bluuebunny/crossref_metadata_2025 huggingface dataset:
Key Techniques in Intelligent Predictive Maintenance (IPdM) – A Framework of Intelligent Faults Diagnosis and Prognosis System (IFDaPS)
Authors: Wang Ke Sheng
Published: October 2014

Intelligent predictive maintenance (IPdM) is a maintenance strategy that makes maintenance decisions automatically and dynamically based on Artificial Intelligence and Data mining techniques through condition monitoring of machines, equipment and production processes. IPdM system consists of the following main modules: sensor and data acquisition, signal and data processing, feature extractions, maintenance decision-making, key performance indicators, maintenance scheduling optimization and feedback control and compensation. Among them, the most important part of IPdM is maintenance decision-making, which includes diagnostics and prognostics. This paper proposes a framework of intelligent faults diagnosis and prognosis system (IFDaPS) and discuss some key technologies for implement IPdM policy in manufacturing and industries. A case study focus on the vibration signals collected from the sensors mounted on a pressure blower for critical components monitoring. We decompose the pre-processed signals into several signals using Wavelet Packet Decomposition (WPD), and then the signals are transformed to frequency domain using Fast Fourier Transform (FFT). The features extracted from frequency domain are used to train Artificial Neural Network (ANN). Trained ANN model is able to identify the fault of the components and predict its Remaining Useful Life (RUL). The case study demonstrates how to implement the proposed framework and intelligent technologies for IPdM and the result indicates its higher efficiency and effectiveness comparing to traditional methods.
Investigation on Spray Quality of Diesel Nozzles Based on Precise Grinding Process
Authors: Bai Yu Jie , Yu Tao , Cai Hong Xia , Yang Shu Zhen
Published: October 2014

Spray quality of Multi-hole nozzles decides the quality of diesels, but the control of spray is a hard work in the field of internal combustion engines. The spray quality can be changed by abrasive suspend jet which is a flexibility manufacturing method and the quality will vary with system pressure, abrasive kind, diameter of abrasive, preparation method, viscosity of working medium and grinding allowance and some other parameters. This paper tries to optimize the spray quality of nozzles by using orthogonal experimental design to select the values of these parameters. To evaluate the quality of spray, a scoring method was offered and input parameters were organized to three parameters before experiment. According to the orthogonal table of factor level (L16(45)), the line charters between the parameters and the spray quality was shown. This paper considers that the optimal combination is A2B2C2. Then the relationship between spray quality and the parameters optimized is deduced. And the significance of the forum was checked, it shows that the forum was significant at level α=0.01.
A 3D Vision-Based Quality Inspection Study for Molded Part with Multiple Geometry Shapes
Authors: Yu Quan , Wang Ke Sheng
Published: October 2014

3D vision based quality inspection has been widely applied in manufacturing industry. Product quality is retrieved from the point cloud obtained using 3D vision methods. Generally, three sorts of quality inspection methods can be selected according to the specific requirements. This paper studied a combining quality inspection method for the quality inspection of a plastic molded part with multiple geometry shapes. Only incomplete point cloud is available because of the characteristics of the part material. Shape fitting and template matching methods are applied for deformation detection with respect to different shapes. Experiment result shows the proposed method can accomplish the quality inspection task for the part with multiple geometry shapes.
Justifying AMTs: Matching Tools and Technologies
Authors: Iakymenko Natalia , Alfnes Erlend , Kollberg Tomassen Maria
Published: October 2014

Manufacturing companies rely on advanced manufacturing technologies (AMT) in order to increase their competitive position in global markets. Successful implementation of AMT depends greatly on justification tools. The availability of a large amount of tools with varying complexity makes it difficult for managers to choose the most appropriate ones. This study investigates application of various justification tools for different levels of AMT integration. The results are presented in a framework for AMT justification tools selection that could be used by managers. The research also suggests further research directions.
The Method of Fundamental Solutions for the Moving Boundary Problem of the One-Dimension Heat Conduction Equation
Authors: Jiang Xin , Wang Xiao Gang , Bai Yue Wei , Pang Chang Tao
Published: October 2014

The melting of the material is regarded as the moving boundary problem of the heat conduction equation. In this paper, the method of fundamental solution is extended into this kind of problem. The temperature function was expressed as a linear combination of fundamental solutions which satisfied the governing equation and the initial condition. The coefficients were gained by use of boundary condition. When the metal wire was melting, process of the moving boundary was gained through the conversation of energy and the Prediction-Correlation Method. A example was given. The numerical solutions agree well with the exact solutions. In another example, numerical solutions of the temperature distribution of the metal wire were obtained while one end was heated and melting.
High Performance Manufacturing - The SUMTM Concept, beyond LEAN II
Authors: Sandengen Odd Christian , Estensen Leif , Schjølberg Per
Published: October 2014

This abstract is an introduction to High Performance Manufacturing through process management, teamwork and continuous improvement. We focus on methods and techniques as SMED, OEE (Overall Equipment Effectiveness), Hidden factories and Quality management in order to increase performance. However our main issue is the link between performance and profit, waste and loss. High performance manufacturing demands that we measure and improve processes continuously. OEE is well known standardized tool for this purpose. Techniques and methods are just that, but we need to integrate and adapt these into a business system in order to achieve profit. Management normally acts on the bases of facts and financial performance. In most companies increased profit is the overall goal. See also our previous paper called “High Performance Innovative teams.
Intelligent Real-Time Control in Manufacturing and Supply Chain Processes
Authors: Strandhagen Jan Ola , Arica Emrah , Dreyer Heidi C.
Published: October 2014

