WorldWideScience

Sample records for submicrometer ceramic particles

  1. Filtration of submicrometer particles by pelagic tunicates.

    Science.gov (United States)

    Sutherland, Kelly R; Madin, Laurence P; Stocker, Roman

    2010-08-24

    Salps are common in oceanic waters and have higher per-individual filtration rates than any other zooplankton filter feeder. Although salps are centimeters in length, feeding via particle capture occurs on a fine, mucous mesh (fiber diameter d approximately 0.1 microm) at low velocity (U = 1.6 +/- 0.6 cmxs(-1), mean +/- SD) and is thus a low Reynolds-number (Re approximately 10(-3)) process. In contrast to the current view that particle encounter is dictated by simple sieving of particles larger than the mesh spacing, a low-Re mathematical model of encounter rates by the salp feeding apparatus for realistic oceanic particle-size distributions shows that submicron particles, due to their higher abundances, are encountered at higher rates (particles per time) than larger particles. Data from feeding experiments with 0.5-, 1-, and 3-microm diameter polystyrene spheres corroborate these findings. Although particles larger than 1 microm (e.g., flagellates, small diatoms) represent a larger carbon pool, smaller particles in the 0.1- to 1-microm range (e.g., bacteria, Prochlorococcus) may be more quickly digestible because they present more surface area, and we find that particles smaller than the mesh size (1.4 microm) can fully satisfy salp energetic needs. Furthermore, by packaging submicrometer particles into rapidly sinking fecal pellets, pelagic tunicates can substantially change particle-size spectra and increase downward fluxes in the ocean.

  2. Focusing of sub-micrometer particles and bacteria enabled by two-dimensional acoustophoresis

    DEFF Research Database (Denmark)

    Antfolk, M.; Muller, Peter Barkholt; Augustsson, P.

    2014-01-01

    particles as small as 0.5 μm in diameter in microchannels of square or rectangular cross sections, is demonstrated. Numerical analysis was used to determine generic transverse particle trajectories in the channels, which revealed spiral-shaped trajectories of the sub-micrometer particles towards the center......Handling of sub-micrometer bioparticles such as bacteria are becoming increasingly important in the biomedical field and in environmental and food analysis. As a result, there is an increased need for less labor-intensive and time-consuming handling methods. Here, an acoustophoresis......-based microfluidic chip that uses ultrasound to focus sub-micrometer particles and bacteria, is presented. The ability to focus sub-micrometer bioparticles in a standing one-dimensional acoustic wave is generally limited by the acoustic-streaming-induced drag force, which becomes increasingly significant the smaller...

  3. Hygroscopic behavior of individual submicrometer particles studied by X-ray spectromicroscopy.

    Science.gov (United States)

    Ghorai, Suman; Tivanski, Alexei V

    2010-11-15

    A novel application of single particle scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy is presented for quantitative analysis of hygroscopic properties and phase transitions of individual submicrometer particles. The approach utilizes the exposure of substrate-deposited individual particles to water vapor at different relative humidity followed by STXM/NEXAFS spectromicroscopy analysis. The hygroscopic properties of atmospherically relevant NaCl, NaBr, NaI, and NaNO(3) submicrometer particles were measured to evaluate the utility of the approach. An analytical approach for quantification of a water-to-solute ratio within an individual submicrometer particle during hydration and dehydration cycles is presented. The results for the deliquescence and efflorescence phase transitions and quantitative measurements of water-to-solute ratios are found in excellent agreement with available literature data. Oxygen K-edge NEXAFS spectra of submicrometer sodium halide droplets are reported along with a unique experimental observation of the formation of the halide-water anionic complex in NaBr and NaI microdimensional droplets. The analytical approach provides a unique opportunity for spectromicroscopy studies of water uptake on environmental particles collected in both laboratory and field studies.

  4. Submicrometer particles and their effects on the association between air temperature and mortality in Brisbane, Australia.

    Science.gov (United States)

    Wang, Lina; Tong, Shilu; Toloo, Ghasem Sam; Yu, Weiwei

    2014-01-01

    Air temperature and pollution can jointly affect human health. Submicrometer particles appearing to have particularly harmful effects compared with the coarse ones. However, little is known about how the association between temperature and mortality is affected by these particles. This study examined the association between air temperature and mortality before and after adjustment for particle concentrations among different age and disease groups from 1995 to 2000 in Brisbane, Australia. The monitoring of particle size distribution within the 15-750nm range was carried out by a Scanning Mobility Particle Sizer. Corresponding climate and air pollutant data were collected from relevant government agencies. The association between temperature and mortality was quantified using a Poisson time-series model within a distributed lag non-linear modelling framework. The results showed that the effects of air temperature on mortality were lower among the elderly and people with respiratory diseases, and greater among people with cardiovascular diseases after controlling for submicrometer particle concentrations. Submicrometer particles seem to be an important confounder for the temperature-mortality relationship, particularly among vulnerable groups, and should be taken into account when assessing the impacts of air temperature on human health. Crown Copyright © 2013 Published by Elsevier Inc. All rights reserved.

  5. Sub-micrometer refractory carbonaceous particles in the polar stratosphere

    Science.gov (United States)

    Schütze, Katharina; Wilson, James Charles; Weinbruch, Stephan; Benker, Nathalie; Ebert, Martin; Günther, Gebhard; Weigel, Ralf; Borrmann, Stephan

    2017-10-01

    Eleven particle samples collected in the polar stratosphere during SOLVE (SAGE III Ozone loss and validation experiment) from January until March 2000 were characterized in detail by high-resolution transmission and scanning electron microscopy (TEM/SEM) combined with energy-dispersive X-ray microanalysis. A total of 4202 particles (TEM = 3872; SEM = 330) were analyzed from these samples, which were collected mostly inside the polar vortex in the altitude range between 17.3 and 19.9 km. Particles that were volatile in the microscope beams contained ammonium sulfates and hydrogen sulfates and dominated the samples. Some particles with diameters ranging from 20 to 830 nm were refractory in the electron beams. Carbonaceous particles containing additional elements to C and O comprised from 72 to 100 % of the refractory particles. The rest were internal mixtures of these materials with sulfates. The median number mixing ratio of the refractory particles, expressed in units of particles per milligram of air, was 1.1 (mg air)-1 and varied between 0.65 and 2.3 (mg air)-1. Most of the refractory carbonaceous particles are completely amorphous, a few of the particles are partly ordered with a graphene sheet separation distance of 0.37 ± 0.06 nm (mean value ± standard deviation). Carbon and oxygen are the only detected major elements with an atomic O/C ratio of 0.11 ± 0.07. Minor elements observed include Si, S, Fe, Cr and Ni with the following atomic ratios relative to C: Si/C: 0.010 ± 0.011; S/C: 0.0007 ± 0.0015; Fe/C: 0.0052 ± 0.0074; Cr/C: 0.0012 ± 0.0017; Ni/C: 0.0006 ± 0.0011 (all mean values ± standard deviation).High-resolution element distribution images reveal that the minor elements are distributed within the carbonaceous matrix; i.e., heterogeneous inclusions are not observed. No difference in size, nanostructure and elemental composition was found between particles collected inside and outside the polar vortex. Based on chemistry and nanostructure

  6. Sub-micrometer refractory carbonaceous particles in the polar stratosphere

    Directory of Open Access Journals (Sweden)

    K. Schütze

    2017-10-01

    Full Text Available Eleven particle samples collected in the polar stratosphere during SOLVE (SAGE III Ozone loss and validation experiment from January until March 2000 were characterized in detail by high-resolution transmission and scanning electron microscopy (TEM/SEM combined with energy-dispersive X-ray microanalysis. A total of 4202 particles (TEM  =  3872; SEM  =  330 were analyzed from these samples, which were collected mostly inside the polar vortex in the altitude range between 17.3 and 19.9 km. Particles that were volatile in the microscope beams contained ammonium sulfates and hydrogen sulfates and dominated the samples. Some particles with diameters ranging from 20 to 830 nm were refractory in the electron beams. Carbonaceous particles containing additional elements to C and O comprised from 72 to 100 % of the refractory particles. The rest were internal mixtures of these materials with sulfates. The median number mixing ratio of the refractory particles, expressed in units of particles per milligram of air, was 1.1 (mg air−1 and varied between 0.65 and 2.3 (mg air−1. Most of the refractory carbonaceous particles are completely amorphous, a few of the particles are partly ordered with a graphene sheet separation distance of 0.37 ± 0.06 nm (mean value ± standard deviation. Carbon and oxygen are the only detected major elements with an atomic O∕C ratio of 0.11 ± 0.07. Minor elements observed include Si, S, Fe, Cr and Ni with the following atomic ratios relative to C: Si∕C: 0.010 ± 0.011; S∕C: 0.0007 ± 0.0015; Fe∕C: 0.0052 ± 0.0074; Cr∕C: 0.0012 ± 0.0017; Ni∕C: 0.0006 ± 0.0011 (all mean values ± standard deviation.High-resolution element distribution images reveal that the minor elements are distributed within the carbonaceous matrix; i.e., heterogeneous inclusions are not observed. No difference in size, nanostructure and elemental composition was found between

  7. Direct Surface Tension Measurements of Individual Sub-Micrometer Particles Using Atomic Force Microscopy.

    Science.gov (United States)

    Lee, Hansol D; Estillore, Armando D; Morris, Holly S; Ray, Kamal K; Alejandro, Aldair; Grassian, Vicki H; Tivanski, Alexei V

    2017-11-02

    Understanding the role of sea spray aerosol (SSA) on climate and the environment is of great interest due to their high number concentration throughout the Earth's atmosphere. Despite being of fundamental importance, direct surface tension measurements of SSA relevant sub-micrometer particles are rare, largely due to their extremely small volumes. Herein, atomic force microscopy (AFM) is used to directly measure the surface tension of individual sub-micrometer SSA particle mimics at ambient temperature and varying relative humidity (RH). Specifically, we probed both atmospherically relevant and fundamentally important model systems including electrolyte salts, dicarboxylic acids, and saccharides as single components and mixtures. Our results show that the single particle surface tension depends on RH or solute mole percentage and chemical composition. Moreover, for liquid droplets at and below 100 Pa s in viscosity, or at corresponding RH, we show good agreement between the AFM single particle and the bulk solution surface tension measurements at overlapping concentration ranges. Thus, direct surface tension measurements of individual particles using AFM is shown over a wide range of chemical systems as a function of RH, solute mole percentage, and viscosity than previously reported.

