Hiroaki Katsuki

• Doctor of Engineering
• Fellow at Korea Institute of Ceramic Engineering and Technology

Alumina, mullite, and cordierite powder were added to a whiteware porcelain slurry and sintered at 1280 °C to investigate the correlation between porcelain composition and strength. The X-ray diffraction patterns of the sintered bodies show that no new phase was formed, and that the added material remained intact. Except for the sample group to whi...

Electrode materials of high-performance are the key for lithium-ion and aqueous batteries, and supercapacitors. Although there are many studies about iron oxides as electrode materials, few or no studies focused on the dependence of electrochemical properties on both their structure and crystal size. Here, we focused on electrochemical properties o...

Microwave-hydrothermal (M-H) synthesis of α-Sn(HPO4)2•H2O (α-SnP) was achieved here in as low as 5 minutes at 194oC compared to several days by others previously. The use of microwaves in conjunction with the hydrothermal process enhanced the α-SnP synthesis reaction at least by two orders of magnitude. The super fast synthesis was apparently due t...

The objectives of this study were to examine the role of the addition of kaolin on the firing of white clay for Korean porcelain by characterizing the fired composites at 1000–1300°C, and finally to estimate the production conditions of ancient Korean white porcelain in the Joseon Dynasty. Yanggu white clay disks composed of 57.1 wt% quartz and 38....

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 to...

Porous ceramic plates were prepared from Onggi clay and bamboo charcoal powder at 1100 and 1200oC 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 depe...

This paper reports on the synthesis of hexagonal plates of hematite, α-Fe2O3 crystals using microwave-hydrothermal (M-H) and conventional-hydrothermal (C-H) reactions. Platy α-Fe2O3 crystals which show dark red wine color were synthesized from 2M-FeCl3 and 8M-NaOH solution at both 140 and 180 °C and their morphology and crystal size were investigat...

The effect of mixing process of FeCl3 and NaOH solution on the formation of platy (hexagonal) α-Fe2O3 was investigated at 160 and 180 oC 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 instea...

The influence of talc addition on the pyroplastic deformation of alumina-strengthened porcelain was investigated in this study. Along with the lower content of feldspar, the addition of talc contributed to the crystallization of the cordierite during the firing process, and the resulting cordierite crystals formed complicated filler structures. The...

In this paper, mineral and sintering properties of high alumina-containing clay (Yamase clay) derived from a weathered granite stone were investigated, and compared with those of low alumina-containing clay derived from a weathered sandstone (Hobashira clay) for the ancient Karatsu ware. Content of Al2O3 in Yamase clay was 30.8-33.1 mass%, and show...

K-based geopolymer binder was prepared by reacting metakaolin with alkaline solutions having different potassium contents and by water curing at room temperature and 80 °C as well as steam curing at 150 and 180 °C. The phase formation, microstructure and Al and Si nearest neighbor environments were studied using XRD, TEM and 27 Al and 29 Si MAS NMR...

Anthracite briquettes were developed using mainly waste anthracite fines, plant byproducts of rice hulls and rice hull ash and silicon metal powder as an ecofriendly fuel and as an alternative to conventional coke used in a cupola furnace. Si metal powder reacts with anthracite to form SiC, which provides high mechanical strength to an anthracite b...

Four sedimentary clays for Karatsu ware which were geologically derived from the weathered sandstone and granite were mined and used in this study. The chemical composition, mineral composition and morphology of minerals were investigated by XRF, XRD, SEM and TEM analysis. The mineral composition of normative alpha-quartz, feldspar and kaolin of tw...

Anatase and Ca, Sr and Ca0.5Sr0.5 hydroxyapatites were synthesized by conventional-hydrothermal (C-H) as well asmicrowave-hydrothermal (M-H)methods.Microwave-assisted reactions led to accelerated syntheses of anatase but no such acceleration of reactions could be detected with the syntheses of hydroxyapatites because the crystallization of the latt...

The effect of firing atmosphere on the oxidation states of Fe in Arita celadon glaze and the glaze color was examined by using Mössbauer spectroscopy. The celadon glaze was prepared from feldspar, BaCO3, kaolin, α-quartz, and Fe2O3 powders and fired on the white porcelain biscuit plate at 1300°C for 0.5 h under several reduction atmospheres. The co...