Production scheduling and control under uncertainty is among the most persistent challenges in the field of operation management. Despite the significant amount of research in this domain, many studies still underline the gap between scheduling theory and practice. In this paper, we outline the important aspects to consider in the design and implementation of decision support systems for the scheduling task by reviewing the literature. From the identified guidelines, we examine a practical case and propose a decision support system for the production scheduling task in an actual manufacturing environment.
Stiffness Analysis of the Paddle in Continuous Diffusion Furnace for Solar Cells
Authors: Du Peng Cheng , Lu Li Xin , Li Gui Qin , Li Hong Bo , Yuan Xiao
Published: October 2014

Diffusion is a key step in solar cells production. A new continuous diffusion furnace was put forward to promote productivity. However, the paddle system of continuous diffusion furnace, not same as that of traditional ones, has two paddles to handover silicon wafers. When loading silicon wafers, the paddle produces a deformation. The deflection has a significant influence on stability and efficiency. A deflection calculation method is presented as to a specific paddle in continuous diffusion furnace. The mechanical analysis and the finite element analysis are done. The test result of deformation shows that the calculation result is close to actual situation and meets the design requirements. The calculation results are valuable references in paddle system design.
Preparation of Protonic Conductor BaZr0.5Ce0.3Ln0.2O3-δ (Ln=Y, Sm, Gd, Dy) by Using a Solid State Reactive Sintering Method
Authors: Bu Jun Fu , Jönsson Pär G. , Zhao Zhe
Published: October 2014

Protonic conductors of BaZr0.5Ce0.3Ln0.2O3-δ (BZCLn532, Ln=Y, Sm, Gd, Dy) were successfully synthesized by using a cost-effective solid state reactive sintering (SSRS) method with 1 wt.% NiO was added as a sintering aid. The pellets of the BZCLn532 were obtained at sintering temperatures between 1300 - 1600 °C. The results show that the morphologies and the final relative densities of the obtained BZCLn532 pellets are influenced significantly when different sintering temperatures were applied. Densified pellets of the BZCLn532 can be prepared at sintering temperatures of 1600 °C (BaZr0.5Ce0.3Y0.2O3-δ) and 1400 °C (BaZr0.5Ce0.3Sm0.2O3-δ, BaZr0.5Ce0.3Gd0.2O3-δ and BaZr0.5Ce0.3Dy0.2O3-δ,). The conductivity results show that the BaZr0.5Ce0.3Y0.2O3-δ (BZCY532) and BaZr0.5Ce0.3Dy0.2O3-δ (BZCD532) ceramics are demonstrated to be good candidates of oxygen ion conductor and proton conductor materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) applications.
A Mixed SVD-Neural Network Approach to Optimal Control of Ceramic Mould Manufacturing in Lost Wax Cast Processes
Authors: Caramiello Ciro , Iannuzzi Stefania , Acernese Alessandro , D'Addona Doriana
Published: October 2014

We account for the problem of optimal control of ceramic mould manufacturing in lost wax cast processes with the aid of a mixed linear algebraic-statistical approach based on the employment of Singular Value Decomposition (SVD) and Neural Networks (NN).We consider the peculiar aspect of minimizing ceramic inclusions occurrence in equiaxed superalloy turbine components which are manufactured resorting to gravitational pouring. The optimization consists in finding optimal extrema of scalar and/or vectorial functions of the type Rk->Rmi.e. Key Process Variable domain (KPV) vs. Target Variable domain (TV) over a large set of experimental data affected by acquisition noise leading to a typical sparse multiblock array.The goal of the work consists in the assessment of possible significant statistical multivariate correlations amongst the KPV and TV when the dimension of domain space, k, has an order of magnitude of tens, in the presence of quasi-rank deficient input matrix.
Sintering of Al2O3-TiO2 Mixtures Obtained by High-Energy Ball Milling
Authors: Ramos Alfeu Saraiva , de Souza Marisa Aparecida , Magnago Roberto de Oliveira , dos Santos Claudinei , da Silva Camila Aparecida Araujo , de Almeida Fortes Bianca
Published: October 2014

In this work, the preparation of Al2O3-TiO2 ceramics by high-energy ball milling varying the molar fraction in 1:1 and 3:1 was investigated. The powder mixtures were processed in a planetary mill at 250rpm and a ball-to-powder weight ratio of 5:1, for 120min. Compacts were obtained by cold pressing at 100MPa. These specimens were heated at 1000◦C for 30min to promote the water evaporation, and subsequently sintered at 1500◦C for 240min. Samples were characterized by relative density and X-ray diffraction. Hardness and fracture toughness were determined by Vickers Indentation Method. The crystallite sizes were lower than 420 and 560Å in Al2O3-TiO2 and 3Al2O3-TiO2 powders, respectively. After sintering, XRD analysis indicates Al2TiO5 and Al2O3/Al2TiO5 as major crystalline phases for Al2O3-TiO2 and 3Al2O3-TiO2 compositions, respectively. The relative density of the Al2O3-TiO2 ceramics was higher than 90% in both compositions. However, hardness and fracture toughness results of 10.7GPa or 10.5GPa and 3.2MPa.m1/2 or 2.6MPa.m1/2 for Al2O3-TiO2 and 3Al2O3-TiO2 mixtures respectively, indicates that microstructure duplex composed by Al2O3 and Al2TiO5 grains lead to improvement of toughness of these ceramics.
Structural and Electrical Properties of Ca2+ Substituted Pb[(Zr0.52Ti0.48)0,98(Cr3+0.5, Ta5+0.5)0,02]0,96 P0,04 O3 Ceramics
Authors: Hamzioui Louanes , Kahoul Fares , Boutarfaia Ahmed
Published: October 2014

