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Square-shaped boron carbide ceramic composites have been produced by spark plasma sintering with the addition of 5 to 20 vol % titanium metal powder in the B4C matrix in order to initiate an in situ self-propagating high-temperature synthesis (SHS) of TiB2. The SHS reaction not only enhances many of the physical and mechanical properties of B4C, but also reduces the required sintering temperature and pressure because of the enthalpy of reaction between metallic Ti and B4C. Sintering has been carried out in the SPS-temperature range of 1450 to 1550 °C with a uniaxial pressure of 40 MPa and a dwell time of 4 min under a 1 atm argon atmosphere. The effects of various amounts of Ti additions and sintering temperature on the phase composition, density, hardness, fracture toughness, and microstructure are examined. X-ray diffraction and transmission electron microscopy evaluations have shown that added Ti completely transforms into TiB2, resulting in a core–shell microstructure with a carbon core, surrounded by a TiB2shell in the B4C matrix. Moreover, by carrying out a control experiment where TiB2was added instead of Ti, and performing a molecular dynamics simulation of the B4C-Ti interface, the significance of the in situ SHS process has been validated.

Cobalt, nickel, and their mixed hydroxides were electrochemically deposited on polythiophene-coated carbon-cloth substrate to develop new pseudo-capacitive electrodes for energy storage devices. Thiophene was electro-polymerized on carbon-cloth by the potentiodynamic method in acetonitrile containing 1-butyl-2,3-dimethylimidazolium hexafluorophosphate ionic-liquid as supporting electrolyte. The scanning-electron-microscopy images imply that flower-like Co(OH)2microstructures deposited on bamboo-like polythiophene coatings on carbon-fibers but they are covered by net curtain like thin Ni(OH)2layer. The Co-Ni layered-double-hydroxide deposited from their equimolar sulfate solutions is composed of large aggregates. The electron-dispersive-spectrum exhibits that Co/Ni ratio equals unity in the layered-double-hydroxide. The capacitances of Co, Ni, and Co-Ni hydroxide-coated PTh electrodes are 100, 569, and 221 F/g at 5 mA/cm2in 1 M KOH solution, respectively. Their corresponding oxides obtained by calcination at 450 °C in de-aerated medium possess higher capacitance up to 911, 643, and 696 F/g at 2 A/cm2. The shape of cyclic-voltammetry and galvanostatic-charge-discharge curves, as well as the Nyquist plots derived from electrochemical-impedance-spectroscopy measurements, reveal that hydroxide coatings on the polythiophene-coated carbon-cloth are more promising electrode materials for supercapacitor applications. The mixed hydroxide-coated electrode shows good cyclic stability of 100% after 400 cycles at 5 mA/cm2.

In this paper, the correlation between structural and mechanical properties of nanostructured austenitic oxide dispersion strengthened (ODS) steel prepared by powder metallurgy were studied. High efficient milling process was applied to achive an optimal dispersion of ceramic oxide particles in the steel matrix. The austenitic powder with or without Y2O3 addition was milled by two different milling process (wet and dry). Spark plasma sintering as a fast and effective compaction method was used as sintering equipment. The morphology and structural properties of ODS were studied by X-ray diffraction and scanning electron microscopy. Mechanical properties, such as microhardness, bending strength and modulus of nanostructured ODS were also determined.

Si3N4 based composites containing different amounts of SiC and SiAlON were produced by reactive spark plasma sintering of Si3N4, SiO2 and C black. Y2O3 and AlN were added as sintering additives. The SPS process was carried out at sintering temperature of 1650 0C for 5 min with uniaxial pressure of 40 MPa in a nitrogen atmosphere.The mechanic properties and morphology of Si3N4 ceramic composite were determined. Microstructures of the sintered samples were observed by SEM images and phase compositions were analysed by XRD.

The aim of this study was to produce dense and mechanically strong boron carbide ceramics with the help of different oxide additives. Physical properties of two different grades of pure boron carbide powders were analysed and sintered by Spark Plasma Sintering method. Starting powders were prepared by ball milling with the addition of 5 wt. % Y2O3, Al2O3, SiO2 and Y2O3 + Al2O3. In the sintering step, powder mixtures were sintered by SPS method in round-shaped graphite dies under 50 MPa for 5 minutes in the range of 1700-1800oC. In the characterization step, sintered sample compositions and microstructures were characterized by XRD and SEM analysis respectively. The hardness values were measured under 1000 g load and the density values were measured with Archimedes' principle. The fracture toughness analysis were also carried out.

