the history of hip implants from a tribological point of view with a focus on ceramic-on-ceramic replacements, which represent the most advanced solution in terms of wear strength and chemical inertness. The main drawbacks of these implants, as the brittleness and the squeaking, are discussed and novel solutions examined.
Critical Review of the Oxidation of Cr2AlC
Authors: Lee Dong Bok
Published: October 2014

The Cr2AlC ternary compounds were synthesized via a powder metallurgical route, and their oxidation behavior was investigated at 700-1300°C in air for up to 360 days. A thin Al2O3 layer always formed on the surface. Since Al was consumed to produce the Al2O3 layer, Al-depletion and Cr-enrichment occurred underneath the Al2O3 layer. This led to the formation of a Cr7C3 sublayer containing some voids. Up to 1000 °C, the Al2O3 layer effectively improved the oxidation resistance. Above 1100 °C, the Al2O3 layer began to crack and spall locally to a certain extent. At 1300 °C, the oxidation resistance became poor owing to the formation of voids in the Cr7C3 sublayer and the spallation of the Al2O3 scales.
Evaluation of Wearing Properties of Polyamide 66 Containing Glass Wool
Authors: Tsukamoto Masaya , Yoshimura Yukio , Kuroki Yuichiro , Okamoto Tomoichiro , Takata Masasuke
Published: October 2014

Glass wool is discontinuous glass fiber with the average diameters of 3-4 μm produced by means of centrifugal process, and mainly applied to heat and acoustic insulation. But, there are few reports on glass wool applied to reinforcement of plastic materials in which chopped strand made by chopping continuous glass fiber is used primarily. In this study, the polyamide 66-based composite material samples containing glass wool were prepared and its wear property as a mechanical property was evaluated. It was found that the composite has an advantage on the wear property compared with a conventional glass fiber reinforced plastic, and the result suggests that glass wool has a possibility as a reinforcement material applied to plastic parts required wear resistance.
Two-Step Pressureless Sintering of Silicon Carbide-Based Materials
Authors: Magnani Giuseppe , Sico Giuliano , Brentari Alida
Published: October 2014

Pressureless sintering of silicon carbide powder requires addition of sintering aids and high sintering temperature (>2100°C) in order to achieve high sintered density (>95% T.D.). The high sintering temperature normally causes an exaggerated grain growth which can compromise the mechanical properties. Two-step sintering (TSS) can be used to overcome this problem. By this method, high sintered density is obtained avoiding the grain growth associated to the last step of the sintering. Two-step sintering was successfully applied to different commercial silicon carbide powders with different sintering mechanism: solid-state and liquid-phase sintering. In both cases the sintering temperature was set nearly 100 °C below the temperature conventionally required. Microstructures of samples obtained by TSS and conventional sintering (CS) processes were compared. TSS-SiC showed finer microstructure consisted of equiaxed grains with very similar density. The beneficial effects of the two-step sintering process were more evident in the solid state sintering. In this case sintered density higher than 98% was achieved with T<2000 °C.
Fracture Mechanics of Y2O3 Ceramics at High Temperatures
Authors: Boniecki Marek , Librant Zdzislaw , Wesołowski Władysław , Gizowska Magdalena , Osuchowski Marcin , Perkowski Krzysztof , Witosławska Irena , Witek Adam
Published: October 2014

Fracture toughness KIc and four-point bending strength σc at high temperature (up to 1500 °C) of Y2O3 ceramics of various grain size were measured. The ceramics were prepared by pressureless air sintering and next hot isostatic pressing of high purity (99.99%) Y2O3 powder. Relative density of about 99 % was achieved. Photos of microstructures revealed small pores distributed mainly inside grains. For smallest grain size (2 - 9 μm) ceramics KIc and σc are almost constant from 20 ° to 1200 °C and next they decrease. For biggest grain size (about 44 μm) they increase up to 800 °C and next they keep constant up to 1200 °C. The micrographs analyses of fracture surfaces indicated that transgranular mode of fracture at room temperature changes to almost intergranular at higher temperatures.
Persistent Luminescence Cr3+ Doped Spinels and Use as Biomarker for In Vivo Imaging
Authors: Sharma Suchinder K. , Gourier D. , Viana B. , Maldiney T. , Teston E. , Scherman D. , Richard C.
Published: October 2014

ZnGa2O4 (ZGO) is a normal spinel. When doped with Cr3+ ions, ZGO:Cr becomes a high brightness persistent luminescence material with an emission spectrum perfectly matching the transparency window of living tissues. It allows in vivo mouse imaging with a better signal to background ratio than classical quantum dots. The most interesting characteristic of ZGO:Cr lies in the fact that its LLP can be excited with red light, well below its band gap energy and in the transparency window of living tissues. A mechanism based on the trapping of carriers localized around a special type of Cr3+ ions namely CrN2 can explain this singularity. The antisite defects of the structure are the main responsible traps in the persistent luminescence mechanism. When located around Cr3+ ions, they allow, via Cr3+ absorption, the storage of not only UV light but also all visible light from the excitation source.
Rare Earth Doped Glasses for Displays and Light Generation
Authors: Caldiño Ulises , Bettinelli Marco , Ferrari Maurizio , Pasquini Elisa , Pelli Stefano , Speghini Adolfo , Righini Giancarlo C.
Published: October 2014

