Palestras
01-057 Arcillas: panorama argentino y procesos de activación
Palestrante: Cristina Volzone
Volzone, C./CETMIC
Resumo: COMENTARIO IMPORTANTE: ESTE RESUMEN CORRESPONDE A UNA
PRESENTACION EN FORMA DE PALESTRA. NO PUEDO SELECCIONAR PALESTRA
EN FORMA DE PRESENTACION SOLO PERMITE POSTER. Una breve reseña
sobre arcillas argentinas será comentada en esta presentación, las
cuales, en general son muy utilizadas en la industria cerámica.
Sin embargo, con el objeto de aumentar su eficiencia y/o
aplicabilidad hacia otro tipo de industria se expondrán diferentes
procesos de activación (ácida, pilarización, tratamiento con
orgánicos, etc.), analizando los cambios en las propiedades
fisicoquímicas que ocurren en las arcillas.
03-062 Avaliação do Ciclo de Vida e Eficiência Energética na
Cerâmica Vermelha.
Palestrante: Antônio Carlos Pimenta Araújo
Araújo, A. C. P./ANICER
Resumo: A ANICER promoveu uma ACV – Avaliação do Ciclo de Vida,
que mensurou os impactos ambientais e à saúde humana da produção
de telhas cerâmicas versus telhas de concreto. A ACV é um método
de avaliação do ciclo de vida de um produto ou processo e neste
estudo as telhas cerâmicas apresentaram um desempenho bem superior
às telhas de concreto. Os resultados confirmaram as expectativas
sobre a fabricação de produtos de cerâmica vermelha e além das
avaliações comparativas aos produtos de concreto, a ACV dos
produtos cerâmicos também servirá para propostas de melhorias para
o setor, na área industrial e marketing, baseadas na
sustentabilidade. Entre as propostas para otimizar os resultados
da ACV, auditorias de Eficiência Energética na indústria de
cerâmica vermelha, tanto térmica quanto elétrica, podem contribuir
muito no diagnóstico e projetos aos fabricantes de blocos, telhas
e tijolos cerâmicos.
08-029 Structural aspects of the mixed-ion effect in phosphate
glasses
Palestrante: Jose Fabian Schneider
José Schneider(1), Jefferson Tscuchida(1), Rashmi Desphandes(2),
Hellmut Eckert (1)/(1) Instituto de Física de São Carlos,
Universidade de São Paulo, São Carlos-SP; (2) Institut für
Physikalische Chemie, Westfälische Wilhelms-Universi
Resumo: The mixed-ion effect (or mixed-alkali effect) is the
dramatic non-linear reduction in the values of transport
properties in glasses due to restriction in ionic mobility upon
mixing. A satisfactory explanation of this phenomenon has been
elusive during five decades. Metaphosphate glasses AxB1-xPO3 with
two mobile monovalent cations A+ and B+ are archetypical systems
for analysis of the mixed-ion effect in d.c. conductivity, which
is strongly dependent on the nature of the mixed chemical species.
