Hot-pressed graphene nanoplatelets or/and zirconia reinforced hybrid alumina nanocomposites with improved toughness and mechanical characteristics

Ahmad, Iftikhar; Islam, Mohammad; Habis, Nuha Al; Parvez, Shahid

doi:10.1016/j.jmst.2019.08.048

Cited by 23 publications

(6 citation statements)

References 47 publications

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“…These findings are in correlation with other publications [2,40,41]. Higher relative density, hence higher hardness, may be achieved when, for example, hot-pressing (HP) is used to prepare Al2O3-ZrO2 composites [42], hot isostatic pressing [43] or by spark plasma sintering (SPS) [44].…”

Section: Resultssupporting

confidence: 88%

Hardness and Indentation Fracture Toughness of Slip Cast Alumina and Alumina-Zirconia Ceramics

et al. 2019

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Alumina (Al2O3) and zirconia (ZrO2) have good overall properties and thus are widely used oxide technical ceramics. The biggest drawback of Al2O3 is its low fracture toughness. In contrast, ZrO2 is relatively tough, but is also much more expensive. In order to improve the alumina toughness, composite ceramics are being developed. Slip casting technology has economic advantages over the conventional hot isostatic pressure technology, but problems may arise when preparing stable highly-concentrated suspensions (slip) for filling the mold. The purpose of this study is to prepare aqueous suspensions using 70 wt. % α-Al2O3, with 0, 1, 5 and 10 wt. % of added t-ZrO2. Suspensions were electrosterically stabilized using the ammonium salt of polymethylacrylic acid, an alkali-free anionic polyelectrolyte dispersant. Also, magnesium oxide in form of magnesium aluminate spinel (MgAl2O4) was used to inhibit the abnormal alumina grain growth during the sintering process. Minimum viscosities were used as stability estimators, where an increase in ZrO2 content required adding more dispersant. After sintering, the Vickers indentation test was used to determine the hardness and the indentation fracture toughness from the measurement of the crack length. Also, the brittleness index (Bi, μm−1/2) was calculated from values of Vickers hardness and the Vickers indentation fracture toughness. It was found that with increasing ZrO2 content the fracture toughness increased, while the hardness as well as the brittleness index decreased. Zirconia loading reduces the crystallite sizes of alumina, as confirmed by the X-ray diffraction analysis. SEM/EDS analysis showed that ZrO2 grains are distributed in the Al2O3 matrix, forming some agglomerates of ZrO2 and some pores, with ZrO2 having a smaller grain size than Al2O3.

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Section: Resultssupporting

confidence: 88%

Hardness and Indentation Fracture Toughness of Slip Cast Alumina and Alumina-Zirconia Ceramics

et al. 2019

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“…Adapted from [58], no permission required. K IC /K 0 reported for basic bulk composites in recent years, separated by matrix type (b) oxides [11,12,22,31,32,[59][60][61][62], (c) nitrides [15][16][17]41,46,[63][64][65][66][67] and (d) carbides [19][20][21]25,27,28,[68][69][70][71]. Materials already reported in Figure 2a have been included in black colour.…”

Section: Methods For Measuring the Fracture Toughnessmentioning

confidence: 99%

“… method/solvent lateral size (µm) thickness (nm) ref. sonication/ethanol-PEG-PVP 0.5–5 0.8–1.2 [ 39 ] Hummers-thermal exfoliation/water 2–3 5 [ 12 ] ball mill/ethanol 6–150 [ 40 ] sonication/water 1–4 0.7–1.2 [ 22 ] planetary mill/NMP 2 20 [ 41 ] H 2 SO 4 −thermal exfoliation/DMF 15–25 6–8 [ 42 ] sonication/NMP 1.5 1 [ 10 ] sonication and stirring/water-PVA 1–2 0.7–2 [ 29 ] attrition/ethanol 1–5 6–8 [ 43 ] Hummers-sonication/ethanol 5 5 [ 44 ] planetary mill/melamine 25 6–8 [ 16 ] Hummers-sonication/water-hydrazine 2 …”

Section: Materials Design and Processing Methodsmentioning

confidence: 99%

10 years of research on toughness enhancement of structural ceramics by graphene

Ramírez

2022

Phil. Trans. R. Soc. A.

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Over the past decade, a new family of ceramic matrix composites has been developed from the incorporation of homogeneously dispersed graphene-based fillers (graphene nanoplatelets/GNP, graphene oxide sheets/rGO or graphene nanoribbons/GNR) into the ceramic matrices. These composites have shown a significant increment of their fracture toughness accompanied by other electrical and thermal functionalities, which make them potentially attractive for a wide range of applications. Here, the main methods for testing the fracture toughness of these composites are described, then the principal observations on the reinforcing mechanisms responsible for this improvement are briefly reviewed, and we discuss the relation with graphene platelets type, morphology and alignment. This article is part of the theme issue 'Nanocracks in nature and industry'.

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“…Nanocomposite materials have attracted significant interest due to their unique properties, which are absent in conventional composites [ 1 ]. The specific properties of nanocomposite materials differ from those of the bulk compounds, which have led to further studies of nanocomposites in many different fields [ 2 ].…”

Section: Introductionmentioning

confidence: 99%

Preparation and Antibacterial Activity of Nano Copper Oxide- Loaded Zeolite 10X

Hou

2022

IJMS

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Copper oxide nanosheet-loaded zeolite 10X nanocomposites (CuO-zeolite NCs) were successfully prepared by modifying zeolite 10X with CuSO4 aqueous solution. The formation of copper oxide nanosheets on the surface of zeolite 10X was observed by SEM. The thickness of CuO nanosheets was about 30–40 nm, and the width ranged from 200 nm to 300 nm. The XRD patterns showed that the new diffraction peaks of copper oxide appeared at 35.6° and 38.8°. According to the XPS results, the Cu 2p3/2 and Cu 2p1/2 peaks in CuO-zeolite NC were centered at 934.1 eV and 953.8 eV, which could be attributed to Cu(II). The EDS analysis revealed that the energy spectra of calcium gradually decreased as the copper ion concentration increased during the preparation of CuO-zeolite NCs. Meanwhile, the energy spectra of copper increased gradually, and the highest content of copper in CuO-zeolite NCs reached 22.35 wt.%. The BET surface areas of zeolite 10X and CuO-zeolite NCs were 587 and 363 m2/g, respectively, based on the N2 adsorption–desorption experiment. The antibacterial activities of CuO-zeolite NC were evaluated using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The antibacterial activities were related to both copper ion content in CuO-zeolite NCs and the particle size of copper oxide. The results showed that nano CuO-loaded zeolite 10X inhibited the activity of E. coli and S. aureus. CuO-zeolite NCs are expected to be further used in antifouling coating.

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Hot-pressed graphene nanoplatelets or/and zirconia reinforced hybrid alumina nanocomposites with improved toughness and mechanical characteristics

Cited by 23 publications

References 47 publications

Hardness and Indentation Fracture Toughness of Slip Cast Alumina and Alumina-Zirconia Ceramics

Hardness and Indentation Fracture Toughness of Slip Cast Alumina and Alumina-Zirconia Ceramics

10 years of research on toughness enhancement of structural ceramics by graphene

Preparation and Antibacterial Activity of Nano Copper Oxide- Loaded Zeolite 10X

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