Glasses are very versatile materials, also because of the ease of doping them with various elements and compounds. In particular, rare-earth-doped glasses have greatly contributed to the development of optical amplifiers, lasers, active optical waveguides and white-light-emitting devices. White light emitting diodes (W-LEDs) and color LEDS obtained by the combination of an UV emitting LED, such as AlGaN-based LED, with a glass phosphor exhibit very interesting properties. In the present contribution we report the luminescence characteristics of zinc-sodium-aluminosilicates glasses variously doped, namely either singly doped with Eu3+, Tb3+ or Sm3+, or co-doped with Tb3+-Eu3+, Tb3+-Sm3+ and Tb3+-Ce3+. These glasses have also proved to be suitable for ion exchange and therefore for the production of active optical waveguides.
Photoluminescence, Ferroelectric, Dielectric and Piezoelectric Properties of Sol-Gel-Derived Er-Doped KNN-LN Lead-Free Multifunctional Ceramics
Authors: Wu Xiao , Lin Mei , Lau Chi Man , Kwok Kin Wing
Published: October 2014

A sol-gel method has been utilized to prepare lead-free 2 mol% Er-doped K0.5Na0.5NbO3-xLiNbO3 (Er-KNN-xLN, x = 0, 0.08 and 0.10) ceramics. The X-ray diffraction results show that the ceramics have the perovskite structure and Er3+ ions have diffused into the host lattice. Compared to the solid-state reaction method, the sol-gel method is favor to reduce the sintering temperatures (~ 50 °C) of ceramics. Better compositional homogeneity, as well as finer and uniform grains is resulted from the sol-gel process, which have been confirmed by the scanning electron microscope images. The photoluminescence properties of ceramic bulks have been systemically studied. Under the excitation of 980 nm, the ceramics exhibit visible up-conversion green (510-570 nm) and red (640-685 nm) emissions. The emission colors of them are located in the yellowish green region. The down-conversion emissions in near-infrared (1450-1650 nm) and mid-infrared (2600-2870 nm) regions have been exhibited. The ferroelectric, dielectric and piezoelectric properties of ceramics have also been investigated. Because of the good electrical and excellent photoluminescence performances, our sol-gel-derived Er-doped KNN-LN ceramics should have great potential for multifunctional optoelectronic applications, such as optical-electro integrated materials and devices.
Metal-Organic Chemical Vapor Deposition of BiFeO3 Based Multiferroics
Authors: Catalano Maria Rita , Condorelli Gugliemo Guido , Lo Nigro Raffaella , Malandrino Graziella
Published: October 2014

BiFeO3 films undoped and doped with Ba and/or Ti have been fabricated through Metal-Organic Chemical Vapor Deposition (MOCVD) on SrTiO3 (100), SrTiO3:Nb (100) and YSZ (100) substrates. Films have been deposited using a multi-metal source, consisting of the Bi (phenyl)3, Fe (tmhd)3, Ba (hfa)2•tetraglyme and Ti (tmhd)2(O-iPr)2 (phenyl= -C6H5, H-tmhd=2,2,6,6-tetramethyl-3,5-heptandione; O-iPr= iso-propoxide; H-hfa=1,1,1,5,5,5-hexafluoro-2,4-pentanedione; tetraglyme = CH3O(CH2CH2O)4CH3) precursor mixture. The structural and morphological characterization of films has been carried out using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Chemical compositional studies have been performed by energy dispersive X-ray (EDX) analysis. Structural and morphological characterizations point to the formation of crystalline phases and homogeneous surfaces for both undoped and doped BiFeO3 films. Piezoresponse force microscopy (PFM) and piezoresponce force spectroscopy (PFS) have been applied to study the piezoelectric and ferroelectric properties of the films.
The PiezoElectronic Switch: A Path to High Speed, Low Energy Electronics
Authors: Newns Dennis M. , Martyna Glenn J. , Elmegreen Bruce G. , Copel Matt , Kuroda Marcelo A. , Solomon Paul M. , Shaw Thomas M. , Schrott Alejandro G. , Liu Xiao Hu , Trolier-McKinstry Susan
Published: October 2014

