Development of Ti-Mo alloys for biomedical applications: Microstructure and electrochemical characterization

Ti-Mo alloys from 4 to 20 Mo wt.% were arc-melted. Their compositions and surfaces were analyzed by EDX, XRF and SEM. The Mo mapping shows a homogeneous distribution for all alloys. The XRD analysis showed that the crystal structure of the alloys is sensitive to the Mo concentration; a mixture of the hexagonal alpha' and orthorhombic alpha '' phases was observed for the Ti-4Mo alloy, and the alpha '' phase is observed almost exclusively when the concentration of Mo added to the Ti reaches 6%. A significant retention of the beta phase is observed for the alloy containing 10% Mo, while at higher Mo concentrations (15% and 20%), retention of phase beta is only verified. Preliminary electrochemical studies have indicated a valve-metal behavior and good corrosion resistance in aerated Ringer solution for all alloys. (c) 2006 Published by Elsevier B.V.

Changes of microstructure in alpha AgZn during post-deformation annealing after cold-rolling

The annealing processes of deformation-induced defects after cold-rolling to about 30 and 60% thickness reduction were investigated for Ag-21, 23, 28 at% Zn by means of residual electrical resistivity, microhardness, light microscopy and transmission electron microscopy (TEM) Three annealing stages have been detected and consistently interpreted as annealing-out of mainly point defects and their agglomerates (stage I), formation of dislocation cells and recrystallized strain-free grains (stage II) and grain growth (stage III). Further, it is tried to determine the evolution of defect production (point defects and dislocations) during rolling deformation from measured changes of electrical resistivity and microhardness. Copyright (C) 1996 Acta Metallurgica Inc.

High hydrostatic pressure processing on microstructure of probiotic low-fat yogurt

The effect of milk processing on the microstructure of probiotic low-fat yogurt was studied. Skim milk fortified with skim milk powder was subjected to three treatments prior to innoculation: thermal treatment at 85 degrees C for 30 min, high hydrostatic pressure at 676 MPa for 5 min, and combined treatments of high hydrostatic pressure (HHP) and heat. The processed milk was then fermented by using two different starter cultures containing Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus acidophilus, and Bifidobacterium longum. The microstructure of heat-treated milk yogurt had fewer interconnected chains of irregularly shaped casein micelles, forming a network that enclosed the void spaces. on the other hand, microstructure of HHP yogurt had more interconnected clusters of densely aggregated protein of reduced particle size, with an appearance more spherical in shape, exhibiting a smoother more regular surface and presenting more uniform size distribution. The combined HHP and heat milk treatments led to compact yogurt gels with increasingly larger casein micelle clusters interspaced by void spaces, and exhibited a high degree of cross-linking. The rounded micelles tended to fuse and form small irregular aggregates in association with clumps of dense amorphous material, which resulted in improved gel texture and viscosity. (C) 2007 Elsevier Ltd. All rights reserved.

Dielectric properties and microstructure of SrTiO3/BaTiO3 multilayer thin films prepared by a chemical route

Multilayer thin films with perovskite structures were produced by the polymeric precursor method. SrTiO3/BaTiO3 (STO/BTO) multilayers were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by the spin-coating technique and heated in air at 700 degreesC. The microstructure and crystalline phase of the multilayered thin films were examined by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), resolution-high transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and X-ray diffraction. The SrTiO3/BaTiO3 multilayer thin films consisted of grainy structures with an approximate grain size of 60 nm. The multilayered thin films showed a very clear interface between the components. The SrTiO3/BaTiO3 multilayer thin films revealed dielectric constants of approximately 527 and loss tangents of 0.03 at 100 kHz. The dielectric constant calculated for this multilayer film system is the value of the sum of each individual component of the film, i.e. The total value of the sum of each SrTiO3 (STO) and BaTiO3 (BTO) layer. The multilayer SrTiO3/BaTiO3 obtained by the polymeric precursor method, also showed a ferroelectric behavior with a remanent polarization of 2.5 muC/cm(2) and a coercive field of 30 kV/cm. The multilayer films displayed good fatigue characteristics under bipolar stressing after application of 10(10) switching cycles. (C) 2001 Published by Elsevier B.V. B.V. All rights reserved.

