Influence of flash sintering on phase transformation and conductivity of hydroxyapatite

Lavagnini, Isabela R.; Campos, João V.; Storion, Ana Gabriela; Lobo, Anderson Oliveira; Raj, Rishi; Pallone, Elíria Maria de Jesus Agnolon

doi:10.1016/j.ceramint.2020.12.036

Cited by 18 publications

(4 citation statements)

References 55 publications

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“…The suppression of the decomposition of HAp during flash sintering has also been demonstrated in the literature. 6), 7) SEM images in the HAp bodies sintered under 800 and 2000 V•cm ¹1 were shown in Fig. 5.…”

Section: Fast and Flash Sinteringmentioning

confidence: 99%

“…3),4) HAp is usually produced as a powder, and the raw material is subjected to high temperature, typically around 1200 °C to obtain a high mechanical strength. 5),6) The sintering process improves the mechanical properties but often induces phase decomposition and consequent degradation in mechanical strength; 5), 7) though HAp ceramic does not require very high sintering temperature for densification, HAp could decompose into ¡and ¢-tricalcium phosphate (TCP) and tetracalcium phosphate (TTCP) at temperature beyond 1100 °C, resulting in a decrease in relative density and mechanical strength of sintered HAp body. 8) Recently, flash sintering has been employed to consolidate HAp ceramics in order to reduce the sintering temperature and to avoid the phase decomposition at high temperatures; 6),7),9), 10) it is expected that HAp may be densified within a short sintering time by the usage of flash sintering.…”

Section: Introductionmentioning

confidence: 99%

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Densification of hydroxyapatite ceramics by field-assisted sintering followed by controlled current ramp sintering

Li,

Masuda,

Murata

et al. 2023

J. Ceram. Soc. Japan

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Field-assisted sintering technique (FAST) and flash sintering experiments were conducted on hydroxyapatite (HAp) ceramics to attaining highly densified HAp body with uniform microstructure. FAST region, in which the densification was gradually accelerated, was observed from 800 °C under all fields examined. Under the field strength beyond 1000 V•cm ¹1 , the FAST followed by flash sintering took place. The phase decomposition can be effectively suppressed by the FAST/flash sintering. During the FAST region, microstructure remained uniform and the relative density of 94 % was achieved. By the flash sintering at 1000 V•cm ¹1 , the relative density of 97 % was achieved, but inhomogeneous microstructure appeared. By conducting controlled current rate sintering, the densification of the HAp with homogeneous microstructure was attained. The avoidance of current surge and localized current path through the specimen was crucial to attain the uniform, densified microstructure in the HAp ceramics.

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Section: Fast and Flash Sinteringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Densification of hydroxyapatite ceramics by field-assisted sintering followed by controlled current ramp sintering

Li,

Masuda,

Murata

et al. 2023

J. Ceram. Soc. Japan

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“…where r water is the density of water at 27 °C (0.996542 g cm -3 ) and r HA is the theoretical density of HA (3.156 g cm -3 ) [51].…”

Section: Bulk and Relative Density Measurementsmentioning

confidence: 99%

Synthesis and Characterization of Chicken Bone‐Derived Hydroxyapatite Incorporating Pectin

Teoh

Lee

et al. 2023

Chem Eng & Technol

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Hydroxyapatite (HA) was synthesized from chicken bone waste by calcination. Pectin was extracted from orange peels by microwave irradiation, and 1 and 3 wt % of pectin was incorporated into the HA. The resulting powders were then pressed into disk samples before being sintered at temperatures of 1050, 1150, and 1250 °C for 2 h. Various analytical techniques, including Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, density measurement, and Vickers microhardness tests, were used to evaluate the characteristics and mechanical properties of the samples. The incorporation of pectin did not interfere with the pure phases of HA, and minimal amounts of β‐tricalcium phosphate were detected in the XRD patterns. Both ball milling and the addition of pectin effectively reduced the particle size of HA. However, the addition of pectin above 1 wt % did not contribute significantly to the densification and hardness of chicken bone‐derived HA (CHA) compared with ball‐milled CHA. Samples sintered at 1050 °C had the lowest relative density, owing to incomplete particle fusion. Increasing the sintering temperature resulted in a maximum relative density of ca. 95 % and a Vickers microhardness of 4.12 GPa for ball‐milled CHA samples sintered at 1250 °C. Sintering temperature and ball milling were observed to play a more significant role in the densification and hardness of CHA compared with the addition of pectin.