For the first time two different nanoclay minerals were combined with nanophase anatase for the synthesis of three-phase nanocomposites with improved photocatalytic properties. The novel halloysite (H) + palygorskite (Pal)–TiO2 nanocomposites were prepared using palygorskite and halloysite from Greece. Three nanocomposites were synthesized using [H...

Nanophase anatase was synthesized by a novel simplified one-pot method using Ti alkoxides and hydrogen peroxide under conventional- and microwave-hydrothermal conditions. The specific surface areas (SSAs) of anatase ranged from 147 to 298 m(2)/g under different hydrothermal conditions but higher SSAs were obtained under microwave-hydrothermal condi...

In this paper we describe the synthesis and characterization of small-sized TiO2 particles supported on palygorskite (Pal) with Pal to TiO2 mass ratios of 10:90, 20:80, 30:70,40:60 and 50:50. The above Pal-TiO2 nanocomposites were prepared by deposition of anatase form of TiO2 on the Pal surfaces using a sal-gel method with titanium isopropoxide as...

Clays for Karatsu ware were prepared from ground three sandstones by a stamp-milling and elutriation processes. The chemical and mineralogical properties were studied and compared with those of Amakusa pottery stones for Arita porcelain. Karatsu clays were composed of α-quartz, feldspar and kaolin minerals without sericite, and the mineral composit...

Two halloysite–TiO2 nanocomposites were prepared with two different tubular halloysite clays by depositing anatase-TiO2 on the halloysite surfaces using titanium isopropoxide under hydrothermal treatment at 180 °C. The nanocomposites were characterized by X-Ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy...

Apparently C-doped and undoped or pure nanoparticles of anatase were synthesized using a microwave hydrothermal process in the temperature range of 140–180 °C for 1 h from several Ti precursors, such as Ti ethoxide, Ti isopropoxide and Ti oxysulfate. Nanoparticles of anatase samples were characterized by powder X-ray diffraction, transmission elect...

Nano-sized cubic BaTiO3 was prepared rapidly at 90 °C using TiO2 and Ba(OH)2 as precursors by a home-built semi-continuous microwave-assisted synthesis system. Cubic BaTiO3 particles of 30 to 50 nm were obtained after treatment for 5 min at 90 °C. The conversion of TiO2 to BaTiO3 reached 100% after 15 min. The approximate total energy consumption o...

Thermal expansion behavior method in reheating process was used to evaluate firing temperature of white porcelains excavated in Yanggu area, Jangpyung-Ri No.1 (J1, 17~20 centuries) and Songhyun-Ri No.5 (S5, 14~15 centuries). For standard specimen used for evaluation of the firing temperature, we used starting materials (YC) that have similar chemic...

Parameters such as temperature, time and presence or absence of microwaves affected the particle size and magnetic properties of synthetic magnetite. The presence of microwaves during crystallization significantly increased the particle size of magnetite in a short time with improved magnetic properties. Magnetite samples were characterized by X-ra...

A variety of oraganosilicas such as MCM-41 and MCM-48 and composites of rice husks with MCM-48 were synthesized under an array of conditions and characterized by powder X-ray diffraction (XRD). Various MCM-41 mesoporous materials were prepared at room temperature using different surfactants. MCM-48 silica and its composites with rice husks were syn...

Effects of firing atmosphere on the color manifestation of celadon were studied. The firing atmosphere was obtained by the combustion of LPG, which generates CO gas during incomplete combustion, which acted as the reducing agent. The amount of CO gas increased as the amount of injected LPG gas increased. As the amount of generated CO gas was few li...

Old celadon samples produced at four early Arita kiln sites in the 1640-1650's were used for the macroscopic, microscopic, compositional, and color studies of glaze and body using XRD, SEM, XRF and colorimeter. Molar ratio of SiO2/Al2O3 of the early Arita celadon glaze was 8.4-9.3, and the glaze and body had 1.68-3.95 and 1.07-2.21 wt % Fe2O3, resp...

Nano-sized BaTiO3 particles were prepared at 90 degrees C using TiO2 and Ba(OH)(2) as precursors by microwave-assisted (M-A) heating and conventional-heating (C-H) processes. Compared to the formation of BaTiO3 particles using the C-H process, the M-A process led to increased rate of formation by about 6 times. BaTiO3 particles of 29 nm in average...

The perchlorate uptake of hydrotalcite- and hydrocalumite-type layered double hydroxides (LDHs), and surfactant modified clay minerals were compared. Perchlorate uptake by both hydrotalcite- and hydrocalumite-type LDHs was in the range of 0.011 to 0.197 meq/g from a 2 mM perchlorate solution. The nitrate form of Mg:Al LDH had the highest uptake of...

