Grain growth kinetics and growth mechanism of columnar Al2O3 crystals in xNb2O5–7.5La2O3-Al2O3 ceramic composites

Du, Wenya; Ai, Yongfeng; He, Wen; Zhang, Jianjun; Fan, Yaqi; Gong, Yuxing

doi:10.1016/j.ceramint.2018.12.171

Cited by 16 publications

(4 citation statements)

References 23 publications

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“…The related correlation coefficients ( R 2 , shown in Figure 5) were quite high (.988–.997), indicating these data were stable and reliable. The results in Table 1 indicated that the magnitude of n reduced with the increase in sintering temperature, implying faster grain growth rates at higher sintering temperature 28 . It was in closely keeping with the acceleration of grain growth at elevated temperature, owning to the forcefully enhanced diffusion rate.…”

Section: Resultssupporting

confidence: 53%

“…The results in Table 1 indicated that the magnitude of n reduced with the increase in sintering temperature, implying faster grain growth rates at higher sintering temperature. 28 It was in closely keeping with the acceleration of grain growth at elevated temperature, owning to the forcefully enhanced diffusion rate. In the solid phase sintering process, material migration is mainly determined by the…”

Section: Grain Growth Kineticsmentioning

confidence: 73%

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Sintering kinetics and properties of NiFe₂O₄‐based ceramics inert anodes doped with TiN nanoparticles

Zhang

2022

Int J Applied Ceramic Tech

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Sintering kinetics of NiFe 2 O 4 -based ceramics inert anodes for aluminum electrolysis doped 7 wt% TiN nanoparticles were conducted to investigate densification and grain growth behaviors. The linear shrinkage increased gradually with the increasing sintering temperature between 1000 and 1450 • C, whereas the linear shrinkage rate exhibited a broad peak. The maximum linear shrinkage rate was obtained at 1189.4 • C, and the highest densification rate was achieved at the relative density of 75.20%. Based on the pressureless sintering kinetics window, the sintering process was divided into the initial stage, the intermediate stage, and the final stage. The grain growth exponent reduced with increased sintering temperature, whereas the grain growth activation energy decreased by increasing sintering temperature and shortening dwelling time. The grain growth was mainly controlled by atomic diffusion. NiFe 2 O 4 -based ceramics possessed hightemperature semiconductor essential characteristics. The electrical conductivity of NiFe 2 O 4 -based ceramics first increased and then decreased with increasing sintering temperature, reached their maximum value (960 • C) of 33.45 S/cm under 1300 • C, mainly attributed to the relatively dense and uniform microstructure. The thermal shock resistance of NiFe 2 O 4 -based ceramic was improved by a stronger grain boundary bonding strength and lower coefficient of linear thermal expansion.

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Section: Resultssupporting

confidence: 53%

Section: Grain Growth Kineticsmentioning

confidence: 73%

Sintering kinetics and properties of NiFe₂O₄‐based ceramics inert anodes doped with TiN nanoparticles

Zhang

2022

Int J Applied Ceramic Tech

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“…The authors calculated activation energy values for grain growth during microwave sintering in the range from 254 kJ/mol to 388 kJ/mol, with heating rates of 50, 75 and 100 ºC/min. Du et al 25 reported values for an alumina composite. The values were calculated in the range from 361.2 kJ/mol to 423.3 kJ/mol, depending on the niobium oxide amount added.…”

Section: Kinetics Study Of the Grain Growth During Microwave Sinteringmentioning

confidence: 99%

Effect of the Heating Rate and Processing Time on Grain Growth of Hematite Nanopowders in Conventional and Microwave-Assisted Sintering

Togashi,

Perdomo,

Kiminami

2023

Mat. Res.

