| 1. |
- Ali, Amjad, et al.
(författare)
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A potential electrolyte (Ce1-x CaxO2-delta) for fuel cells:Theoretical andexperimental study
- 2018
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Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 44:11, s. 12676-12683
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Tidskriftsartikel (refereegranskat)abstract
- First-principles calculations are performed using density function theory to explore the effects of dopant Ca in ceria (Ce1-x CaxO2-delta). The impact of oxygen vacancy on band gap and density of states is examined in doped ceria using generalized gradient approximations. Vacancy association and vacancy formation energies of the doped ceria are calculated to reveal the effect of dopant on ion conduction. The experimental study of the sample Ce0.875Ca0.125O2-delta) was performed to compare with the theoretical results. The obtained results from theoretical calculation and experimental techniques show that oxygen vacancy increases the volume, lattice constant (5.47315 angstrom) but decrease the band gap (1.72 eV) and bulk modulus. The dopant radius (1.173 angstrom) and lattice constant (5.4718 angstrom) are also calculated by equations which is close to the DFT lattice parameter. The result shows that oxygen vacancy shifts the density of states to lower energy region. Band gap is decreased due to shifting of valence states to conduction band. Vacancy formation shows a significance increase in density of states near the Fermi level. Density of states at Fermi level is proportional to the conductivity, so an increase in density of states near the Fermi level increases the conductivity. The experimental measured ionic conductivity is found to 0.095 S cm(-1) at 600 degrees C. The microstructural studies is also reported in this work.
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| 2. |
- Ali, Sharafat, 1976-, et al.
(författare)
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Issues associated with the development of transparent oxynitride glasses
- 2015
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 41:3, s. 3345-3354
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Tidskriftsartikel (refereegranskat)abstract
- Oxynitride glasses and glass ceramics are increasingly recognized as potential materials in specialist applications in modern industrial sectors. Oxynitride glasses have superior mechanical, rheological and optical properties to their oxide glass counterparts. Properties of these glasses can be tailored by changes in nitrogen content and additions of various alkaline-earth and or rare-earth elements. In contrast to oxide glasses, oxynitride glasses are difficult to prepare which adds to production costs. Furthermore, they contain impurities in the form of elemental silicon and silicides, have poor oxidation resistance in air above their glass transition temperatures and have poor transparency in the visible region. This article reviews the above issues in relation to the potential applications of these glasses.
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| 3. |
- Archana, M. S., et al.
(författare)
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Influence of applied pressure during field-assisted sintering of Ti(C,N)-WC-FeAl based nanocomposite
- 2015
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Ingår i: Ceramics International. - 0272-8842 .- 1873-3956. ; 41:2, s. 1986-1993
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Tidskriftsartikel (refereegranskat)abstract
- Ti(C,N)-WC-FeAl based nanocomposites are processed by field-assisted sintering at 1500 degrees C. The phase and microstructural evolution during the process under the influence of different applied pressures of 30, 50 and 100 MPa are studied using x-ray diffraction and scanning electron microscopy. Lattice parameters of (Ti,W)(C,N) solid solution and binder phases after sintering are found to vary with applied pressure. The nanocomposite grains are observed to possess a core-rim microstructure. Microstructural variations in terms of type, size and fraction of "corerim" structure as a function of applied pressure are investigated. The hardness and indentation fracture toughness values are in the range of 17.6-18.4 GPa and 5.9-6.8 MPa root m, respectively. These values are comparable with those reported for Ti(C,N)-based composites with metal binder. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
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| 4. |
- Barick, P., et al.
