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  • Journal article
    Zhang T, Vandeperre LJ, Cheeseman CR, 2014,

    Formation of magnesium silicate hydrate (M-S-H) cement pastes using sodium hexametaphosphate

    , Cement and Concrete Research, Vol: 65, Pages: 8-14, ISSN: 0008-8846

    Magnesium silicate hydrate (M-S-H) gel is formed by the reaction of brucite with amorphous silica during sulphate attack in concrete and M-S-H is therefore regarded as having limited cementing properties. The aim of this work was to form M-S-H pastes, characterise the hydration reactions and assess the resulting properties. It is shown that M-S-H pastes can be prepared by reacting magnesium oxide (MgO) and silica fume (SF) at low water to solid ratio using sodium hexametaphosphate (NaHMP) as a dispersant. Characterisation of the hydration reactions by x-ray diffraction and thermogravimetric analysis shows that brucite and M-S-H gel are formed and that for samples containing 60 wt.% SF and 40 wt.% MgO all of the brucites react with SF to form M-S-H gel. These M-S-H cement pastes were found to have compressive strengths in excess of 70 MPa.
  • Journal article
    Kuenzel C, Li L, Vandeperre L, Boccaccini AR, Cheeseman CRet al., 2014,

    Influence of sand on the mechanical properties of metakaolin geopolymers

    , CONSTRUCTION AND BUILDING MATERIALS, Vol: 66, Pages: 442-446, ISSN: 0950-0618
  • Journal article
    Barg S, Perez FM, Ni N, Pereira PDV, Maher RC, Garcia-Tunon E, Eslava S, Agnoli S, Mattevi C, Saiz Eet al., 2014,

    Mesoscale assembly of chemically modified graphene into complex cellular networks

    , Nature Communications, Vol: 5, Pages: 1-10, ISSN: 2041-1723

    The widespread technological introduction of graphene beyond electronics rests on our ability to assemble this two-dimensional building block into three-dimensional structures for practical devices. To achieve this goal we need fabrication approaches that are able to provide an accurate control of chemistry and architecture from nano to macroscopic levels. Here, we describe a versatile technique to build ultralight (density ≥1 mg cm−3) cellular networks based on the use of soft templates and the controlled segregation of chemically modified graphene to liquid interfaces. These novel structures can be tuned for excellent conductivity; versatile mechanical response (elastic-brittle to elastomeric, reversible deformation, high energy absorption) and organic absorption capabilities (above 600 g per gram of material). The approach can be used to uncover the basic principles that will guide the design of practical devices that by combining unique mechanical and functional performance will generate new technological opportunities.
  • Journal article
    Poologasundarampillai G, Yu B, Tsigkou O, Wang D, Romer F, Bhakhri V, Giuliani F, Stevens MM, McPhail DS, Smith ME, Hanna JV, Jones JRet al., 2014,

    Poly(gamma-glutamic acid)/Silica Hybrids with Calcium Incorporated in the Silica Network by Use of a Calcium Alkoxide Precursor

    , Chemistry-A European Journal, Vol: 20, Pages: 8149-8160, ISSN: 1521-3765

    Current materials used for bone regeneration are usually bioactive ceramics or glasses. Although they bond to bone, they are brittle. There is a need for new materials that can combine bioactivity with toughness and controlled biodegradation. Sol-gel hybrids have the potential to do this through their nanoscale interpenetrating networks (IPN) of inorganic and organic components. Poly(γ-glutamic acid) (γ-PGA) was introduced into the sol-gel process to produce a hybrid of γ-PGA and bioactive silica. Calcium is an important element for bone regeneration but calcium sources that are used traditionally in the sol-gel process, such as Ca salts, do not allow Ca incorporation into the silicate network during low-temperature processing. The hypothesis for this study was that using calcium methoxyethoxide (CME) as the Ca source would allow Ca incorporation into the silicate component of the hybrid at room temperature. The produced hybrids would have improved mechanical properties and controlled degradation compared with hybrids of calcium chloride (CaCl2), in which the Ca is not incorporated into the silicate network. Class II hybrids, with covalent bonds between the inorganic and organic species, were synthesised by using organosilane. Calcium incorporation in both the organic and inorganic IPNs of the hybrid was improved when CME was used. This was clearly observed by using FTIR and solid-state NMR spectroscopy, which showed ionic cross-linking of γ-PGA by Ca and a lower degree of condensation of the Si species compared with the hybrids made with CaCl2 as the Ca source. The ionic cross-linking of γ-PGA by Ca resulted in excellent compressive strength and reduced elastic modulus as measured by compressive testing and nanoindentation, respectively. All hybrids showed bioactivity as hydroxyapatite (HA) was formed after immersion in simulated body fluid (SBF).
  • Journal article
    Jones NG, Humphrey C, Connor LD, Wilhelmsson O, Hultman L, Stone HJ, Giuliani F, Clegg WJet al., 2014,