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“…Na Figura 6.3 é possível observar ainda que a HAp pura apresentou uma banda por volta de 400 °C. A formação deste pico está relacionada ao fato da condutividade iônica da HAp ser baseada em mecanismos de 'hopping' (saltos) de prótons, que são eliminados em forma de água durante essa primeira etapa do aquecimento (LAVAGNINI et al, 2021), conforme discutido no Capítulo 5 .…”

Section: Temperatura (ºC)unclassified

Sinterização de zircônia, hidroxiapatita e compósito hidroxiapatita-zircônia via >i<Flash Sintering>/i<

Lavagnini¹

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A Flash Sintering (FS) é uma técnica alternativa à sinterização convencional que se destaca por ser capaz de sinterizar materiais cerâmicos em poucos segundos sob menores temperaturas de forno. Parâmetros intrínsecos e extrínsecos da técnica, bem como das cerâmicas utilizadas, influenciam não só durante a FS, mas também nas propriedades finais do material sinterizado. Devido a estas variáveis, a compreensão dos fenômenos e mecanismos que ocorrem durante a utilização da FS precisam ainda ser elucidados. Com o intuito de contribuir para essa elucidação, esse trabalho teve como objetivo avaliar a influência da utilização de diferentes parâmetros durante a FS (e.g., tipo de controle e magnitude de corrente elétrica, método de conformação) nas propriedades finais (e.g., densificação, microestrutura e evolução de fase cristalina) de três diferentes sistemas cerâmicos: a zircônia estabilizada com 3 %mol. de ítria (3YSZ), a hidroxiapatita (HAp) e o compósito HAp-3YSZ (HZ). Os resultados mostraram que o controle da corrente elétrica e a compactação dos pós (conformado por diferentes métodos) apresentaram grande influência na homogeneidade microestrutural de 3YSZ. Para a HAp, observou-se que a magnitude da corrente elétrica influenciou na microestrutura (tamanho de grão, tipo de fratura e porosidade) e na quantidade de fases cristalinas secundárias formadas, além de evitar a formação de β-fosfato tricálcico (β-TCP), como observado nas amostras sinterizadas convencionalmente. Em relação ao compósito HZ, apesar das amostras submetidas à FS apresentarem históricos térmicos semelhantes às sinterizadas convencionalmente, os resultados microestruturais não foram semelhantes. O compósito HZ submetido à FS apresentou a formação de micro agulhas em sua microestrutura, além disso a HAp foi convertida majoritariamente para α-fosfato tricálcico (α-TCP) e a 3YSZ foi estabilizada em sua fase cúbica (durante o flash e mantida após o resfriamento) devido à inclusão de Ca 2+ em sua estrutura. Esses resultados sugerem que o campo elétrico aplicado no material tem um papel importante, gerando efeitos atérmicos durante o processo de FS.

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Influence of flash sintering on phase transformation and conductivity of hydroxyapatite

Cited by 18 publications

References 55 publications

Densification of hydroxyapatite ceramics by field-assisted sintering followed by controlled current ramp sintering

Densification of hydroxyapatite ceramics by field-assisted sintering followed by controlled current ramp sintering

Synthesis and Characterization of Chicken Bone‐Derived Hydroxyapatite Incorporating Pectin

Sinterização de zircônia, hidroxiapatita e compósito hidroxiapatita-zircônia via >i<Flash Sintering>/i<

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