bluuebunny/crossref_metadata_2025 huggingface dataset:
New Low Toxic Water-Soluble Monomers for Gelcasting of Ceramic Powders
Authors: Szafran Mikolaj , Szudarska Agnieszka , Bednarek Paulina
Published: October 2010

In this paper the two new low toxic water-soluble monomers: glycerol monoacrylate and
3-O-acrylic-D-glucose are introduced and their application in gelcasting of alumina powder is
reported, in comparison with 2-hydroxyethyl acrylate, the commercial monomer. Both
synthesized substances do not need an addition of cross-linking agent to the ceramic slurry,
because hydrogen bonds can be formed in the polymer network, owing to the presence of two
or more hydroxyl groups in their molecules, unlike in the case of 2-hydroxyethyl acrylate.
Rheological behavior of alumina gelcasting suspensions containing these monomers has been
studied, as well as the characteristics of raw and sintered elements formed from these slurries
by initializing an in situ polymerization.
Pulsed Electric Current Sintering of Electrical Discharge Machinable Ceramics
Authors: Vleugels Jef , Malek Olivier , Vanmeensel Kim , Huang Shui Gen , Ran Song Lin , Van der Biest Omer , Lauwers Bert
Published: October 2010

Pulsed electric current sintering allows densifying most ceramics at high heating and
cooling rates within very short times at elevated temperature, allowing to minimise grain growth. In
order to fully explore the PECS potential, it is beneficial to flow the current through the powder
compact by either using conductive powder or a powder compact that becomes conductive during
densification. Although in-situ Joule heating of the powder compact allows very fast heating rates, it
does not necessarily result in a homogeneous temperature distribution. The influence of the current
flow on densification and the impact of electrical conductivity on the temperature distribution
during PECS are illustrated. The PECS technology at present is limited to the fabrication of simple
geometrical shapes. Electrical Discharge Machining (EDM) on the contrary allows production of
complex shapes, providing the ceramic has a minimum electrical conductivity. Although EDM has
no mechanical impact, the thermal impact is high and the EDM parameters should be carefully
selected in order to optimise surface quality and component strength. During wire-EDM, the fast
and rough initial cut has to be followed by a sequence of lower energy finishing cuts to optimise the
surface quality. The case studies presented are B4C-TiB2 ceramics and ZrO2-based composites with
electrically conductive phase addition.
Reactive Spark Plasma Sintering of Si3N4 Based Composites
Authors: Taslicukur Zeynep , Şahin Filiz Çinar , Goller Gultekin , Onüralp Yücel , Kuskonmaz Nilgun
Published: October 2010

Si3N4 based composites containing different amounts of SiC and SiAlON were produced by reactive spark plasma sintering of Si3N4, SiO2 and C black. Y2O3 and AlN were added as sintering additives. The SPS process was carried out at sintering temperature of 1650 0C for 5 min with uniaxial pressure of 40 MPa in a nitrogen atmosphere.The mechanic properties and morphology of Si3N4 ceramic composite were determined. Microstructures of the sintered samples were observed by SEM images and phase compositions were analysed by XRD.
Modelling Multi-Cracking in Thin Films during Constrained Sintering Using Anisotropic Constitutive Law and Material Point Method
Authors: Li Fan , Pan Jing Zhe
Published: October 2010

The sintering of thin films is widely used for surface coatings and because of its
technological importance has generated extensive research interest. During the sintering process, the
thin film is constrained by the substrate, which generates considerably high levels of stresses.
Crackings are often observed and are considered as one of the major problems of the surface coating
technique. This paper has proposed a new numerical method in order to tackle the traditional
difficulties in simulating multi-crackings during constrained sintering. Main features of the present
method include: (i) the material data is represented by an anisotropic constitutive law, (ii) a new
numerical scheme is developed for the crack initialization and growth based on the material point
method, (iii) the 3D viscous film shrinkage model is solved by using a dynamic FE scheme, and (iv)
the random nature of the initial green body density is represented by statistical variabilities. It is
shown that the model proposed by the present paper is capable for the nucleation and propagation of
multi-cracks in a straightforward manner. Cracking patterns are shown to be consistent with
experimental understandings. The focus of the paper is on the numerical issues and demonstrating
the capacity of the model.
Simultaneous Synthesis and Sintering of Al2O3/Mo2N Composites Using Capsule-Free Nitrogen Hot Isostatic Pressing and their Characterization
Authors: Ken Hirota , Katsuya Takaoka , Yasushi Murase , Masaki Kato
Published: October 2010

Synthesis of dense materials with the compositions of Al2O3/Mo2N=100/0 ~ 40/60 vol% has
been attempted directly from Al2O3/Mo mixed raw powder compacts using capsule-free N2 hot
isostatic pressing (HIP). During HIPing [1500°C/(16~20)MPa]/1h], solid/gas reaction between Mo
and N2 was introduced to form Mo2N. Most sintered composites consisting of only Al2O3 and Mo2N
phases reached a higher relative density than 98.0% with closed pores nevertheless capsule-free
HIPing. Distribution of Mo2N particles just formed suppressed the grain growth of Al2O3 during
sintering. Mechanical properties, such as bending strength (Σb), Vickers hardness (HV), fracture
toughness (K1C), and other properties have been evaluated as a function of their compositions. The
best mechanical values of Σb (c.a. 573 MPa), HV (c.a. 20.3 GPa) and K1C (c.a. 5.00 MPa･m1/2) were
attained at the composition of Al2O3/Mo2N=90/10 vol%, due to a high density (98.6%) and small
grain size of Al2O3 matrix (Gs c.a. 4.70 μm). Further addition of Mo2N reduced the sinterability of
matrix grains, resulting in low densities of around 90% at the 40/60 vol% composition.
Numerical Modeling and Experimental Characterization of the Pyroplasticity in Ceramic Materials during Sintering
Authors: Bene Pasquale , Bardaro Danilo , Bello Daniela , Manni Orazio
Published: October 2010