Microstructure and electrical properties of perovskite (Pb, La)TiO3 thin film deposited at low temperature by the polymeric precursor method

High-quality (Pb, La)TiO3 ferroelectric thin films were successfully prepared on a Pt(111)/Ti/SiO2/Si(100) substrate for the first time by spin coating, using the polymeric precursor method. The X-ray diffraction patterns show that the films are polycrystalline in nature. This method allows for low temperature (500 degrees C) synthesis, a high quality microstructure and superior dielectric properties. The effects on the microstructure and electrical properties were studied by changing the La content. The films annealed at 500 degreesC have a single perovskite phase with only a tetragonal or pseudocubic structure. As the La content is increased, the dielectric constant of PLT thin films increases from 570 up to 1138 at room temperature. The C-V and P-E characteristics of perovskite thin films prepared at a low temperature show normal ferroelectric behavior, representing the ferroelectric switching property. The remanent polarization and coercive field of the films deposited decreased due to the transformation from the ferroelectric to the paraelectric phase with an increased La content. (C) 2001 Kluwer Academic Publishers.

Texture and Microstructure of Gelatin/Corn Starch-Based Gummy Confections

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Structure, microstructure and dielectric properties of 100-x(Bi0.5Na0.5)TiO3-x[SrTiO3] composites ceramics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of the morphology and microstructure on the photocatalytic properties of titanium oxide films obtained by sparking anodization in H3PO4

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Rietveld refinement, microstructure, conductivity and impedance properties of Ba[Zr0.25Ti0.75]O-3 ceramic

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Microstructure of doped barium titanate prepared from polymeric precursors

Barium titanate is used extensively as a dielectric in ceramic capacitors, particularly due to its high dielectric constant and low dielectric loss characteristics. It can be made semiconducting by addition of certain dopants and by proper modification of grains and grain boundary properties obtaining very interesting characteristics for various applications. The synthesis method and sintering regime have a strong influence on properties of obtained barium titanate ceramics. Doped barium titanate was prepared with Nb+5 and Y+3 ions as donor dopants, and with Mn+2 ions as acceptor dopant by polymeric precursors method. By this procedure nanosized powders were obtained after calcination. Sintering was performed in the temperature range of 1290°C to 1380°C The microstructure of doped BaTiO3 was performed using scanning electron microscopy. The influence of dopants and sintering temperature on grain size was analysed.

The synergistic effects of Nb/Mn and Sb/Mn on the microstructure and electrical characteristics of BaTiO3 based ceramics

The microstructure and dielectric properties of Nb-Mn or Sb-Mn codoped BaTiO3 compositions were investigated. Starting ceramics powders were prepared by Pechini method. The composites were sintered at 1310°C and 1330°C in an air atmosphere for two hours. The microstructure and compositional investigations were done with SEM equipped with EDS. Two distinguish microstructure regions are observed in Nb/0.05Mn doped BaTiO 3 ceramics sintered at low temperature. The first, large one, with grain sizes from 5-40 μm and the second region with small grain sizes from 1 to 5 μm. Sintering at higher temperature, independent of Mn content, enables to achieve a uniform microstructure with grains less than 6 μm. In Sb/Mn doped ceramics, for both sintering temperatures, bimodal microstructures with fine grained matrix and grains up to 10 μm is formed. The highest value of permittivity at room temperature and the greatest change of permittivity in function of temperature are observed in Nb/0.01Mn doped ceramics compared to the same ones in Sb/Mn doped ceramics. The greatest shift of Curie temperature towards lower temperature has been noticed in Sb/Mn BaTiO3 ceramics compared to others samples. In all investigated samples the dielectric loss after initially large values at low frequency maintains a constant value for f>3 kHz.