(författare)
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Effect of concentration and molecular weight of polyethylenimine on zeta potential, isoelectric point of nanocrystalline silicon carbide in aqueous and ethanol medium
- 2015
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Ingår i: Ceramics International. - : Elsevier Ltd. - 0272-8842 .- 1873-3956. ; 41:3, s. 4289-4293
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Tidskriftsartikel (refereegranskat)abstract
- The effect of dispersant concentration and its molecular weight on zeta potential of nanocrystalline silicon carbide in an aqueous medium was investigated. An increase in the concentration of the dispersant, such as polyethylenimine (PEI), in slurry prepared from nanosized silicon carbide, was found to augment the iso-electric point and zeta potential. However, the zeta potential was observed to decline as the pH of the slurry shifts towards the basic region. This aforementioned behavior is attributed to the enhanced mutual repulsion between the polymer chains of the dispersant adsorbed on the surfaces of SiC particles and those approaching the surfaces. The higher ionization potential of polymers in the acidic region compared to the basic region increases the adsorption. The relationship between zeta potential and pH is however, noted to remain virtually unchanged with molecular weight of PEI. Further, it is observed that zeta potential of SiC decreases with the increase in solid content of the slurry. Rheology study reveals that the ethanol based slurry has a lower viscosity than the water based slurry, making ethanol the preferred dispersing medium for colloidal processing of nanometric SiC powder. © 2014 Elsevier Ltd and Techna Group S.r.l.
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| 5. |
- Barick, Prasenjit, et al.
(författare)
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Effect of pressure and temperature on densification, microstructure and mechanical properties of spark plasma sintered silicon carbide processed with β-silicon carbide nanopowder and sintering additives
- 2016
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 42:3, s. 3836-3848
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Tidskriftsartikel (refereegranskat)abstract
- The effects of applied pressure and temperature during spark plasma sintering (SPS) of additive-containing nanocrystalline silicon carbide on its densification, microstructure, and mechanical properties have been investigated. Both relative density and grain size are found to increase with temperature. Furthermore, with increase in pressure at constant temperature, the relative density improves significantly, whereas the grain size decreases. Reasonably high relative density (~96%) is achieved on carrying out SPS at 1300 °C under applied pressure of 75 MPa for 5 min, with a maximum of ~97.7% at 1500 °C under 50 MPa for 5 min. TEM studies have shown the presence of an amorphous phase at grain boundaries and triple points, which confirms the formation of liquid phase during sintering and its significant contribution to densification of SiC at relatively lower temperatures (≤1400 °C). The relative density decreases on raising the SPS temperature beyond 1500 °C, probably due to pores caused by vaporization of the liquid phase. Whereas β-SiC is observed in the microstructures for SPS carried out at temperatures ≤1500 °C, α-SiC evolves and its volume fraction increases with further increase in SPS temperatures. Both hardness and Young׳s modulus increase with increase in relative density, whereas indentation fracture toughness appears to be higher in case of two-phase microstructure containing α and β-SiC.
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| 6. |
- Berg, Camilla, et al.
(författare)
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Ion substitution induced formation of spherical ceramic particles
- 2019
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Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 45:8, s. 10385-10393
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Tidskriftsartikel (refereegranskat)abstract
- How to precipitate ceramic nano- and microspheres in water based solutions only using inorganic ions is a challenge. In this study, spherical particles of alkaline earth phosphates and fluorides were synthesized using a precipitation reaction. Substituting ions, through inhibition of crystal growth, was used to induce sphere formation and to alter the morphology, size and composition of the spheres. The difference in ionic radius between the substituting ion (Mg, Ca and Sr) and the main cation (Sr and Ba) influenced the critical concentration to allow for sphere formation as well as the crystallinity. The larger difference, the lower was the concentration needed to form spheres. Low concentrations of Mg was enough to generate amorphous spheres of Sr- and Ba- phosphates whereas higher concentrations were needed if the radius difference were smaller. An increasing degree of substitution leads to a decrease in crystallinity of precipitated particles. The degree of substitution was determined to 16-55% where a low degree of ion substitution in the phosphates resulted in the formation of spheres (500-800 nm) with rough surfaces composed of apatite like phases. A higher degree of substitution resulted in amorphous spheres (500 nm- (1) mu m) with smooth surfaces.
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| 7. |
- Bhatti, Muhammad Ali, et al.