Pb1-x Ca x [(Zr0.52Ti0.48)0,98(Cr3+0.5, Ta5+0.5)0,02]0,96 P0,04 O 3 (x = 0,00, 0.02, 0.04, 0.06) ceramics were prepared using the conventional mixed-oxide route. The resultant samples were sintered at different temperatures and subsequently characterized in terms of both microstructure and dielectric properties to study the effects of sintering behavior. X-ray diffraction analysis reveals that all specimens are a pure perovskite phase without pyrochlore phase and exhibits a phase transition from a rhombohedral phase to the coexistence of rhombohedral and tetragonal phases with an increase of sintering temperature. The grain size first increases up to x = 0.02 and then decreases. Comparing with the undoped ceramics, the dielectric properties of the Ca-doped PZT–PCTP specimens are significantly improved. The results show that the ceramics sintered at 1180 °C have optimum electrical properties for x= 0.02: a high dielectric constant (εr = 16800) at Tc, a low dissipation factor (tanδ = 0.009) and a low resistivity (ρ= 0.09 ×10+4) (Ω.cm) at 1 kHz, which indicates that the PZT–CCTP ceramics are promising for lead practical applications.
Soft Synthesis of FAU Nanozeolites and Microporous Membranes
Authors: Mastropietro Teresa Fina , Drioli Enrico , Poerio Teresa
Published: October 2014

An alternative strategy to the conventional seeded-assisted synthesis of Faujasite (FAU) nanozeolites and their assembling into thin films on ceramic substrates are reported. The method, which can be easily extended to other zeolite topologies, offers good opportunities for industrial applications. The molar composition of the precursor gel used for the synthesis of FAU nanozeolites and membranes was conceived to achieve a high degree of supersaturation and trigger a uniform and abundant nucleation. Tubular alumina supports seeded with NaX particles of 2μm have been used to address the crystallization process. The synthesis was carried out in “soft condition” at near ambient temperature (30°C). Pure-phase FAU zeolites having uniform particle size dimensions in the range of 35-56 nm have been produced in high yield. Moreover, a uniform gel layer containing precursor entities has been concomitantly formed on the inner surface of the support after immersion in the synthesis gel. Thin and dense FAU membranes have been prepared through dry-gel conversion at higher temperatures. SEM images showed that the FAU layers have a thickness of ca. 2 μm and are constituted by closely packed, well intergrown nanocrystals, whose dimension was ca. 20-30 nm. The mass transport properties of the prepared membranes were probed by feeding dry single gases (N2 and CO2) at ambient temperature, obtaining low permeance (ca. 3.8·10-9 molm-2s-1Pa-1 for N2) and ideal selectivity higher than the corresponding Knudsen value.
Characteristic and Sinterability of Alumina-Zirconia-Yttria Nanoparticles Prepared by Different Chemical Methods
Authors: Grabis J. , Jankovica Dzidra , Steins Ints , Smits Krisjanis , Sipola Inta
Published: October 2014

The characteristics and sinterability of the Al2O3-ZrO2(Y2O3) nanoparticles produced by simple and effective microwave and molten salts methods and processed by using spark plasma sintering were studied and compared. The crystalline powders with the specific surface area in the range of 72–108 m2/g and crystallite size of 5–13 nm were obtained by calcination of samples prepared by both methods at 800 °C. The content of t-ZrO2 phase depends on concentration of Al2O3, Y2O3 and on calcination temperature but the impact of the preparation method is insignificant. The phase transition of tetragonal ZrO2 to monoclinic for the samples without Y2O3 started at 1000 °C though it was incomplete in the case of high content of Al2O3. The bulk materials with relative density of 86.1–98.7% were fabricated by the spark plasma sintering method at 1500–1600 °C depending on the content of Al2O3 and Y2O3.
Development of Highly Dispersed Hybrid Nanoalumina with the Sol-Gel Method
Authors: Petrakli Foteini , Sioulas Dimitris , Tsetsekou Athena
Published: October 2014

A hybrid sol-gel method was employed to develop a uniform and highly dispersed alumina nanopowder in the presence of hyperbranched dendritic poly(ethylene)imine (PEI) acting as template material and complexation agent for aluminium ions. For this purpose, the hydrolysis and polycondensation reactions followed the complexation reaction between the Al(NO3)3 precursor and PEI, whereas ammonium polymethacrylate was added to improve the powder dispersion. The as-formed nanopowder was characterized before and after calcination studies carried out in the temperature range 100-1200 °C. For this purpose Scanning Electron Microscopy (SEM), Field Emission SEM, Transmission Electron Microscopy (TEM), X Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric and Differential Thermal Analysis (TG-DTA), N2 porosimetry and ζ-potential measurements at different pH were carried out. The analysis confirmed the successful formation of a boehmite-PEI hybrid material of uniform tiny spheroid crystals (~ 1-2 nm) and small agglomerates. The boehmite phase is kept up to 300 °C, whereas after calcination at 600 °C a stabilized γ-alumina powder of high surface area and crystal sizes around 2-5 nm results. This phase is quite stable being kept even after calcination at 1000 °C. The transformation to the stable α-alumina phase is completed at 1100 °C leading to an easily dispersed nanopowder with crystal sizes ranging between 5-25 nm.
Study of Gamma Alumina Synthesis – Analysis of the Specific Surface Area
Authors: Munhoz Jr. Antônio Hortêncio , de Paiva H. , Figueiredo de Miranda L. , de Oliveira E.C. , Andrades Raphael Cons , Ribeiro Roberto R.
Published: October 2014