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Microwave-assisted sintering of ceramic materials has proven to be a very favorable processing technique that can promote lower grain growth and densification with shorter dwell times. Hematite is considered a good microwave absorber due to its high loss tangent value, calculated in the range of 0.001 to 0.2 between room temperature and 750 ºC for 2.45 GHz 1 , thus showing good interaction with this electromagnetic radiation. However, there are few studies on grain growth kinetics of hematite during microwave sintering, as well as the relationship with grain growth parameters. Therefore, the aim of this work was to evaluate the effect of the heating rate and dwell time on grain growth kinetics, during microwave-assisted sintering (2.45 GHz) of hematite nanopowders. In an initial characterization, dilatometry tests were performed by conventional heating and microwave-assisted heating using the same heating rate (20 °C/min). From these results, the temperature ranges of the initial and intermediate stages of sintering and the onset of linear shrinkage were determined. Considering these results, the samples were sintered in a conventional oven from 750 ºC to 1200 ºC with increments of 50 ºC, varying the dwell time in 6, 12 and 36 minutes. Thus, the diffusional mechanism (N) could be calculated, a value used for the approximate calculation of microwave sintering kinetics. Additionally, sintering was performed in a microwave oven using three heating rates (20, 30 and 50 °C/min) to evaluate the effect of the heating rate on grain growth. The estimated activation energies for the grain growth process during microwave sintering were approximately 237.5 to 272.3kJ/mol, which were higher compared to conventional sintering, in the range of 206.0 to 242.0 kJ /mol. It was found that with increasing microwave heating rate, the activation energy for grain growth tends to be higher.

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“…It is known that processing conditions, including sintering temperature, could refine the microstructure and, in turn, mechanical properties of the final ceramic product [17]. The ceramic grains could be refined based on the grain growth kinetics [18]. The grain growth exponent (n) and apparent activation energy for grain growth (Q) play a key role in the expression of grain growth kinetics.…”

Section: Introductionmentioning

confidence: 99%

Microstructure evolution, grain growth kinetics and mechanical properties of Ca2MgSi2O7 bioceramics sintered at various temperatures

Mohammadi

Ismail

Shariff

et al. 2021

PAC

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Akermanite (Ca2MgSi2O7) ceramic powders were prepared by a wet solid-state synthesis process using a mixture of oxide sources. The mechanism of phase formation included the formation of transition compounds such as diopside and merwinite. The compacted disks of the dried mixture were sintered at 1200, 1225 and 1250?C for different dwell times (2, 4 and 6 h). The effect of sintering temperature on the physical properties (relative density and diameter shrinkage), grain growth kinetics (grain growth activation energy) and mechanical properties (flexural strength) of the akermanite ceramics were evaluated. It was shown that the increase in sintering temperature from 1200 to 1250?C decreased the porosity and increased the diameter shrinkage and relative density of Ca2MgSi2O7 ceramics. The grain growth activation energy was also found to increase with the increase of sintering temperature. Finally, the increase in density yielded ceramics with high mechanical strength.

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Grain growth kinetics and growth mechanism of columnar Al2O3 crystals in xNb2O5–7.5La2O3-Al2O3 ceramic composites

Cited by 16 publications

References 23 publications

Sintering kinetics and properties of NiFe₂O₄‐based ceramics inert anodes doped with TiN nanoparticles

Sintering kinetics and properties of NiFe₂O₄‐based ceramics inert anodes doped with TiN nanoparticles

Effect of the Heating Rate and Processing Time on Grain Growth of Hematite Nanopowders in Conventional and Microwave-Assisted Sintering

Microstructure evolution, grain growth kinetics and mechanical properties of Ca2MgSi2O7 bioceramics sintered at various temperatures

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Grain growth kinetics and growth mechanism of columnar Al2O3 crystals in xNb2O5–7.5La2O3-Al2O3 ceramic composites

Cited by 16 publications

References 23 publications

Sintering kinetics and properties of NiFe2O4‐based ceramics inert anodes doped with TiN nanoparticles

Sintering kinetics and properties of NiFe2O4‐based ceramics inert anodes doped with TiN nanoparticles

Effect of the Heating Rate and Processing Time on Grain Growth of Hematite Nanopowders in Conventional and Microwave-Assisted Sintering

Microstructure evolution, grain growth kinetics and mechanical properties of Ca2MgSi2O7 bioceramics sintered at various temperatures

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Sintering kinetics and properties of NiFe₂O₄‐based ceramics inert anodes doped with TiN nanoparticles

Sintering kinetics and properties of NiFe₂O₄‐based ceramics inert anodes doped with TiN nanoparticles