  8. Quantifying the Hygroscopic Growth of Individual Submicrometer Particles with Atomic Force Microscopy.

    Science.gov (United States)

    Morris, Holly S; Estillore, Armando D; Laskina, Olga; Grassian, Vicki H; Tivanski, Alexei V

    2016-04-05

    The water uptake behavior of atmospheric aerosol dictates their climate effects. In many studies, aerosol particles are deposited onto solid substrates to measure water uptake; however, the effects of the substrate are not well understood. Furthermore, in some cases, methods used to analyze and quantify water uptake of substrate deposited particles use a two-dimensional (2D) analysis to monitor growth by following changes in the particle diameter with relative humidity (RH). However, this 2D analysis assumes that the droplet grows equally in all directions. If particle growth is not isotropic in height and diameter, this assumption can cause inaccuracies when quantifying hygroscopic growth factors (GFs), where GF for a for a spherical particle is defined as the ratio of the particle diameter at a particular relative humidity divided by the dry particle diameter (typically about 5% RH). However, as shown here, anisotropic growth can occur in some cases. In these cases, a three-dimensional (3D) analysis of the growth is needed. This study introduces a way to quantify the hygroscopic growth of substrate deposited particles composed of model systems relevant to atmospheric aerosols using atomic force microscopy (AFM), which gives information on both the particle height and area and thus a three-dimensional view of each particle. In this study, we compare GFs of submicrometer sized particles composed of single component sodium chloride (NaCl) and malonic acid (MA), as well as binary mixtures of NaCl and MA, and NaCl and nonanoic acid (NA) determined by AFM using area (2D) equivalent diameters, similar to conventional microscopy methods, to GFs determined using volume (3D) equivalent diameter. We also compare these values to GFs determined by a hygroscopic tandem differential mobility analyzer (HTDMA; substrate free, 3D method). It was found that utilizing volume equivalent diameter for quantifying GFs with AFM agreed well with those determined by substrate-free HTDMA

  9. Seasonal variation of aliphatic amines in marine sub-micrometer particles at the Cape Verde islands

    Directory of Open Access Journals (Sweden)

    H. Herrmann

    2009-12-01

    Full Text Available Monomethylamine (MA, dimethylamine (DMA and diethylamine (DEA were detected at non-negligible concentrations in sub-micrometer particles at the Cap Verde Atmospheric Observatory (CVAO located on the island of São Vicente in Cape Verde during algal blooms in 2007. The concentrations of these amines in five stage impactor samples ranged from 0–30 pg m−3 for MA, 130–360 pg m−3 for DMA and 5–110 pg m−3 for DEA during the spring bloom in May 2007 and 2–520 pg m−3 for MA, 100–1400 pg m−3 for DMA and 90–760 pg m−3 for DEA during an unexpected winter algal bloom in December 2007. Anomalously high Saharan dust deposition and intensive ocean layer deepening were found at the Atmospheric Observatory and the associated Ocean Observatory during algal bloom periods. The highest amine concentrations in fine particles (impactor stage 2, 0.14–0.42 μm indicate that amines are likely taken up from the gas phase into the acidic sub-micrometer particles. The contribution of amines to the organic carbon (OC content ranged from 0.2–2.5% C in the winter months, indicating the importance of this class of compounds to the carbon cycle in the marine environment. Furthermore, aliphatic amines originating from marine biological sources likely contribute significantly to the nitrogen content in the marine atmosphere. The average contribution of the amines to the detected nitrogen species in sub-micrometer particles can be non-negligible, especially in the winter months (0.1% N–1.5% N in the sum of nitrate, ammonium and amines. This indicates that these smaller aliphatic amines can be important for the carbon and the nitrogen cycles in the remote marine environment.

  10. Hygroscopic growth of sub-micrometer and one-micrometer aerosol particles measured during ACE-Asia

    Directory of Open Access Journals (Sweden)

    A. Massling

    2007-06-01

    Full Text Available Hygroscopic properties of aerosol particles in the sub-micrometer and one-micrometer size ranges were measured during the ACE-Asia study (Aerosol Characterization Experiment-Asia in spring 2001. The measurements took place off the coasts of Japan, Korea, and China. All instruments contributing to this study were deployed in a container on the forward deck of the NOAA Research Vessel Ronald H. Brown. Air masses with primarily marine influence and air masses from the Asian continent affected by both anthropogenic sources and by the transport of desert dust aerosol were encountered during the cruise.

    Results showed very different hygroscopic behavior in the sub-micrometer size range compared to the one-micrometer size range. In general, for all continentally influenced air masses, the one-micrometer particle population was characterized by two different particle groups – a nearly hydrophobic fraction with growth factors around 1.0 representative of dust particles and a sea salt fraction with hygroscopic growth factors around 2.0. The number fraction of dust particles was generally about 60% independent of long-range air mass origin.

    For sub-micrometer particles, a dominant, more hygroscopic particle fraction with growth factors between 1.5 and 1.9 (depending on dry particle size consistent with ammonium sulfate or non-neutralized sulfates as major component was always found. In marine air masses and for larger sizes within the sub-micrometer range (Dp=250 and 350 nm, a sea salt fraction with growth factors between 2.0 and 2.1 was also observed. For all other air masses, the more hygroscopic particle fraction in the sub-micrometer size range was mostly accompanied by a less hygroscopic particle fraction with growth factors between 1.20 and 1.55 depending on both the continental sources and the dry particle size. Number fractions of this particle group varied between 4 and 39% depending on dry particle size and air mass

  11. Performance of combination drug and hygroscopic excipient submicrometer particles from a softmist inhaler in a characteristic model of the airways.

    Science.gov (United States)

    Longest, P Worth; Tian, Geng; Li, Xiang; Son, Yoen-Ju; Hindle, Michael

    2012-12-01

    Excipient enhanced growth (EEG) of inhaled submicrometer pharmaceutical aerosols is a recently proposed method intended to significantly reduce extrathoracic deposition and improve lung delivery. The objective of this study was to evaluate the size increase of combination drug and hygroscopic excipient particles in a characteristic model of the airways during inhalation using both in vitro experiments and computational fluid dynamic (CFD) simulations. The airway model included a characteristic mouth-throat (MT) and upper tracheobronchial (TB) region through the third bifurcation and was enclosed in a chamber geometry used to simulate the thermodynamic conditions of the lungs. Both in vitro results and CFD simulations were in close agreement and indicated that EEG delivery of combination submicrometer particles could nearly eliminate MT deposition for inhaled pharmaceutical aerosols. Compared with current inhalers, the proposed delivery approach represents a 1-2 order of magnitude reduction in MT deposition. Transient inhalation was found to influence the final size of the aerosol based on changes in residence times and relative humidity values. Aerosol sizes following EEG when exiting the chamber (2.75-4.61 μm) for all cases of initial submicrometer combination particles were equivalent to or larger than many conventional pharmaceutical aerosols that frequently have MMADs in the range of 2-3 μm.

  12. Surface organic monolayers control the hygroscopic growth of submicrometer particles at high relative humidity.

    Science.gov (United States)

    Ruehl, Christopher R; Wilson, Kevin R

    2014-06-05

    Although many organic molecules commonly found in the atmosphere are known to be surface-active in macroscopic aqueous solutions, the impact of surface partitioning of organic molecules to a microscopic aqueous droplet interface remains unclear. Here we measure the droplet size formed, at a relative humidity (∼99.9%) just below saturation, on submicrometer particles containing an ammonium sulfate core and an organic layer of a model compound of varying thickness. The 12 model organic compounds are a series of dicarboxylic acids (C3 to C10), cis-pinonic, oleic, lauric, and myristic acids, which represent a broad range in solubility from miscible (malonic acid) to insoluble. The variation in droplet size with increasing organic aerosol fraction cannot be explained by assuming the organic material is dissolved in the bulk droplet. Instead, the wet droplet diameters exhibit a complex and nonlinear dependence on organic aerosol volume fraction, leading to hygroscopic growth that is in some cases smaller and in others larger than that predicted by bulk solubility alone. For palmitic and stearic acid, small droplets at or below the detection limit of the instrument are observed, indicating significant kinetic limitations for water uptake, which are consistent with mass accommodation coefficients on the order of 10(-4). A model based on the two-dimensional van der Waals equation of state is used to explain the complex droplet growth with organic aerosol fraction and dry diameter. The model suggests that mono- and dicarboxylic acids with limited water solubility partition to the droplet surface and reduce surface tension only after a two-dimensional condensed monolayer is formed. Two relatively soluble compounds, malonic and glutaric acid, also appear to form surface phases, which increase hygroscopicity. There is a clear alternation in the threshold for droplet growth observed for odd and even carbon number diacids, which is explained in the model by differences in the

  13. Highly Localized Acoustic Streaming and Size-Selective Submicrometer Particle Concentration Using High Frequency Microscale Focused Acoustic Fields.