Different samples of pseudoboehmite (PB) were synthesized through the sol-gel process, using aluminum nitrate as precursor. The influence of variables on the synthesis and calcinations of the PB on the specific area of the obtained gamma-Alumina were studied. The variables were the ageing temperature (25 and 130o C), addition or not of polyvinyl alcohol to the precursor solution and the ageing time of the PB. The pH adjustment of the precursor solution was made by using ammonium carbonate. The products, which were obtained on different conditions, were then characterized by x-ray diffraction, specific area measurements through the BET process, and by thermal analysis (DTA and TG). After characterization, the synthesis products were calcined at 500°C; during this process the gamma-Alumina transformation was observed. The calcination products were characterized by the same methods (x-ray diffraction, BET, DTA and TG) and the desorption-absorption curves were obtained as well, in order to measure the pore volume of the samples. Finally, the results were analyzed through an experimental factorial planning, which showed that high specific surface area gamma-Al2O3 (around 330m²/g) can be obtained through this process.
Synthesis and Characterization of Nanocomposite HA/α-Al2O3 Sol-Gel Powders for Biomedical Applications
Authors: Camargo Nelson Heriberto Almeida , Corrêa Pricyla , Franczak Priscila F. , Gemelli Enori
Published: October 2014

The calcium phosphate nanostructured bioceramics and nanocomposites with calcium phosphate matrix are subjects of research and have raised scientific, political, industrial and commercial interest because these biomaterials present differentiated properties from microporosity, bioactivity and cell adhesion on the surface of grain and micropores compared to conventional biomaterials. This work aimed at the wet synthesis of a nanostructured hydroxyapatite bone matrix for subsequent preparation of nanocomposite hydroxyapatite/α-Al2O3 sol-gel powders, at concentrations 1, 2, 3 and 5% in volume of nanocrystalline α-Al2O3 dispersed in inter-intragranular position in the hydroxyapatite matrix. The method used for the preparation of HA/α-Al2O3 nanocomposite powders was high-energy attrition milling. This method allows obtaining nanocomposite powders formed by fine particles with sizes smaller than 100nm. The technique of scanning electron microscopy served for observation of morphology, microstructure and nanostructure. The X-ray diffractometry, laser particle analysis method and differential thermal analysis technique were used to identify the phases, particle sizes and thermal behavior for nanostructured powders retrieved from the attrition milling.
Effect of Ammonium Sulfate on Morphology of Y2O3 Nanopowders Obtained by Precipitation and its Impact on the Transparency of YAG Ceramics
Authors: Tomaszewski Henryk , Wajler Anna , Weglarz Helena , Sidorowicz Agata , Brykała Urszula , Jach Katarzyna
Published: October 2014

As known fabrication of fully transparent YAG ceramics using solid-reaction method needs highly sinterable Y2O3 and Al2O3 powders. In the work reported, as a source of alumina Taimicron TM-DR nanopowder was used, but Y2O3 nanopowder with controlled morphology was prepared by AHC precipitation starting from nitrates. The effect of ammonium sulfate was intensively studied throughout the precipitation process. As found, sinterability of final Y2O3 powders were strongly affected by the addition of (NH4)2SO4. Transmittance of sintered YAG ceramics based on commercial alumina and yttria powders prepared showed that an optimum of ammonium sulfate addition exists. Mechanism of Y2O3 nanopowders properties regulation by presence of ammonium sulfate in precipitation process was studied and discussed.
Segregation and Color Change on (Cr,Ca) Codoped Nanocrystalline Tin Dioxide
Authors: Gouvêa Douglas , Ucha Rocha Danielle , Batista Caliman Lorena
Published: October 2014

The intense violet color and the high catalyst activity of Cr-doped SnO2 nanoparticles have motivated several authors to understand the solid solution formation and the oxidation state of chromium ions after synthesis. Recent work has demonstrated the ability of surface segregation in chromium-doped tin oxide system but the oxidation state is still misunderstood. Calcium oxide addition changes the color of (Cr,Ca) codoped nanocrystalline tin dioxide pigments from violet to yellow simultaneously to a high particle size stabilization demonstrating that co-segregation could be associated to color change due to chemical environment change of chromium ions and specific surface area increase. High solubility of Cr+6 and Ca+2 allow us to determine the surface excess of both cations by ionic chromatography and the color change after surface solubilization.
Microstructural Characterization of Activated Carbon Obtained from Waste Tires
Authors: Mazzanti Francesca , Magnani Giuseppe , Grilli Selene , Brillante Aldo , Salzillo Tommaso , Brentari Alida , Burresi Emiliano , Mingazzini Claudio , Fabbri Paride
Published: October 2014