Mesoporous MCM-41 silica and rice husk composites were synthesised under hydrothermal conditions using cetyltrimethylammonium bromide (CTAB) as an organic template, aqueous ammonia solution (NH4OH) and rice husk, the latter as a silica source and substrate for the deposition of MCM-41. Both untreated and carbonised rice husks were used for preparin...

Anatase and Ca, Sr and Ca0.5Sr0.5 hydroxyapatites were synthesized by conventional-hydrothermal (C-H) as well asmicrowave- hydrothermal (M-H)methods.Microwave-assisted reactions led to accelerated syntheses of anatase but no such acceleration of reactions could be detected with the syntheses of hydroxyapatites because the crystallization of the lat...

Palygorskite-TiO2 nanocomposites were prepared by deposition of the anatase form of TiO2 on the clay surfaces using a sol-gel method with titanium isopropoxide as a precursor under hydrothermal treatment at 180°C. The same procedure was followed in the formation of halloysite-TiO2 nanocomposites using a halloysite sample. Phase composition, particl...

Mn-kaolinite containing both Mn and Al in the octahedral sheet was prepared under hydrothermal conditions of 100–200 °C for 6–96 h by using Al-nitrate, Mn-carbonate, silicic acid and aqueous solutions of NaOH or KOH. The synthetic phases were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microsc...

The objectives of this study were to (i) synthesize cost-effective layered double hydroxides (LDH) or anionic clays to remove arsenate from water and (ii) quantify arsenate uptake by LDH and understand the mechanisms of uptake. Hydrotalcite and hydrocalumite-type LDHs were synthesized by coprecipitation at room temperature or higher with different...

The role of in situ stirring under microwave-hydrothermal (M-H) conditions on the synthesis of barium titanate was investigated for the first time by powder X-ray diffraction and scanning and transmission electron microscopy. Stirring under M-H conditions in the temperature range of 150–200°C led to enhanced crystallization of Ba titanate as reveal...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Micorwave-hydrothermal (M-H) processes have received considerable attention as a new promising method for rapid synthesis, energy saving, crystallization of new phases, and selective crystallization of ceramic powders. In this review, the effect of microwave radiation on the formation of smaller and uniform α-Fe2O3 powders from FeCl3 solution at 10...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Hydrothermal synthesis of Mn–mica was achieved using metakaolin and manganese carbonate or silicic acid and aluminum nitrate as aluminosilicate sources along with manganese carbonate in aqueous solutions of KOH. The mixtures of starting materials were treated under hydrothermal conditions at 100–200 °C for 24–48 h. The use of metakaolin and mangane...

Na-A and/or Na-X zeolite/porous carbon composites were prepared under hydrothermal conditions by NaOH dissolution of silica first from carbonized rice husk followed by addition of NaAlO2 and in situ crystallization of zeolites i.e., using a two-step process. When a one-step process was used, both Na-A and Na-X zeolites crystallized on the surface o...

Two types of layered double hydroxides (LDHs), hydrotalcite and hydrocalumite with different composition of layers and interlayers were investigated for the removal of arsenite from solutions. The kinetics study showed that anion exchange process was very fast and apparently attained a steady-state in the range of 8-16 h. Arsenite removal was found...

Statistical analysis of the strength of porcelain tableware is very important; however, there are few reports on impact strength of product wares. In this research, the impact strength of commercial reinforced porcelain plates were measured using pendulum-type impact tester based on an ASTM C368. Statistical dispersion of the impact strength was an...

Novel foams and plates of Fe2O3−Li2O−SiO2−Al2O3 composition made from a mixture of Fe3O4 and petalite mineral have been discovered to get rapidly heated under microwave irradiation and have relatively high heat energy holding ability compared to the presently used commercial ceramics. The Fe3O4 component transformed to Fe2O3 is responsible for micr...

The formation of novel ZSM-5 zeolite/porous carbon composite from carbonized rice husk has been investigated using microwave- and conventional-hydrothermal reaction at 140–160 °C. ZSM-5 zeolite crystals were formed on porous carbonized rice husk by the dissolution and in situ crystallization of silica in the carbonized rice husk. Compared to the co...