The aim of the work is the study of the pyroplasticity in ceramic materials in order to
simulate the deformations of complex ceramic component during sintering. A ceramic material
undergoing densification can be treated as a linear viscous material. Generally, the viscosity
decreases as the temperature increases, however the densification and the consequent grain growth,
result in a viscosity increase.
A bending creep test is proposed for measuring the change in viscosity of the ceramic material
during densification. Equations, based on beam deflection theory, are derived to determine the
viscosity during the whole firing cycle by measuring the deflection in the centre of specimens. In
addition, dilatometric analyses are performed to measure the sintering shrinkage and the specimen
density, which continuously changes during the sintering process. On the basis of an accurate
experimental characterization the parameters of Maxwell viscoelastic constitutive law are derived.
A numerical-experimental procedure has been adopted in order to calibrate the numerical model
that, finally, has been used to predict the pyroplastic deformations of complex ceramic components.
Description of Carbides Sintering Process Using Kuczynski and Frenkel Sintering Models
Authors: Gubernat Agnieszka
Published: October 2010

This work presents measurements concerning sintering description according to two the: Kuczynski and Frenkel models. Investigation covered selected metal–like carbides: TiC0,8, NbC and WC. Kinetic equations were also developed, according to Kuczynski model to describe sintering of each carbide and it was attempted to determine mechanisms of mass transport mechanism dominating at each sintering stage. Parameters describing sintering process of each of investigated carbides: α and β constants, the initial shrinkage rate α-1, the limit of shrinkage at infinite time β-1 and initial apparent viscosity of system were in turn determined using Frenkel model. Such data allowed to achieve full characterization of carbide sintering.
Effect of the Two-Step Sintering in the Microstructure of Ultrafine Alumina
Authors: Chinelatto Adriana Scoton Antonio , Manosso Milena Kowalczuk , Pallone Elíria Maria Jesus Agnollon , Souza Ana Maria , Chinelatto Adilson Luiz
Published: October 2010

Sintering in two-steps has been applied with success for densification of nanometric and submicrometer ceramic powders without grain growth. In this work the applicability of two-step sintering as a means of suppressing the grain growth of submicrometer alumina is verified. Experiments, in which the grain growth and densification were characterized after conventional sintering and two-step sintering, were conducted. Conventional sintering is used as a choice of the steps for two-step sintering. In the first two-step sintering studied, one hypothesis that the maximization of final density with minimum grain growth can be achieved by improving the narrowing of grain size distribution at a pre-densification sintering stage was assumed. And the other two-step sintering is based on works of Chen and Wang, in which the samples are first heated to a higher temperature to achieve an intermediate density, and then cooled down and held at a lower temperature until they are dense. The results showed that the choice of steps does not permit to suppress grain growth, but, the two-step sintering influenced in the development of the final microstructure, taking to microstructures which were finer grained than in alumina sintered conventionally.
Synthesis and Sintering of Mullite Ceramics Using Microwave Heating
Authors: Ebadzadeh Touradj , Barzegar-Bafroei H.
Published: October 2010

Mullite ceramics have been known as the engineering materials due to their special properties such
as high refractoriness, good thermal shock resistance, low thermal expansion, good strength at low
and high temperatures, good creep resistance and low dielectric constant. In the present work,
mullite samples were prepared by reaction sinteing of alumina and silica gel and subsequent
sintering in a microwave process. The sintering of samples was carried out at temperatures in the
range of 1400-1500°C with no soaking time. Density and porosity measurements showed a high
density (89.3% TD) and low porosity (5.8%) for samples sintered at 1400°C under microwave
conditions while for samples sintered conventionally at this temperature after 2h heating, density
decreased (81.9% TD) and porosity increased (18.5%). By increasing sintering temperature to 1450
and 1500°C under microwave conditions, density increased (93.3 and 93.8% TD) and porosity
decreased (0.31 and 0.36%), respectively. Microhardness measurements showed 27.6% increment
when sintering temperature increased from 1400 to 1500°C. The mean grain size increased (34.8%)
for samples sintered in furnace rather than those sintered in microwave process.
Low-Temperature Sintering of Apatite-Type Lanthanum Silicate with Fluoride Additives
Authors: Takahashi Junichi , Honda Hidetoshi , Akashi Takaya , Abe Kazutomo , Itoh Hidenobu , Kishi Masami
Published: October 2010

Various fluorides (3 - 8 wt%) were added to a La9.33Si6O26 (LSO) powder synthesized by
calcining the corresponding oxides mixture at 1100°C for 4 h. The addition of BaF2, AlF3 or
Ba3Al2F12 caused an appreciable and substantial increase in bulk density after sintering at 1400º and
1450°C, respectively. These fluorides melt below 1400°C to form liquid phase which could assist
the densification at low temperatures. Abnormal grain growth was observed for LSO samples with
the addition of AlF3 and Ba3Al2F12, but it was effectively suppressed by stepwise sintering at 1400º
and 1450°C. The BaF2 addition brought about the simultaneous promotion of densification and
moderate grain growth, leading to the production of a densified LSO sample showing a conductivity
of 1.5 x 10–2 Scm–1 at 800°C with an activation energy of 1.23 eV.
Synthesis of Scandium Oxide Nanoparticles from Solution
Authors: Poirot Nathalie , Boy Philippe , Belleville Philippe , Bianchi Luc
Published: October 2010