(författare)
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Efficient photo catalysts based on silver doped ZnO nanorods for the photo degradation of methyl orange
- 2019
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Ingår i: Ceramics International. - Oxford : Elsevier. - 0272-8842 .- 1873-3956. ; 45:17, Part B, s. 23289-23297
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the doped ZnO nanorods with silver (Ag) as photosensitive material are prepared by the solvothermal method. The structural and optical characterization is carried out by the scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy and UV–visible spectroscopy. The use of Ag as dopant did not alter the morphology of ZnO except sample 4 which has flower like morphology. The Ag, Zn and O are the main constituent of doped materials. The XRD revealed a hexagonal phase for ZnO and cubic phase for silver and confirmed the successful doping of Ag. The photocatalytic activity of Ag doped ZnO nanorods was investigated for the photo degradation of methyl orange. The photocatalytic measurements show that 88% degradation of methyl orange by the sample 4 within the 2 h of UV light treatment (365 nm) is significant advancement in the photocatalyst and provide the inexpensive and promising materials for the photochemical applications. © 2019 Elsevier Ltd and Techna Group S.r.l.
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| 8. |
- Bu, Junfu, et al.
(författare)
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Preparation of 30 mol.% Y-doped hafnia (Hf0.7Y0.3O2-delta) using a modified solid-state reaction method
- 2015
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 41:2, s. 2611-2615
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Tidskriftsartikel (refereegranskat)abstract
- A pure and well-crystallized Hf0.7Y0.3O2-delta (YSH) powder was synthesized using a modified solid-state reaction method. Water-based milling and freeze drying process were implemented to facilitate powder synthesis and final densification process. The improved powder performance, in aspects of phase development and sintering behaviour, was investigated by systematic comparison between different powder processing procedures. Dense YSH ceramic material with a relative density of 0.975 was successfully obtained using conventional sintering at 1650 degrees C for 10 h. XRD, SEM and EDS were employed to characterize the synthesized powder and dense YSH ceramics. Dense YSH ceramic possesses a fluorite cubic structure with an a value of 5.1406 angstrom, and the ionic radius of Y3+ in YSH was determined to be 0.1006 nm.
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| 9. |
- Bu, Junfu, et al.
(författare)
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Sintering behaviour of the protonic conductors BaZr(x)Ce(0.8-x)Ln(0.2)O(3-delta) (x=0.8, 0.5, 0.1; Ln=Y, Sm, Gd, Dy) during the solid-state reactive-sintering process
- 2015
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 41:2, s. 2558-2564
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Tidskriftsartikel (refereegranskat)abstract
- The protonic conductors BaZr(x)Ce(0.8-x)Ln(0.2)O(3-delta) (x=0.8, 0.5, 0.1; Ln=Y, Sm, Gd, Dy) were successfully prepared using a solid-state reactive-sintering method. NiO (1 wt.%) was added as a sintering aid, and it was proven that NiO produced tremendous enhancement in the densification process. The morphologies of the variously doped BaZr(0.8)Ln(0.2)O(3-delta), BaZr(0.5)Ce(0.3)Ln(0.2)O(3-delta) and BaZr(0.1)Ce(0.7)Ln(0.2)O(3-delta) ceramics, as well as their sintering behaviour, were investigated. The results show that the Ce content in the BaZr(0.8)Ln(0.2)O(3-delta), BaZr(0.5)Ce(0.3)Ln(0.2)O(3-delta) and BaZr(0.1)Ce(0.7)Ln(0.2)O(3-delta) compounds influences the sintering temperature significantly, and a larger Ce content will lead to a lower sintering temperature. In addition, ionic radii of the dopants that are similar to the ionic radii of the B-site will also result in a lowered sintering temperature. Based on the present study, NiO has no influence on the lattice parameters.
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| 10. |
- Bu, Junfu, et al.
(författare)
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Transport properties of BaZr0.5Ce0.3Y0.2O3-δ proton conductor prepared by spark plasma sintering
- 2016
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 42:3, s. 4393-4399
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Tidskriftsartikel (refereegranskat)abstract
- Dense BaZr0.5Ce0.3Y0.2O3-δ (BZCY532) proton conductors were prepared by a spark plasma sintering method. Their conductivities were determined in different atmospheres: dry air, wet N2 and wet H2. Moreover, the potential electronic conductivity contribution to the total conductivity was also identified by testing their total conductivities at different oxygen partial pressures (1-10-24 atm) in combination with an XPS analysis. It is found that the prepared dense BZCY532 ceramics are good proton conductors at 600 °C. In addition, the Ce3+ concentration in the dense BZCY532 ceramics is around 3.5 atm% of the total Ce element, and the electronic contribution to the total conductivity can be neglected after a postheat treatment.