    Science.gov (United States)

    Collins, David J; Ma, Zhichao; Ai, Ye

    2016-05-17

    Concentration and separation of particles and biological specimens are fundamental functions of micro/nanofluidic systems. Acoustic streaming is an effective and biocompatible way to create rapid microscale fluid motion and induce particle capture, though the >100 MHz frequencies required to directly generate acoustic body forces on the microscale have traditionally been difficult to generate and localize in a way that is amenable to efficient generation of streaming. Moreover, acoustic, hydrodynamic, and electrical forces as typically applied have difficulty manipulating specimens in the submicrometer regime. In this work, we introduce highly focused traveling surface acoustic waves (SAW) at high frequencies between 193 and 636 MHz for efficient and highly localized production of acoustic streaming vortices on microfluidic length scales. Concentration occurs via a novel mechanism, whereby the combined acoustic radiation and streaming field results in size-selective aggregation in fluid streamlines in the vicinity of a high-amplitude acoustic beam, as opposed to previous acoustic radiation induced particle concentration where objects typically migrate toward minimum pressure locations. Though the acoustic streaming is induced by a traveling wave, we are able to manipulate particles an order of magnitude smaller than possible using the traveling wave force alone. We experimentally and theoretically examine the range of particle sizes that can be captured in fluid streamlines using this technique, with rapid particle concentration demonstrated down to 300 nm diameters. We also demonstrate that locations of trapping and concentration are size-dependent, which is attributed to the combined effects of the acoustic streaming and acoustic forces.

  14. Influence of short chain organic acids and bases on the wetting properties and surface energy of submicrometer ceramic powders.

    Science.gov (United States)

    Neirinck, Bram; Soccol, Dimitri; Fransaer, Jan; Van der Biest, Omer; Vleugels, Jef

    2010-08-15

    The effect of short chained organic acids and bases on the surface energy and wetting properties of submicrometer alumina powder was assessed. The surface chemistry of treated powders was determined by means of Diffuse Reflectance Infrared Fourier Transform spectroscopy and compared to untreated powder. The wetting of powders was measured using a modified Washburn method, based on the use of precompacted powder samples. The geometric factor needed to calculate the contact angle was derived from measurements of the porous properties of the powder compacts. Contact angle measurements with several probe liquids before and after modification allowed a theoretical estimation of the surface energy based on the surface tension component theory. Trends in the surface energy components were linked to observations in infrared spectra. The results showed that the hydrophobic character of the precompacted powder depends on both the chain length and polar group of the modifying agent. Copyright 2010 Elsevier Inc. All rights reserved.

  15. Slip casting nano-particle powders for making transparent ceramics

    Science.gov (United States)

    Kuntz, Joshua D [Livermore, CA; Soules, Thomas F [Livermore, CA; Landingham, Richard Lee [Livermore, CA; Hollingsworth, Joel P [Oakland, CA

    2011-04-12

    A method of making a transparent ceramic including the steps of providing nano-ceramic powders in a processed or unprocessed form, mixing the powders with de-ionized water, the step of mixing the powders with de-ionized water producing a slurry, sonifing the slurry to completely wet the powder and suspend the powder in the de-ionized water, separating very fine particles from the slurry, molding the slurry, and curing the slurry to produce the transparent ceramic.

  16. An integrated experimental-modeling approach to study the acid leaching behavior of lead from sub-micrometer lead silicate glass particles

    Energy Technology Data Exchange (ETDEWEB)

    Elteren, Johannes T. van, E-mail: elteren@ki.si [Analytical Chemistry Laboratory, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); Grilc, Miha [Laboratory of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); Beeston, Michael P. [Analytical Chemistry Laboratory, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); TSI GmbH, Neuköllner Str. 4, 52068 Aachen (Germany); Reig, Milagros Santacatalina [General Foundation, University of Alicante, E-03690 San Vicente del Raspeig (Alicante) (Spain); Department of Chemical Engineering, University of Alicante, P.O. Box 99, E-03080 Alicante (Spain); Grgić, Irena [Analytical Chemistry Laboratory, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia)

    2013-11-15

    Highlights: • Generation of particles by laser ablation of lead silicate glass. • Collection of particles on filters and continuous acid leaching and ICP-MS monitoring. • Fitting of the lead leaching profile to a mathematical intraparticle diffusion model. • Extraction of individual leaching profiles for selected mono-dispersed size fractions. • Leaching kinetics is based on ion-exchange and correlated with particle size. -- Abstract: This work focuses on the development of a procedure to study the mechanism of leaching of lead from sub-micrometer lead glass particles using 0.3 mol l{sup −1} HNO{sub 3} as a leachant. Glass particles with an effective size distribution range from 0.05 to 1.4 μm were generated by laser ablation (213 nm Nd:YAG laser) and collected on an inline 0.2 μm syringe filter. Subsequently, the glass particles on the filter were subjected to online leaching and continuous monitoring of lead (Pb-208) in the leachate by quadrupole ICP-MS. The lead leaching profile, aided by the particle size distribution information from cascade impaction, was numerically fitted to a mathematical model based on the glass intraparticle diffusion, liquid film distribution and thermodynamic glass-leachant distribution equilibrium. The findings of the modeling show that the rate-limiting step of leaching is the migration of lead from the core to the surface of the glass particle by an ion-exchange mechanism, governed by the apparent intraparticle lead diffusivity in glass which was calculated to be 3.1 × 10{sup −18} m{sup 2} s{sup −1}. Lead leaching is illustrated in the form of graphs and animations of intraparticle lead release (in time and intraparticle position) from particles with sizes of 0.1 and 0.3 μm.

  17. Fragment and particle size distribution of impacted ceramic tiles

    NARCIS (Netherlands)

    Carton, E.P.; Weerheijm, J.; Ditzhuijzen, C.; Tuinman, I.

    2014-01-01

    The fragmentation of ceramic tiles under ballistic impact has been studied. Fragments and aerosol (respirable) particles were collected and analyzed to determine the total surface area generated by fracturing (macro-cracking and comminution) of armor grade ceramics. The larger fragments were

  18. Particle-induced amorphization complex ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, R.C.; Wang, Lu-Min

    1996-02-16

    The presently funded three-year research program, supported by the Division of Materials Sciences of the Office of Basic Energy Sciences, was initiated on August 1, 1993; during the period in which the grant will have been active, $249,561 of support have been provided to date with an additional $79,723 to be spent during the third, final year (ending July 30, 1996). The primary purpose of the program is to develop an understanding of heavy-particle radiation effects -- {alpha}-recoil nuclei, fission fragments, ion-irradiations -- on ceramic materials and the thermal annealing mechanisms by which crystallinity might be restored. During the past two years, we have completed major studies on zircon (ZrSiO{sub 4}), olivine (Mg{sub 2}SiO{sub 4} and ten other compositions), spinel (MgAl{sub 2}O{sub 4} and four other compositions), and silica polymorphs (quartz, coesite and stishovite), as well as berlinite (AlPO{sub 4}) which is isomorphous with quartz. In addition, based on the above research, we propose the use of zircon as a host phase for the immobilization of plutonium resulting from weapons dismantlement.

  19. Native and thermally modified protein-polyphenol coassemblies: lactoferrin-based nanoparticles and submicrometer particles as protective vehicles for (-)-epigallocatechin-3-gallate.

    Science.gov (United States)

    Yang, Wei; Xu, Chenqi; Liu, Fuguo; Yuan, Fang; Gao, Yanxiang

    2014-11-05

    The interactions between native, thermally modified lactoferrin (LF) and (-)-epigallocatechin-3-gallate (EGCG) at pH 3.5, 5.0, and 6.5 were investigated. Turbidity, particle size, and charge of LF-EGCG complexes were mainly dominated by pH value and secondary structure of protein. At pH 3.5 and 5.0, LF-EGCG complexes were nanoparticles which had high ζ-potential, small size, and soluble state. At pH 6.5, they were submicrometer particles which exhibited low ζ-potential, large size, and insoluble state. The infrared spectra of freeze-dried LF-EGCG complexes showed that they were different from LF and EGCG alone. Far-UV CD results indicated that heat denaturation might irreversibly alter the secondary structure of LF and EGCG induced a progressive increase in the proportion of α-helix structure at the cost of β-sheet and unordered coil structure of LF at pH 3.5, 5.0, and 6.5. EGCG exhibited a strong affinity for native LF but a weak affinity for thermally modified LF at pH 5.0 and 6.5. An inverse result was observed at pH 3.5. These results could have potential for the development of food formulations based on LF as a carrier of bioactive compounds.

