Phase transition in mayenite Ca12Al14O33

Tolkacheva, A. S.; Шкерин, С. Н.; Korzun, I. V.; Плаксин, С. В.; Хрустов, В. Р.; Ординарцев, Д. П.

doi:10.1134/s0036023612070182

Cited by 18 publications

(8 citation statements)

References 12 publications

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“…This feature classifies mayenite as an anti-zeolite phase. Recent studies pointed out that mayenite, besides releasing peroxide ions from 350 ºC to 650 ºC, reducing the number of filled cages, undergoes phase transition close to 650 ºC, giving rise to a phase in which the lattice parameter increases more rapidly with the temperature [20,22].…”

Section: Figurementioning

confidence: 99%

“…This hydrate phase decomposes close to 600 ºC, resulting in lime (CaO) and mayenite (12CaO.7Al2O3 or C12A7) [17]. Moreover, it is known that mayenite has intrinsic nanometric porosity resulted by the nanosized cages present in its microstructure, which are partially filled by weakly bounded O 2- [20,21]. This feature classifies mayenite as an anti-zeolite phase.…”

Section: Introductionmentioning

confidence: 99%

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Al2O3–CaO macroporous ceramics containing hydrocalumite-like phases

Borges

Santos

Salvini

et al. 2020

Ceramics International

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A mechanism to explain the lower onset strengthening temperature induced by CaCO3 in alumina-based macroporous ceramics is proposed, which relies on hydrocalumite-like phase formation during processing. Close to 600 °C, such phases are decomposed to lime and mayenite (12CaO·7Al2O3), where the latter, due to its intrinsic nanoporosity and high thermal reactivity, generates bonds between the ceramic particles at ~700ºC, resulting in microstructure strengthening. Based on this premise, the authors concluded that other Ca 2+ sources could act similarly. Indeed, compositions containing Ca(OH)2 or CaO showed the same effect on the onset strengthening temperature, which reinforces the proposed mechanism. The results attained indicated that macroporous insulators could be thermally treated at lower temperatures, just to acquire enough mechanical strength for installation, finishing in-situ their firing process. Besides that, lower sintering temperatures could be used to produce macroporous ceramics that would be applied in low thermal demand environments, e.g. aluminum industries.

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Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Al2O3–CaO macroporous ceramics containing hydrocalumite-like phases

Borges

Santos

Salvini

et al. 2020

Ceramics International

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“…The endothermic peak #2 appearing on the curve corresponds to the melting point of the BNi2 filler metal. Tolkacheva et al [ 24 ] stated that in the DSC curve, the temperature of a thermal event is measured as its onset temperature, more specifically, the intersection point between the tangents to two DSC curve segments, one belonging to the base line and the other to the peak front. Therefore, the melting point of BNi2 is considered to be 978.2 °C, which is consistent with the paper of Arafin et al [ 25 ].…”

Section: Resultsmentioning

confidence: 99%

Wetting Kinetics and Microstructure Analysis of BNi2 Filler Metal over Selective Laser Melted Ti-6Al-4V Substrate

Liu

Ouyang

et al. 2020

Materials

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The wetting kinetics of nickel-based filler metal (BNi2) over selective laser-melted Ti-6Al-4V (SLMed TC4) titanium alloy in a protective argon atmosphere is experimentally investigated using a real-time in situ hot stage equipped with an optical microscope. The spreading processes at different temperatures are similar, and the overall wetting/spreading process can be roughly divided into three stages: (i) an initial stage, (ii) a rapid spreading stage, and (iii) an asymptotic stage. Moreover, the wetting kinetics of the BNi2/SLMed TC4 system can be expressed by empirical power exponential function Rn~t with n = ~1. In the process of spreading, Ti-based solid solution (Ti(ss)) and intermetallic compound (Ti2Ni and TiB2) were formed at the interface within the reaction domain, and the phase transition of α’ martensitic to α-Ti and β-Ti also took place. The influence of elevated temperature on the spreading and wetting kinetics of the BNi2/SLMed TC4 system was studied, and the results show that the increase of temperature has a slightly promoting effect on the spreading, but a limited impact on the value of n. In addition, the spreading and wetting kinetics of BNi2/SLMed TC4 system are similar to those of BNi2 on conventional forged TC4 substrate.

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“…3(A). An isomorphous compound of katoite, Ca 3 Al 2 (OH) 12 , was formed followed by the decomposition of Ca/Al hydrotalcites [30,31]. This evidence implied that the mechanism of CaTiO 3 formation may involve the hydrolysis of titanium hydroxides under alkaline conditions, which significantly increases the attractive force between Ca 2+ and Ti(OH) 4 À .…”

Section: Characterization Of Sorbentsmentioning

confidence: 88%