Scandium oxides nanopowders have been synthesized using a sol-gel route. ScOOH nanoparticles have been first prepared in solution using ScCl3, xH2O as precursor. Influence of pH and reflux time on particles size and shape has been studied. Sc2O3 nanoparticles were then obtained after ScOOH sol drying. Sols were characterized by laser granulometry, thermogravimetry and differential analysis (TGA- DSC). Depending on pH, 40 to 1000 nm size ScOOH particles can be obtained. At a given pH, the reflux time duration also influences the ScOOH particles size. The ScOOH sol can be used to prepare highly pure Sc2O3 nanopowders. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microcopy (TEM), were used to characterize Sc203 nanopowders obtained from the various ScOOH solutions. The DSC and laser granulometry data indicate a strong relation between the nanoparticles size and the temperature of transformation of g-ScOOH to Sc2O3. Depending on the sol preparation various particles Sc2O3 size can then be obtained allowing the selection of the more suitable powder for transparent ceramic preparation.
Elaboration and Mechanical Characterization of Al2O3-ZrO2-YAG Ultrafine Composites
Authors: Palmero Paola , Naglieri Valentina , Spina Giulia , Montanaro Laura
Published: October 2010

Al2O3-YAG-ZrO2 composites have been produced by surface modification of a commercial nano-crystalline alumina powder with inorganic precursors of the desired second phases. The doped powders were calcined at various temperatures and for different times: as a function of the thermal treatment, zirconia directly crystallized on the alumina surface, while YAG phase was yielded by solid state reaction among an amorphous yttrium-rich precursor and alumina powder. Several compositions, with increasing second phases volume fractions, were investigated, precisely, Alumina-5vol.%YAG-5vol.%ZrO2, Alumina-20vol.%YAG-20vol.%ZrO2 and Alumina- 33vol.%YAG-33vol.%ZrO. Slip cast bodies were produced by aqueous suspensions of calcined and well-dispersed powders; free-sintering performed at 1500°C for 3 h allowed to reach full densification. The role of the second phases amount on the microstructural features and on some mechanical data preliminary evaluated was established.
Influences of Eu2+ and Dy3+ Contents on the Properties of Long Afterglow Strontium Aluminate Phosphors
Authors: Kaya Selvin Yesilay , Karasu Bekir , Kaya Guray , Karacaoğlu Erkul
Published: October 2010

The detailed preparation process of Eu2+ and Dy3+ ion co-doped phosphor powders in Sr4Al14O25:Eu2+/Dy3+ phosphor system with bluish-green long afterglow produced by solid state reaction method under reducing atmosphere is here reported.
X-ray diffraction (XRD), scanning electron microscopy (SEM), and particle size analysis were made to assign the effects of Eu and Dy ions on the luminescent properties of the synthesized phosphors, which were determined by measuring the photoluminescence spectra. The maximum emission intensity of these phosphors under excitation was investigated. As a result, the relevant values were obtained from the phosphorescent pigment with 0.21% and 0.05% molar percent of Eu2+ and Dy3+.
Spray Freeze Granulation of Nano Powders for Die Pressing
Authors: Binner Jon , Annapoorani Ketharam , Vaidhyanathan Bala
Published: October 2010

The processing of nanocrystalline yttria doped zirconia powder via dry forming routes has been
investigated via the granulation of the powder using spray freeze drying (SFD). Free-flowing and
crushable powders suitable for either die or isosatic pressing have been achieved via the combination of
SFD with additions of up to 2 vol% of Freon 11; the latter reducing the strength of the granules whilst
not affecting the powder flowability into the die. The approach has allowed relic-free green bodies of
up to 55% of theoretical density to be produced using pressures as low as 250 MPa.
Novel Sol-Gel Synthesis of LiMn2O4 and LiNixCo1-xO2 Powders
Authors: Deptula Andrzej , Łada Wiesława , Olczak Tadeusz , Wawszczak Danuta , Brykala Marcin , Zaza Fabio , Goretta Kenneth C.
Published: October 2010

A modified complex sol-gel process was developed to synthesize LiMn2O4 and
LiNixCo1-xO2 powders. Sols were prepared from 1.5 M of Mn2+ or 1 M of xNi2+ and (1-x)Co2+
acetates plus ascorbic acid aqueous solutions by alkalizing them with LiOH and NH4OH. Ascorbic
acid was added to prevent precipitation in the precursor solutions. When the sols were concentrated
to one-third of their initial volume under reduced pressure and then gelled by drying for 10 days,
heat treatment to ≥700 °C was accompanied by foaming, violent self-ignition, and formation of
carbonates in the Ni-containing species. Significant improvements to the process and resulting
powders were gained by modifying the gelation step. When gelation and drying were carried out
under reduced total pressure, subsequent heating produced self-ignition, but no foaming, for all
heating rates. The resulting products were determined to be nearly phase pure and carbonate free by
thermogravimetric, differential thermal, X-ray, and infrared spectroscopy methods.
Smart Processing for Ceramics Structure Tectonics: Fabrication of Dielectric Micro Patterns for Artificial Photosynthesis in Terahertz Wave Regions by Using Stereolithography
Authors: Kirihara Soshu , Komori Naoki , Ohta Noritoshi
Published: October 2010