  20. The Particle Distribution in Liquid Metal with Ceramic Particles Mould Filling Process

    Science.gov (United States)

    Dong, Qi; Xing, Shu-ming

    2017-09-01

    Adding ceramic particles in the plate hammer is an effective method to increase the wear resistance of the hammer. The liquid phase method is based on the “with the flow of mixed liquid forging composite preparation of ZTA ceramic particle reinforced high chromium cast iron hammer. Preparation method for this system is using CFD simulation analysis the particles distribution of flow mixing and filling process. Taking the 30% volume fraction of ZTA ceramic composite of high chromium cast iron hammer as example, by changing the speed of liquid metal viscosity to control and make reasonable predictions of particles distribution before solidification.

  1. Process for making ultra-fine ceramic particles

    Science.gov (United States)

    Stangle, Gregory C.; Venkatachari, Koththavasal R.; Ostrander, Steven P.; Schulze, Walter A.

    1995-01-01

    A process for producing ultra-fine ceramic particles in which droplets are formed from a ceramic precursor mixture containing a metal cation, a nitrogen-containing fuel, a solvent, and an anion capable of participating in an anionic oxidation-reduction reaction with the nitrogen containing fuel. The nitrogen-containing fuel contains at least three nitrogen atoms, at least one oxygen atom, and at least one carbon atom. The ceramic precursor mixture is dried to remove at least 85 weight percent of the solvent, and the dried mixture is then ignited to form a combusted powder.

  2. Hygroscopic properties of submicrometer atmospheric aerosol particles measured with H-TDMA instruments in various environments-a review

    Science.gov (United States)

    Swietlicki, E.; Hansson, H.-C.; Hämeri, K.; Svenningsson, B.; Massling, A.; McFiggans, G.; McMurry, P. H.; Petäjä, T.; Tunved, P.; Gysel, M.; Topping, D.; Weingartner, E.; Baltensperger, U.; Rissler, J.; Wiedensohler, A.; Kulmala, M.

    2008-07-01

    The hygroscopic properties play a vital role for the direct and indirect effects of aerosols on climate, as well as the health effects of particulate matter (PM) by modifying the deposition pattern of inhaled particles in the humid human respiratory tract. Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA) instruments have been used in field campaigns in various environments globally over the last 25 yr to determine the water uptake on submicrometre particles at subsaturated conditions. These investigations have yielded valuable and comprehensive information regarding the particle hygroscopic properties of the atmospheric aerosol, including state of mixing. These properties determine the equilibrium particle size at ambient relative humidities and have successfully been used to calculate the activation of particles at water vapour supersaturation. This paper summarizes the existing published H-TDMA results on the size-resolved submicrometre aerosol particle hygroscopic properties obtained from ground-based measurements at multiple marine, rural, urban and free tropospheric measurement sites. The data is classified into groups of hygroscopic growth indicating the external mixture, and providing clues to the sources and processes controlling the aerosol. An evaluation is given on how different chemical and physical properties affect the hygroscopic growth.

  3. Different immunomodulatory effects associated with sub-micrometer particles in ambient air from rural, urban and industrial areas.

    Science.gov (United States)

    Wichmann, Gunnar; Franck, Ulrich; Herbarth, Olf; Rehwagen, Martina; Dietz, Andreas; Massolo, Laura; Ronco, Alicia; Müller, Andrea

    2009-03-29

    Immunomodulatory effects of chemicals adsorbed to particles with aerodynamic diameter below 0.49 microm (PM(0.5)) collected in winter 2001 at three sampling points (industrial area [LPIn], traffic-influenced urban area [LPCi], and control area [LPCo]) of La Plata, Argentina, were investigated. The sampling of particulate matter was carried out with high-volume collectors using cascade impactors. PM(0.5)-adsorbed compounds were hexane-extracted by accelerated solvent extraction. For immunological investigations, human peripheral blood lymphocytes were activated by phytohemagglutinin and exposed to dimethyl-sulfoxide dilutions of PM(0.5)-extracts for 24h. Vitality/proliferation was quantified using MTT, released interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) by ELISA. Cytokine production but not vitality/proliferation was significantly suppressed by all of the highest extract concentrations. Generally, suppression of IFN-gamma by PM(0.5)-extracts was stronger than those of IL-4. Based on administered mass of PM(0.5), all extracts suppressed IFN-gamma production nearly uniform. Contrary, LPCi-extracts exerted maximum IFN-gamma suppression based either on air volume or regarding PM(0.5)-adsorbed PAH. Also the ranking of PM(0.5)-associated effects on IL-4 production differs in dependence of the chosen reference points, either mass or [microg/ml] or air volume [m(3)/ml] related dust quantities in cell culture. Based on the corresponding air volume, LPCi-extracts inhibited IL-4 production to the maximum extend, whereas suppression of IL-4 was comparable based on concentrations. This indicates that not only the disparate PM(0.5)-masses in air cause varying impacts, but also that disparities in PM(0.5)-adsorbed chemicals provoke different effects on immune responses and shifts in the regulatory balance that might have implications for allergy and cancer development.

  4. Metal particles in a ceramic matrix--scanning electron microscopy and transmission electron microscopy characterization.

    Science.gov (United States)

    Konopka, K

    2006-09-01

    This paper is concerned with ceramic matrix (Al(2)O(3)) composites with introduced metal particles (Ni, Fe). The composites were obtained via sintering of powders under very high pressure (2.5 GPa). Scanning electron microscopy and transmission electron microscopy were chosen as the tools for the identification and description of the shape, size and distribution of the metal particles. The Al(2)O(3)-Ni composite contained agglomerates of the Ni particles surrounded by ceramic grains and nanometre-size Ni particles located inside the ceramic grains and at the ceramic grain boundaries. In the Al(2)O(3)-Fe composite, the Fe particles were mostly surrounded by ceramic grains. Moreover, holes left by the Fe particles were found. The high pressure used in the fabrication of the composites changed the shape of the metal and ceramic powder grains via plastic deformation.

  5. Effect of etching and airborne particle abrasion on the microstructure of different dental ceramics.

    Science.gov (United States)

    Borges, Gilberto Antonio; Sophr, Ana Maria; de Goes, Mario Fernando; Sobrinho, Lourenço Correr; Chan, Daniel C N

    2003-05-01

    The ceramic composition and microstructure surface of all-ceramic restorations are important components of an effective bonding substrate. Both hydrofluoric acid etching and airborne aluminum oxide particle abrasion produce irregular surfaces necessary for micromechanical bonding. Although surface treatments of feldspathic and leucite porcelains have been studied previously, the high alumina-containing and lithium disilicate ceramics have not been fully investigated. The purpose of this study was to assess the surface topography of 6 different ceramics after treatment with either hydrofluoric acid etching or airborne aluminum oxide particle abrasion. Five copings each of IPS Empress, IPS Empress 2 (0.8 mm thick), Cergogold (0.7 mm thick), In-Ceram Alumina, In-Ceram Zirconia, and Procera (0.8 mm thick) were fabricated following the manufacturer's instructions. Each coping was longitudinally sectioned into 4 equal parts by a diamond disk. The resulting sections were then randomly divided into 3 groups depending on subsequent surface treatments: Group 1, specimens without additional surface treatments, as received from the laboratory (control); Group 2, specimens treated by use of airborne particle abrasion with 50-microm aluminum oxide; and Group 3, specimens treated with 10% hydrofluoric acid etching (20 seconds for IPS Empress 2; 60 seconds for IPS Empress and Cergogold; and 2 minutes for In-Ceram Alumina, In-Ceram Zirconia, and Procera). Airborne particle abrasion changed the morphologic surface of IPS Empress, IPS Empress 2, and Cergogold ceramics. The surface topography of these ceramics exhibited shallow irregularities not evident in the control group. For Procera, the 50-microm aluminum oxide airborne particle abrasion produced a flattened surface. Airborne particle abrasion of In-Ceram Alumina and In-Ceram Zirconia did not change the morphologic characteristics and the same shallows pits found in the control group remained. For IPS Empress 2, 10% hydrofluoric

  6. QUANTITATIVE ANALYSIS FOR SHAPE IRREGULARITY OF CERAMIC PARTICLES BASED ON RICHARDSON EFFECT

    OpenAIRE

    Tatsuo, SAKAI; Masashi, FUJIKAWA; Suzie, LAURICH-McINTYRE; Richard C., BRADT; Department of Mechanica Engineering, Ritsumeikan University; Graduate School of Science and Engineering, Ritsumeikan University; Ceramic Tooling Division, PYRO MEDIA; Department of Metallurgical and Materials Engineering, University of Alabama

    1996-01-01

    Quanitative analysis for the shape irregularity of ceramic particles was performed by applying the concept of"Fractal"proposed by B. B. Mandelbrot. Two types of ceramic particles processed by different methods were employed as samples. Silhouette of each particle was repcatedly observed along 3-dimensional Cartesian axes, and then Richardson effect of the configuration of the respective silhouette was normalized by the perimeter. In this normalized Richardson effect, a characteristic aspect c...

  7. Particle Swarm Optimization approach to defect detection in armour ceramics.

    Science.gov (United States)

    Kesharaju, Manasa; Nagarajah, Romesh

    2017-03-01

    In this research, various extracted features were used in the development of an automated ultrasonic sensor based inspection system that enables defect classification in each ceramic component prior to despatch to the field. Classification is an important task and large number of irrelevant, redundant features commonly introduced to a dataset reduces the classifiers performance. Feature selection aims to reduce the dimensionality of the dataset while improving the performance of a classification system. In the context of a multi-criteria optimization problem (i.e. to minimize classification error rate and reduce number of features) such as one discussed in this research, the literature suggests that evolutionary algorithms offer good results. Besides, it is noted that Particle Swarm Optimization (PSO) has not been explored especially in the field of classification of high frequency ultrasonic signals. Hence, a binary coded Particle Swarm Optimization (BPSO) technique is investigated in the implementation of feature subset selection and to optimize the classification error rate. In the proposed method, the population data is used as input to an Artificial Neural Network (ANN) based classification system to obtain the error rate, as ANN serves as an evaluator of PSO fitness function. Copyright © 2016. Published by Elsevier B.V.