    On the relevance of kinking to reversible hysteresis in MAX phases

    , Acta Materialia, Vol: 69, Pages: 149-161, ISSN: 1359-6454

    This paper examines the idea that reversible hysteresis in MAX phases is caused by the formation, growth and collapse of unstable, or incipient, kink bands. In situ X-ray diffraction of polycrystalline Ti3SiC2 in compression showed that residual elastic lattice strains developed during the first loading cycle and remained approximately constant afterwards. These residual strains were compressive in grains with a low Schmid factor and tensile in grains with a high Schmid factor, consistent with previous observations of plastically deformed hexagonal metals. In contrast, incipient kink bands would be expected to collapse completely, without any residual strain. Elastoplastic self-consistent simulations showed that reversible hysteresis is predicted if some grains yield by slip on the basal plane, while others remain predominantly elastic, giving both the experimentally observed magnitude of the work dissipated and its dependence on the maximum applied stress. The reversible hysteresis in single crystals was studied by cyclically indenting thin films of Ti3SiC2 and Ti3SiC2/TiC multilayers on Al2O3 substrates. The work dissipated in the multilayer films was greater than in Ti3SiC2 alone, despite the reduction in volume fraction of Ti3SiC2. Reversible hysteresis was also observed during indentation of single-crystal cubic MgO, demonstrating that this behaviour can occur if there are insufficient slip systems to accommodate the strain around the indentation. These results show that reversible hysteresis is associated with conventional dislocation flow, without the need for unstable kinking.
  • Journal article
    Chen Z, Wang X, Giuliani F, Atkinson Aet al., 2014,

    Surface quality improvement of porous thin films suitable for nanoindentation

    , CERAMICS INTERNATIONAL, Vol: 40, Pages: 3913-3923, ISSN: 0272-8842
  • Journal article
    Wong LLC, Barg S, Menner A, Pereira PDV, Eda G, Chowalla M, Saiz E, Bismarck Aet al., 2014,

    Macroporous polymer nanocomposites synthesised from high internal phase emulsion templates stabilised by reduced graphene oxide

    , POLYMER, Vol: 55, Pages: 395-402, ISSN: 0032-3861
  • Conference paper
    Glymond D, Vick M, Pan MJ, Giuliani F, Vandeperre LJet al., 2014,

    The effect of the addition of ceria stabilised zirconia on the creep of mullite

    , Pages: 69-77, ISSN: 0196-6219

    Mullite is considered a promising candidate for ceramic recuperators in turbo propelled engines, due to due to its low thermal conductivity, adequate thermal shock resistance, low cost, low density, thermodynamic stability, and reasonable strength at high temperatures. Unfortunately, the limited fracture toughness of mullite (∼1.8-2.8 MPa m1/2) is considered too low. Improving the fracture toughness to 4.7 MPa m1/2 is possible by the addition of ceria stabilised zirconia (CSZ). However, the addition of CSZ to mullite may also affect other properties. In this paper the effect of the addition of CSZ on the creep resistance is described by comparing a mullite-zirconia composite made with a commercially available mullite powder against the creep behaviour of mullite made from the same mullite powder. The stress exponent is close to 1 and the activation energies for creep were similar at 426±38 kJ mol-1 and 452±15 kJ mol-1. However, the resistance to creep as expressed by a given strain rate for a given stress is 250°C lower in the 20 vol% zirconia-mullite composite compared to the baseline.
  • Journal article
    Ni N, Kaufmann Y, Kaplan WD, Saiz Eet al., 2014,

    Interfacial energies and mass transport in the Ni(Al)–Al2O3 system: The implication of very low oxygen activities

    , Acta Materialia, Vol: 64, Pages: 282-296, ISSN: 1359-6454
  • Journal article
    Fu Q, Saiz E, Rahaman MN, Tomsia APet al., 2013,

