In-situ formation of plate-like Al4O4C and MWCNTs in Al2O3–C refractories with Al4SiC4 additives

Yu, Chao; Dong, Bo; Deng, Chengji; Ding, Jun; Zhu, Hui; Di, Jiancheng

doi:10.1016/j.matchemphys.2021.124363

Cited by 21 publications

(9 citation statements)

References 59 publications

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“…Obviously, this is closely related to the in situ ceramic phase formed by Al 2 O 3 ‐SiC powder in the MgO aggregate. Similar results and theories have been widely discovered and confirmed 23–26 . Due to the difference in thermal properties between the in situ ceramic phase (spinel) and the MgO matrix, the residual strength of the MgO‐C samples after thermal shock is increased 27 .…”

Section: Resultssupporting

confidence: 81%

“…22 Conversely, due to excessive volume expansion, the apparent porosity of samples M5 and M7.5 increases slightly. [23][24][25][26] Due to the difference in thermal properties between the in situ ceramic phase (spinel) and the MgO matrix, the residual strength of the MgO-C samples after thermal shock is increased. 27 In addition, the MgO-C samples with Al 2 O 3 -SiC powder can reduce the oxidation rate of graphite, so they maintain a relatively high thermal conductivity, thereby further delaying the damage of thermal stress.…”

Section: Effects Of As-synthesized Al 2 O 3 -Sic Powder On the Physic...mentioning

confidence: 99%

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Synthesis of Al₂O₃‐SiC powder from electroceramics waste and its application in low‐carbon MgO‐C refractories

Ren

Zhi

et al. 2021

Int J Applied Ceramic Tech

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Composite additives are an efficient means to improve the high‐temperature stability and slag resistance of low‐carbon MgO‐C refractories. In this work, Al2O3‐SiC powder was firstly synthesized from electroceramics waste by carbon embedded method at 1500°C, 1550°C, and 1600°C for 4 h, and then the as‐synthesized Al2O3‐SiC powder was used as an additive to low‐carbon MgO‐C refractories. The effects of its addition amounts of 0, 2.5 wt.%, 5.0 wt.%, and 7.5 wt.% on the properties of the refractories were investigated in detail. It was found that increasing the heat treatment temperature is beneficial to the phase conversion of mullite and quartz to alumina and silicon carbide in the electroceramics waste. Furthermore, the addition of Al2O3‐SiC powder effectively improves the performance of low‐carbon MgO‐C samples, and the formation of spinel dense layer and high‐viscosity isolation layer is the internal reason for the improvement of the oxidation resistance and slag resistance of low‐carbon MgO‐C samples. This work provides ideas for the reuse of electroceramics waste and presents an alternative strategy for the performance optimization of low‐carbon MgO‐C refractories.

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Section: Resultssupporting

confidence: 81%

Section: Effects Of As-synthesized Al 2 O 3 -Sic Powder On the Physic...mentioning

confidence: 99%

Synthesis of Al₂O₃‐SiC powder from electroceramics waste and its application in low‐carbon MgO‐C refractories

Ren

Zhi

et al. 2021

Int J Applied Ceramic Tech

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“…5,[18][19][20][21] Al 4 O 4 C is a promising compound for high-temperature applications and refractory because of their high melting point (1890 • C), low density (2.684 g/cm 3 ), and excellent oxidation resistance. [21][22][23][24][25][26][27] The study on high-temperature behavior of pressed Al 4 O 4 C pellets under a nitrogen atmosphere indicated that a nitride layer generated on the surface and thereby slowed the nitrogen diffusion into the substrate. 28 Wu et al 29 also found that the surface of dense Al 4 O 4 C could form an Al 2 OC-AlN solid solution layer, consequently restricting the further nitridation.…”

Section: Introductionmentioning

confidence: 99%

A novel strategy for the fabrication of AlN–AlON refractories: Nitrogen gas pressure sintering of Al₄O₄C

Zheng

Xing

et al. 2022

J Am Ceram Soc.

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A novel strategy was exploited for the fabrication of AlN-AlON refractories via nitrogen gas pressure sintering of Al 4 O 4 C. The phase transformation and microstructure evolution during the reaction at 1600-1800 • C were thoroughly investigated. The results indicated that the high N 2 pressure was essential for the effective nitridation. The in situ generated AlN-AlON refractories had a homogeneous local chemical composition, and the (101) plane of AlN and the (222) lattice plane of Al 5 O 6 N were bonded at their grain boundary with no amorphous phase. The as-fabricated AlN-AlON refractories treated at 1700 • C by a 20 atmnitrogen pressure exhibited an optimum bending strength of 111.10 MPa, combining an apparent porosity of 20% with a low bulk density of 1.97 g/cm 3 . The diffusion of the generated oxygen led to an increase in the apparent porosity and decrease in the bulk density at 1800 • C. Furthermore, the fabrication mechanism of AlN-AlON refractories under the nitrogen gas-pressure was discussed.