  8. About scavenging of near-water submicrometer aerosol in Arctic and Sub-Arctic regions

    Science.gov (United States)

    Polkin, V. V.; Polkin, Vas. V.

    2014-11-01

    Situations with scavenging of submicrometer aerosol particles by precipitation are analyzed. Experiments were carries out in Arctic region (NABOS expedition) onboard research vessels "Akademik Fedorov" and "Professor Khlyustin" in August-September 2013.

  9. Effect of different air-abrasion particles on metal-ceramic bond strength

    OpenAIRE

    Külünk, Tolga; Kurt, Murat; Ural, Çağrı; Külünk, Şafak; Baba, Seniha

    2011-01-01

    Background/purpose: Chipping and delaminating of veneering ceramics are critical problems in the fabrication of metal-ceramic restorations. The purpose of this study was to evaluate the effect of different air-abrasion particles on the shear bond strength of a ceramic to nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloys. Materials and methods: Forty square specimens (10 mm × 10 mm × 1.5 mm) were cast for each Ni-Cr and Co-Cr alloys. Specimens were divided into four groups for the ...

  10. ON THE EFFECT OF NANO-PARTICLE CLUSTERING ON TOUGHENING OF NANO-COMPOSITE CERAMICS

    Institute of Scientific and Technical Information of China (English)

    董照旭; 方岱宁; 苏爱嘉

    2002-01-01

    In this paper, two and three-dimensional clustering models are developed to characterize the effect of nano-particle clustering on toughening of nanocomposite ceramics. It is found that crack pinning toughens the nano-composite ceramics because a higher stress intensity factor is needed for crack to propagate around or to pull-out the nano-particle. The nano-particle along the grain boundary steers the crack into the matrix grain due to the strong cohesion between the nanoparticle and the matrix. Since the fracture resistance of the grain boundary is lower than that of the grain lattice, the higher the probability of transgranular fracture induced by nano-particles, the tougher is the nano-composite. However, both crack pinning and transgranular fracture are affected by nano-particle clustering. Nanoparticle clustering, which increases with increasing volume fraction of nano-particles,leads to reduction of both the strength and toughness of the nano-composite ceramics. The larger the size of the clustered particle, and the more defects it contains, the easier it is for the crack to pass through the clustered particle, which means that the nano-particle clustering can reduce toughening induced by crack pinning and transgranular fracture. The theoretical prediction, based on the combination of the three mechanisms of nano-particles, is in agreement with the experimental data.

  11. Effect of particle size on osteoinductive potential of microstructured biphasic calcium phosphate ceramic.

    Science.gov (United States)

    Wang, Liao; Barbieri, Davide; Zhou, Hongyu; de Bruijn, Joost D; Bao, Chongyun; Yuan, Huipin

    2015-06-01

    Material factors such as chemistry, surface microstructure and geometry have shown their influence on osteoinduction of calcium phosphate ceramics. Hereby we report that osteoinduction of a micro-structured biphasic calcium phosphate ceramic (BCP) has a relation with the particle sizes. BCP particles with the size of 212-300 µm, 106-212 µm, 45-106 µm, and smaller than 45 µm were prepared and implanted in paraspinal muscle of dogs for 12 weeks. Histological evaluation of the explants showed abundant bone in all samples with particle size of 212-300 µm, 106-212 µm, and 45-106 µm, while no bone was seen in any sample having particle size smaller than 45 µm. Bone was formed as early as 3 weeks after implantation in implants having BCP particles bigger than 45 µm and the volume of the formed bone was similar among the implants with particles larger than 45 µm after 12 weeks implantation. The results herein show that a size limitation of microstructured calcium phosphate ceramic particles for osteoinduction. It is most likely that the particle size affect inductive bone formation via macroporous structures for body fluid infiltration, cell/tissue ingrowth and angiogenesis. © 2014 Wiley Periodicals, Inc.

  12. Seasonal Variations in Health Hazards from Polycyclic Aromatic Hydrocarbons Bound to Submicrometer Particles at Three Characteristic Sites in the Heavily Polluted Polish Region

    Directory of Open Access Journals (Sweden)

    Barbara Kozielska

    2014-12-01

    Full Text Available Suspended particles with aerodynamic diameters not greater than 1 μm (PM1 were sampled at the urban background; regional background; and urban traffic points in southern Poland. In total, 120 samples were collected between 2 August 2009 and 27 December 2010. Sixteen polycyclic aromatic hydrocarbons (PAHs were determined in each sample. The samples were collected with a high volume sampler (Digitel. Afterwards, they were chemically analyzed with a gas chromatograph equipped with a flame ionization detector (Perkin Elmer Clarus 500. The mean concentration values of the PAH sum (ΣPAH and particular PAHs; the percentages of carcinogenic PAHs in total PAHs (ΣPAHcarc/ΣPAH; carcinogenic equivalent (CEQ; mutagenic equivalent (MEQ; and TCDD-toxic equivalent (TEQ were much higher in the winter (heating season than in the summer (non-heating one. For both periods, the resulting average values obtained were significantly higher (a few; and sometimes a several dozen times higher in the researched Polish region than the values observed in other areas of the world. Such results indicate the importance of health hazards resulting from PM1 and PM1-bound PAHs in this Polish area.

  13. Behavior of micro-particles in monolith ceramic membrane filtration with pre-coagulation.

    Science.gov (United States)

    Yonekawa, H; Tomita, Y; Watanabe, Y

    2004-01-01

    This paper is intended to clarify the characteristics unique to monolith ceramic membranes with pre-coagulation by referring to the behavior of micro-particles. Flow analysis and experiments have proved that monolith ceramic membranes show a unique flow pattern in the channels within the element, causing extremely rapid flocculation in the channel during dead-end filtration. It was assumed that charge-neutralized micro-particles concentrated near the membrane surface grow in size due to flocculation, and as a result, coarse micro-particles were taken up by the shearing force to flow out. As the dead end points of flow in all the channels are located near the end of the channels with higher filterability, most of the flocculated coarse particles are formed to a columnar cake intensively at the dead end point. Therefore cake layer forming on the membrane other than around the dead end point is alleviated. This behavior of particle flocculation and cake formation at the dead end point within the channels are unique characteristics of monolith ceramic membranes. This is why all monolith ceramic membrane water purification systems operating in Japan do not have pretreatment equipment for flocculation and sedimentation.

  14. Thermal Protection of Carbon Fiber-Reinforced Composites by Ceramic Particles

    Directory of Open Access Journals (Sweden)

    Baljinder Kandola

    2016-06-01

    Full Text Available The thermal barrier efficiency of two types of ceramic particle, glass flakes and aluminum titanate, dispersed on the surface of carbon-fiber epoxy composites, has been evaluated using a cone calorimeter at 35 and 50 kW/m2, in addition to temperature gradients through the samples’ thicknesses, measured by inserting thermocouples on the exposed and back surfaces during the cone tests. Two techniques of dispersing ceramic particles on the surface have been employed, one where particles were dispersed on semi-cured laminate and the other where their dispersion in a phenolic resin was applied on the laminate surface, using the same method as used previously for glass fiber composites. The morphology and durability of the coatings to water absorption, peeling, impact and flexural tension were also studied and compared with those previously reported for glass-fiber epoxy composites. With both methods, uniform coatings could be achieved, which were durable to peeling or water absorption with a minimal adverse effect on the mechanical properties of composites. While all these properties were comparable to those previously observed for glass fiber composites, the ceramic particles have seen to be more effective on this less flammable, carbon fiber composite substrate.

  15. Coatings with laser melt injection of ceramic particles

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Ocelik, V.; de Oliveira, U.; Seal, S; Dahotre, NB; Moore, JJ; Suryanarayana, C; Agarwal, A

    2003-01-01

    The conditions for a successful Laser Melt Injection (LMI) of SiC and WC particles into the melt pool of Al8Si and Ti6Al4V alloys were studied experimentally and theoretically by FEM calculations. The laser employed is a high power Nd:YAG The formation of a relatively thick aluminium oxide layer on

  16. Nanopore fabrication by heating au particles on ceramic substrates

    NARCIS (Netherlands)

    de Vreede, Lennart; van den Berg, Albert; Eijkel, Jan C.T.