    Toward Strong and Tough Glass and Ceramic Scaffolds for Bone Repair

    , ADVANCED FUNCTIONAL MATERIALS, Vol: 23, Pages: 5461-5476, ISSN: 1616-301X
  • Journal article
    Houmard M, Fu Q, Genet M, Saiz E, Tomsia APet al., 2013,

    On the structural, mechanical, and biodegradation properties of HA/β-TCP robocast scaffolds

    , JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART B-APPLIED BIOMATERIALS, Vol: 101, Pages: 1233-1242, ISSN: 1552-4973
  • Journal article
    Genet M, Houmard M, Eslava S, Saiz E, Tomsia APet al., 2013,

    A two-scale Weibull approach to the failure of porous ceramic structures made by robocasting: Possibilities and limits (vol 33, pg 679, 2013)

    , JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, Vol: 33, Pages: 1393-1393, ISSN: 0955-2219
  • Journal article
    Chen Z, Wang X, Bhakhri V, Giuliani F, Atkinson Aet al., 2013,

    Nanoindentation of porous bulk and thin films of La0.6Sr0.4Co0.2Fe0.8O3−δ

    , Acta Materialia, Vol: 61, Pages: 5720-5734, ISSN: 1873-2453

    In this paper we show how reliable measurements on porous ceramic films can be made by appropriate nanoindentation experiments and analysis. Room-temperature mechanical properties of the mixed-conducting perovskite material La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF6428) were investigated by nanoindentation of porous bulk samples and porous films sintered at temperatures from 900 to 1200 °C. A spherical indenter was used so that the contact area was much greater than the scale of the porous microstructure. The elastic modulus of the bulk samples was found to increase from 33.8 to 174.3 GPa and hardness from 0.64 to 5.32 GPa as the porosity decreased from 45% to 5% after sintering at 900–1200 °C. Densification under the indenter was found to have little influence on the measured elastic modulus. The residual porosity in the “dense” sample was found to account for the discrepancy between the elastic moduli measured by indentation and by impulse excitation. Crack-free LSCF6428 films of acceptable surface roughness for indentation were also prepared by sintering at 900–1200 °C. Reliable measurements of the true properties of the films were obtained by data extrapolation provided that the ratio of indentation depth to film thickness was in the range 0.1–0.2. The elastic moduli of the films and bulk materials were approximately equal for a given porosity. The 3-D microstructures of films before and after indentation were characterized using focused ion beam/scanning electron microscopy tomography. Finite-element modelling of the elastic deformation of the actual microstructures showed excellent agreement with the nanoindentation results.
  • Journal article
    Garcia-Tunon E, Barg S, Bell R, J V M W, Walter C, Goyos L, Saiz Eet al., 2013,

    Designing Smart Particles for the Assembly of Complex Macroscopic Structures

    , Angewandte Chemie-International Edition
  • Journal article
    Walter C, Barg S, Ni N, Maher RC, Garcίa-Tuñón E, Muzzafar Zaiviji Ismail M, Babot F, Saiz Eet al., 2013,

    A novel approach for the fabrication of carbon nanofibre/ceramic porous structures

    , Journal of the European Ceramic Society
  • Journal article
    Kim H, Saiz E, Chhowalla M, Mattevi Cet al., 2013,

    Modeling of the self-limited growth in catalytic chemical vapor deposition of graphene

    , NEW JOURNAL OF PHYSICS, Vol: 15, ISSN: 1367-2630
  • Conference paper
    Wong LLC, Barg S, Menner A, Bismarck A, Saiz Eet al., 2013,

    Graphene oxide macroporous polymer foam nanocomposites synthesised via emulsion templating

    , 245th National Spring Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
  • Journal article
    Genet M, Houmard M, Eslava S, Saiz E, Tomsia APet al., 2013,

    A two-scale Weibull approach to the failure of porous ceramic structures made by robocasting: Possibilities and limits

    , J. Eur. Ceram. Soc., Vol: 33, Pages: 679-688
  • Journal article
    Huang J, Ten E, Liu G, Finzen M, Yu W, Lee JS, Saiz E, Tomsia APet al., 2013,

    Biocomposites of pHEMA with HA/β-TCP (60/40) for bone tissue engineering: Swelling, hydrolytic degradation, and <i>in vitro</i> behavior

    , POLYMER, Vol: 54, Pages: 1197-1207, ISSN: 0032-3861
  • Journal article
    Huang J, Zhao D, Dangaria SJ, Luan X, Diekwisch TGH, Jiang G, Saiz E, Liu G, Tomsia APet al., 2013,