The deepest known reduction in conductivity is observed in Rb-Li
metaphosphates, attaining 8 orders of magnitude. In contrast,
reductions of only 1 order of magnitude are observed in Ag-Na
metaphosphates. In the first part of this lecture, recent
significant experimental and theoretical developments in the
understanding of the mixed-ion effect will be reviewed. In
particular, the relevance of the structural properties of the
glass on the manifestation of the effect will be discussed. On the
second part of the lecture, a recent systematic analysis of local
order and the alkali distribution in mixed metaphosphates will be
presented, covering glasses with A-B pairs as Na-Li, Na-Ag, Na-K,
Na-Rb, Na-Cs, and Li-Rb, Li-Cs, Ag-Cs. The aim to of this study is
the identification of segregation or random mixture of cation
species and their possible dependence with the cation size
mismatch or differences in ionic potential. A broad set of Nuclear
Magnetic Resonance (NMR) techniques were applied: 31P, 23Na, 7Li
and 133Cs high-resolution NMR, 109Ag-NMR , 23Na Triple-Quantum-MAS
NMR, REDOR between 31P, 23Na, 7Li and 133Cs, 87Rb quadrupole
Carr-Purcel-Meiboom-Gill, and 23Na-NMR spin-echo decay. The
structural picture emerging from these results reveals the
similarity in local environments around each kind of alkali,
irrespective of the substitution ratio. A common structural
adjustment on the cation environment was discovered, consisting in
the compression of the oxygen environment around the smaller
cation of the pair as their concentration is reduced. The
compression causes an increase in the local symmetry of the
coordination polyhedra. The set of results show also a mixture of
cations species at atomic scale. However, the 23Na-23Na magnetic
coupling reveals that this mixing is not statistical, existing a
detectable like-cation preference at short range for some systems
(Na-K, Na-Cs). These findings support recent structural approaches
used to calculate the diffusion pathways for the mobile cations,
indicating the possible generalization of these models of the
mixed-ion effect to many other glass systems.
08-089 Multifuncional organic-inorganic hybrids based on silk,
biocellulose and vegetable oils
Palestrante: Sidney J.L. Ribeiro
Ribeiro S.J.L., Silva R.R., Vorpagel A.J., Santos M.V. Santos,
Santos D.B., Cavicchioli M., Christovam L.M., Messaddeq Y.,
Pecoraro E., Trovati E., Barud H.S. /Instituto de Química- UNESP
Resumo: New organic-inorganic hybrids have benn obtaining by using
three different hosts: biocellullose (BC), fibroin and ricinoleic
acid (RA). BC is produced in carbohydrate rich culture medium by
Gluconacetobacter xylinus strains in the form of highly hydrated
(98% water) membranes. The chemical structure is the same of the
one found for plants cellulose but BC presents a pure cellulose
network composed of a random assembly of ribbon shaped fibers less
than 100 nm wide. The unique properties provided by the nanometric
structure have lead to a number of different applications ranging
from opto-electronics to medicine including, food industry [1].
Silks on the other side are the strongest and toughest natural
fibers known. Silk fibroin extracted from cocoons of Bombyx mori
silkworm can be processed as hydrogels, optical films,
controlled-release coatings, 3D porous matrices and fibers [2].
Castor oil is a natural oil obtained from the seed of the
so-called castor plant. It is unique due to the fact that it is
composed of approximately 90% of the hydroxy, unsaturated C18
fatty acid, ricinoleic acid. New organic-inorganic amidosil
hybrids are obtained from the reaction of RA and amino-modified
siloxanes. We have been exploring the multifunctional character of
these three host materials by studying luminescence (photoluminescence
and upconversion) and redox properties of derived membranes. Metal
colloids (Te, Ag, Au, Ag-Au) containing membranes have been
obtained either by light induced process or by using well known
reducing agents. Luminescence is being explored by obtaining
lanthanide containing luminescent materials from BC/fibroin/amidosil
membranes and Eu3+ complexes of sylilated or not beta-diketonate
ligands and Yb3+-Ln (Ln- Tm3+, Er3+ and Ho3+) pairs. The
interaction metal colloids- luminescent centers, mediated by the
host, is explored aiming new photonic applications. References [1]
"Bacterial Cellulose from Glucanacetobacter xylinus: Preparation,
Properties and Applications", E. Pecoraro, D. Manzani, Y.
Messaddeq, S. J.L. Ribeiro, Ch. 17 pp369-383 in Monomers, Polymers
and Composites from Renewable Resources. Ed.: M.N. Belgacem and A.
Gandini, ISBN: 978-0-08-045316-3 2008 Elsevier Ltd [2] S.T.
Parker, P. Domachuk, J. Amsden, J. Bressner, J.A. Lewis, D.L.
Kaplan, F.G. Omenetto, Adv. Mater. 2009, 21, 241
10-069 Novas técnicas de sinterização de materiais cerâmicos.