In contrast to the Moore’s Law exponential growth in CMOS transistor areal density, computer clock speeds have been frozen since 2003 due to excessive power dissipation. We present the development of a new digital switch, the PiezoElectronic Transistor (PET), designed to circumvent the speed and power limitations of the CMOS transistor. The PET operates on a novel principle: an electrical input is transduced into an acoustic pulse by a piezoelectric (PE) actuator, which, in turn, drives a continuous insulator-to-metal transition in a piezoresistive (PR) channel, thus switching on the device. Predictions of theory and simulation, assuming bulk materials properties can be approximately retained at scale, are that PETs can operate at one-tenth the present voltage of CMOS technology and 100 times less power, while running at multi-GHz clock speeds. CMOS-like computer architectures, such as a simulated adder, can be fully implemented. Materials development for PE and PR thin films approaching the properties of bulk single crystals, and a successful fabrication scheme, are the key to realizing this agenda. We describe progress in developing PE films (where d33 is critical) and PR films (characterized by conductance and ON/OFF ratio) of demonstration quality. A macroscopic-scale PET has been built to demonstrate PET viability over large numbers of switching cycles. The perspective for the development of pressure-driven electronics will be outlined.
Relationship between Residual Stresses and Damaging in Thermally Grown Oxide on Metals: Raman Spectroscopy and Synchrotron Micro-Diffraction Contributions
Authors: Grosseau-Poussard Jean Luc , Guerain Mathieu , Goudeau Philippe , Geandier Guillaume , Panicaud Benoit , Tamura Nobumichi , Kunz Martin , Dejoie Catherine , Micha Jean Sebastien
Published: October 2014

Ni-30Cr and Fe-47Cr alloys have been oxidized at 900 and 1000°C in air. The influence of the oxidation and cooling conditions on the magnitude of residual stresses present in the oxide scale as well as the existing relaxation modes are studied. A rigorous determination of the residual stresses at both macroscopic scale in the oxide film adherent to the substrate and local scale over the damaged areas allows a comparison with models describing thin film delamination. A multi-scale approach is then proposed : Residual stress levels are determined thanks to conventional x-ray diffraction and Raman spectroscopy while mappings are done over different types of buckling using Raman micro-spectroscopy and synchrotron micro-diffraction. Additional morphological information combined to associated stress levels is injected in the mechanical laws for buckling in order to extract the interfacial toughness.
Hydrogen Production from Thermochemical Water-Splitting Using Ferrites Prepared by Solution Combustion Synthesis
Authors: Walters I. , Shende R. , Puszynski J.A.
Published: October 2014

Currently, there are several methods to produce spinel ferrite powder material such as sol-gel synthesis, self-propagating high-temperature synthesis (SHS), aerosol spray pyrolysis, and solution combustion synthesis (SCS). These methods have been shown to produce nominally phase pure ferrites for use in hydrogen generation by thermochemical water-splitting. Among these methods, the ferrites derived by SCS have not been fully investigated for hydrogen generation from thermochemical water-splitting. SCS, in general, has several advantages such as it being a simple synthesis that can be done relatively quickly and produces materials with high specific surface area. In this study, nickel, zinc, cobalt, and manganese ferrites were synthesized using SCS and analyzed by XRD, BET, and SEM. Each ferrite material was placed inside an Inconel tubular reactor and five consecutive thermochemical cycles to determine hydrogen production. The regeneration and water-splitting temperatures were performed with water-splitting and regeneration temperatures of 900°C and 1100°C, respectively. Nickel ferrite produced significantly higher average hydrogen volume as compared to the other ferrites over the five thermochemical cycles. However, all four ferrites showed a decrease in hydrogen volume generation with increase in consecutive water-splitting cycle, which could be due to the grain growth as observed by BET and SEM analyses.
Fabrication and Characterization of Geopolymers from Japanese Volcanic Ashes
Authors: Hashimoto Shinobu , Takeda Hayami , Machino Tatsuya , Kanie Haruka , Honda Sawao , Iwamoto Yuji
Published: October 2014

Geopolymers were fabricated from some Japanese volcanic ashes. 30 g of volcanic ash with 200μm in diameter was mixed with 10 ml of sodium hydroxide solution with various concentrations to form slurry which became geopolymer after curing. When 8.5~11.5 mol/L of sodium hydroxide solution was used, the compressive strength of the resultant geopolymers reached to 25-35MPa. However, when the volcanic ash with high silica content was used, the compressive strength of the geopolymer was under 20 MPa. Furthermore, the addition of sodium silicate hydrate into starting slurry which was consisted of volcanic ash and sodium silicate solution had not effected on the compressive strength of geopolymer. In contrast, the compressive strength of the geopolymer decreased to 30 % of compressive strength compared to that of original geopolymer after water immersion for 3 days. However, crushing treatment of the volcanic ash contributed to retain the compressive strength. Actually, when 10μm of volcanic ash was used to fabricate geopolymer, the compressive strength improved to 70% compared to that of original geopolymer.