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| 11. |
- Chen, Song, et al.
(författare)
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Eu3+ doped monetite and its use as fluorescent agent for dental restorations
- 2018
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Ingår i: Ceramics International. - : Saunders Elsevier. - 0272-8842 .- 1873-3956. ; 44:9, s. 10510-10516
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Tidskriftsartikel (refereegranskat)abstract
- It is essential but challenging to distinguish the dental restorations from the surrounding teeth when removing filling materials from cavity. In this study, Eu3+ doped monetite was proposed as a fluorescent agent for dental restorations to meet this challenge. Eu3+ doped monetite with enhanced fluorescent property was obtained via a precipitation method. The presence of Eu3+ could prevent the phase transformation of brushite to monetite. However, all the brushite particles transformed to monetite at 300 °C and to tricalcium phosphate at 800 °C. The emission intensity increased with the addition of Eu3+ and reached the maximum when 12 mol% Eu3+ was added into the aqueous solution. With either 254 nm or 393 nm excitation, Eu3+ doped monetite showed the strongest fluorescence emission peaking at 616 nm and other two moderate bands peaking at 699 nm and 593 nm. The excitation spectra at the emission wavelength of 616 nm showed strong absorption peaks at 254 nm and 393 nm. We further investigate the fluorescence properties of Eu3+ doped monetite in one type of dental restorations. Glass ionomer cement with Eu3+ doped monetite exhibited clear fluoresce with origin color under UV irradiation at 254 nm, showing that Eu3+doped monetite is a promising fluorescent agent for dental restorations.
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| 12. |
- Cheng, Z., et al.
(författare)
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Ink-jet printed BNT thin films with improved ferroelectric properties via annealing in wet air
- 2018
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 44:9, s. 10700-10707
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Tidskriftsartikel (refereegranskat)abstract
- In this work, an ink-jet printing process based on the sol-gel route was applied to prepare lead-free ferroelectric Na0.5Bi0.5TiO3(BNT) thin films for the first time. Dense and crack-free films with perovskite structure were obtained from a modified precursor solution through multiple printing and pyrolysis processes. The ferroelectric, dielectric and electrical properties were significantly affected by the annealing temperature and atmosphere. The film annealed at 670 °C in wet air showed a high remnant polarization of 24.7 μC/cm2 with a low coercive field of 263 kV/cm, the dielectric constant and loss were 185 and 0.1 at 10 kHz, respectively. It was found that wet air was an alternative to reduce oxygen vacancies and enhance properties of ferroelectric films, which can be explained by the defect chemical reaction between water and oxygen vacancies. X-ray photoelectron spectroscopy(XPS) confirmed the decrease of oxygen vacancies after annealing with water presence, with a formation of Ohmic conduction mechanism dominated by charged hydroxyl groups.
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| 13. |
- Choopani, S., et al.
(författare)
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Ferromagnetic resonance and magnetic anisotropy in biocompatible Y3Fe5O12@Na0.5K0.5NbO3 core-shell nanofibers
- 2019
-
Ingår i: Ceramics International. - : Elsevier Ltd. - 0272-8842 .- 1873-3956. ; 46:2, s. 2072-2078
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Tidskriftsartikel (refereegranskat)abstract
- Y3Fe5O12@Na0.5K0.5NbO3 (YIG@NKN) core-shell nanofibers were synthesized by the coaxial electrospinning technique. For comparison, samples of YIG and NKN nanofibers were prepared. Scanning Electron Microscopy (SEM) and 3D laser-scanning confocal microscopy (TDLM) of YIG@NKN nanofibers revealed long uniform size distributed fibers with the average diameter of 100–150 nm. X-Ray diffraction (XRD) examination shows the existence of the distinct peaks of orthorhombic NKN and cubic YIG. Magnetic force microscopy (MFM) of individual YIG@NKN nanofiber demonstrates a magnetic core that is extended in one half of the diameter of the fiber. These nanofibers show obvious Ferromagnetic resonance (FMR) with resonance near 2 KOe similar to YIG fibers but in such a way that it starts to increase linearly with applying magnetic field from zero up to near resonance field. Also they show a soft magnetic behavior with saturation magnetization of 10 emu/gr. Furthermore, we propose a model to explain line shape of randomly oriented fibers and extract all the magnetic anisotropy parameters from FMR data. The results rely the shape anisotropy as dominant effect, however the dipolar field among fibers should be considered. The highest degree of asymmetry observed in the case of core-shell fibers in hard direction that it can be originated from magneto electric effects. By taking into account the observed FMR, the ability of adequate control of microwave absorption by applying magnetic field and biocompatibility, the synthesized core-shell nanofibers are the most promising candidate for clinical application such as microwave cancer thermotherapy and adjustable microwave absorbers.