Smart processing for ceramics structure tectonics is new strategy of science and engineering to create novel functional materials with special patterns and morphologies. In this lecture, various investigations to develop the functionally structured materials by using smart processes of stereo- lithography will be introduced. For example, photonic crystals with periodic arrangements in dielectric constants are strong candidates of artificial functional materials to control electromagnetic wave energies effectively. Special modifications of dielectric micro patterns to harmonize electromagnetic waves in terahertz frequency ranges with molecule vibrations of various biochemical solutions will be introduced as investigative results of artificial photosynthesis.
Influence of Binder on Porous Ceramic Properties Prepared by Polymeric Sponge Method
Authors: Jach Katarzyna , Pietrzak Katarzyna , Kalinski Dariusz , Chmielewski Marcin
Published: October 2010

Porous ceramic materials are used in medicine as well as in industry. They can be prepared in the
form of filter components, thermal insulators, or composite components. Preforms of this type can
only be applied if they meet the respective structural requirements. In the present study, such a
porous ceramic material was produced by the polymeric sponge method using a polyurethane
sponge and a-Al2O3 Almatis. The aqueous suspension was prepared with binders of the two types:
polyvinyl alcohol and a dispersion based on methacrylic acid esters and styrene. The aim of this
study was to find the relationship between the composition of the weight slips, sintering conditions,
and the structure of the porous ceramic obtained. The paper presents the results of studies on the
rheological properties of the ceramic slurries and the results of strength tests of the ceramic
material.
Aluminum Oxide Ceramics Obtained by Commercial Starch Consolidation with Gradient Porosity
Authors: Mota Rogério Pinto , Sampaio Fernandes Rodrigo , de Campos Élson , Ferreira de Lucena Emerson , Algatti Mauricio A.
Published: October 2010

The starch consolidation technique is commonly used for obtaining porous ceramics due to bonding and porous-maker starch characteristic during gelling process. The method adopted here improved the water drainage by using a plaster porous base (70 and 90 consistency values) improving the water drainage by action of gravity and the capillary effect. It used slip with 50 vol% solids and as precursors oxide A-1000SG and commercial cornstarch with a mass concentration varying from 10 to 40%. For comparison between the present method and the common one, slip was put in impermeable and permeable base moulds. The gelling occurred at 70°C for 2 hours and the drying at 110°C. Pre-sintering was carried out at 1000°C and the sintering at 1600°C with a plateau of 1 hour. Results showed that the plaster consistency of the mould bases was preponderant on ceramics porosity. Porosity and apparent density measurements using light and electron microscopy revealed variation of 5% of porosity from the top to the bottom of the samples.
Solution Combustion as a Promising Method for the Synthesis of Nanomaterials
Authors: Mukasyan Alexander S.
Published: October 2010

Solution–combustion is an attractive approach to synthesis of nanomaterials for a variety
of applications, including catalysts, fuel cells, and biotechnology. In this paper, several novel
methods based on the combustion of a reactive solution are presented. These methods include selfpropagating
sol-gel combustion and combustion of impregnated inert and active supports. It was
demonstrated that, based on the fundamental understanding of the considered combustion processes,
a variety of extremely high surface area materials could be synthesized. The controlling process
parameters are defined and discussed. Examples of materials synthesized by the above methods are
presented. A continuous technology for production of nanopowders by using the solution
combustion approach is also discussed.
Double SHS of W2B5 Powder from CaWO4 and B2O3
Authors: Yazici Sertac , Derin Bora
Published: October 2010

A synthesis study of W2B5 powder was carried out by double self-propagating hightemperature
synthesis (D-SHS) from CaWO4, Mg and B2O3 mixture and followed by HCl leaching
methods. In the first stage of SHS reaction, molar composition ratio of CaWO4:B2O3:Mg mixture
was selected as 1:1:8 (SHS-1) and 1:2.5:8 (SHS-2). The both SHS products were then acid leached
(HCl) at optimum conditions for 1 hour and 80 °C to eliminate MgO, Mg3B2O6 and Ca3(BO3)2
phases. The first leached products were consisted of W, WB, W2B5, and W2B phases. In the second
stage of SHS process, the both leached products were reacted with the same amount of Mg and
B2O3 mixture keeping previous initial ratio values (1:8 and 2.5:8). A successful SHS reaction was
achieved only by using the mixture with leached SHS-2 product. After following acid leaching, the
chemical composition of the leached D-SHS product was found to be 98.2 wt. % W2B5, 1.2 wt. %
WB4, and 0.6 wt. % WB.
Utilization of NbC Nanoparticles Obtained by Reactive Milling in Production of Alumina Niobium Carbide Nanocomposites
Authors: Trombini Vania , Bressiani Ana Helena Almeida , Agnolon Pallone Elíria Maria de Jesus , Tomasi Roberto
Published: October 2010