Palestrante: R. Muccillo
R. Muccillo, E.N.S.Muccillo, M.Kleitzb/CCTM, IPEN / LEPMI, INPG
Resumo: O processo de sinterização é uma das principais etapas na
consolidação de materiais cerâmicos. Alem do processo
convencional, que consiste basicamente no aquecimento a uma taxa
DTa/Dt (~2 - ~20 grau/min) até um patamar Ts por um tempo ts e
resfriamento a uma taxa DTr/Dt ao ar ou sob atmosfera oxidante ou
redutora, há outros processos: (1) sinterização por prensagem a
quente; (2) sinterização por aquecimento rápido (fast firing), DT/Dt
> ~100 grau/min; (3) sinterização por microondas; (4) sinterização
em duas etapas (two-step sintering), a primeira até uma alta
temperatura T1 para atingir ~75% da densidade teórica tornando
instáveis os poros, a segunda a uma menor temperatura T2
promovendo densificação sem crescimento de grãos; (5) sinterização
ativada por campo elétrico, com (a) passagem de alta corrente
elétrica dc em matriz de grafite promovendo aquecimento rápido
simultâneo à aplicação de pressão (spark plasma sintering), (b)
passagem de alta corrente elétrica no material cerâmico com
aplicação de voltagem dc a alta temperatura sem aplicação de
pressão. Todos esses procedimentos têm suas vantagens e
desvantagens, dependendo da aplicação pretendida para o material
cerâmico. Serão apresentados os resultados obtidos recentemente em
nossos laboratórios com um novo método de consolidação de pós
cerâmicos, o método de soldagem instantânea dos grãos (flash grain
welding), que consiste basicamente na passagem de um flash de
corrente elétrica ac preferencialmente nos contornos de grão,
promovendo o aquecimento local por efeito Joule com soldagem dos
grãos (eliminando o bloqueio de portadores de carga no caso de
condutores iônicos), dissipação de calor e conseqüente
sinterização local.
18-004 Carbonos e Nanocarbonos: Conceitos & Perspectivas
Palestrante: Guilherme Frederico Bernardo Lenz E Silva
Lenz e Silva, G. F. B.; Silva, M. F. P. da /USP
Resumo: O carbono é um dos elementos mais versáteis da natureza.
Seja na forma pura ou combinado o carbono está presente em grande
parte dos compósitos cerâmicos e materiais refratários. Ele
participa como ligante (piches ou resinas), em sua forma elementar
(grafita ou negro de fumo), como aditivo polimérico ou mesmo na
forma de carbetos. Mais recentemente, novas formas alotrópicas do
carbono como os nanotubos, nanofibras, fulerenos e grafenos têm
aberto novas oportunidades de aplicação destes materiais. Este
trabalho faz uma revisão sobre as principais propriedades e novas
perspectivas de aplicação destes materiais.
18-006 Nanotecnologia – Desafios Experimentais, Teóricos e
Ambientais - Conhecê-los é a nossa principal defesa
Palestrante: Valéria Longo
Longo, V.M. (1); Moreira, M.L. (1); Cavalcante, L. S. (1); Andrés,
J. (2); Longo, E. (1); Varela, J.A. (1)/(1) UNESP; (2) Universitat
Jaume I
Resumo: A fabricação controlada de materiais inorgânicos com
morfologia, arquitetura e funcionalidade controlada na escala
micro- e nano é um desafio para a ciência dos materiais
atualmente. Muitas aplicações tais como catálise heterogenia,
sensores de gás, conversão e armazenamento de energia, são
bastante sensíveis à estrutura atômica do bulk e da superfície.