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| 14. |
- Elbadawi, Mohammed, 1987-, et al.
(författare)
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Guar Gum: A Novel Binder for Ceramic Extrusion
- 2017
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 43:18, s. 16727-16735
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic honeycomb extrusion is a technique capable of attaining high strength, porous ceramics. However, challenges prevent the realisation of its potential. These include the design of an intricate honeycomb die and the formulation of an extrudable paste. The present study addresses the latter by using guar gum (GG) as a binder. GG was rationally selected because hydrogels thereof exhibit strong shear-thinning and high stiffness properties, which are required for extrusion. Rheological analyses demonstrated ceramic pastes with similar qualities were achieved, with hydroxyapatite (HA) used as the model ceramic. The shear stiffness modulus of HA pastes was determined as 8.4 MPa with a yield stress of 1.1 kPa. Moreover, this was achieved with GG as the sole additive, which further facilitates the overall fabrication process. The binder extraction notably occurred at relatively low temperatures when other high molecular weight polymers demand temperatures above 1000 °C; therefore the latter precludes the use of ceramics with low sintering onset. The process culminated in a porous HA scaffold with similar porosity to that of a commercial HA graft, but with higher compressive strength. Lastly, the study notes that the biological and water-soluble properties of GG can broaden its application into other ceramic fabrication processes.
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| 15. |
- Ganvir, Ashish, 1991-, et al.
(författare)
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Failure analysis of thermally cycled columnar thermal barrier coatings produced by high-velocity-air fuel and axial-suspension-plasma spraying : A design perspective
- 2018
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 44:3, s. 3161-3172
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Tidskriftsartikel (refereegranskat)abstract
- Axial-suspension-plasma spraying (ASPS) is a fairly recent thermal spray technology which enables production of ceramic top coats in TBCs, incorporating simultaneously the properties of both the conventional-plasma sprayed (highly insulating porous structures) and electron-beam-physical-vapor-deposited (strain-tolerant columnar structures) top coats. TBCs are required to insulate the hot components in a gas turbine engine against high temperature and harsh operating conditions. Periodic heating and cooling of turbine engines during operation can create severe thermal cyclic fatigue conditions which can degrade the performance of these coatings eventually leading to the failure. An in-depth experimental investigation was performed to understand the failure behavior of columnar TBCs subjected to thermal cyclic fatigue (TCF) test at 1100 C. The study revealed that the TCF performance was influenced to an extent, by the top coat microstructure, but was primarily affected by the severity of thermally grown oxide (TGO) growth at the bond coat-top coat interface. Mixed failure modes comprising crack propagation through the bond coat-TGO interface, through TGO and within the top coat were identified. Based on the analysis of the experimental results and thorough discussion a novel design of microstructure for the high TCF performance columnar TBC is proposed. © 2017 Elsevier Ltd and Techna Group S.r.l.
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| 16. |
- Hussain, Fida, et al.