SOREME project (LIFE 11 ENV/IT/109) is aimed at synthesizing an innovative sorbent based on activated carbon obtained from the carbonization of waste tires. Microstructural characterization was mainly performed in order to define crystallinity, morphology and porosity of the activated carbon powders obtained in different conditions. In particular, XRD analysis always revealed a partially crystalline structure with different crystallite size of the nanographitic structure. The disorder of these structures was determined by Raman spectroscopy. This evaluation was made on the basis of the ratio of the integrated area of the D and G bands typical of the graphitic structure. Finally, SEM was used to put in evidence the mesopores and macropores.
Transparent Tetragonal Zirconia Ceramics by Colloidal Processing of Nanoparticle Suspension
Authors: Trunec Martin , Bera Oskar
Published: October 2014

Colloidal processing was applied to a commercial 5 vol% 3Y-ZrO2 nanosuspension with a particle size of 10-15 nm. The nanosuspension was concentrated by evaporation or by the newly developed method of osmotic dehydration. The viscosity and stability of concentrated suspensions were investigated. The concentrated nanosuspension prepared by osmotic dehydration was consolidated by centrifugation in non-porous moulds. The dried deposit had a relative density of 46% and pores ranged from 4 to 8 nm. This deposit was densified by pressureless presintering to closed porosity, followed by hot isostatic pressing in order to obtain transparent ceramics. After sintering, the tetragonal zirconia retained the nanocrystalline structure with an average grain size of 65 nm and an in-line transmission of 25 % (at 633 nm wavelength and 0.5 mm plate thickness).
Thick Film Processing Challenges in the Realisation of a Co-Fired Solid Oxide Fuel Cell Roll
Authors: Cassidy Mark , Connor Paul , Etches Marielle , Kalecheff Yann , MacHado Marina , Nairn Julie , Irvine John
Published: October 2014

The Solid Oxide Fuel Cell Roll (SOFCRoll) is a novel design based on a double spiral. Combining structural advantages of tubular geometries with processing advantages of thick film methods, it utilises a single cofiring process. The initial concept used separate tape cast layers which were laminated before rolling. To optimise layer thickness to function, thinner screen printed layers were combined into the tape cast structure in 2nd generation cells. This presented several processing challenges, such as achieving dense electrolyte layers, maintaining porous electrode and current collecting layers and incorporation of integral gas channels. Performance has been promising with open circuit voltages close to 1V and cell power of over 400mW at 800°C, however cracking is still evident. Therefore further iterations are in development where thinner layers are sequentially cast, aiming to improve interfacial bonding and better match plasticity and burn out to reduce cracking. This paper reviews key aspects of understanding and development of the SOFRoll , the challenges that have been tackled and what challenges remain, along with future directions for development and potential applications for this device.
Coupling SHS and SPS Processes
Authors: Orrù Roberto , Licheri Roberta , Musa Clara , Cao Giacomo
Published: October 2014

The consolidation of refractory ceramic powders at relatively milder conditions with respect to conventional methods represents an important target to achieve. Based on results recently reported in the literature, it is possible to state that the combination of the Self-propagating High-temperature Synthesis (SHS) with the Spark Plasma Sintering (SPS) technologies provides a useful contribution in this direction. Specifically, the two-steps processing route consisting in the synthesis of the ceramic powders by SHS and their subsequent densification by SPS is successfully utilized to obtain various dense MB2-based materials (M= Zr, Hf, Ta). In this regard, an important role is played by the SHS process, particularly for the synthesis of composite powders. Indeed, stronger interfaces are established among the different phases formed in-situ, so that diffusion phenomena are promoted during SPS. Additional benefits are produced by the use of the latter technology, due to the direct passage of the electric current through the powders undergoing sintering and the die containing them.
Characterization of Furnace Sintered Mullite and Oxide Ceramic Matrix Composites (O-CMC) by Using Glass Solders
Authors: Gadelmeier Christian , Schmidt Jens , Göthe M. , Jovanovic Dorde
Published: October 2014

Energy efficiency is becoming more and more important in high temperature processes or for high temperature applications. In order to achieve thermally efficient processes, heat accumulators and heat exchangers are increasingly being used to store or to recover the process heat [1]. Currently used commercial heat exchanger systems are based on stacked plates or tubes. Primarily they are produced from metals which have a high thermal conductivity and show gas-tightness. Ceramics or ceramic matrix composites (CMC) are novel material candidates due to their higher resistance in severe environments, their ability to withstand extremely high operating temperatures and especially, their high thermal shock resistance. In order to fabricate HX with ceramic designs, joining is the key technology to perform complex shaped components [2].
New Developments of FAST/SPS Tool Materials
Authors: Raethel Jan , Hennicke Juergen , Dyatlova Yanina , Herrmann Mathias , Rumyantsev Vladimir
Published: October 2014

Since FAST/SPS technology ensures an adequate and fast consolidation of different materials the demand for suitable pressing tool materials is growing. Graphite based materials are widely used and well known as FAST/SPS tool materials but they also have some unwanted or weak properties, for example, a possible reaction or reduction of sample material as well as low mechanical values compared to other tool materials. In this paper, an approach for the FAST/SPS consolidation of ZTA-Ti (C,N) and TiN-TiB2 based cutting tool inserts in newly developed FAST/SPS tool materials which can be used for fully automated FAST2 devices is presented. Furthermore, a general strategy for the further development of FAST/SPS tool materials is focused.
Microwave Technique: An Innovated Method for Sintering β-Eucryptite Ceramic Materials
Authors: Benavente Rut , Salvador María Dolores , Peñaranda-Foix Felipe L. , García-Moreno Olga , Torrecillas San Millan Ramon , Borrell Amparo
Published: October 2014

