Powders were obtained using an indium chloride solution and were characterized as a function of precipitation pH, aging time, and concentration of the liquid synthetic medium. Indium hydroxide (In(OH)(3)) and indium oxide hydroxide (InOOH) coexisted in the pH range of 5 to 8, but only indium hydroxide was present at pH 9 and 10. The crystallite size of In(OH)(3) had a stronger dependence on pH than on the concentration of the reaction medium compared to InOOH. Hence, the relative crystallite size of In(OH)(3) increased significantly with increasing pH compared to that of InOOH, which barely changed with increasing concentration and pH. Although the crystallite size of In(OH)(3) increased slightly with increasing precipitate aging time, the specific surface area decreased significantly. These results can help control the synthesis of indium oxide particles used to make indium tin oxide targets.

Crystal growth of alpha-Fe2O3 nanosized particles of 80 similar to 90 nm in size, which were hydrothermally prepared from 0.03 M FeCl3 solution at 100 degrees C, was investigated in Pb-containing and Pb-free frit. By heating alpha-Fe2O3 nanosized particles in two frits at 800 degrees C, the average diameter of particles in frits was increased to 200 similar to 210 nm and 150 similar to 160 nm, respectively, and the crystal growth due to the aggregation and sintering of several alpha-Fe2O3 particles was observed. Formation ratios of larger particles over 100 nm in diameter were 54 % in Pb-free frit and 85 % in Pb-containing frit. After heating alpha-Fe2O3 particles in frits at 800 degrees C, 7 similar to 9 nm in average diameter of pores were formed in particles. Theses pores were derived from the porous structure of original alpha-Fe(2)O(3 )particles and confined in particles during sintering.

Porous ceramic plates were prepared from Onggi clay and bamboo charcoal powder at 1100 and 1200C and their porous properties and water absorption, and the cooling effect of porous plates, were investigated to produce eco-friendly porous ceramics for a self-cooling system that relies on the evaporation of absorbed water. Porous properties were dependent on the particle size of charcoal powder pore forming additive and the firing temperature; properties were also found to be dependent on the total pore volume, average pore size and porosity, which had values of 0.103 0.243 cm/g, 0.81 2.56 mm and 20.9 38.2%, respectively, at 1100C and 0.04 0.18 cm/g, 0.33 2.03 mm and 10.8 30.9%, respectively, at 1200C. Cooling temperature difference of flowing air parallel to surface of porous ceramic plates fired with two kinds of charcoal powder at 1100C was 3.5 3.6C at 26C and 60% of relative humidity in a closed box. Cooling temperature difference was dependent on the number of porous plates and the distance between porous plates. A simple and eco-friendly cooling system using porous ceramic plates fired from Onggi clay and charcoal powder was proposed.

Indium hydroxide powder was prepared by precipitation method. The reaction temperature (150 similar to 250 degrees C) and the holding time at each reaction temperature (1-72 h) were used as experimental variables. The particle size, microstructure and crystal phase of each prepared powder were observed through X-ray diffraction (XRD), Transmission electron microscope (FE-TEM) and BET. In this study, we investigated the phase and microstructural change induced by heat treatment of indium hydroxide nanoparticles at various temperatures for different holding times.

This paper reports on the synthesis of hexagonal plates of hematite, alpha-Fe2O3 crystals using microwave-hydrothermal (M-H) and conventional-hydrothermal (C-H) reactions. Platy alpha-Fe2O3 crystals which show dark red wine color were synthesized from 2M-FeCl3 and 8M-NaOH solution at both 140 and 180 degrees C and their morphology and crystal size were investigated. Average crystal size of hexagonal alpha-Fe2O3 was 0.9-1.6 mu m at 140 degrees C and 0.8-2.1 mu m at 180 degrees C under both M-H and C-H reactions. Compared to the formation of platy alpha-Fe2O3 crystals via C-H reaction, the M-H reaction led to increased rate of formation by 8 and 15 times at 140 and 180 degrees C, respectively. The M-H reaction yielded hexagonal plates of hematite in 2 min at 180 degrees C. The suspensions of platy alpha-Fe2O3 powders prepared at 140 and 180 degrees C by both C-H and M-H reactions showed dark red wine color due to similar crystal size and morphology, which have potential applications in cosmetic pigments, as anode materials in Li ion batteries. (C) 2017 Elsevier B.V. All rights reserved.

