Preliminary investigation of hydroxyapatite microstructures prepared by flash sintering

Abstract

Flash sintering is a novel and emerging route for sintering ceramics within a few seconds, even under pressure-less conditions. In the current study, hydroxyapatite (HA) was fully densified by flash sintering at a furnace temperature of 1020°C. Flash sintering with constant electric fields of 750 and 1000 V cm −1 reduced the grain growth rate significantly compared to that sintered in the absence of an electric field at 1400°C. The microstructure of HA consolidated by flash sintering was compared with that of the without electric field sintered samples. The flashsintered samples showed smaller grains (160 ∼ 320 nm) than the without electric field sintered samples (∼15 µm). The samples with a higher applied electric field showed slightly better densification than those with the lower field by flash sintering. Overall, the electric flash reduces the sintering temperature effectively and decreases the holding time to densify highly insulating ceramics, such as HA.

Particle curvature effects on microstructural evolution during solid-state sintering: phenomenological insights from phase-field simulations

“…3a3 and Fig. 3b3), consistent with sintered microstructures seen in many materials [4][5][6][7][8][9][10][11][12][13].…”

“…Solid-state sintering is a processing technique that involves densifying green powder compacts by employing temperature, pressure or combination thereof [1][2][3]. This technique is used for processing high-temperature alloys, ceramics, nanocomposites [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] and, even, ice compacts [4,20]. Therefore, due to the wide application of sintering, a mechanistic understanding of the processes involved is mandated, particularly from the perspective of theory and simulation that can take into account coupling of multiple competing mechanisms [1,21,[21][22][23][24][25][26][27][27][28][29][30][31][32][33][34].…”

Phase-pure BiFeO3 produced by reaction flash-sintering of Bi2O3 and Fe2O3

“…where it has been concluded that Bi 3+ ions diffuse into Fe2O3 particles. 48 It is of note that Bi25FeO39 is often an intermediate phase before the formation of BiFeO3 in different methods of synthesis, including solid-state reaction, 18 hydrothermal precipitation 68 and mechanosynthesis. 19 Point #2 in Fig.…”

“…16,17 This approach, called "Flash Sintering", has been applied to the densification of a number of different materials. [18][19][20][21][22][23][24][25][26][27][28][29][30][31] The aim of the present work is to explore if chemical reactions and sintering can be merged into a single step in flash experiments. We are able to show that single phase, nearly dense, polycrystals of BiFeO3 can be synthesized from powders of Bi2O3 and Fe2O3 in just a few seconds; we call it reaction flash sintering (RFS).…”

Crystallization Behavior of the Low-Temperature Mineralization Sintering Process for Glass Nanoparticles

“…Many sintering techniques, such as the application of high pressure and the addition of a liquid phase as an aid during sintering, have been investigated in a bid to reduce the sintering temperature required to fabricate ceramic and glass materials [ 3 , 4 ]. Moreover, more efficient sintering techniques, such as microwave sintering [ 5 , 6 ], spark plasma sintering [ 7 , 8 ], and flash sintering [ 9 , 10 ], which utilize electrical means, have been developed to densify ceramic materials at lower temperatures. Although these sintering processes have improved the sintering properties of ceramic materials, for example, producing a constant grain size and higher densification rate, the required sintering temperatures are still almost or more than 800 °C [ 11 ].…”