Esse fato torna-se ainda mais importante na escala nanométrica em
que a energia superficial contribui significantemente para a
energia total do
19-031 Tendências Futuras Para os Materiais Cerâmicos e Análise
do Nível de Maturidade Tecnológica em Projetos de P&D&I
Palestrante: Francisco Cristovão Lourenço de Melo
Melo, F.C.L./IAE
Resumo: Serão abordados, nesta palestra, resultados de trabalhos
de prospecção tecnológica e análise documental e utilizando-se uma
linha do tempo de 20 anos sobre o tema amplo “Materiais
Cerâmicos”, sobre as principais perspectivas para o P&D&I
referente a esta classe de materiais. Nesta apresentação será dada
ênfase aos trabalhos de Prospecção Tecnológica que estão sendo
desenvolvidos na Divisão de Materiais do instituto de Aeronáutica
e Espaço, onde além do levantamento de tendências futuras está se
fazendo, a um estudo do Nível de Maturidade da Tecnologia (TRL -
Technology Readiness Level). Nesta apresentação serão abordados os
resultados do levantamento do TRL para o projeto MARIMBA –
Materiais Resistentes ao Impacto balístico com destaque para aos
materiais cerâmicos estudados e desenvolvidos ao longo da pesquisa
Na ocasião será apresentado também, além da à metodologia
utilizada uma proposta para um amplo estudo para o setor cerâmico
no país
19-032 Panorama da indústria cerâmica brasileira na última
década
Palestrante: Ulisses Soares Do Prado
Prado, U.S.(1); Bressiani, J.C.(2)/(1)Lining; (2) IPEN
Resumo: Foi feito um levantamento dos resultados da indústria
cerâmica brasileira no período de 2001 a 2010 que serão
apresentados e discutidos neste trabalho. Os setores que são
suportados diretamente ou indiretamente pelo setor da construção
civil apresentaram bom desempenho no período com taxas de
crescimento expressivas, como as indústrias de cerâmica estrutural
e vermelha, louça sanitária, cimento portland, vidros, fritas e
refratários. Algumas dessas indústrias enfrentaram nesseo período
uma forte concorrência de produtos importados devido ao câmbio
desfavorável e a crise econômica internacional, que fez com que
muitas empresas externas se voltassem para o mercado brasileiro. A
maioria dos setores da cerâmica nacional reagiu bem a essa
situação, porém as indústrias de louça de mesa e cerâmica elétrica
e técnica foram fortemente impactados pela concorrência externa,
provocando uma retração importante nesses ramos industriais.
19-033 Degradação mecânica por crescimento subcrítico de
trincas em biocerâmicas para restaurações dentárias
Palestrante: Humberto Naoyuiki Yoshimura
Yoshimura, H.N.(1)/(1) UFABC
Resumo: O fenômeno do crescimento subcrítico (ou lento) de trincas
resulta em diminuição gradativa da resistência mecânica durante a
aplicação de cerâmicas e vidros, o que diminui o seu tempo de vida
útil. Serão apresentados os principais conceitos relacionados ao
crescimento subcrítico de trincas (CST), os diferentes métodos
para determinação dos parâmetros de CST e os efeitos deste
fenômeno na diminuição da resistência mecânica e na previsão do
tempo de vida em biocerâmicas dentárias (porcelanas,
vitrocerâmicas e compósitos).
08-084- Nanoparticles in Oxide Glasses: Fundamental Approach
and Photonic Applications
Palestrante: Marcelo Naim
Nalin, M. /UFSCar
Oxide glasses containing transition metal nanoparticles have been
intensively studied in the last ten years. Such materials, also
called nanoglass-ceramics, are interesting for photonic
applications such as lasers, optical switching and optical
amplifiers operating in the infrared region, as well as in
spin-photonics in magnetic glasses. Metallic nanoparticles
embedded in glasses are very interesting from the technological
point of view, due to the surface plasmon resonance (SPR). SPR
localized near the boundary between the metal nanostructure and
the surrounding dielectric produces an enhanced electromagnetic
field at the interface. This enhanced field is the basis of an
important application related to metallic nanoparticles: the
enhancement of the intensity of intra-4f electronic transitions in
lanthanide ions close to the particles, which has applications as
broadband optical amplifiers. The size and shape of the particles
play an important role in the optical properties of such glasses
and can be controlled during synthesis. Nanoparticle formation
inside a glass matrix has been achieved by different methodologies,
including melting and quenching followed by thermal treatment or
laser irradiation. This lecture reviews the fundamentals of
nanoparticles embedded in glasses technology, as well as some
highlights in photonic applications.