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“…24 In further studies, the application of one dimensional multi-walled carbon nanotubes (MWCNTs) and mullite rods, owing to their outstanding thermal and mechanical properties at elevated temperatures, attracted much attention. [28][29][30][31][32][33][34][35][36][37] For instance, the strength and toughness of Al 2 O 3 -C refractories can be improved by using a liquid phenolic resin binder together with a nickel nitrate (Ni(NO 3 ) 2 ⋅6H 2 O) catalyst inducing the formation of MWCNTs in the matrix. 30,33 It was also reported that transition metal oxides including NiO and Fe 2 O 3 not only helped reduce the temperature of mullite formation, but had an important influence on the morphology of mullite rods and then enhanced the strength of Al 2 O 3 -C refractories.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, highly‐reactive expanded graphite promoted indeed the formation of SiC whiskers with high aspect ratio in the matrix and a higher strength was obtained 24 . In further studies, the application of one dimensional multi‐walled carbon nanotubes (MWCNTs) and mullite rods, owing to their outstanding thermal and mechanical properties at elevated temperatures, attracted much attention 28–37 . For instance, the strength and toughness of Al 2 O 3 ‐C refractories can be improved by using a liquid phenolic resin binder together with a nickel nitrate (Ni(NO 3 ) 2 ·6H 2 O) catalyst inducing the formation of MWCNTs in the matrix 30,33 .…”

Section: Introductionmentioning

confidence: 99%

Enhanced mechanical properties of lightweight Al₂O₃‐C refractories reinforced by combined one‐dimensional ceramic phases

Chen

Yan

Schafföner

et al. 2021

Int J Applied Ceramic Tech

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We prepared a new lightweight Al2O3‐C refractory material with a higher strength by using microporous corundum aggregates instead of dense tabular corundum aggregates, which was reinforced by in situ formed SiC whiskers, multi‐walled carbon nanotubes (MWCNTs), and mullite rods. A comparative study of the microstructure, mechanical properties, and fracture behavior was carried out for dense and lightweight Al2O3‐C refractories coked at 1200°C and 1400°C, respectively. By using the microporous corundum aggregates, a better aggregate/matrix interface bonding and an optimized distribution of SiC whiskers were obtained. The SiC whiskers formed inside the microporous corundum aggregates and simultaneously in the matrix by a vapor‐solid reaction mechanism, resulting in an enhancement at the microporous aggregate/matrix interface. Furthermore, the in situ formed MWCNTs and well‐developed mullite rods at 1200°C in the matrix also contributed to the better interface structure. Thus, due to the improved microporous aggregate/matrix interface, the crack propagation along the aggregate/matrix interface was suppressed, resulting in an increased crack propagation within the aggregates. Consequently, the synergy between microporous corundum aggregates and combined one‐dimensional ceramic phases caused a lower bulk density but a markedly higher strength, a higher fracture energy, and a higher toughness of lightweight Al2O3‐C refractories compared to the dense ones. Overall, our study allows to overcome the traditional concept that a higher strength of refractories is reached by a higher density.

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In-situ formation of plate-like Al4O4C and MWCNTs in Al2O3–C refractories with Al4SiC4 additives

Cited by 21 publications

References 59 publications

Synthesis of Al₂O₃‐SiC powder from electroceramics waste and its application in low‐carbon MgO‐C refractories

Synthesis of Al₂O₃‐SiC powder from electroceramics waste and its application in low‐carbon MgO‐C refractories

A novel strategy for the fabrication of AlN–AlON refractories: Nitrogen gas pressure sintering of Al₄O₄C

Enhanced mechanical properties of lightweight Al₂O₃‐C refractories reinforced by combined one‐dimensional ceramic phases

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In-situ formation of plate-like Al4O4C and MWCNTs in Al2O3–C refractories with Al4SiC4 additives

Cited by 21 publications

References 59 publications

Synthesis of Al2O3‐SiC powder from electroceramics waste and its application in low‐carbon MgO‐C refractories

Synthesis of Al2O3‐SiC powder from electroceramics waste and its application in low‐carbon MgO‐C refractories

A novel strategy for the fabrication of AlN–AlON refractories: Nitrogen gas pressure sintering of Al4O4C

Enhanced mechanical properties of lightweight Al2O3‐C refractories reinforced by combined one‐dimensional ceramic phases

Contact Info

Product

Resources

About

Synthesis of Al₂O₃‐SiC powder from electroceramics waste and its application in low‐carbon MgO‐C refractories

Synthesis of Al₂O₃‐SiC powder from electroceramics waste and its application in low‐carbon MgO‐C refractories

A novel strategy for the fabrication of AlN–AlON refractories: Nitrogen gas pressure sintering of Al₄O₄C

Enhanced mechanical properties of lightweight Al₂O₃‐C refractories reinforced by combined one‐dimensional ceramic phases