Surface effects in field-assisted sintering

Groza, Joanna R.; Garcia, M.; Schneider, Judy

doi:10.1557/jmr.2001.0043

Cited by 85 publications

(63 citation statements)

References 25 publications

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“…É uma técnica de consolidação de pós caracterizada pela aplicação simultânea de pressão uniaxial e corrente contínua pulsada (on-off) através de uma amostra comprimida em matriz de grafite, o que torna possível sinterizações em curto espaço de tempo [6,7]. O princípio da transferência de massa utilizado neste processo permite a aplicação de altas taxas de aquecimento e de resfriamento, promovendo elevada densificação com menor crescimento de grãos, mantendo a integridade das propriedades intrínsecas dos pós nos produtos densificados [7].…”

Section: Sinterização Por Plasma Pulsadounclassified

SINTERIZAÇÃO DE COMPÓSITOS CERÂMICOS TIB2 – AlN VIA PLASMA PULSADO

Júnior¹,

Simão²,

Skury³

et al. 2018

ABM Proceedings

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ResumoAs propriedades e caracteristicas do diboreto de titânio (TiB2) e nitreto de alumínio (AlN) tornam esses materiais ideais para aplicações termomecânicas. Entretanto, a dificuldade de sinterizar compósitos cerâmicos à base de TiB2 -AlN tem limitado suas aplicações na indústria contemporânea. Nesse sentido, o presente trabalho tem por objetivo avaliar a técnica de sinterização por plasma pulsado (SPS), como uma alternativa para consolidação de compósito cerâmico em um curto intervalo de tempo. Após a caracterização das matérias primas, as amostras foram sinterizadas utilizando temperaturas entre 1.500°C e 1.900°C, além de 80 MPa de pressão e 10 minutos de permanência na temperatura máxima. A técnica "SPS" mostrou-se eficiente na sinterização desse sistema, alcançando densificações de até 98%. E ainda, como era esperado, a incompatibilidade dos coeficientes de expansão térmica entre o TiB2 e o AlN provocaram um processo de tenacificação nos compósitos. Palavras-chave: Sinterização, Compósitos, Cerâmica, Caracterização. SINTERING CERAMIC COMPOSITES TiB2 -AIN BY WAY OF PULSED PLASM AbstractThe properties and characteristics of titanium diboride (TiB2) and aluminum nitride (AlN) make these ideal materials for thermomechanical applications. However, the difficulty of ceramic composites sintering the based in TiB2 -AlN has limited its applications in th contemporary industry. In this sense, the present study aims to assess the sintering technique pulsed plasm (SPS) as an alternative to ceramic composite consolidation in a short period of time. After the characterization of raw materials, the samples were sintered using temperatures between 1,500°C and 1,900°C, and 80 MPa pressure and 10 minutes permanency at the maximum temperature. The "SPS" technique proved efficient in the sintering of this system, reaching densification up to 98%. And, as expected, the incompatibility of thermal extension coefficient between TiB2 and the AlN in motion a process of toughening of composites.

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Section: Sinterização Por Plasma Pulsadounclassified

SINTERIZAÇÃO DE COMPÓSITOS CERÂMICOS TIB2 – AlN VIA PLASMA PULSADO

Júnior¹,

Simão²,

Skury³

et al. 2018

ABM Proceedings

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“…Moreover it has been shown that molten surfaces would lead to a viscous flow [9]. Our implementation of the flow of molten particles is able to describe both mechanisms.…”

Section: Simulation Model and Setupmentioning

confidence: 99%

Simulation of current-activated pressure-assisted densification

Angst¹,

Schierning²,

Wolf³

2013

AIP Conference Proceedings

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Abstract. Cohesive particles usually form very porous agglomerates. They support loads up to a consolidation pressure, which increases with decreasing particle size. Compaction of nano-powders can therefore be very costly and time consuming. If the particles are electrically conducting, which is the case e.g. for novel nano-structured thermoelectric materials, the technique of current-activated pressure-assisted densification (CAPAD) turns out to have many advantages. Electrical power deposited locally as Joule heat lowers the consolidation pressure such that higher densities without much coarsening are obtained. We present a new model combining particle dynamics, calculated by molecular dynamic methods, with a network model including thermoelectric properties.

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“…The lower density attained at higher heating rates is attributable to premature necking possibly resulting from the formation of local hot spots and melting via arcing (i.e., dielectric breakdown) at the initial stages of heating. [23,28,57,58] This premature necking is thought to be responsible for entrapment of porosities and, thereby, a lower final density. Even though the underlying mechanisms are not fully understood, the formation of a dielectric breakdown event at the interparticle spacing during field activated sintering processes has been previously mentioned in the literature.…”

Section: B Densificationmentioning

confidence: 99%

“…Even though the underlying mechanisms are not fully understood, the formation of a dielectric breakdown event at the interparticle spacing during field activated sintering processes has been previously mentioned in the literature. [28] The localization and increase in magnitude of a dielectric breakdown event are both factors that are expected to be higher at lower applied pressures and higher heating rates during SPS processing. [59] A lower applied pressure provides smaller contact areas and larger spacing between individual particles, whereas a high heating rate requires a high applied current.…”

Section: B Densificationmentioning

confidence: 99%

“…[18,26,27] SPS has emerged as a possible consolidation pathway for NS materials given the shorter sintering times involved, which reportedly limit the grain growth, relative to the longer time exposures typically involved in conventional methods, such as hot pressing (HP) and hot isostatic pressing. [19,20,26,28] Interestingly, however, and despite numerous scientific studies completed with different materials, the underlying mechanisms that govern sintering during SPS are poorly understood. [20,27,29] The main characteristics of the SPS process can be listed as: (1) a relatively high heating rate (typically 50 K/min to 200 K/min, 1000 K/min [50°C/min to 200°C/min, 1000°C…”

Section: Introductionmentioning

confidence: 99%

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Nanostructured Ti Consolidated via Spark Plasma Sintering

Ertörer

Topping

et al. 2010

Metall Mater Trans A

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Cryomilled nanocrystalline commercially pure (CP)-Ti powders were spark plasma sintered (SPS) using different process parameters (heating rate, temperature, pressure, and dwell time) to study densification, microstructure, and mechanical behavior. The results were rationalized on the basis of the relevant literature and experimental results, and they reveal a strong dependence on SPS parameters. An interesting finding was that the measured high ductility was accompanied by a moderate strength (yield strength [YS] = 770 MPa, ultimate tensile strength [UTS] = 840 MPa with~27 pct elongation to failure). The combinations of microstructure and mechanical response were attributed to the multistep processing at different temperature ranges as well as to the presence of interstitial solutes.

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Surface effects in field-assisted sintering

Cited by 85 publications

References 25 publications

SINTERIZAÇÃO DE COMPÓSITOS CERÂMICOS TIB2 – AlN VIA PLASMA PULSADO

SINTERIZAÇÃO DE COMPÓSITOS CERÂMICOS TIB2 – AlN VIA PLASMA PULSADO

Simulation of current-activated pressure-assisted densification

Nanostructured Ti Consolidated via Spark Plasma Sintering

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