    2015-01-01

    We found that gold nanoparticles, when heated to close to their melting point on substrates of amorphous SiO2 or amorphous Si3N4, move perpendicularly into the substrate. Dependent on applied temperatures, particles can become buried or leave nanopores of extreme aspect ratio (diameter congruent to

  17. Investigation into the morphology, composition, structure and dry tribological behavior of rice husk ceramic particles

    Science.gov (United States)

    Hu, Enzhu; Hu, Kunhong; Xu, Zeyin; Hu, Xianguo; Dearn, Karl David; Xu, Yong; Xu, Yufu; Xu, Le

    2016-03-01

    To expand the application of rice husk (RH) resource, this study developed carbon-based RH ceramic (RHC) particles using a common high-temperature carbonization method. The morphology, composition, and structure of the RHC particles were characterized with a series of modern analysis technologies and were then compared with those of the initial RH powder and carbonized RH (CRH) particles. The dry tribological behavior of RHC particle adobes (RHAs) was also investigated. Results showed the sheet-shaped morphology of the RHC particles. The graphitization degree of the RHC particles was lower than that of the CRH particles possibly because the phenolic resin (PR) filled the micro-pores of the RH particles, thereby prompting the formation of amorphous carbon in the RHC particles as a result of high-temperature carbonization. The appearance of a hydroxy function group (sbnd OH) on the surface of the RHC particles was ascribed to the decomposition of PR at 900 °C. The friction coefficients and mass loss rates of the RHAs almost increased with the rise in load and velocity. In addition, the friction coefficients of the RHAs decreased at high load (5 N) and velocity (0.261 m/s) conditions. Such outcome indicated that the variation of contact area between steel ball and RHA at high load and velocity conditions resulted in the abrasive wear or catastrophic wear.

  18. Hydrogen template assisted electrodeposition of sub-micrometer wires composing honeycomb-like porous Pb films

    Science.gov (United States)

    Cherevko, Serhiy; Xing, Xiaoli; Chung, Chan-Hwa

    2011-07-01

    High surface area porous Pb films are electrodeposited using a hydrogen bubble dynamic template. The influence of the experimental parameters on the morphology features such as the pore size, wall thickness, and sub-micrometer size features is investigated. Two structural transformations between sub-micrometer wires and particles obtained by adjusting the HClO4 concentration are observed. At a low HClO4 concentration, the growth of sub-micrometer wires is favored. The deposition of particles or wires covered by particles is observed at higher H+ concentrations. The addition of sodium citrate as an additive facilitates the preservation of Pb in the form of wires. Adjusting the concentration of Pb(ClO4)2·3H2O influences the mass transfer of Pb and affects its morphology. At low concentrations, the deposition of porous Pb films composed of porous wires is shown. The additional deposition of particles on wires is observed at high concentrations. The formation process of honeycomb-like porous structures is revealed by analysis of films deposited during different deposition time. The influence of the current density on the micro and sub-micrometer scale morphologies is presented.

  19. In-flight behavior of dissimilar co-injected particles in the spraying of metal-ceramic functionally gradient materials

    Energy Technology Data Exchange (ETDEWEB)

    Fincke, J.R.; Swank, W.D.; Haggard, D.C. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1997-12-31

    In the spraying of functionally gradient coatings the particle ensemble delivered to the substrate can vary from a relatively low melting point metallic particle to a significantly higher melting point ceramic particle. At various stages in the spray process the particle ensemble can be either predominantly metallic, ceramic, or an intermediate combination. For co-injected particles the mixtures do not behave as a simple linear superposition of the spray patterns of the individual particle types. The particle temperature, velocity, size distributions, and pattern characteristics of the resulting spray fields is examined for all ceramic particle sprays (ZrO{sub 2}), all metallic particle sprays (NiCrAlY), and for a 1:1 mixture. The major particle-particle interaction occurs in the injector itself and results in a modified spray pattern which is different from that of either material sprayed alone. The particle velocity distributions generally exhibit a bimodal nature which is dependent on the size and density of the injected particles.

  20. Mutation particle swarm optimization of the BP-PID controller for piezoelectric ceramics

    Science.gov (United States)

    Zheng, Huaqing; Jiang, Minlan

    2016-01-01

    PID control is the most common used method in industrial control because its structure is simple and it is easy to implement. PID controller has good control effect, now it has been widely used. However, PID method has a few limitations. The overshoot of the PID controller is very big. The adjustment time is long. When the parameters of controlled plant are changing over time, the parameters of controller could hardly change automatically to adjust to changing environment. Thus, it can't meet the demand of control quality in the process of controlling piezoelectric ceramic. In order to effectively control the piezoelectric ceramic and improve the control accuracy, this paper replaced the learning algorithm of the BP with the mutation particle swarm optimization algorithm(MPSO) on the process of the parameters setting of BP-PID. That designed a better self-adaptive controller which is combing the BP neural network based on mutation particle swarm optimization with the conventional PID control theory. This combination is called the MPSO-BP-PID. In the mechanism of the MPSO, the mutation operation is carried out with the fitness variance and the global best fitness value as the standard. That can overcome the precocious of the PSO and strengthen its global search ability. As a result, the MPSO-BP-PID can complete controlling the controlled plant with higher speed and accuracy. Therefore, the MPSO-BP-PID is applied to the piezoelectric ceramic. It can effectively overcome the hysteresis, nonlinearity of the piezoelectric ceramic. In the experiment, compared with BP-PID and PSO-BP-PID, it proved that MPSO is effective and the MPSO-BP-PID has stronger adaptability and robustness.

  1. Dynamic competitive adsorption of bone-related proteins on calcium phosphate ceramic particles with different phase composition and microstructure.

    Science.gov (United States)

    Wang, Jing; Zhang, Huijie; Zhu, Xiangdong; Fan, Hongsong; Fan, Yujiang; Zhang, Xingdong

    2013-08-01

    The biocompatibility and bioactivity of biomaterials used for hard tissue repair are closely related to their adsorption capacities for bone-related proteins. In the present study, three types of calcium phosphate (CaP) ceramic particles with different phase composition or microstructure were fabricated, and their protein adsorption abilities were investigated by a self-made device under the simulated dynamic physiological circumstance. The results of X-ray diffraction, field emission scanning electron microscopy, mercury penetration test, and nitrogen sorption test showed that the irregular hydroxyapatite (HA) ceramic particles obtained by conventional drying and sintering (named as HA-C) had fewer micropores and lower specific surface area (SSA) than did the spherical HA or biphasic calcium phosphate (BCP) ceramic particles made by spray drying and sintering (named as HA-S and BCP-S, respectively). The dynamic protein adsorption study proved that both the phase composition and microstructure of CaP ceramic particles affected their adsorption capacities for those bone-related proteins. The spherical HA-S and BCP-S particles with abundant micropores and high SSA showed higher adsorption of serum proteins, including fibronectin and vitronectin, than the irregular HA-C did. On the other hand, in spite of the relatively high concentration of bovine serum albumin (BSA) in the binary bone morphogenetic protein 2 (BMP-2)/BSA solution, BMP-2 adsorption on the three CaP ceramic particles increased with the increase in its initial concentration. Similarly, HA-S and BCP-S particles had a larger amount of the adsorbed BMP-2 per gram solid than HA-C did. Therefore, it could be believed that the difference of various CaP ceramics in the phase composition and microporous structure would affect their binding capacity for those bone-related proteins and thus lead to their difference in osteoinduction. Copyright © 2013 Wiley Periodicals, Inc.

  2. Localized dispersing of ceramic particles in tool steel surfaces by pulsed laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hilgenberg, K., E-mail: hilgenberg@uni-kassel.de [Metal Forming Technology, University of Kassel (Germany); Behler, K. [Laser Technology, THM University of Applied Sciences (Germany); Steinhoff, K. [Metal Forming Technology, University of Kassel (Germany)

    2014-06-01

    In this paper the capability of a localized laser dispersing technique for changing the material microstructure and the surface topology of steels is discussed. The laser implantation named technique bases on a discontinuous dispersing of ceramic particles into the surface of steels by using pulsed laser radiation. As ceramic particles TiC, WC and TiB{sub 2} are used, substrate material is high-alloyed cold working steel (X153CrMoV12). The influence of the laser parameters pulse length and pulse intensity was investigated in a comprehensive parameter study. The gained surface topology and microstructure were evaluated by optical microscopy, energy dispersive X-ray spectroscopy (EDX) and white light interferometry; mechanical properties were analyzed by micro hardness measurement. The experiments reveal that the alignment of separated, elevated, dome-shaped spots on the steel surface is feasible. The geometrical properties as well as the mechanical properties are highly controllable by the laser parameters. The laser implanted spots show a mostly crack-free and pore-free bonding to the substrate material as well as a significant increase of micro hardness.

  3. Localized dispersing of ceramic particles in tool steel surfaces by pulsed laser radiation

    Science.gov (United States)

    Hilgenberg, K.; Behler, K.; Steinhoff, K.

    2014-06-01

    In this paper the capability of a localized laser dispersing technique for changing the material microstructure and the surface topology of steels is discussed. The laser implantation named technique bases on a discontinuous dispersing of ceramic particles into the surface of steels by using pulsed laser radiation. As ceramic particles TiC, WC and TiB2 are used, substrate material is high-alloyed cold working steel (X153CrMoV12). The influence of the laser parameters pulse length and pulse intensity was investigated in a comprehensive parameter study. The gained surface topology and microstructure were evaluated by optical microscopy, energy dispersive X-ray spectroscopy (EDX) and white light interferometry; mechanical properties were analyzed by micro hardness measurement. The experiments reveal that the alignment of separated, elevated, dome-shaped spots on the steel surface is feasible. The geometrical properties as well as the mechanical properties are highly controllable by the laser parameters. The laser implanted spots show a mostly crack-free and pore-free bonding to the substrate material as well as a significant increase of micro hardness.