Aqueous colloidal suspensions in the two systems of CVD-processed ultrafine mullite powder (<0.1 μm), -Si3N4 whisker and -mullite whisker, were prepared near the isoelectric point of mullite (pH 7.0) to prevent cracking during drying of wet green compacts consolidated by filtration. The freeze-dried porous green compacts were hot-pressed with a car...

This paper reports the synthesis of technologically important ferrites such as ZnFe2O4, NiFe2O4, MnFe2O4, and CoFe2O4 by using novel microwave-hydrothermal processing. Nanophase ferrites with high surface areas, in the range of 72-247m2/g, have been synthesized in a matter of a few minutes at temperatures as low as 164°C. The rapid synthesis of nan...

Hydroxyapatite (HAp) crystals were synthesized from gypsum powder with diammonium hydrogen phosphate solution via microwave-hydrothermal treatment at 100°C, and their properties were studied. Gypsum powder could be completely converted to fine HAp crystals 30-300 nm long with 0.5M diammonium hydrogen phosphate at 100°C in 5 min. Compared to the for...

Synthesis of monodispersed nanophase α-Fe2O3 (hematite) powder to be used as a red pigment in porcelains was investigated using microwave-hydrothermal and conventional-hydrothermal reactions using 0.018M FeCl3·6H2O and 0.01M HCl solutions at 100°–160°C. Acicular and yellow β-FeOOH (akaganite) particles 300 nm in length and 40 nm in thickness were d...

Niobium- or vanadium-doped anatase sols were prepared by hydrothermal treatment of 0.1 mol/dm3 peroxotitanium complex aqueous solutions dissolving 0–10 mol% niobium or vanadium at 100°C for 8 h. Niobium-doping caused the increase of lattice constants of anatase and the shape change of anatase crystal from spindle-like to cubic-like structure, but n...

To produce a new red pigment for Japanese porcelains, some hematite (α-Fe2O3) powders produced by different methods were investigated by mixing them with lead-free frit powders and firing them on white porcelain plates at 800°C. Commercial hematite powders and uniform α-Fe2O3 powders 155 and 53 nm in diameter which were prepared using conventional-...

The present investigation reports a mixed micellar supramolecular templating approach to obtain microporous–mesoporous silica frameworks having textural characteristics close to supermicroporous frameworks under microwave-hydrothermal conditions. The crystallization of such frameworks was achieved by templating a silica precursor with a mixed micel...

Two- and three-dimensional hierarchical microstructures that are composed of rare-earth compound nanotubes have been formed by utilizing both the self-assembly phenomenon of the nanotubes and reactions at various interfaces. The template-free synthesis of the nanotubes by a homogeneous precipitation method controlled via coexisting anions is also d...

The synthesis of cerium compound nanowires and nanorings templated by mixed organic molecules, which contained alkyl alcohol and (bis(2-ethylhexyl) sulfosuccinate) (AOT) anions, was investigated. The nanostructural control of the cerium compound nanostructures by the carbon number of the alkyl alcohol was also described. The nanowire and nanorings...

Monodispersed alpha-Fe2O3 nanoparticles were prepared at 100degrees, 120degrees, and 140degreesC using 0.02, 0.05, and 0.1 M-Fe (NO3)(3) (.) H2O solutions by microwave-hydrothermal (M-H) and conventional-hydrothermal (C-H) reactions. Compared to the formation of monodispersed alpha-Fe2O3 particles using the C-H reaction, the M-H reaction led to inc...

There is no standardized method in Japan for the estimation of impact strength for strengthened porcelain tableware. In many cases, a measurement is carried out by ASTM C368 using a pendulum formula impact tester. However, there are many unknown factors about statistical dispersion in impact strength values, and the relation between the number of t...

The microwave-assisted polyol process was investigated for the synthesis of several nanophase metals under different conditions in the temperature range of 100 to 200 °C. Nanophase Ag metal particle synthesis using ethylene glycol (EG) was carried out at 100 and 150 °C in the presence of polyvinyl pyrrolidone (PVP), dodecyl amine (DDA), oleic acid...

Microwave-solvothermal processes have been previously found to be highly suited for the synthesis of a wide variety of ceramic and metal powders. In this paper, the effect of microwave radiation on the formation of Ag powders from AgNO 3 using ethylene glycol as a reducing agent at 100 - 200°C was investigated. Silver powders were rapidly produced...