(författare)
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Comparative electrochemical investigation of zinc based nano-composite anode materials for solid oxide fuel cell
- 2019
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 45:1, s. 1077-1083
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Tidskriftsartikel (refereegranskat)abstract
- The structural and electrochemical properties of zinc based nano-composites anode materials with a composition of X0.25Ti0.5Zn0.70 (where X = Cu, Mn, Ag) have been investigated in this present study. The proposed Xo.zsTiousZno.70 oxide materials have been synthesized through sol-gel method. The doping effect of Cu, Mn, and Ag on TiZn oxides were analyzed in terms of electronic conduction and power density in hydrogen atmosphere at comparatively low temperature in the range of 650 degrees C. The crystal structure and surface morphology were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis techniques. The XRD patterns of composites depict that the average crystalline sizes lie in the range of 20-100 nm. Four -probe DC conductivity technique was used to measure the conductivity of the materials and maximum electrical conductivity of Ag0.25Ti0.05Zn0.70 oxide was found to be 7.81 S/cm at 650 degrees C. The band gap and absorption spectra were determined by ultra-violet visible (UV-Vis) and Fourier Transform Infrared spectroscopy (FTIR) techniques respectively. The maximum power density was achieved to be 354 mW/cm(2) at 650 degrees C by Ag0.25Ti0.05Zn0.70 oxide anode with SDC (electrolyte) and BSCF (conventional cathode) materials.
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| 17. |
- Islavath, N., et al.
(författare)
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Spray coated seed layer for scalable synthesis of aligned ZnO nanowire arrays on FTO substrate and their photovoltaic properties
- 2015
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Ingår i: Ceramics International. - : Elsevier Ltd. - 0272-8842 .- 1873-3956. ; 41:3, s. 4118-4122
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Tidskriftsartikel (refereegranskat)abstract
- Spray coating has been employed as a non-vacuum route for deposition of a ZnO seed layer on large-area fluorine-doped tin oxide (FTO) glass substrates. Optimization of spray parameters, particularly precursor flow rate and volume, was found to yield preferably oriented and uniform ZnO seed layer. Vertically aligned single crystalline ZnO nanowire arrays with controlled features were grown on aforementioned substrate at 95 °C by a hydrothermal method. The current-voltage characteristics of dye-sensitized solar cells fabricated with the aligned ZnO nanowire arrays as photoanode have demonstrated a maximum photocurrent density of 1.86 mA cm-2 under 1 sun illumination (100 mW cm-2, AM 1.5G). © 2014 Elsevier Ltd and Techna Group S.r.l.
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| 18. |
- Jiang, Zhiwu, et al.
(författare)
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In Situ Fabrication and Properties of 0.4MoB-0.1SiC-xMoSi2 Composites by Self-propagating Synthesis and Hot-press sintering
- 2018
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 44:1, s. 51-56
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Tidskriftsartikel (refereegranskat)abstract
- Mo, Si and B4C powders were used to fabricate 0.4MoB-0.1SiC-xMoSi2 composites by self-propagating high-temperature synthesis (SHS) and hot pressing (HP). The effects of MoSi2 content (x=1, 0.75, 0.5 and 0.25) on phase composition, microstructure and properties of the composites were investigated. The results showed that the 0.4MoB-0.1SiC-xMoSi2 composite exhibited Vickers hardness of 10.7–15.2 GPa, bending strength of 337–827 MPa and fracture toughness of 4.9–7.0 MPa∙m1/2. The fracture toughness increased with the increasing volume fraction of MoB and SiC particles which were promoted by the toughening mechanisms, such as crack bridging, cracks deflection and crack branching. Moreover, the electrical resistivity showed an increasing trend with decreasing volume fraction of MoSi2.
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| 19. |
- Jurków, Dominik, et al.
(författare)
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Investigation of High Temperature Co-fired Ceramic tapes lamination conditions
- 2015
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 41:6, s. 7860-7871
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Tidskriftsartikel (refereegranskat)abstract
- The main goal of this paper was to analyze the influence of lamination process conditions and High Temperature Co-fired Ceramic (HTCC) tape composition on the lamination quality (existence of delaminations). The second aim was to estimate the influence of lamination conditions and HTCC tape composition on three process outputs: compressibility, surface roughness and density of High Temperature Co-fired Ceramics and to recognize if these outputs can be useful from lamination quality investigation point of view. The bonding quality was investigated using scanning acoustic microscopy (SAM). The analyzed ceramics was fabricated using water based slurries in the frame of tape casting process. The paper additionally discusses limitations and drawbacks of the used investigation methods and experiment design.
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| 20. |
- Kanhed, Satish, et al.
