Journal of Asian Ceramic Societies

Kuroki, Takashi; Matsushima, Yuta; Unuma, Hidero

doi: 10.1016/j.jascer.2016.07.003pmid: N/A

AbstractElectrochromic tungsten trioxide (WO3) thin films are attracting renewed attention as transmittance-controllable windows for use in automobile, aircraft, and building applications. In order to achieve high electrochromic performance, high cycle stability, and high reliability, the microstructure and compositional homogeneity of WO3 thin films have to be optimized. In this study, non-doped WO3 and TiO2-doped WO3 thin films were fabricated from water-soluble precursors of tungsten and titanium, and their electrochromic response was investigated. Amorphous WO3 and TiO2-doped WO3 thin films were fabricated by calcining the spin-coated films at 573 K. The use of a PEO-PPO-PEO block copolymer as a porogen facilitated the redox reactions occurring on the thin film/electrolyte interface. Although the effect of TiO2-doping on the cycle stability of WO3 thin films has not been fully elucidated, this study demonstrated that TiO2 doping up to 15 mol% effectively enhanced the cycle stability.

Nyounguè, A.; Bouzid, S.; Dossou, E.; Azari, Z.

doi: 10.1016/j.jascer.2016.07.004pmid: N/A

AbstractThis paper presents the study of float glass fracture under static and dynamic loading, with the use of experimental and numerical fracture mechanics methods. It has been shown that the value of notch fracture toughness under static loading depends neither on the kind of test nor on specimen geometry. This makes it possible to replace the three-points-bending specimens with the Brazilian discs which are, under certain test conditions, simpler and convenient to study. For both types of specimens, an analysis of the fracture strength, the notch stress intensity factor and fragmentation of specimens was carried out.

Joyson Abraham, S.; Chandra Rao Madane, S.; Dinaharan, I.; John Baruch, L.

doi: 10.1016/j.jascer.2016.08.001pmid: N/A

AbstractFriction stir processing (FSP) has been accepted as a potential method to produce aluminum matrix composites (AMCs) without the drawbacks of liquid metallurgy methods. The present work focuses on the development of AMCs reinforced with quartz (SiO2) particles using FSP. Grooves with various dimensions were machined on AA6063 plates and compacted with quartz particles. A single pass FSP was carried out using a combination of optimized process parameters. The volume fraction of quartz particles in the AMCs was varied from 0 to 18 vol.% in steps of 6 vol.%. The developed AA6063/Quartz AMCs were characterized using optical, scanning and transmission electron microscopy. The quartz particles were distributed uniformly in the aluminum matrix irrespective of the location within the stir zone. The grains of the AA6063 were extensively refined by the combination of thermomechanical effect of FSP and the pinning effect of quartz particles. The dispersion of the quartz particles improved the microhardness and wear resistance of the AMCs. The role of quartz particles on the worn surface and wear debris is reported.

Tamura, Shinji; Araki, Ken-ichiro; Imanaka, Nobuhito

doi: 10.1016/j.jascer.2016.08.002pmid: N/A

AbstractA new trivalent gallium (Ga3+) ion conducting solid was successfully developed by selecting the three dimensionally well-ordered NASICON-type structure. Although Ga is accepted as a species whose covalency is so high that trivalent Ga3+ ion is inappropriate ionic species in solids to migrate due to its strong bonding with surrounding ions such as oxide anion, we demonstrated the trivalent Ga3+ ion conduction in the NASICON-type (GaxTi1−x)4/(4−x)Nb(PO4)3 solids by strictly selecting the constituent cations. Among the samples prepared, (Ga0.1Ti0.9)40/39Nb(PO4)3 showed the highest Ga3+ ion conductivity of 5.1 × 10−5 S cm−1 at 600 °C.

Li, Jinhui; Inukai, Koji; Takahashi, Yosuke; Shin, Woosuck

doi: 10.1016/j.jascer.2016.09.001pmid: N/A

AbstractMonodispersed, spherical nanoparticles of the BaTiO3–polyvinylpyrrolidone (BT–PVP) composite were synthesized through the surface modification of the oxide BT by the polymer PVP, using TiCl4, BaCl2, PVP, and KOH (as the mineralizer) in an aqueous solution. To reduce the size of the particles and ensure that they were monodispersed, the concentrations of the Ba and Ti sources were increased and the reaction parameters such as reaction temperature, reaction time, and KOH concentration were optimized. As a result, monodispersed BT–PVP particles with an average diameter of 114 nm (coefficient of variation, CV = 20.0%) were obtained from a Ba-rich solution ([Ti]/[Ba] = 0.2 M:0.3 M; [KOH] = 1.4 M), and their dynamic light scattering in an aqueous suspension demonstrated that the average diameter was 162 nm (CV = 26.6%). A higher KOH concentration resulted in smaller particles, but the excess KOH promoted particle aggregation and PVP gelation. The mechanism of dispersion and aggregation of BT–PVP will be discussed in detail.

Onoda, Hiroaki; Yamazaki, Shin

doi: 10.1016/j.jascer.2016.10.001pmid: N/A

AbstractIn this work, we prepared calcium phosphate by a general homogenous hydrothermal process, either from commercial calcium carbonate and phosphoric acid, or from corbicula shells and phosphoric acid. The chemical composition and properties of the resulting products were also investigated. Commercial calcium carbonate and corbicula shells reacted with phosphoric acid to produce calcium hydrogen phosphate and hydroxyapatite via a homogeneous hydrothermal process. The chemical composition of the products was influenced by both processing temperature as well as time. The compositions themselves influenced the substitution of calcium with iron and the absorption of trimethylamine gas.