The increased interest in nanostructured materials is due to improvements in the
mechanical properties presented for these materials. Significant increases in properties such as
hardness, wear resistance and in some cases, strength and toughness of nanostructured ceramics
have been reported, compared to conventional ceramics. High-energy milling can lead to selfsustaining
reactions in a variety of systems. In this study, reactive high-energy milling was used to
synthesis niobium carbide (NbC) nanoparticles. The reaction products were de-agglomerated and
mixed with commercial ultra-fine alumina powder to produce alumina matrix nanocomposites with
5vol% of nanometric NbC. Alumina/NbC nanocomposite produced using powder obtained by
reactive present good microstructural characteristic, high densities, good hardness and higher
toughness. What makes this material an interesting alternative for production of ceramic cutting
tools.
Self-Propagating High-Temperature Synthesis of Iron- and Copper-Matrix Cermets
Authors: Chrysanthou Andreas
Published: October 2010

The presentation will report on the adoption of two different approaches based on selfpropagating
high-temperature synthesis (SHS) to produce cermets. The first of these concerns the
formation of the solid solution carbide, (Ti,V)C, of various compositions in an iron matrix by
starting with elemental powders. It was observed that two types of carbide particles were generated
within the matrix; a (Ti,V)C carbide of submicron size and a TiC-rich carbide of slightly higher
size. Comparison of SHS Fe-TiC products showed that the addition of vanadium led to refinement
of the carbide dispersions. The mechanism of formation of Fe-(Ti,V)C cermets will be discussed
using chemical thermodynamic analysis. The second SHS approach involves the reaction between
titanium and graphite by dropping compacted powders into a copper melts at 1250°C. The process
yielded dispersions of TiC within the matrix as well as graphite flakes. The reaction mechanism
will be discussed and the potential of SHS to yield dispersions within metal matrices will be
assessed.
Sintering and Hot-Pressing of Ti2AlC Obtained by SHS Process
Authors: Chlubny Leszek , Lis Jerzy , Bućko Mirosław M.
Published: October 2010

Some of ternary materials in the Ti-Al-C system are called MAX-phases and are characterised by heterodesmic layer structure. Their specific structure consisting of covalent and metallic chemical bonds influence its semi-ductile features locating them on the boundary between metals and ceramics, which may lead to many potential applications, for example as a part of a ceramic armour. Ti2AlC is one of this nanolaminate materials. Self-propagating High-temperature Synthesis (SHS) was applied to obtain sinterable powders of Ti2AlC Utilization of heat produced in exothermal reaction in adiabatic conditions to sustain process until all substrates are transformed into product is one of the advantages of the method that result in low energy consumption and low cost combined with high efficiency. Different substrates were used to produce fine powders of ternary material. Phase compositions of obtained powder were examined by XRD method. Than selected powders were used for sintering in various temperature both in a presureless sintering and hot-pressing in argon atmosphere. Properties and phase composition of obtained products were examined.
Mass-Forced SHS Technology of Ceramic Materials
Authors: Odawara Osamu
Published: October 2010

Self-propagating High-temperature Synthesis (SHS) technology is characterized with
high-temperature generation, spontaneous reaction propagation and rapid synthesis. Our research
and development on simultaneous synthesis and sintering has progressed by applying mass force
effects to SHS technologies; metal-ceramic composite pipe formation with centrifugal force on
thermite reactions (“Centrifugal-thermite Process”) and fine ceramic composite synthesis under
micro-gravity environments (MGE) formed with a free-fall, parabolic flight and sounding rocket.
The process has successfully attained to produce more than 3 m long composite-layered pipes with
significant feature for the production in its reaction propagation under centrifugal effect as well as
the centrifugal force and reaction heat. In the latter, the TiB2-Al composite synthesis under a free
fall MGE, for example, has made clear that the lack of mass migration and the improvement of
wetting between TiB2 and Al under the MGE affect the formation of a fine and dense cermet-like
structure in the products. An advanced approach on the mass-forced SHS technologies performed
is introduced by designing product densities and SHS reaction system.
The Potential of Spark Plasma Sintering (SPS) Method for the Fabrication on an Industrial Scale of Functionally Graded Materials
Authors: Tokita Masao
Published: October 2010

Functionally Grated Materials (FGMs) have usually been expected as candidates for a wide variety of industrial applications due to their desirable properties such as high heat resistance capability, good wear resistance, bio-compatibility, chemical stability and so on. Scaling-up and three dimensional (3-D) near-net shape forming technique for FGMs are one of the most important key-factor to produce the industrial engineering components and products in practical use. On the other hand, it is generally well known that the Spark Plasma Sintering (SPS) method is a novel process to produce homogeneous FGMs, nano-structural sintered compact, thermoelectric semiconductors and bio-medical materials in shorter sintering time with finer microstructure. This paper will present development of FGMs fabricated by SPS and future prospects of SPS on research and industrialization activities in Japan. A brief historical review progress of SPS technology is also given and the applicable field is exemplified. Then, the paper is focused on manufacturing processes on FGM by SPS technology. 
Atomic and Electronic Structure of Zinc and Copper Pyrovanadates with Negative Thermal Expansion
Authors: Krasnenko Tatiana , Medvedeva Nadezhda , Bamburov Vitalii G.
Published: October 2010