  4. Influence of glass particle size of resin cements on bonding to glass ceramic: SEM and bond strength evaluation.

    Science.gov (United States)

    Valentini, Fernanda; Moraes, Rafael R; Pereira-Cenci, Tatiana; Boscato, Noéli

    2014-05-01

    This study investigated the effect of the filler particle size (micron or submicron) of experimental resin cements on the microtensile bond strength to a glass-ceramic pretreated with hydrofluoric acid (HFA) etching or alumina airborne-particle abrasion (AA). Cements were obtained from a Bis-GMA/TEGDMA mixture filled with 60 mass% micron-sized (1 ± 0.2 µm) or submicron-sized (180 ± 30 µm) Ba-Si-Al glass particles. Ceramic blocks (PM9; VITA) were treated with 10% HFA for 60 s or AA for 15 s. Silane and adhesive were applied. Ceramic blocks were bonded to resin composite blocks (Z250; 3M ESPE) using one of the cements. Bonded specimens were sectioned into beams (n = 20/group) and subjected to microtensile bond strength tests. Data were analyzed using ANOVA and Student-Newman-Keuls' tests (5%). Failure modes were classified under magnification. Morphologies of the treated ceramic surfaces and bonded interfaces were evaluated by scanning electron microscopy. The HFA-submicron group had lower bond strengths than the other groups. All AA-submicron specimens debonded prematurely. Mixed failures were predominant for HFA groups, whereas interfacial failures predominated for AA groups. SEM revealed a honeycomb-like aspect in the HFA-treated ceramic, whereas the AA-treated groups showed an irregular retentive pattern. Continuity of cement infiltration along the bonded interface was more uniform for HFA-treated compared to AA-treated specimens. Cracks toward the bulk of the ceramic were observed in AA-treated specimens. Particle size significantly influenced the ceramic bond strength, whereas surface treatment had a minor effect. Copyright © 2014 Wiley Periodicals, Inc.

  5. Effects of silica and calcium levels in nanobioglass ceramic particles on osteoblast proliferation.

    Science.gov (United States)

    Moorthi, A; Parihar, P R; Saravanan, S; Vairamani, M; Selvamurugan, N

    2014-10-01

    At nanoscale, bioglass ceramic (nBGC) particles containing calcium oxide (lime), silica and phosphorus pentoxide promote osteoblast proliferation. However, the role of varied amounts of calcium and silica present in nBGC particles on osteoblast proliferation is not yet completely known. Hence, the current work was aimed at synthesizing two different nBGC particles with varied amounts of calcium oxide and silica, nBGC-1: SiO2:CaO:P2O5; mol%~70:25:5 and nBGC-2: SiO2:CaO:P2O5; mol%~64:31:5, and investigating their role on osteoblast proliferation. The synthesized nBGC particles were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies. They exhibited their size at nanoscale and were non-toxic to human osteoblastic cells (MG-63). The nBGC-2 particles were found to have more effect on stimulation of osteoblast proliferation and promoted entering of more cells into G2/M cell cycle phase compared to nBGC-1 particles. There was a differential expression of cyclin proteins in MG-63 cells by nBGC-1 and nBGC-2 treatments, and the expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment. Thus, these results provide us a new insight in understanding the design of various nBGC particles by altering their ionic constituents with desirable biological properties thereby supporting bone augmentation. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Effects of silica and calcium levels in nanobioglass ceramic particles on osteoblast proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Moorthi, A.; Parihar, P.R.; Saravanan, S.; Vairamani, M.; Selvamurugan, N., E-mail: selvamurugan.n@ktr.srmuniv.ac.in

    2014-10-01

    At nanoscale, bioglass ceramic (nBGC) particles containing calcium oxide (lime), silica and phosphorus pentoxide promote osteoblast proliferation. However, the role of varied amounts of calcium and silica present in nBGC particles on osteoblast proliferation is not yet completely known. Hence, the current work was aimed at synthesizing two different nBGC particles with varied amounts of calcium oxide and silica, nBGC-1: SiO{sub 2}:CaO:P{sub 2}O{sub 5}; mol% ∼ 70:25:5 and nBGC-2: SiO{sub 2}:CaO:P{sub 2}O{sub 5}; mol% ∼ 64:31:5, and investigating their role on osteoblast proliferation. The synthesized nBGC particles were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies. They exhibited their size at nanoscale and were non-toxic to human osteoblastic cells (MG-63). The nBGC-2 particles were found to have more effect on stimulation of osteoblast proliferation and promoted entering of more cells into G2/M cell cycle phase compared to nBGC-1 particles. There was a differential expression of cyclin proteins in MG-63 cells by nBGC-1 and nBGC-2 treatments, and the expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment. Thus, these results provide us a new insight in understanding the design of various nBGC particles by altering their ionic constituents with desirable biological properties thereby supporting bone augmentation. - Highlights: • nBGC particles with varied amounts of calcium and silica were synthesized. • They were non-toxic to human osteoblastic cells. • nBGC-2 particles had more effect on stimulation of osteoblast proliferation. • nBGC-2 particles promoted entering of osteoblasts into G2/M cell cycle phase. • Expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment.

  7. Effect of processing induced particle alignment on the fracture toughness and fracture behavior of multiphase dental ceramics.

    Science.gov (United States)

    Gonzaga, Carla C; Okada, Cristina Yuri; Cesar, Paulo F; Miranda, Walter G; Yoshimura, Humberto N

    2009-11-01

    To investigate the processing induced particle alignment on fracture behavior of four multiphase dental ceramics (one porcelain, two glass-ceramics and a glass-infiltrated-alumina composite). Disks (Ø12 mm x 1.1mm-thick) and bars (3 mm x 4 mm x 20 mm) of each material were processed according to manufacturer instructions, machined and polished. Fracture toughness (K(Ic)) was determined by the indentation strength method using 3-point bending and biaxial flexure fixtures for the fracture of bars and disks, respectively. Microstructural and fractographic analyses were performed with scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The isotropic microstructure of the porcelain and the leucite-based glass-ceramic resulted in similar fracture toughness values regardless of the specimen geometry. On the other hand, materials containing second-phase particles with high aspect ratio (lithium disilicate glass-ceramic and glass-infiltrated-alumina composite) showed lower fracture toughness for disk specimens compared to bars. For the lithium disilicate glass-ceramic disks, it was demonstrated that the occurrence of particle alignment during the heat-pressing procedure resulted in an unfavorable pattern that created weak microstructural paths during the biaxial test. For the glass-infiltrated-alumina composite, the microstructural analysis showed that the large alumina platelets tended to align their large surfaces perpendicularly to the direction of particle deposition during slip casting of green preforms. The fracture toughness of dental ceramics with anisotropic microstructure should be determined by means of biaxial testing, since it results in lower values.

  8. A particle swarm-based algorithm for optimization of multi-layered and graded dental ceramics.

    Science.gov (United States)

    Askari, Ehsan; Flores, Paulo; Silva, Filipe

    2017-10-04

    The thermal residual stresses (TRSs) generated owing to the cooling down from the processing temperature in layered ceramic systems can lead to crack formation as well as influence the bending stress distribution and the strength of the structure. The purpose of this study is to minimize the thermal residual and bending stresses in dental ceramics to enhance their strength as well as to prevent the structure failure. Analytical parametric models are developed to evaluate thermal residual stresses in zirconia-porcelain multi-layered and graded discs and to simulate the piston-on-ring test. To identify optimal designs of zirconia-based dental restorations, a particle swarm optimizer is also developed. The thickness of each interlayer and compositional distribution are referred to as design variables. The effect of layers number constituting the interlayer between two based materials on the performance of graded prosthetic systems is also investigated. The developed methodology is validated against results available in literature and a finite element model constructed in the present study. Three different cases are considered to determine the optimal design of graded prosthesis based on minimizing (a) TRSs; (b) bending stresses; and (c) both TRS and bending stresses. It is demonstrated that each layer thickness and composition profile have important contributions into the resulting stress field and magnitude. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Method of manufacturing molded articles from metallic or ceramic powdered particles and binder system suitable for use therein

    NARCIS (Netherlands)

    Vervoort, P.J.; Vetter, R.; Duszczyk, J.

    1995-01-01

    The invention relates to a method of manufacturing molded articles by mixing metallic or ceramic powder particles homogeneously with a binder system, whereafter the mixture is shaped in fluid condition by injection molding, the molding obtained is treated with an aqueous liquid in order to wash out

  10. Stress–rupture measurements of cast magnesium strengthened by in-situ production of ceramic particles

    Directory of Open Access Journals (Sweden)

    Nagaraj M. Chelliah

    2017-06-01

    Full Text Available We have introduced a polymer precursor into molten magnesium and then in-situ pyrolyzed to produce castings of metal matrix composites (P-MMCs containing silicon-carbonitride (SiCNO ceramic particles. Stress-rupture measurements of as-cast P-MMCs was performed at 350 °C (0.69TM to 450 °C (0.78TM under dead load condition corresponding to tensile stress of 2.5 MPa to 20 MPa. The time-to-fracture data were analyzed using the classical Monkman–Grant equation. The time-to-fracture is thermally activated and follows a power-law stress exponent exhibiting dislocation creep. Fractography analysis revealed that while pure magnesium appears to fracture by dislocation slip, the P-MMCs fail from the nucleation and growth of voids at the grain boundaries.