08-082 - New approaches towards optical materials: Highly
efficient molecular emitters dispersed in sol-gel mesoporous
hosts.
Palestrante - Andrea Simone Stucchi de Camargo Alvarez Bernardez
A.S.S. de Camargo/ IFSC/USP
Sol-gel silicate glasses and ordered mesoporous materials hosting
luminescent molecular species such as organic dyes and lanthanide
or transition metal complexes, have been at the focus of much
attention for photonic devices and bionalytical applications. The
ability to exploit the synergy between the intrinsic
characteristics of sol–gel hosts (highly controlled purity,
versatile shaping and patterning, excellent optical quality, easy
control of the refractive index, encapsulation of large amounts of
isolated emitting centers protected by the host) and the
luminescence features of the molecular emitters (high quantum
yields, narrow (or large) bandwidths, long- (or short-) lived
emissions, ligand-dependent luminescence sensitization and large
Stokes shifts), allows the design and fabrication of materials
with tunable properties. Promising applications include light
emitting devices, active waveguides in the visible and near-IR
spectral regions, active coatings, bio-medical actuators and
sensors and biological markers, opening up exciting directions in
materials science and related technologies, with significant
implications in the integration, miniaturization, and
multifunctionalization of devices. In all these applications, and
particularly for the biological ones, it is very important to
assure high luminescence efficiency while avoiding contamination
of the surrounding environments by leakage of the active species.
In this sense, the sol-gel silicate hosts with high surface areas
and easy functionalization offer vast possibilities to disperse
the guest molecules so as to decrease, or completely prevent, the
formation of non-emissive molecular aggregates (as common for dye
molecules), and to protect them from exposure to well known
luminescence quenching agents such as OH- (for most lanthanide
complexes) and singlet oxygen (e.g. for iridium complexes).
Recently, our research group at the University of São Paulo has
dedicated efforts to the development of modern host-guest hybrid
materials, and to their structural and photophysical studies.
Examples include ordered mesoporous silica (MCM-41),
organo-modified silica xerogels, and sodium-aluminophosphate
glasses, incorporated with Rhodamine 6G dye, Ir(III)- and
Eu(III)-complexes. In all cases, new approaches are sought to
achieve host-guest interactions leading to high dispersion of the
guest molecules (as probed by various spectroscopic techniques),
and avoidance of leakage. In this way, we have succeeded in
obtaining optical materials with remarkable improvements of
photophysical properties in comparison to those of the molecular
species in solutions. In this presentation, I will give an
overview of the field and its recent advances, and present our
most relevant contributions.
08-086 - OH- free calcium aluminosilicate glasses for laser
emission and smart white lighting
Palestrante– Mauro Luciano Baesso
Baesso M.L. (1); Andrade L.H.C. (2); LIma, S.M. (2); Guyot Y. (3);
Nunes L.A.O. (4)/ 1Departamento de Física, Universidade Estadual
de Maringá, Maringá, PR, Brazil 2Grupo de Espectroscopia Óptica e
Fototérmica, UEMS, Dourados, MS, Brazil 3Physical Chemistry of
Luminescent Materials (LPCML), University of Lyon, Lyon, France
4Instituto de Física de São Carlos, USP, São Carlos, SP, Brazil
Calcium aluminosilicate (CAS) and low silica calcium
aluminosilicate (LSCAS) OH- free glasses have been shown to be
promising candidates for the development of solid state active
laser media and luminophore hosts due to their superior thermal,
optical and mechanical properties. Examples have already been
shown for laser emissions using Nd3+, Er3+ and Yb3+, and white
light emitters with Ce3+, Eu3+ and Eu2+ luminescent ions. In this
work, an over view of the potentialities of these systems will be
given, with special attention to the structural characterization
in relationship with their spectroscopic properties like
concentration quenching phenomenon, ions oxidation states and
energy transfer processes. Laser measurements at 1037nm, 1054nm
and 1550nm will shown. In addition, the development of a smart
white lighting device with these glasses will be presented.