Zinc and copper pyrovanadates are promising materials for micro- and optoelectronics
due to their negative coefficient of volume thermal expansion (NTE). Besides, solid solutions on the
base of these compounds can be used to obtain grade materials with variable thermal coefficients.
Thermal deformation of both Zn2V2O7 and Cu2V2O7 structures was studied. According to the
structural data, NTE of these substances is provided by the zigzag shape of zinc (copper) chains
alongside with stable distances between layers. The structural and electronic characteristics
depending on temperature were studied for α-Zn2V2O7 and α-Cu2V2O7 by using the first principle
method. Our results demonstrate that the lowest total energies corresponds to the structural
parameters at 400° C and 200° C for α-Zn2V2O7 and α-Cu2V2O7, respectively. We predict that α-
Zn2V2O7 is a semiconductor with the band gap of 1,5 эВ and the bottom of conduction band is
determined by the vanadium 3d states with small addition of antibonding oxygen 2р-states. For α-
Cu2V2O7, the lowest interband transitions correspond to energy of 1,6 eV and involve also the O2p
and V 3d states.
High-Strength Reaction-Sintered Silicon Carbide for Large-Scale Mirrors - Effect of Surface Oxide Layer on Bending Strength
Authors: Suyama Shoko , Itoh Yoshiyasu
Published: October 2010

Reaction-sintered silicon carbide of 800 MPa class bending strength had been newly developed. The developed silicon carbide showed good rigidity, high thermal conductivity, and high density, like a conventional sintered silicon carbide. The developed silicon carbide is one of the most attractive materials for large-scale ceramic structures because of its low processing temperature, good shape capability, low-cost processing and high purity. We had fabricated some lightweight space mirrors, such as a high-strength reaction-sintered silicon carbide mirror of 650 mm in diameter. In this study, experiments were conducted to investigate the effect of annealing on the bending strength of high-strength reaction-sintered silicon carbide. The annealing heat treatments were carried out at 1073 K, 1273 K, and 1473 K in an air atmosphere. The maximum bending strength of 1091 MPa at room temperature was achieved by the annealing heat-treatment at 1273 K for 10 h in air. We confirmed that annealing heat treatment was effective to improve the bending strength of reaction-sintered silicon carbide by inducing compressive residual stress at the surface oxide layer.
Reactive Milling and Mechanical Alloying in Electroceramics
Authors: Rivas-Marquez Riva , Gomez-Yanez Carlos , Velasco-Davalos Ivan , Cruz-Rivera Jesus
Published: October 2010

Using Mechanical Activation it is possible to obtain small grain size and good
homogeneity in a ceramic piece. For ZnO varistor devices Mechanical Activation appears to be a
good fabrication technique, since good homogeneity and small grain sizes are advantageous
microstructural features. The typical formulation is composed by ZnO, Bi2O3, Sb2O3, CoO, MnO2
and Cr2O3 as raw materials, and during sintering, several dissolutions and reactions to form
pyrochlore and spinel phases occur. When Mechanical Activation is applied to the entire
formulation, it is difficult to know what processes are being mechanically activated due to the
complexity of the system. The aim of the present work was to clarify how the mechanical activation
is taking place in a typical ZnO varistor formulation. The methodology consisted in the formation of
all possible combinations of two out of the five oxides above mentioned and to apply mechanical
activation on the mixture of each pair of powders. The results showed that systems containing
Bi2O3 are prone to react during mechanical activation. Also, reduction reactions were observed in
MnO2. In addition, the powder mixture corresponding to the whole formulation was milled in a
planetary mill, pressed and sintered, and varistor devices were fabricated. Improvement in the nonlinearity
coefficient and breakdown voltage was observed.
Numerical Simulation of Spark Plasma Sintering
Authors: Garcia Cristina , Olevsky Eugene
Published: October 2010

A macro-scale model of spark plasma sintering (SPS) that couples electrical, thermal, stress-strain and densification components is presented. The continuum theory of sintering is incorporated enabling the evolution of the densification based on local conditions, thus a true spatial density distribution could be obtained. Specimen behavior is described through a non-linear viscous constitutive relation. The simulation is based on an FEM computer code. Several examples are shown and results are compared with experimental data available.
Densification Mechanism of MgAl2O4 Spinel during Spark-Plasma-Sintering
Authors: Morita Koji , Kim Byung Nam , Yoshida Hidehiro , Hiraga Keijiro , Sakka Yoshio
Published: October 2010

The densification mechanism during the park-plasma-sintering (SPS) processing was
examined in high purity MgAl2O4 spinel. As the density ρt increases, that is, as the effective stress σeff
decreases, stress exponent n evaluated from σeff dependence of densification rate varies from n ≥ 4 in
the low ρt region, n ≈ 2 in the intermediate ρt region to n ≈ 1 in the high ρt region. TEM observation
shows that significant stacking faults caused by partial dislocations are observed in the low ρt region,
but limited in the high ρt region. The ρt dependent densification behavior and microstructure suggest
that the predominant densification mechanism during the SPS processing changes with ρt from plastic
flow by partial dislocation motion for the low ρt region (n ≥ 4) to diffusion-related creep for the high
ρt region (n ≈ 1).
New Synthesis Process of Li, Na and K Niobates from Metal Alkoxides
Authors: Suyama Yoko , Yamada Tetsuya , Hirano Yosuke , Takamura Kazuo , Takahashi Kenjiro
Published: October 2010