Nanocrystalline alumina (Al2O3) powders were sintered by Spark Plasma Sintering (SPS) method in a vacuum atmosphere to obtain highly dense and fine grained final ceramic products. In the first section of experiments, 0.4 % wt MgO doped and 0.4 wt % Y2O3 doped Al2O3 were sintered at high temperatures and under high pressure with a SPS system. Later sintering procedures were carried out with codoping Y2O3 with the cathodic ratio of 0.4 wt % in order to investigate dopant effects on spark plasma sintered alumina. The microstructures of all samples were observed using scanning electron microscope and the properties such as density, hardness and fracture toughness were examined.

This study was carried out to produce and characterize B4C - TiB2 ceramics by spark plasma sintering. Initial B4C and TiB2 powders were mixed in ethanol solution with YSZ balls for 1 hour. Sintering was performed with 5, 10, 15 and 20 volume % TiB2 containing mixtures respectively in disc-shaped graphite dies. The applied pressure was 40 MPa at 1760 °C for 5 minute sintering duration. The improvement of low sinterability and low strength of B4C was investigated as well as strength of flexibility, hardness and fracture toughness. The obtained products were characterized by X-ray diffraction and SEM imaging. The hardness values were measured under 1000 g load and the density values were measured with Archimedes' principle. The 3-point bending tests and modulus of elasticity measurements were also conducted.

The aim of this study was to produce dense and mechanically strong boron carbide ceramics with the help of different oxide additives. Physical properties of two different grades of pure boron carbide powders were analysed and sintered by Spark Plasma Sintering method. Starting powders were prepared by ball milling with the addition of 5 wt. % Y2O3, Al2O3, SiO2 and Y2O3 + Al2O3. In the sintering step, powder mixtures were sintered by SPS method in round-shaped graphite dies under 50 MPa for 5 minutes in the range of 1700-1800oC. In the characterization step, sintered sample compositions and microstructures were characterized by XRD and SEM analysis respectively. The hardness values were measured under 1000 g load and the density values were measured with Archimedes' principle. The fracture toughness analysis were also carried out.

Nanocrystalline alumina (Al2O3) powders were sintered by Spark Plasma Sintering (SPS) method in a vacuum atmosphere to obtain highly dense and fine grained final ceramic products. In the first section of experiments, 0.4 % wt MgO doped and 0.4 wt % Y2O3 doped Al2O3 were sintered at high temperatures and under high pressure with a SPS system. Later sintering procedures were carried out with codoping Y2O3 with the cathodic ratio of 0.4 wt % in order to investigate dopant effects on spark plasma sintered alumina. The microstructures of all samples were observed using scanning electron microscope and the properties such as density, hardness and fracture toughness were examined.

This study was carried out to produce and characterize B4C - TiB2 ceramics by spark plasma sintering. Initial B4C and TiB2 powders were mixed in ethanol solution with YSZ balls for 1 hour. Sintering was performed with 5, 10, 15 and 20 volume % TiB2 containing mixtures respectively in disc-shaped graphite dies. The applied pressure was 40 MPa at 1760 °C for 5 minute sintering duration. The improvement of low sinterability and low strength of B4C was investigated as well as strength of flexibility, hardness and fracture toughness. The obtained products were characterized by X-ray diffraction and SEM imaging. The hardness values were measured under 1000 g load and the density values were measured with Archimedes' principle. The 3-point bending tests and modulus of elasticity measurements were also conducted.

Si3N4 based composites containing different amounts of SiC and SiAlON were produced by reactive spark plasma sintering of Si3N4, SiO2 and C black. Y2O3 and AlN were added as sintering additives. The SPS process was carried out at sintering temperature of 1650 0C for 5 min with uniaxial pressure of 40 MPa in a nitrogen atmosphere.The mechanic properties and morphology of Si3N4 ceramic composite were determined. Microstructures of the sintered samples were observed by SEM images and phase compositions were analysed by XRD.