(författare)
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Porosity distribution affecting mechanical and biological behaviour of hydroxyapatite bioceramic composites
- 2017
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 43:13, s. 10442-10449
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Tidskriftsartikel (refereegranskat)abstract
- The present work aims to the study of developing porosity in hydroxyapatite (HAp) scaffold by using graphite porogen (with 0-30 vol%) followed by engineering the changes achieved by conventional- (CS) and microwave sintering (MS) techniques. The generated porosity was controlled between similar to 6-27% as the porogen concentration increases in HAp scaffold. Voronoi tessellation was utilized in order to evaluate the distribution of pores. The enhanced mechanical properties including fracture toughness (0.83 MPa m(1/2)), fracture strength (7.5 MPa), and hardness (183.7 VHN) were observed for microwave sintered HAp scaffold with 8% porosity. The fitting between porosity and fracture strength elicited that microwave sintered HAp with 8% porosity provides maximum crack-propagation resistance while restricting grain size (similar to 0.23 mu m) and eliciting high extent of sintering (similar to 1.34) because of their rapid heating rates. The cell viability (MTT assay) and cell culture confirm the cytocompatibility of porous HAp for application as bone implant that need accelerated replacement of bone tissues.
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| 21. |
- Khort, A. A., et al.
(författare)
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Preparation of BaTiO3 nanopowders by the solution combustion method
- 2016
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Ingår i: Ceramics International. - : Elsevier Ltd. - 0272-8842 .- 1873-3956. ; 42:14, s. 15343-15348
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Tidskriftsartikel (refereegranskat)abstract
- Barium titanate was synthesized by the method of exothermal combustion in solutions using barium nitrate, titanium dioxide (TiO2) and titanyl nitrate (TiO(NO3)2) as sources of titanium and barium and reducing agents such as glycine (C2H5NO2), carbamide (СН4N2O) and glycerol (C3H5(OH)3). In an effort to form a barium titanate phase, the materials synthesized using titanium dioxide were subjected to additional calcination at 800 °С. With titanyl nitrate the use of glycine and carbamide enabled carrying out a single-step synthesis of barium titanate. The obtained materials have pseudo-cubic lattice and are characterized by high stability of properties in a wide range of temperatures and frequencies of the electromagnetic field.
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| 22. |
- Kurtan, U., et al.
(författare)
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Influence of calcination rate on morphologies and magnetic properties of MnFe2O4 nanofibers
- 2016
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 42:16, s. 18189-18195
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we succesfully synthesized electrospun MnFe2O4 nanofibers (NFs) from poly(N-vinylpyrrolidone)/manganese(II) nitrate composite by electrospinning and then as-spun NFs were calcined 450 degrees C for 2 h in air atmosphere to remove the polymer matrix and fabricate inorganic MnFe2O4 nanofibers. In order to investigate the sintering behavior of MnFe2O4 nanofibers in air atmosphere, the synthesized as-spun nanofibers were calcined with different calcination rates. Thus the effect of calcination rate on structure and morphology of nanofibers were discussed clearly. The structural, magnetic, morphological, spectroscopic and thermal characterizations were also done by XRD, VSM, TEM, SEM, FTIR and TG analysis. In the presence of slow calcination rate, only peaks of MnFe2O4 could be observed on other hand in the presence of rapid calcination rate, formation of an impurity was observed. Scanning electron microscope images revealed that MnFe2O4 nanorods possess a broader range size distribution with higher particle size. Also, magnetic properties were both size and shape dependent.
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| 23. |
- Lei, Ying, et al.