In this study, we investigated the phase and microstructural changes induced by heat-treatment of indium hydroxide nanoparticles produced by precipitation at various temperatures for different holding times. A white powder was obtained after heating for various times at temperatures of 150-900 degrees C. We also investigated changes in the specific surface area of indium oxide prepared by heating the precipitate between 200 and 900 degrees C. Finally, we propose a model for the formation of indium oxide powder from the precipitate. The model includes processes such as the formation of bundles of rod-shaped particles, generation of voids in the bundle from the evaporation of crystallized water, strong re-agglomeration of rod-shaped particles, collapse of the rod structure, formation of spherical agglomerates, heterogeneous crystal growth, and homogeneous crystal growth.

The effect of mixing process of FeCl3 and NaOH solution on the formation of platy (hexagonal) α-Fe2O3 was investigated at 160 and 180°C by the hydrothermal process. The crystal growth of platy α-Fe2O3 was promoted at higher hydrothermal temperature, higher concentration of NaOH solution and by the addition of FeCl3 solution to NaOH solution instead of the reverse addition. Platy crystals of α-Fe2O3 showed dark red wine color while nanophase equiaxed crystals showed yellowish red color. The platy crystals of 3–6µm in average diameter kept their platy structure after heating at 900 and 1100°C in air due to their higher thermal stability towards sintering.

Recycled cenosphere, which is a hollow shaped particle from fly ash, has become attractive as a building material due to its light weight and excellent heat insulation and soundproof properties. In this paper, we investigated the effect of cenosphere size on the physical and optical properties. High brightness of cenosphere as raw material is required for a wide range of ceramics applications, particularly in fields of building materials and industrial ceramic tiles. Cenospheres were sorted by particle size; the microstructure was analyzed according to the cenosphere size distribution. Cenospheres were generally composed of quartz, mullite, and amorphous phase. Colour measurement corresponding to chemical composition revealed that the contents of iron oxide and carbon in the cenospheres were the major factors determining the brightness of the cenospheres.

Porous ceramic plates were prepared from clay and wood charcoal powder at 900 and 1100 °C and their porous properties, water absorption and the cooling effect of porous plates were investigated to produce eco-friendly porous ceramics for cooling by the evaporation of absorbed water. Porous properties were dependent on the firing temperature, and total pore volume, average pore size and porosity, which were 0.38–0.39 cm3/g, 0.15–0.17 μm and 49–50%, respectively at 900 °C and 0.31–0.33 cm3/g, 2.47–2.59 μm and 43–44%, respectively at 1100 °C. By the addition of wood charcoal powder, the cooling rate of porous plate fired at 1100 °C was 1.7 times faster than that of the plate fired at 900 °C and the cooling temperature difference (∆T) was around 2.3 °C at 22.5 °C and 52–54% of relative humidity and around 3.2 °C at 29 °C and 77–80% of relative humidity. The porous ceramic plates developed here are potential materials for cooling buildings.

Indium hydroxide powders were synthesized using indium nitride, and the characteristics of the indium hydroxide powder were investigated according to the precipitate aging time and the pH and concentration of the liquid synthesis medium. Indium hydroxide (In(OH)(3)) and indium oxide hydroxide (InOOH) phases co-existed in all conditions studied here. The crystallite size of In(OH)(3) was more dependent on the concentration and pH of the reaction medium compared to that of InOOH. Hence, the relative crystallite scale of In(OH)(3) increased with increasing concentration and pH of the reaction liquid more than that of in InOOH. Although the crystallite size did not change much with an increase of precipitate aging time, the specific surface area decreased greatly. Such results can aid in the synthesis of indium oxide particles that are used for producing ITO targets.

Ceramic ink-jet printing technology in art tiles, decorated tablewares and other porcelain products has many advantages of fast and precision printing of various images with high efficiency and low cost. For the application to ink-jet printing, ceramic ink requires a stable dispersibility with nano-sized pigments. In this paper, characteristics of pink-red aqueous ceramic ink for ink-jet printing was demonstrated. CaCr0.1Sn0.8SiO5 pigment was synthesized using solid state reaction and deagglomerated using attrition milling. The aqueous ceramic ink contains 10 wt% of the obtained CaCr0.1Sn0.8SiO5 nanopigment with 0.4 wt% of sodium dodecyl sulfate (SDS) as a dispersion agent. Viscosity of CaCr0.1Sn0.8SiO5 aqueous ceramic ink was adjusted using 0.18 wt% of polyvinyl alcohol (PVA) for a suitable jetting from the nozzle. The prepared pink-red ceramic ink showed a good jetting property with formation of a single sphere-shaped droplet after 180 μs without a tail and satellite droplet.