New synthesis process to prepare nano-particles of lithium niobate, sodium niobate and
potassium niobate by thermal decomposition of the constituent double metal alkoxides was
developed. Single crystals of such double-metal alkoxides as Na-Nb, Li-Nb and K-Nb ethoxides
were newly synthesized from a mixed solution of the constituent metal ethoxides. The doublemetal
alkoxides of the Li-Nb, Na-Nb and K-Nb systems decomposed at low temperatures below
673 K to form nano-particles of LiNbO3, NaNbO3 and LiNbO3. The lattice constants and crystallite
size of the obtained LiNbO3, NaNbO3 and LiNbO3 particles were elucidated. It was shown that this
new synthesis process was useful for preparation of niobate nano-particles at low temperatures.
Microwave Assisted Reaction Sintering of ZrSiO4/α -Al2O3 Mixtures
Authors: Ertugrul Onur , Akpinar Suleyman , Kusoglu I. Murat , Onel Kazim
Published: October 2010

Mullite- zirconia composites have better mechanical properties than monolithic mullite
ceramics and can be produced by reaction sintering of ZrSiO4 and  -Al2O3. The samples were
prepared from high-purity (99.9%) α-alumina and fine zircon (ZrO2>65 wt.%) powders using PVA
as binder. The powder mixtures were compacted under 80 MPa as coin shaped samples by uniaxial
dry pressing and then sintered in a multimode microwave field of 2.45 GHz. The microwave effect
on ZrSiO4 dissociation and mullite formation was evaluated by comparing the microwave sintered
samples with those sintered conventionally. The as-reacted compacts were characterized by X-ray
diffraction and scanning electron microscopy (SEM). The effects of sintering parameters on
mullitization and mullite grain growth were investigated.
Residual Stress Measurement around the Interface of Copper Bicrystal Deformed by Uniaxial Extension
Authors: Takao Hanabusa , Shiro Ayumi , Okada Tatsuya
Published: October 2010

Residual stresses of a copper bicrystal were measured by X-ray diffraction and synchrotron
radiation. A copper bicrystal specimen with a 90-degree tilt boundary was fabricated by the Brigdman
technique. After the plastic extension of 30%, kink bands developed in a deformed matrix along the
grain boundary. In this study, we focused on the residual stress distribution along the transverse direction
of the specimen surface and the residual stresses in deformed matrix and kink band near the grain
boundary. Residual stresses were evaluated by the X-ray single crystal measurement method.
Stereographic projections were used to determine crystal orientations of deformed regions. It was found
that crystal orientations were different between the deformed matrix and the kink band. Residual stresses
in the direction along the grain boundary were compressive in the vicinity of the boundary and tensile in
the region apart from the boundary. Residual stresses in the kink band were large in compression in
compared with those in the deformation matrix. The difference in the results between X-rays and
synchrotron radiation suggests that there is a depth variation in the deformation and therefore the residual
stress development.
Performance of Blended Cement Concrete against Seawater Attack
Authors: Seleem H.H. , Rashad Alaa M. , El-Sabbagh B.A.
Published: October 2010

The current work reports the influence of synthetic seawater on some of the durability aspects of an ordinary concrete mixture (control) and six pozzolan-concrete mixtures. Three types of pozzolanic materials were employed; silica fume (SF), ground granulated blast furnace slag (GGBS) and metakaolin (MK). The pozzolanic materials were employed as an addition to cement in binary and ternary combinations. All mixtures were tested for strength deterioration ratio (SDR) after 3, 6, and 12 months of exposure to synthetic seawater, permeability was measured after 6 and 12 months of exposure. It was found through this investigation that pozzolans increase the ability of concrete to withstand aggressive environment and prevent most of the deterioration signs. The pozzolanic materials serve also to increase the strength and to minimize the strength loss (SDR) upon exposure to seawater. The pozzolanic materials led to reduce concrete permeability compared to control.
The Role of Plastic Deformation in Nanometer-Scale Wear
Authors: Egberts Philip , Bennewitz Roland
Published: October 2010

Scratches on KBr(100) surfaces were produced and examined with an atomic force
microscope (AFM) operated in an ultra-high vacuum (UHV) environment. Scratches with lengths
on the order of 100s of nanometers and depths on the order of atomic layers were investigated.
Non-contact AFM topographic images of scratches revealed screw and edge dislocation activity
around the scratch sites, illuminating the role of plastic deformation in wear processes. Friction
coefficients of approximately 0.3 were measured during scratching, more comparable to
macroscopic friction experiments than those measured in low-load, single asperity experiments.
Effect of Polymorphic Zirconia Phases on the Mechanical and Wear Properties of Cr3C2-NiCr Cermets
Authors: Tür Yahya Kemal , Özer Ali , Duran Cihangir
Published: October 2010

Cr3C2-NiCr type cermets are used in cutting technology for their low sintering temperatures
and relatively low densities. Their high corrosion resistance at high cutting speeds and high
temperatures increases the interest to these materials. In this study, a powder mixture of 75wt% Cr3C2
and 25wt% NiCr with a Ni-Cr ratio of 4/1 by weight was sintered at 1350°C as the master composite.
3 mol % Y2O3 stabilized tetragonal ZrO2 and 8 mol % Y2O3 stabilized cubic ZrO2 powders were
added to study the effect of ZrO2 content on the mechanical and wear properties of Cr3C2-NiCr
cermets at the same sintering temperature. SEM and EDX analysis were performed for identifying
microstructures. Elastic modulus and microhardness of master and doped cermets were measured by
impulse excitation technique and Vickers (HV10), respectively. Wear tests were conducted by ball on
reciprocating flat method to characterize the wear properties.
Overview on Wetting and Joining in Transition Metals Diborides
Authors: Muolo Maria Luigia , Valenza Fabrizio , Sobczak Natalia , Passerone Alberto
Published: October 2010