Microwave sintering has emerged in recent years as a new, fast, cheap and green technology for sintering a variety of materials. The main advantages of microwave heating can be summarized as follow: reduced processing times, energy costs and environmental benefits. Nevertheless, understanding how this specific heating drives to obtain ceramic materials with a combination of unique, structural and functional properties is the big challenge. The present work shows the different and improved properties achieved with β-eucryptite nanocomposite ceramic materials by microwave heating compared with the conventional method. Microcracking evolution in addition to the microstructure of the sintered materials along the several thermal cycles has been studied. Mechanical properties changes observed can be related to this process. Thus, the microwave technique is a promising tool for sintering new materials by controlling the composition of the phases, chemical reactivity and nanostructure, using up to 70% less energy in the whole sintering process than conventional heating. This technique becomes part of the new and innovative technologies "eco-green".
Reactive Sintering of TaB2 Using Spark Plasma Sintering Method
Authors: Laszkiewicz-Łukasik Jolanta , Jaworska Lucyna , Putyra Piotr , Smuk Barbara
Published: October 2014

Tantalum diboride was synthesized and sintered from metallic tantalum powder and amorphous boron powder in one technological process using Spark Plasma Sintering method. The precursors were: tantalum with grain size below 5μm and boron with particle size in the range of 1-2μm. Tantalum powder, before mixing with boron, was subjected to high-energy milling under argon atmosphere in order to reduce specific surface area. The process should be carried out without air, due to protection against the influence of oxygen. During reactive sintering SPS process oxidation participation should be limited because of high exothermic reactions. Morphologies of the powders before and after milling were studied using SEM. Reactive sintering processes were carried out at temperatures from 1800°C up to 2200°C at 48MPa. Sintering duration was in the range of 1-30min. Volume changes of samples and temperature increase during the synthesis were observed and determined. The result of X-Ray phase composition analysis and microstructure observations using SEM are presented. Relative density, Young's modulus, Vickers hardness and fracture toughness of the materials were determined. During the reactive sintering the material of only one phase TaB2, with high level of densification, was obtained.
Laser Synthesis Features of Composite Ceramics Y3Al5O12-Y2Ti2O7-Al2O3-Al2TiO5
Authors: Márquez Aguilar P.A. , Vlasova M. , Lakiza S. , Kakazey M. , Bykov A. , Stetsenko V.
Published: October 2014

The effect of directed laser treatment on the compacted binary mixtures Al2O3–Y2O3, Y2O3–TiO2, Al2O3–TiO2 and ternary mixtures Al2O3−Y2O3−TiO2 was investigated. It was shown that phase formation occurs within the framework of binary mixtures Al2O3–Y2O3, Y2O3–TiO2, Al2O3–TiO2 and is accompanied by the formation of Y3Al5O12, Y2Ti2O7 and Al2TiO5 compounds. The set of phases and microstructures of generated ceramics depend on Al2O3 content and TiO2/Y2O3 ratio in initial mixtures. Basing in the obtained results the tentative phase diagram for the Al2O3–Y2O3−TiO2 system was constructed.
New Results on Structural Macrokinetics Obtained on Multilayer Nanofoils
Authors: Rogachev Alexander S. , Vadchenko Sergey G. , Mukasyan Alexander S.
Published: October 2014

SHS process in the multilayer nanofoils possesses many unique properties, such as unexpectedly high propagating rate (up to 102 m/s) and extremely short time of reaction and product phase formation (10-7 – 10-6 s). Understanding of the mechanism of this process has critical significance not only for the theory of SHS, but also for various applications of the reactive nanofilms, e.g., joining of dissimilar materials and items. An overview of new experimental results shows existence of complex structure of the reaction waves in the multilayer foils and reveals some new “solid-flame” combustion phenomena at macroscopic level. Comparison of these data with the study of the micro- and nano-scale processes by different experimental methods sheds new light on the intrinsic mechanism of the process. The roles of the melts, reactive exothermic dissolution and methastable phases are discussed.
Novel Super-Elastic Materials for Advanced Bearing Applications
Authors: Della Corte Christopher
Published: October 2014

Tribological surfaces of mechanical components encounter harsh conditions in terrestrial, marine and aerospace environments. Brinell denting, abrasive wear and fatigue often lead to life-limiting bearing and gear failures. Novel superelastic materials based upon Nickel-Titanium (NiTi) alloys are an emerging solution. NiTi alloys are intermetallic materials that possess characteristics of both metals and ceramics. NiTi alloys have intrinsically good aqueous corrosion resistance (they cannot rust), high hardness, relatively low elastic modulus, are chemically inert and readily lubricated. NiTi alloys also belong to the family of superelastics and, despite high hardness, are able to withstand large strains without suffering permanent plastic deformation. In this paper, the use of a hard, resilient NiTi alloy for corrosion-proof, shockproof bearing and gear applications is presented. Through a series of bearing and gear development projects, it is demonstrated that NiTi’s unique blend of material properties lead to significantly improved load capacity, reduced weight and intrinsic corrosion resistance not found in any other bearing materials. NiTi thus represents a new materials solution to demanding tribological applications.
Heat-Resistant Inorganic Fibers
Authors: Ishikawa Toshihiro
Published: October 2014