Additional observations on the gross morphology and microstructure of Baccaconularia Hughes, Gunderson et Weedon, 2000, a Cambrian (Furongian) conulariid from the north-central USA

Baccaconularia Hughes, Gunderson et Weedon, 2000, from the Furongian Series (Cambrian System) of the north-central USA, has been interpreted as a conulariid cnidarian, based on a suite of gross morphological similarities shared only with other post-Cambrian genera currently assigned to this group. Closely spaced, squarish to subrectangular facial nodes of Baccaconularia are aligned in distinct longitudinal files. Nodes also display a subtler, more or less rectilinear transverse alignment, though this pattern commonly is disrupted by offset parallel to the longitudinal files. In their shape and pattern of arrangement, the nodes of Baccaconularia are most similar to the squarish to elongate nodes of Pseudoconularia Bouček, 1939. Longitudinal node files of Baccaconularia may also be compared with the longitudinal facial ridges of Conularia cambria Walcott, 1890 from the Furongian of Wisconsin. Apical angles of Baccaconularia range from approximately 13° to 14.5°. Scanning electron imaging of B. cf. robinsoni shows that its thin, phosphatic skeleton is finely lamellar, with the thickness of individual lamellae measuring approximately 1 μm. The skeleton also exhibits microscopic circular pores and crater-like pits that range from approximately 5 to 10 μm in diameter. These pores and pits are similar in size, geometry, areal density and pattern of arrangement to those of many post-Cambrian conulariids. Microscopic circular pores are documented here for the first time in the genus Archaeoconularia Bouček, 1939 from the Upper Ordovician of the Czech Republic. Although the origin of the pores and pits is open to alternative interpretations, the discovery of these features and fine lamination in Baccaconularia strengthens the argument that this genus is a Cambrian conulariid. © 2006 Nanjing Institute of Geology and Palaeontology, CAS.

Effect of molybdenum on the formation of Ti6Si2B in mechanically alloyed Ti-Mo-Si-B powders

This paper discusses on effect of molybdenum on the Ti6Si2B formation in mechanically alloyed and hot-pressed Ti-xMo-22Si-11B (x= 2, 5, 7 and 10 at%) alloys. High-energy ball milling and hot pressing were utilized to produce homogeneous and dense materials, which were characterized by scanning electron microscopy, X-ray diffraction, electron dispersive spectrometry, and Vickers hardness. The excessive agglomeration during milling was more pronounced in Moricher powders, which was minimized with the formation of brittle phases. Hot pressing of mechanically alloyed Ti-xMo-22Si-11B powders produced dense samples containing lower pore amounts than 1%. Ti6Si2B was formed in microstructure of the hot-pressed Ti-2Mo-22Si-11B alloy only. In Mo-richer quaternary alloys, the Ti3Si and Ti5Si3 phases were preferentially formed during hot pressing. Oppositely to the ternary phase, the Ti3Si phase dissolved a significant Mo amount. Vickers hardness values were reduced in hot-pressed Ti-xMo-22Si-11B alloys containing larger Mo amounts, which were dissolved preferentially in Ti solid solution. © (2012) Trans Tech Publications, Switzerland.

Physicochemical analysis of Ti-Si-B powder aalloys

Titanium alloys of Ti-Si-B system were manufactured by blended elemental powder method using Ti, Si and B powders as starting materials. It was found that uniaxial and isostatic pressing followed by hot pressing at around 1000°C, for 20 minutes, provided good densification of such alloys. The physicochemical studies were performed by means of scanning electron microscopy, X-ray diffraction, atomic force microscopy and microindentation/wear tests. The investigations revealed a multiphase microstructure formed mainly by α-titanium, Ti6Si2B, Ti5Si3, TiB and Ti3Si phases. The phase transformations after pressureless sintering at 1200°C was also studied by X-ray diffraction for the Ti-18Si-6B composition. As stated in some other researches, these intermetallics in the α-titanium matrix provide high wear resistance and hardness, with the best wear rate of 0.2 mm3/N.m and the highest hardness of around 1300 HV. © (2012) Trans Tech Publications, Switzerland.

Estudo das propriedades supercondutoras e da microestrutura do supercondutor Mg'B IND. 2' puro e dopado com compostos de carbono

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)