The ultra high temperature performance of ceramic-based complex structures may
require the development of liquid-assisted joining techniques; this in turn requires the definition of
the wettability of these materials by various metals over a wide range of compositions and
temperatures.
After a short description of the relevant experimental aspects of wettability studies at high
temperatures, a discussion is presented on how these results can be used to derive chemical and
structural information on the solid-liquid interactions. Reference is made mainly to metal-ceramic
systems; a summary of the results of sessile drop tests under carefully controlled conditions is given
in relation to the wettability and the interfacial characteristics of systems based on transition metals
(Zr, Hf) diboride ceramics in contact with liquid Ag, Cu, Au and Ni and of some of their alloys
with Ti, Zr, Hf and B to promote/control wettability.
In particular, the utilization of phase diagrams is discussed, as one of the most powerful tool to
design the filler alloy compositions for the optimization of joining (brazing) processes.
Structure Evolution in Al2O3 - ZrO2(Y2O3) Ceramic Composites during Sintering
Authors: Dyatlova Ya. , Ordanyan S.S. , Osmakov Andrey , Pesin V. , Rumyantsev V.
Published: October 2010

The paper demonstrates the possibility to control the degree of tetragonal zirconia
stabilization, microstructure and physical and mechanical behavior of Al2O3 -ZrO2(Y2O3) ceramic
composite.
Control is exerted via the process variables during deposition synthesis of nanosized composite
powders from hydroxide salts, and their subsequent heat treatment and consolidation.
Morphology features of nanosized powder systems and microstructures of the consolidated
nanostructured materials were characterized by BET surface are measurements, scanning electron
microscopy (both standard and HR), and large-angle X-ray diffraction.
Correlations are established between microstructure parameters, physical and mechanical behavior
of composite ceramics and a degree of stabilization of tetragonal ZrO2.
Phase, Structural and Microstructural Changes in the TiC1-x – Cr3C2 Materials
Authors: Rutkowski Paweł , Stobierski Ludosław , Bućko Mirosław M. , Handke Bartosz
Published: October 2010

The earlier studies showed that addition of different chromium carbides to
nonstoichiometric fine titanium carbide improve sintering in the similar way. The phase, structural
and microstructural changes for addition of various chromium carbides were also similar. In the
present work the composite materials were made of various carbon quantity saturated titanium
carbide (as matrix) and commercial chromium carbide Cr3C2 (as additive). The titanium carbide
powders with variable content of carbon in structure were synthesized by the SHS method. The
chromium carbide in quantity of 7.5 % by volume was added to the initial mixture. The influence of
various stoichiometry of titanium carbide on onset temperature of sintering was examined by use of
high temperature dilatometer. The phase and structural changes of examined materials during
sintering were made using XRD and Rietveld method. The evolution of microstructure, versus of
different stoichiometry titanium carbides, was observed by use of scanning electron microscopy.
Stereological Microstructure Description of Structural SiC Ceramics as Composite Material
Authors: Rumyantsev V. , Osmakov Andrey , Boykov S. , Fishev V.
Published: October 2010

Within unified stereological approach the silicon carbide-based ceramics SiSiC , SSiC,
and LPSiC are treated as binary compositions, that despite certain structure ordering differences
might be similarly described as comprising topologically continuous component (that provides the
high level of physical and mechanical properties), and a discrete component.
The paper demonstrates the necessity of using dimensionless criterial parameters for adequate
description of the integral microstructure ordering level; said parameters including the
characteristics of both continuous and discrete components of the composite ceramic material.
Generalized equations are derived for compound stereological parameters of the discussed
materials, along with statistically reliable approximations of the strength characteristics as functions
of these parameters.
Oxidation Resistance of Coated and Uncoated SiC-Based Refractories
Authors: Di Vita Guillaume , Preziosa Olivier , Foucaud Sylvie , Maître Alexandre , Denoirjean A. , Barthélémy C.
Published: October 2010

The potentialities of ceramic coatings as a protective layer have been discussed by the comparison of the oxidation kinetics between coated and uncoated SiC-based materials. It was observed that a thermally sprayed coating of titanium dioxide (TiO2), in the same conditions of oxidation, decreases the kinetics constants and acts as a diffusion barrier. The evolution of the (micro-)structural features of oxidized materials were followed by XRD and SEM.
Defect Detection in Ceramic Armor Using Phased Array Ultrasound
Authors: Ellingson William A. , Steckenrider J. Scott , Meitzler Thomas J.
Published: October 2010

Monolithic ceramic tile is used as part of ceramic-composite armor. Rejection of
individual tile that contain potential threat-defeat-reducing ―defects‖ must be accomplished in a fast
and cost-effective manner. Water-immersion phased-array ultrasound using 10 MHz 128-element
transducers sequenced at 32-elements has been demonstrated to quickly scan and detect 25-50 um
known inclusion-type defects in individual 25 mm thick SiC tile. Further, use of similar phasedarray
transducers and similar transducer-element activation sequences, has shown detection of
intentional internal defects in tests of 40 cm square by 50 mm thick, multi-layered composite
ceramic-armor specimens. Large changes in acoustic velocities of the various layered materials
causes focusing issues of the ultrasonic wave. The use of various digital signal processing methods
can be used to overcome some of these issues. The results show that use of phased array ultrasound
can reliably be used for defect detection in either monolithic or composite ceramic-armor. The
technology and various results are presented.