Green bodies of earthenware tile were prepared from a mixture of earthenware tile powder and SiC as forming agents by applying a conventional process. Granule powder for tile samples was prepared using the spray drying method with commercial earthenware raw material with a quantity of SiC of 0.3 wt%. The applied pressure was 250 kg.f/m(2) and the firing temperature was 1050-1200 degrees C. The effects of the SiC particle size and sintering temperature on the open porosity and total porosity were investigated and the correlative mechanism was also discussed. While total porosity was not significantly changed by decreasing the SiC particle size, the open porosity showed a gradual decrease, which represents an increase of the closed porosity. As the sintering temperature increased, coarsening was made among the pores due to excessive oxidation. The volume shrinkage and bending strength were demonstrated for the sintered tile samples. The sintered bulk density was also measured to determine the weight reduction value.

Considerable research efforts have been explored attempting to enhance the thermal durability of thermal barrier coatings (TBCs) at the high operating temperatures of gas turbines. In this study, the suspension plasma spray (SPS) process was applied to produce TBCs with a segmented structure by using an yttria-stabilized zirconia (YSZ) suspension. Four different experiment sets were carried out by controlling the ratio between surface roughness of the bond coat and feed stock size (R-a/D-50) in order to examine the effect of R-a/D-50 ratio on the microstructure of SPS-prepared coatings. When the R-a/D-50 had a high value of 11.8, a deposited thick coating turned out to have a cone-type columnar microstructure. In contrast, at the low R-a/D-50 values of 2.9 and 0.18, a deposited thick coating appeared to have a dense, vertically-cracked microstructure. However, with the very low R-a/D-50 value of 0.05 the coating was delaminated.

Digital ink-jet printing system has many advantages such as fast and fine printing of various images, high efficiency and low cost process. Generally digital ink-jet printing requires ceramic pigments of cyan, magenta, yellow and black with thermal and glaze stability above 1000 degrees C for the application of porcelain product design. In this study, pink-red colored CaO-SnO2-Cr2O3-SiO2 pigment was synthesized using solid state reaction. The synthesis conditions of Ca(Cr, Sn) SiO5 pigment such as annealing temperature, amount of mineralizer and non-stoichiometric composition were optimized. Crystal structure and morphology of the obtained Ca(Cr, Sn) SiO5 pigment were analyzed using XRD, SEM, PSA, FT-IR and effect of Cr substitution on the pigment color was analyzed using Uv-vis. spectrophotometer and CIE L*a*b* measurement.

Gadolinium zirconate, Gd2Zr2O7, is one of the most promising candidates for replacing yttira-stabilized zirconia (YSZ) in thermal barrier coating (TBC) applications due to its low thermal conductivity and chemical stability at high temperature. In this study, rare-earth zirconate ceramics in the GdO1.5-ZrO2 system with reduced gadolinia contents were fabricated via solid-state reaction as well as hot-pressing at 1800 degrees C. The phase formation, microstructure, and thermo-physical properties of these oxides were examined. The potential application of GdO1.5-ZrO2 ceramics for TBC was also discussed.

The hot corrosion behavior of plasma sprayed 4 mol% Y2O3-ZrO2 (YSZ) thermal barrier coatings (TBCs) with volcanic ash is investigated. Volcanic ash that deposited on the TBCs in gas-turbine engines can attack the surface of TBCs itself as a form of corrosive melt. YSZ coating specimens with a thickness of 430-440 mu m are prepared using a plasma spray method. These specimens are subjected to hot corrosion environment at 1200 degrees C with five different duration time, from 10 mins to 100 h in the presence of corrosive melt from volcanic ash. The microstructure, composition, and phase analysis are performed using Field emission scanning electron microscopy, including Energy dispersive spectroscopy and X-ray diffraction. After the heat treatment, hematite (Fe2O3-TiO2) and monoclinic YSZ phases are found in TBCs. Furthermore the interface area between the molten volcanic ash layers and YSZ coatings becomes porous with increases in the heat treatment time as the YSZ coatings dissolved into molten volcanic ash. The maximum thickness of this a porous reaction zone is 25 mu m after 100 h of heat treatment.

4 mol% Yttria-stabilized zirconia (4YSZ) coatings are fabricated by Air Plasma Spray (APS) and Electron Beam Physical Vapor Deposition (EB-PVD) with top coating of thermal barrier coating (TBC). NiCrAlY based bond coat is prepared as 150 ${\mu}m$ thickness by conventional APS (Air Plasma Spray) method on the NiCrCoAl alloy substrate before deposition of top coating. Each 4YSZ top coating shows different tribological behaviors based on the inherent layer structures. 4YSZ by APS which has splat-stacked structure shows lower friction coefficient but higher wear rate than 4YSZ by EB-PVD which has columnar structure. For 4YSZ by APS, such results are expected due to the sliding wear accompanied with local delamination of splats.