Up to now, many types of inorganic fibers have been developed. The main purpose is to develop composite materials with lightweight and high fracture toughness. Of these, carbon fiber has already established a very big market. By the way, representative oxide fibers (alumina/silica-based fibers) show heat-resistance’s limitation at around 1200°C. In order to improve the heat-resistance, some types of eutectic oxide-fibers have been studied. On the other hand, SiC fibers with both heat-resistance and oxidation-resistance were developed over 30 years ago. After that, lots of improvements have been performed, and finally several types of excellent heat-resistant SiC-polycrystalline fibers, which can be used up to about 1800°C, were developed from polycarbosilane. Using these fibers, lots of applications have been considered in the fields of aerospace, nuclear system, and so on. Furthermore, making the best use of the aforementioned production process, several types of functional ceramic fibers with gradient-like functional surface layers also have been developed. In this paper, of these inorganic fibers, heat-resistant SiC fibers will be addressed along with historical view point on ceramic fibers.
Carbon Based Coatings for Hermetic Compressor Applications
Authors: de Mello Jose Daniel Biasoli
Published: October 2014

Household refrigeration represents 17.3% of home energy consumption in the USA and 47% in Brazil. This article overviews a multidisciplinary approach to develop a traditional hermetic compressor (oil lubricated, with several rotating parts), into an oil-less, linear motion, innovative compressor, with improved efficiency, versatility and sustainability. This involves the development of surface engineering processes combining purpose-oriented phases applied to soft substrates to achieve high wear resistance and load support and low friction coefficient. Initially, the role of the environment (air, CO2 and R600a) on the tribological behaviour of a commercially available Si-rich multifunctional DLC coating deposited on AISI 1020 steel is illustrated. In sequence, the influence of the thickness of different layers (DLC and CrN) on sliding wear is analysed. Results are presented using an original approach (3D triboscopic maps) for two distinct configurations (increasing load and constant load) and findings are confronted with numerical simulations using Film Doctor®. Finally, a low cost process to obtain a multifunctional coating (different nitrided layers + DLC) is described, which uses a unique thermal cycle reactor capable of coating parts in industrial scale with reduced cost.
Amorphization, Field Activated Sintering and Superplastic Forming of UHTCs
Authors: Kimura Hiroshi
Published: October 2014

This article reports new events of amorphization, field activated sintering and superplastic forming of ultrahigh temperature ceramics (UHTCs), in order to provide an advanced method of the integrated material design and solid state synthesis on demand in the framework of material system science and technology. Nonequilibrium reaction ball milling can be used to prepare a variety of amorphous powders of covalent-bonding typed ceramics such as SiC, B4C, HfC and ZrB2, a binary system of B4C∙SiC, and ternary system of B4C∙SiC∙ZrB2, when having a judicious selection of reaction routes and process controls based on thermodynamics and kinetics of mechanically driven amorphization. Then, intelligent nanosintering with multi-variable control makes it possible to obtain full densification of amorphous UHTCs powder below nanocrystallization, and in process amorphous and/or nanocrystalline structure control densification. Especially, millimeter wave pressure sintering makes it possible to obtain rapid densification during enhanced non-Newtonian flow under an electric field at the temperature of below glass transition. The full-density amorphous B4C・SiC shows high-strain rate superplastic forming during viscous flow with compressibility of 0.75 around 1400 K prior to crystallization.
Development and Processing of SiAlON Nano-Ceramics by Spark Plasma Sintering
Authors: Hakeem Abbas Saeed , Khan Raja Muhammad Awais , Al-Malki Moath Mohammad , Patel Faheemuddin , Bakare Akolade Idris , Ali Sadaqat , Hampshire Stuart , Laoui Tahar
Published: October 2014

The development of SiAlON-based ceramics has shown great impact in the field of cutting/drilling tool industry and other engineering applications. It is highly desirable to cut-down the cost of the cutting tools by increasing their service lifetime. Potential ways to improve tool life is by preparing these SiAlON-based ceramics adopting non-conventional synthesis routes and by using different precursors. The present study reports the results of synthesis of SiAlON-based nano-ceramics via spark plasma sintering (SPS) technique. Generally, metal nitride and metal oxide precursors are used for synthesizing self-reinforced SiAlON ceramics. In this work, nano-sized metallic precursors including amorphous-Si3N4 and crystalline β-Si3N4, SiO2, AlN and Al2O3 were used, which could be a novel way to synthesize SiAlONs at low temperatures with enhanced performance. The properties of these SiAlONs are tailored by optimizing the synthesis parameters. The synthesized samples were characterized by X-ray diffraction and field emission scanning electron microscopy to study the effect of processing parameters on microstructure, density and hardness.
Dispersion of Carbon Nanotubes in Alumina Using a Novel Mixing Technique and Spark Plasma Sintering of the Nanocomposites with Improved Fracture Toughness
Authors: Bakhsh Nabi , Khalid Fazal Ahmad , Hakeem Abbas Saeed , Laoui Tahar
Published: October 2014