08-075 - Mechanical properties of glass, glass ceramics and
other brittle materials investigated by intrumented indentation.
Palestrante – Carlos Maurício Lepienski
Lepienski, C. M./ Universidade Federal do Paraná
A critical analysis of indentation and instrumented indentation
results of hardness, elastic modulus, scratch tests, toughness,
and residual stresses of glass, glass ceramics and other brittle
materials is presented. The limits, difficulties and advantages of
this technique for applications in brittle materials with similar
properties will be discussed.
Spark Plasma Sintering of Ultra High Temperature Ceramics
Palestrante – Lia Stanciu/school of Materials Engineering, Purdue
Universty, West Lafayette, IN, USA.
ZrB2 ceramics containing SiC or ZrC of 20, 30, or 50 wt% were
sintered to near full density using spark plasma sintering at
heating rates of 100, 200, and 500oC/min. The effects of the
content and sintering rate upon densification, flexural strength,
hardness, and microstructure were all evaluated. ZrB2 – ZrC
samples were harder to density than their ZrB2 – SiC counterparts,
but full density could be achieved with a slight increase in the
sintering temperature. Samples with ZrC were found to have a
roughly 20% higher flexural strength than those with SiC which was
attributed to SiC’s lower CTE than those of ZrB2 and ZrC. Flexural
strength for both sets of samples was found to be highest for 80
wt% ZrB2 and linearly decreased with increasing secondary phase.
Hardness of ZrB2 – ZrC samples was between 700 - 1000HV,
significantly lower than the 2000 – 2500HV values for ZrB2 – SiC
samples. This is partly due to the porosity in the ZrC samples and
to the inherently lower hardness of ZrC compared to SiC. For SiC
hardness increased linearly with SiC content but was unaffected by
heating rate, while for ZrC hardness was maximized at a heating
rate of 200oC/min. Overall ZrB2 - ZrC ceramics offer increased
flexural strength over ZrB2 - SiC mixtures at the cost of lower
hardness and sinterability.
Direct write assembling of 3D bioactive glass scaffolds for
regenerative medicine and tissue engineering
Palestrante – José M. F. Ferreira/University of Aveiro
José M.F. Ferreira1, Saurabh Kapoor1, A. Lemos1, S. Eqtesadi2, A.
Motealleh2, and Pedro Miranda2/ 1 Department of Ceramics and Glass
Engeneering, CICECO, University of Aveiro, 3810-193 Aveiro,
Portugal 2 Departamento de Ingeniería Mecánica, Energética y de
los Materiales, Universidad de Extremadura, Escuela de Ingenierías
Industriales, Avda. de Elvas s/n, 06006 Badajoz, Spain.
Alkali-free, resorbable, and fast healing bioglass compositions
were developed and fully characterized concerning the structure,
in vitro bioactivity and degradation analysis, and thermal
behaviour. The new bioglasses showed a much faster
biomineralization capability, a slower degradation and smaller pH
changes in comparison to the 45S5 Bioglass®. The powder frits of
the new bioglasses are easily dispersable in water to form stable
concentrated suspensions solids loading as high as 60 vol.%, which
is twice the maximum solids volume fraction achievable with the
45S5 Bioglass frits. The highly concentrated suspensions of the
new bioglasses could be transformed into extrudable paste-like
colloidal systems suitable for rapid fabrication of 3D bioglass
scaffolds for regenerative medicine and tissue engineering by a
robotic deposition method (Robocasting). The extrudable inks for
Direct Write Assembling could be prepared by following the
traditional coagulation approaches, namely, by adding a cationic
additive to the suspension dispersed with an anionic dispersant.