The synthesis of an ordered mesoporous silica, PSU-1 (Pennsylvania State University-1), has been successfully accomplished by co-crystallizing the reactive gels of SBA-15 and MCM-41 under microwave–hydrothermal (M–H) conditions at 373 K. The crystallized framework was characterized by means of powder X-ray diffraction (XRD), thermogravimetric analy...

The synthesis of an ordered mesoporous silica, PSU-1 (Pennsylvania State University-1), has been successfully accomplished by co-crystallizing the reactive gels of SBA-15 and MCM-41 under microwave–hydrothermal (M–H) conditions at 373 K. The crystallized framework was characterized by means of powder X-ray diffraction (XRD), thermogravimetric analy...

NOx sensing properties of semiconductor heterolayer sensors fabricated by slide-off transfer printing have been investigated. A WO3 single layer sensor showed much higher sensitivity to NO2 than that to NO. Loading of Ru or Pt on the surface of WO3 led to a slight improvement of both the sensitivity and the response speed to NO, but the response sp...

Silver metal powders were prepared through reduction of AgNO3 in ethylene glycol using microwave-polyol (M-P) and conventional-polyol (C-P) reactions at 100–200 °C. Powders of Ag were rapidly produced by microwave-assisted reaction at temperatures above 160 °C. The formation yield of Ag powders from AgNO3 reached 97.8% after treatment for 135 min a...

A mesoporous thin film form of tantalum oxide, a wide band gap and semiconductor ceramic, is prepared by templating a tantalum silica precursor (tantalum ethoxide) with pluronic P123 copolymer (EO20PO70EO20; M.W. 5800) using sol–gel-based spin casting approach. The obtained crystalline phase was characterized by means of X-ray diffraction, nitrogen...

Hydrothermal processing is genuinely one of low temperature techniques for ceramic materials. A recent innovation to hydrothermal synthesis of ceramic particles was the introduction of microwave at the temperature range of 100 to 200°C. The microwave hydrothermal technique leads to (a) rapid heating to reaction temperature, (b) enhancement of react...

While there are many techniques for the production of nanophase materials, we have been using a hydrothermal process because it is a low-temperature method that can lead to energy savings. A recent innovation is the introduction of microwaves in the hydrothermal system, and we named this process the microwave-hydrothermal (M-H) process. M-H synthes...

The nanophase metal powders such as platinum and silver were prepared using microwave-polyol process. This experiment for the synthesis of nanophase platinum and silver metals were conducted using chloroplanitic acid and silver nitrate as starting precursors. Some of the advantages of the microwave-assisted reactions are selective formation of one...

The synthesis of barium titanate (BaTiO3) has been investigated under microwave-hydrothermal (M-H) conditions in the temperature range of 60–160°C using BaCl2, and TiCl4 as Ba, and Ti sources, respectively. The crystallized products were characterized by powder X-ray diffraction (XRD), scaning electron microscopy (SEM), thermogravimetric analysis (...

The formation and some properties of sintered kaolin honeycomb monolith with thick silicalite film, prepared by a hydrothermal reaction, were investigated. To enhance the adhesion strength of the silicalite film onto the honeycomb surface and the mechanical strength of the honeycomb body, the Malaysian kaolin was sintered at 1500°C and then treated...

In order to develop new preparation methods of peroxotitanium acid solution and peroxo-modified anatase sol which are useful for the low-temperature formation of photocatalytic thin films, peroxotitanium hydrate was used as a precursor of them. The formation of the transparent peroxotitanium acid solution was achieved by mixing concentrated H2O2 an...

H2 and NOx sensing properties of semiconductor heterolayer sensors fabricated by a slide-off transfer printing method on alumina substrates equipped with electrodes have been investigated at 200–600°C. A TiO2 single layer sensor exhibited high resistance in air and low sensitivity to H2 at every temperature. Stacking of an M-SnO2 layer (M: noble me...

This paper focuses on the synthesis of NaY zeolite crystals by using microwave-hydrothermal (M-H) processing. NaY zeolites were synthesized from colloidal silica, sodium aluminate, sodium hydroxide and deionized water at 100C, and some properties were studied. NaY zeolite crystals with high surface area, in the range of 439 to 716 m2/g, have been p...

Mixtures of small silica particles and activated carbon were heated at 1250–1450°C in an inert atmosphere to make nano- and macro-sized porous silica for incorporating yeast in the porous strucrure. Without activated carbon, porous silica of 45–60% porosity and 15–30 µm pore diameter was produced with a specific surface area below 1 m2/g. By the ad...