    Combinatorial design of hydrolytically degradable, bone-like biocomposites based on PHEMA and hydroxyapatite

    , POLYMER, Vol: 54, Pages: 909-919, ISSN: 0032-3861
  • Journal article
    Saiz E, Zimmermann EA, Lee JS, Wegst UGK, Tomsia APet al., 2013,

    Perspectives on the role of nanotechnology in bone tissue engineering

    , DENTAL MATERIALS, Vol: 29, Pages: 103-115, ISSN: 0109-5641
  • Journal article
    Garcia-Tunon E, Franco J, Eslava S, Bhakhri V, Saiz E, Giuliani F, Guitian Fet al., 2013,

    Synthesis and optimization of the production of millimeter-size hydroxyapatite single crystals by Cl--OH- ion exchange

    , J. Am. Ceram. Soc., Vol: 96, Pages: 759-765
  • Conference paper
    Wang J, Feilden-Irving E, Vandeperre LJ, Giuliani Fet al., 2013,

    THE HARDNESS OF ZrB<sub>2</sub> BETWEEN 1373 K AND 2273 K

    , 36th International Conference and Expo on Advanced Ceramics and Composites, Publisher: AMER CERAMIC SOC, Pages: 187-195, ISSN: 0196-6219
  • Journal article
    Tomsia AP, Lee JS, Wegst UGK, Saiz Eet al., 2013,

    Nanotechnology for Dental Implants

    , INTERNATIONAL JOURNAL OF ORAL & MAXILLOFACIAL IMPLANTS, Vol: 28, Pages: E535-E546, ISSN: 0882-2786
  • Conference paper
    Glymond D, Vick M, Pan M-J, Giuliani F, Vandeperre LJet al., 2013,

    TAILORING MICROSTRUCTURES IN MULLITE FOR TOUGHNESS ENHANCEMENT

    , Mechanical Behavior and Performance of Ceramics and Composites Symposium, Publisher: AMER CERAMIC SOC, Pages: 143-151, ISSN: 0196-6219
  • Journal article
    Eslava S, Zhang L, Vanstreels K, Baklanov MR, Saiz Eet al., 2012,

    Metal-organic framework ZIF-8 as low-k dielectrics in microelectronics

    , Chemistry of Materials, Vol: 25, Pages: 27-33
  • Journal article
    Kuenzel C, Grover LM, Vandeperre L, Boccaccini AR, Cheeseman CRet al., 2012,

    Production of nepheline/quartz ceramics from geopolymer mortars

    , Journal of the European Ceramic Society, Vol: 33, Pages: 251-258, ISSN: 1873-619X

    This research has investigated the mechanical properties and microstructure of metakaolin derived geopolymer mortars containing 50% by weight of silica sand, after exposure to temperatures up to 1200 °C. The compressive strength, porosity and microstructure of the geopolymer mortar samples were not significantly affected by temperatures up to 800 °C. Nepheline (NaAlSiO4) and carnegieite (NaAlSiO4) form at 900 °C in the geopolymer phase and after exposure to 1000 °C the mortar samples were transformed into polycrystalline nepheline/quartz ceramics with relatively high compressive strength (∼275 MPa) and high Vickers hardness (∼350 HV). Between 1000 and 1200 °C the samples soften with gas evolution causing the formation of closed porosity that reduced sample density and limited the mechanical properties.
  • Journal article
    Kuenzel C, Vandeperre LJ, Donatello S, Boccaccini AR, Cheeseman Cet al., 2012,

    Ambient Temperature Drying Shrinkage and Cracking in Metakaolin-Based Geopolymers

    , JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Vol: 95, Pages: 3270-3277, ISSN: 0002-7820
  • Journal article
    Garcia-Tunon E, Couceiro R, Franco J, Saiz E, Guitian Fet al., 2012,

    Synthesis and characterisation of large chlorapatite single-crystals with controlled morphology and surface roughness

    , JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE, Vol: 23, Pages: 2471-2482, ISSN: 0957-4530
  • Journal article
    Esteban-Tejeda L, Cabal B, Malpartida F, Lopez-Piriz R, Torrecillas R, Saiz E, Tomsia AP, Moya JSet al., 2012,

    Soda-lime glass-coating containing silver nanoparticles on Ti-6Al-4V alloy

    , JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, Vol: 32, Pages: 2723-2729, ISSN: 0955-2219

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