However, the same methodology revealed to be ineffective in the
case of 45S5 Bioglass® due to its specific processing difficulties:
(i) high solubility in the aqueous media and the consequent
increase of the ionic strength; (ii) high alkalinity (pH ~10) that
hinders the dissociation of cationic additives. These processing
difficulties explain why no a single research work has been
reported so far on Direct Write Assembling 3D 45S5 Bioglass®
scaffolds. Even though, we succeeded preparing inks for direct
write assembling 45S5 Bioglass® scaffolds for the first time by
using CMC as the single but multifunctional processing additive.
Moreover, the novel bioglass matrix could be full densified by
sintering before the onset of crystallization, resulting in strong
bioglass scaffolds, contrarily to what happens with the 45S5
Bioglass® that readily crystallizes at temperatures above Tg
resulting in scaffolds with poor mechanical properties.
Modelling crack propagation in porcelain-like compositions
undergoing fast cooling
Palestrante – Vicente Cantavella
V. Cantavella(1), F.A. Gilabert(1), E. Sánchez(1), M. Dal Bó(2),
D. Hotza(3)/ (1) Institute of Ceramic Tecnology (ITC), Campus Riu
Sec - UJI, 12006 Castellón, Spain.
(2) Federal University of Santa Catarina (UFSC), 88040-900
Florianópolis, SC, Brazil.
(3) Department of Chemical Engineering (ENQ), Federal University
of Santa Catarina (UFSC), 88040-900 Florianópolis, SC, Brazil.
The present work, focused on modelling, analyses the effect of the
rapid cooling on the crack propagation on a porcelain-like
composition. To validate the results of the simulation several
series of specimens were prepared using sodium feldspar (albite)
with crystalline particles (quartz, alumina and zircon). After
firing we got a glassy matrix which comes mainly from the albite,
some unmelted albite particles and the added crystalline particles.
In the first part of this work we modelled the heat transfer and
the macroscopic stresses which appear during cooling. As a result
of the low viscosity at high temperature, and the high cooling
rates, some residual stresses appear after firing. We measured the
macroscopic residual stresses in the specimens, showing a good
agreement.
In the second part, the effect of macroscopic residual stresses
during cooling on the crack growth was simulated. Depending on the
mechanical properties of the composition, this crack is negligible
or might occur to a certain extent.
Finally, we analysed the combined effect of an isotropic matrix
and a distribution of embedded inclusions. We use a computational
procedure based on the particle-in-cell technique, which is a
combined formulation of the finite element method and particle
dynamics simulations. As all the material properties are
transported by the points, a static structured mesh is used as a
background scratchpad for computations. This feature has
facilitated the incorporation of cracks. The results of these
calculations, confirmed by the SEM, indicate that the morphology
of the crack strongly depends on the shape of the particles.
Fracture of Refractories - Importance of the Following Wake
Region
Palestrante – Richard C. Bradt
Richard C. Bradt/ Prof. of Materials Science and Engineering
University of Alabama Tuscaloosa, AL, USA
The fracture resistance of refractories is considered from a
fracture mechanics and an energy perspective. Both indicate that
larger cracks are more resistant to crack growth or extension.
R-curves of refractories also indicate greater energy dissipation
as a crack becomes longer. Observations that the halves of
specimens from crack growth studies remain together after the
crack has passed completely through the sample indicate that there
remains considerable traction between the newly created surfaces
after a crack has passed through. Examining these items both
individually and together indicate that the following wake region
of a crack in refractories is extremely important. It is concluded
that the crack growth resistance of refractories is primarily
through phenomena in the following wake region.
Atual Estágio da Industria de Revestimentos Cerâmicos no Brasil
Palestrante – Antonio Carlos Kieling
Kieling, A. C./Diretor Superintendente da ANFACER-Associação
Nacional dos Fabricantes de Cerâmica para Revestimento.