The synthesis and properties of ZSM-5 film on a porous mullite honeycomb have been investigated using Malaysia kaolin. Amorphous silica-glass in the kaolin honeycomb sintered at 1450°C was used as a source for ZSM-5 formation. The honeycomb was hydrothermally treated in NaOH, tetrapropylammonium bromide, and water to prepare a novel ZSM-5/mullite h...

Ordered, hydrothermally stable mesoporous molecular sieve SBA-15 with hexagonal channel porosity has been synthesized for the first time under microwave–hydrothermal conditions from aged precursor gel within 15 min at 373 K; the crystallized product has been characterized using X-ray diffraction, nitrogen adsorption–desorption and transmission...

Single layers, multilayers and heterolayers of SnO2-based materials were fabricated by a slide-off printing method and their sensing properties to 1% H2 in air were investigated. By selecting an appropriate combination of materials for the lower and upper layers of a heterolayer sensor, the sensitivity or the resistance decrease upon exposure to H2...

The formation and properties of continuous ZSM-5 film on a porous mullite honeycomb have been investigated. The porous mullite honeycomb coated with ZSM-5 film provides a novel microporous (0.5 nm in diameter)–macroporous (0.5–0.6 μm in diameter) composite. Amorphous silica-glass in the kaolin honeycomb sintered at 1650°C is used as a source for ZS...

Porous hydroxyapatite (HAp) monoliths synthesized from gypsum mold waste were used for removing lead ions from aqueous solution. The gypsum waste was crushed into small blocks and converted directly to porous HAp pieces in a 0.5 mol/dm 3 diammonium hydrogen phosphate solution at 55 and 80°C. Porous structures were effected by reaction temperatures....

Microwave-hydrothermal synthesis of titanium dioxide under various reaction conditions is reported. Crystallization of rutile from TiOCl2 solutions was found to be extremely rapid. Titanium dioxide particle size, morphology and polymorph can be controlled by changing various parameters such as concentration, pH, pressure (or temperature), time and...

Microwave-hydrothermal synthesis of titanium dioxide under various reaction conditions is reported. Crystallization of rutile from TiOCl2 solutions was found to be extremely rapid. Titanium dioxide particle size, morphology and polymorph can be controlled by changing various parameters such as concentration, pH, pressure (or temperature), time and...

Attempts were made to fabricate semiconductor gas sensors of thick film type by a slide-off transfer printing method, which is one of the most popular printing techniques in traditional ceramics. Slide-off transfer sheets of metal oxide powders of In2O3. SnO2 and TiO2 were fabricated by screen printing. The suitable weight ratio of the binder and t...

Photodegradations of gaseous isopropyl alcohol over UV irradiated films prepared from peroxo-modified anatase sol (PA sol) were studied. When the amount of the film formed by PA sol was 0.25mg/cm2, the film showed high photocatalytic activities, however, the activities for the films of 0.075mg/cm2 and 0.15mg/cm2 were low significantly. By use of PA...

Porous hydroxyapatite (HAp) monoliths were synthesized from gypsum mold waste with diammonium hydrogen phosphate solution by hydrothermal treatment at 50-190°C and their properties studied. Gypsum waste samples could be completely converted to HAp with 0.5 mol dm –3 (NH 4 ) 2 HPO 4 at 50°C in 15 days and 100°C in 2 days. This paper describes the ef...

We have developed a novel honeycomb composite structure consisting of microporous ZSM-5 and macroporous mullite by in-situ crystallization of ZSM-5 utilizing glass from a sintered kaolin honeycomb. This in-situ crystallization of ZSM-5 leads to better adhesion and mechanical strength for the zeolite film and results in a graded structure with three...

Semiconductor gas sensors of thick film type were prepared by a slide-off transfer printing method. Slide-off transfer sheets were fabricated by screen printing the paste stuffs of SnO2, TiO2, In2O3 and noble metal-loaded In2O3 mixed with a suitable amount of a printing oil on a mount paper with gum, followed by screen printing a cover coat of lacq...

We studied the properties of the anatase sols obtained by heating the PTA solution at 100°C for 2 to 20h and the photocatalytic activities of the films prepared from the sols for the vegetable oil degradation, obtaining the following results: (1) Well-dispersed anatase sols were obtained by heating the PTA solution at 100°C for 2-6h. (2) The sols c...