(författare)
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Microwave synthesis and enhancement of thermoelectric figure of merit in half-Heusler TiNiSbxSn1-x
- 2017
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Ingår i: Ceramics International. - : Elsevier Ltd. - 0272-8842 .- 1873-3956. ; 43:12, s. 9343-9347
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Tidskriftsartikel (refereegranskat)abstract
- The preparation of half-Heusler thermoelectric bulk is complex and time-consuming. In the present work, Sb doped TiNiSbxSn1-x bulks (x=0.01, 0.02, 0.03 and 0.04) were prepared via cold press forming, microwave synthesis and sintering in vacuumed sealed quartz in a few minutes. The microstructures of samples were characterized by using X-ray diffractometer (XRD) and scanning electron microscopy (SEM) techniques. The thermoelectric properties i.e. Seebeck coefficient (S), electrical resistivity (ρ) and thermal conductivity (κ) were measured on Seebeck coefficient/resistance analysis system (S/RAs) and laser flash thermal analyzer (LFT). The results show that high purity single phase was obtained after microwave sintering. The point defects came from Sb doping and the in-suit nanostructures attributed to microwave sintering process were found to lead to special microstructure. The variation trends of S, ρ, κ with temperature were analyzed. The influences of Sb doping to electrical and thermal properties were discussed. The electrical resistivity was decreased by ~84% at the cost of decreasing the Seebeck coefficient by ~25-30%. The maximum power factor of 2560 μWm-1K-2 was achieved at 673K. The lattice and total thermal conductivities are merely 1.1-1.3 and 3.8-4.0 Wm-1K-1 respectively. The thermoelectric figure of merit for TiNiSb0.03Sn0.97 was enhanced from 0.30 (773K) to 0.44 (673K and 723K) when compared to that of non-doped TiNiSn. © 2017 Elsevier Ltd and Techna Group S.r.l.
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| 24. |
- Lyu, Yezhe, 1987-, et al.
(författare)
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On the Microstructure and Wear Resistance of Fe-based Composite Coatings Processed by Plasma Cladding with B4C Injection
- 2015
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 41:9, s. 10934-10939
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Tidskriftsartikel (refereegranskat)abstract
- Fe-based composite coatings were fabricated on Q235 steel substrate by plasma cladding. B4C particles were injected at the center and edge of the melting pool as strengthening phase. Scanning electron microscopy and pin-on-disc tribometer were applied to study the microstructure and wear resistance of the coatings. The results showed that the central injected B4C particles dissolved during plasma cladding and cementite generated. Edge injected B4C particles remained and performed metallurgical bonding with the metal matrix. With Fe-based coating containing edge injected B4C particles, wear resistance increased largely and the wear rate became 1/8 of the Q235 substrate. Afterwards, Fe-based coatings with edge injected B4C particles were prepared on real pieces of 50 picks and 12 chutes, which were taken into field probations. Average service lives of the coated picks and chutes increased 3.4 times and 5.6 times, respectively, compared with the conventional 16Mn and 42CrMo pick and chute components.
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| 25. |
- Malek Khachatourian, Adrine, et al.
(författare)
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Microwave assisted synthesis of monodispersed Y2O3 and Y2O3:Eu3+ particles
- 2015
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 41:2, s. 2006-2014
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Tidskriftsartikel (refereegranskat)abstract
- Monodisperse spherical Y2O3 and Y2O3:Eu3+ nanocrystalline particles with particle size between 100 nm and 350 nm were successfully prepared by microwave assisted urea precipitation method followed by a thermochemical treatment. Fast microwave heating, controlled decomposition of urea and burst nucleation of metal ions in aqueous solution led to the formation of non-aggregated spherical particles with narrow size dispersion. The particle size and size dispersion was controlled by adjusting the urea/metal ions ratio, the metal ions concentration, the reaction time and the temperature. X-ray diffraction (XRD) analysis indicated that the as prepared particles have Y(OH)CO3 composition, which converted to highly crystalline cubic Y2O3 after calcination at temperatures above 600 degrees C. The calcined Y2O3 particles preserved the spherical morphology of the as prepared particles and exhibited polycrystalline structure. The size of the crystallites increased from similar to 8 nm to similar to 37 nm with the increase of the calcination temperature from 500 degrees C to 900 degrees C. In order to transform these nanostructures to luminescent composition, Eu3+ doping has been performed. Y2O3:Eu3+ particles inherited the morphology and polycrystalline structure of the host Y2O3 particles. Photoluminescence (PL) analysis of Y2O3:Eu3+ particles showed a strong red emission peak at 613 nm corresponding to D-5(0)-F-7(2) forced electric dipole transition of Eu3+ ions under UV excitation. All these critical characteristics, and being heavy-metal free, make these particles useful for bioimaging, and display devices.
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