The present study emphasizes on the fabrication of carbon nanotubes (CNTs) reinforced alumina nanocomposites for structural applications. A new technique for the mixing and dispersion of CNTs in alumina powder was employed. Spark plasma sintering (SPS) technique was used for the fabrication of nanocomposites with varying amounts of as-received CNTs (1, 2 and 3 weight %) in alumina matrix. Densification behavior, hardness and fracture toughness of the nanocomposites were studied. A comparison of mechanical properties of the desired nanocomposites was presented. An improvement in fracture toughness of approximately 14% at 1 wt% CNT-alumina nanocomposite over monolithic alumina compacts was observed due to better dispersion of CNTs in alumina matrix that ultimately helped in grain growth suppression to provide finer grain in the nanocomposites. The fractured surfaces also revealed the presence of CNTs bridging and pull out that aided in the improvement of mechanical properties. The synthesized samples were characterized using field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, densification, Vickers hardness testing and fracture toughness measurements.
Observing the Chiral Charge Ordering Transition in TiSe2
Authors: van Wezel Jasper
Published: October 2014

The charge density wave order in titanium diselenide is unusual in that it is characterized by a breakdown of inversion symmetry as well as translational symmetry, leading to the emergence of a chiral crystal structure. This novel state of matter was recently described theoretically in terms of the simultaneous and cooperative onset of both charge and orbital order. Here, we discuss the analysis of recent X-ray diffraction and related measurements on 1T-TiSe2 in terms of the predictions of that theoretical model. It is show that the experimental observations agree with the expectations from an emerging combined charge and orbital ordered phase.
Transparent Nano-Glass-Ceramic for Photonic Applications - Distribution of RE-Doping Elements in the Fluoride Nano-Crystals Analysed by XAS and HR-TEM
Authors: de Pablos-Martín Araceli , Pascual Maria J. , Durán Alicia
Published: October 2014

Rare-earth (RE) ions-doped oxyfluoride transparent glass-ceramics containing nano-crystalline phases with very low phonon energies like LaF3, NaLaF4 and KLaF4 combine the superior optical performance of low phonon energy phases with the high mechanical, chemical and thermal stability of oxide silicates. The insertion of the doping RE ions in the fluoride nanocrystals enhances the radiative optical emission processes currently focused on up- and down-conversion emissions. Thus, a key point is to identify and quantify the RE ions in the fluoride nano-crystals. In this contribution an oxyfluoride glass and the corresponding glass-ceramics of composition 55 SiO2. 20 Al2O3.15 Na2O.10 LaF3 mol % doped with 1 mol % Tm2O3 is presented. The Tm3+ incorporation in the precipitated LaF3 nano-crystals has been analysed by two different techniques. Firstly, TEM and Energy Dispersive X-Ray Spectroscopy (EDXS) were used to perform elemental distribution mappings of RE elements that allow to directly localising RE ions in the glass and glass-ceramics. Additionally, X-ray absorption spectroscopy (XAS) measurements were performed to analyse the distribution and first coordination sphere of Tm3+ ions in the glass and glass–ceramics by using X-ray absorption near edge structure spectroscopy (XANES) and extended absorption X-ray fine structure spectroscopy (EXAFS), which have allow to quantify the Tm3+ incorporation in the LaF3 nano-crystals.
Characterization of Nanostructured Phases and Peculiar Phase Transitions in BNBT Lead-Free Piezoceramics
Authors: Pardo Lorena , García Alvaro , Brebøl Klaus , Mercadelli Elisa , Galassi Carmen
Published: October 2014

Submicron-structured (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT6) dense ceramics, from nanometric powder synthesized by sol gel auto-combustion at 500°C and obtained by hot-pressing (800°C-2h) and subsequent recrystallization at moderate temperature (1000-1050°C-1h), have been studied. In-situ measurements at the shear mode of electromechanical resonance of non-standard thickness-poled shear plates as a function of the temperature show higher depolarization temperature than measurements at the radial mode of thin disks. Shear mode related material coefficients are measurable up to 160°C, being k15≈30% and d15≈250 pC.N-1 at 130°C. Depolarization is a complex phenomena caused by a ferroelectric (FE) macrodomains thermal randomization and a phase transition from the field-induced FE phase to a relaxor phase. The early stage of such a transition involves a non-negligible piezoelectricity arising most probably by the percolative coexistence of ferroelectric macrodomains in the resonator under the given stress field for each resonance mode.
The Investigations on Luminescence Characteristics and Influence of Doping and Co-Doping Different Rare Earth Ions in White Phosphorescence Materials Having Different Luminescent Centers
Authors: Karacaoglu Erkul , Karasu Bekir , Öztürk Esra
Published: October 2014

The Akermanite type alkaline earth silicate Ca2MgSi2O7 activated by different types of rare earths was prepared by the conventional solid state reaction method under weak reductive atmosphere. The phase formation, particle size distribution, particle morphologies and photoluminescence properties of the samples have been investigated respectively. The comparative results of SEM and laser particle size analysis revealed that the relatively regular morphology, smaller particle size distribution could be achieved for the phosphors synthesized by the solid state reaction method including dry-ground after which powders were sieved below 170 meshes. The effects of rare earth oxides; Nd2O3, Pr6O11, Ce2O3 and Sm2O3 on the luminescence properties of the host material, Ca2MgSi2O7, were studied. Remarkable enhancement and novel color emitting including white in luminescence characteristics of host material were observed as a result of doping the mentioned rare-earths were doped.