Anatase films for a photocatalyst have been prepared on substrates by a dip-coating technique using peroxotitanic acid (PTA) solution and peroxo-modified anatase (PA) sol. The as-dried film prepared from PA sol had already crystallized to anatase phase, while the film prepared from PTA solution crystallized above 300°C. Adhesion strength of the fil...

A microwave-hydrothermal treatment with 1 and 5N-NaOH solution was used at 150°C and 190°C to dissolve excess silica glass and thus make porous mullite ceramics from a fired New Zealand kaolin honeycomb. The effect of microwave-hydrothermal (M-H) treatment time on the dissolution of the glass was examined and compared to the result of conventional-...

Whisker formation on alumina particles was attempted through growth of a number of fine mullite whiskers by the thermal decomposition of clay for porcelain at 1400 to 1600°C. After firing, the excess silica phase was hydrothermally dissolved in 2N NaOH solution at 180°C. The effect of firing temperature, and compositions of alumina and clay on the...

A peroxo titanic acid (PTA) solution has been prepared by mixing titanic acid wet gel and hydrogen peroxide solution. The PTA solution was a neutral, transparent, stable liquid. The PTA crystallized to form an anatase phase after calcination at a temperature above 250°C. When the PTA solution was autoclaved at a temperature above 100°C for 6h, it c...

A conventional hydrothermal treatment with various concentrations of NaOH was used at 150 and 190C to dissolve excess silica glass and thus make porous mullite ceramics from a fired New Zealand kaolin body. The effect of hydrothermal treatment time on the dissolution of the glass was examined. At 150C, the dissolution of glass was almost complete a...

LaMO3 (M=Co, Cr, Al) films were prepared on substrates by introducing ultrasonically atomized metal nitrate solutions into an inductively coupled plasma under atmospheric pressure (spray-ICP technique). Dense perovskite-type oxide films of LaCoO3 and LaCrO3 were obtained at 600–900°C, while the LaAiO3 films consisted of loosely packed aggregates. D...

In an attempt to utilize LaNiO3 as a bottom electrode for PbTiO3 ferroelectric film, PbTiO3 and LaNiO3 films were prepared by the spray-ICP technique under atmospheric pressure. The dense LaNiO3 films crystallized with preferred (1 1 1) and (1 0 0) orientations on sapphire (0 0 1) and MgO (1 0 0), respectively. Resistivities of the LaNiO3 films dep...

PbTiO3 thin films were prepared on various substrates by spraying an ultrasonically atomized aqueous solution of Pb(NO3)2 + TiO (NO3)2 into an inductively coupled plasma (ICP) under atmospheric pressure. Single-phase PbTiO3 with perovskite structure was obtained at 500–650 °C. The perovskite obtained below 600 °C showed less tetragonality due to th...

Inorganic porous membranes (pore size <10 μm) are widely used in separation processes such as gas filtration and purification of products in chemical synthesis. For separation processes, the porous membranes must be as thin as possible because of the permeability of the medium. Fibrous materials are expected to be superior to spherical ones in prep...

Alumina/kaolin laminated composites have been fabricated at 1650 °C by firing multilayers of 1 mm thick alumina sheets and 50 or 100 μm thick kaolin tapes. During firing, the kaolin layers changed to mixed phases of mullite and SiO2-rich glass. The bending strength of these composites does not depend on the numbers of laminated kaolin tapes, but de...

Composite alumina ceramics with a mullite whisker content of up to 30vol% were fabricated by hot-pressing at 1400 to 1600°C under 30MPa for 30min. The bending strength, hardness, elastic modulus and fracture toughness of the hot-pressed bodies were investigated. Considerably dense alumina-mullite whisker composite ceramics were obtained by sinterin...

Volatile organometallic compounds were introduced to feed gas (CH4/H2) during the synthesis of diamond by microwave plasma chemical vapor deposition. Addition of Si(CH3)4, Sn(CH3)4, Sn(CH3)4, Fe(AA)3, TiO(AA)2 or Zr(AA)4 increased nucleation density of diamond particles to 2-10 times that without additives. Addition of Zr(AA)4 and TiO(AA)2 made the...

The yield of mullite produced by firing a mixture of New Zealand kaolin and alumina (Al2O3/SiO2=1.0 in molar ratio) increased rapidly above 1500°C as compared with that for kaolin alone. The mullite was recovered by treating the fired body with fluoric acid. The mullite particles obtained by firing the kaolin-alumina mixture at 1600°C for 10h were...