  11. Effects of different lasers and particle abrasion on surface characteristics of zirconia ceramics.

    Directory of Open Access Journals (Sweden)

    Sakineh Arami

    2014-04-01

    Full Text Available The aim of this study was to assess the surface of yttrium-stabilized tetragonal zirconia (Y-TZP after surface treatment with lasers and airborne-particle abrasion.First, 77 samples of presintered zirconia blocks measuring 10 × 10 × 2 mm were made, sintered and polished. Then, they were randomly divided into 11 groups (n=7 and received surface treatments namely, Er:YAG laser irradiation with output power of 1.5, 2 and 2.5 W, Nd:YAG laser with output power of 1.5, 2 and 2.5 W, CO2 laser with output power of 3, 4 and 5 W, AL2O3 airborne-particle abrasion (50μ and no treatment (controls. Following treatment, the parameters of surface roughness such as Ra, Rku and Rsk were evaluated using a digital profilometer and surface examination was done by SEM.According to ANOVA and Tukey's test, the mean surface roughness (Ra after Nd:YAG laser irradiation at 2 and 2.5 W was significantly higher than other groups. Roughness increased with increasing output power of Nd:YAG and CO2 lasers. Treated surfaces by Er:YAG laser and air abrasion showed similar surface roughness. SEM micrographs showed small microcracks in specimens irradiated with Nd:YAG and CO2 lasers.Nd:YAG laser created a rough surface on the zirconia ceramic with many microcracks; therefore, its use is not recommended. Air abrasion method can be used with Er:YAG laser irradiation for the treatment of zirconia ceramic.

  12. Workplace exposure and release of ultrafine particles during atmospheric plasma spraying in the ceramic industry.

    Science.gov (United States)

    Viana, M; Fonseca, A S; Querol, X; López-Lilao, A; Carpio, P; Salmatonidis, A; Monfort, E

    2017-12-01

    Atmospheric plasma spraying (APS) is a frequently used technique to produce enhanced-property coatings for different materials in the ceramic industry. This work aimed to characterise and quantify the impact of APS on workplace exposure to airborne particles, with a focus on ultrafine particles (UFPs, Particle number, mass concentrations, alveolar lung deposited surface area concentration, and size distributions, in the range 10nm-20μm were simultaneously monitored at the emission source, in the potential worker breathing zone, and in outdoor air. Different input materials (known as feedstock) were tested: (a) micron-sized powders, and (b) suspensions containing submicron- or nano-sized particles. Results evidenced significantly high UFP concentrations (up to 3.3×106/cm3) inside the spraying chamber, which impacted exposure concentrations in the worker area outside the spraying chamber (up to 8.3×105/cm3). Environmental release of UFPs was also detected (3.9×105/cm3, outside the exhaust tube). Engineered nanoparticle (ENP) release to workplace air was also evidenced by TEM microscopy. UFP emissions were detected during the application of both micron-sized powder and suspensions containing submicron- or nano-sized particles, thus suggesting that emissions were process- (and not material-) dependent. An effective risk prevention protocol was implemented, which resulted in a reduction of UFP exposure in the worker area. These findings demonstrate the potential risk of occupational exposure to UFPs during atmospheric plasma spraying, and raise the need for further research on UFP formation mechanisms in high-energy industrial processes. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  13. Infrared, spectral, directional-hemispherical reflectance of fused silica, Teflon polytetrafluoroethylene polymer, chrome oxide ceramic particle surface, Pyromark 2500 paint, Krylon 1602 paint, and Duraflect coating.

    Science.gov (United States)

    Persky, Merle J; Szczesniak, Martin

    2008-04-01

    Infrared, spectral, directional-hemispherical reflectivity measurements of polished fused silica, Teflon polytetrafluoroethylene polymer, chrome oxide ceramic particle surface, Pyromark 2500 paint, Krylon 1602 paint, and Duraflect coating are provided. The reflectance was measured with an estimated accuracy of 0.01 to 0.02 units and a precision of 0.005 units. All the surfaces were measured at ambient temperatures. Additionally, the chrome oxide ceramic particle surface was measured at 486 K and the Pyromark 2500 at four temperatures to 877 K. Polarization measurements are also provided for fused silica, Duraflect, chrome oxide ceramic particle surface, and Pyromark 2500 paint. Separate diffuse and specular reflectance components for the Duraflect and chrome oxide ceramic surfaces are included. Fresnel-based predictions for fused silica parallel and perpendicular polarized reflections are compared to measurements. It is notable that the Pyromark 2500 and chrome oxide ceramic particle surfaces exhibit a significant lack of manufacturing repeatability.

  14. Fabrication and characterization of TiAl/Ti3Al-based intermetallic composites (IMCs) reinforced with ceramic particles

    OpenAIRE

    V. Kevorkijan; S.D. Škapin

    2009-01-01

    Purpose: The purpose of the paper is to fabricate and characterise TiAl/Ti3Al-based intermetallic composites (IMCs) reinforced with ceramic particles.Design/methodology/approach: Composites were formulated by blending commercially available powders of either TiAl or Ti3Al (technical grade with traces of Al and Ti) with ceramic powders (B4C, TiC or TiB2) in appropriate amounts to create titanium aluminide-based matrices with 10, 20, 30, 40 and 50 vol. % of B4C, TiC or TiB2 discontinuo...

  15. Low LET protons focused to submicrometer shows enhanced radiobiological effectiveness.

    Science.gov (United States)

    Schmid, T E; Greubel, C; Hable, V; Zlobinskaya, O; Michalski, D; Girst, S; Siebenwirth, C; Schmid, E; Molls, M; Multhoff, G; Dollinger, G

    2012-10-07

    This study shows that enhanced radiobiological effectiveness (RBE) values can be generated focusing low linear energy transfer (LET) radiation and thus changing the microdose distribution. 20 MeV protons (LET = 2.65 keV µm(-1)) are focused to submicrometer diameter at the ion microprobe superconducting nanoprobe for applied nuclear (Kern) physics experiments of the Munich tandem accelerator. The RBE values, as determined by measuring micronuclei (RBE(MN) = 1.48 ± 0.07) and dicentrics (RBE(D) = 1.92 ± 0.15), in human-hamster hybrid (A(L)) cells are significantly higher when 117 protons were focused to a submicrometer irradiation field within a 5.4 × 5.4 µm(2) matrix compared to quasi homogeneous in a 1 × 1 µm(2) matrix applied protons (RBE(MN) = 1.28 ± 0.07; RBE(D) = 1.41 ± 0.14) at the same average dose of 1.7 Gy. The RBE values are normalized to standard 70 kV (dicentrics) or 200 kV (micronuclei) x-ray irradiation. The 117 protons applied per point deposit the same amount of energy like a (12)C ion with 55 MeV total energy (4.48 MeV u(-1)). The enhancements are about half of that obtained for (12)C ions (RBE(MN) = 2.20 ± 0.06 and RBE(D) = 3.21 ± 0.10) and they are attributed to intertrack interactions of the induced damages. The measured RBE values show differences from predictions of the local effect model (LEM III) that is used to calculate RBE values for irradiation plans to treat tumors with high LET particles.

  16. Mechanical behavior of Al-Mg-Si alloys reinforced with ceramic and intermetallic particles

    Energy Technology Data Exchange (ETDEWEB)

    Costa, C.E. da [Dept. de Ingenieria Mecanica y de Materiales, Univ. Politecnica de Valencia (Spain); Martinez, N.; Amigo, V.; Salvador, M.D. [Univ. do Estado de Santa Catarina, Centro de Ciencias Tecnologicas, Dept. Ingenieria Mecanica, Joinville (Brazil)

    2003-07-01

    Aluminum matrix composites (AMCs) reinforced with ceramic and Ti-Al intermetallic particles were prepared in the laboratory by following a powder metallurgy route. Hot extrusion was used as consolidation processes. Different studies were carried out in the composites developed. The influence of production process was also estimated. To evaluate interfaces and possible reaction products between the matrix and reinforcement, heat treatments regarding time were carried out. Tests were developed in fabricated AMCs and in unreinforced aluminum matrix, to evaluate influence of reinforcement type. In this study, optical and scanning electron microscopy with X-ray microanalysis, were used to determine the possible reaction products in the matrix/reinforcement interface and its composition. Ultimate strength and strain to failure were studied. There were performed tests at room temperature and at high temperature of the material in different precipitation state. The type of damage was analyzed by scanning electron microscopy. Ultimate strength trends to grow with reinforcement addition in both T1 and T6 conditions for low temperature. Strain to failure remains the lowest on T6 state. The effect of reinforcement addition decrease for high temperature testing and matrix influence was demonstrated. (orig.)

  17. An investigation into the effect of a ceramic particle trap on the chemical mutagens in diesel exhaust

    Energy Technology Data Exchange (ETDEWEB)

    Bagley, S.T.; Dorie, L.D.; Leddy, D.G.; Johnson, J.H. (Michigan Technological Univ., Houghton (USA))

    1987-01-01

    Diesel exhaust particles and vapor phase samples were collected from the diluted (15:1) exhaust of a 10.4 L displacement medium-duty engine (Caterpillar 3208), operated under EPA steady-state cycle Modes 4 and 5 conditions for load (50 and 75 percent, respectively) and speed (1680 rpm). Baseline (uncontrolled) emissions were compared to the exhaust modified by the use of an uncatalyzed monolithic ceramic trap (Corning). The Salmonella/microsome mutagenicity bioassay (Ames Test) was used to direct the course of chemical analyses. Total particulate matter (TPM), soluble organic fraction (SOF) (from TPM), sulfate fraction (SO4) (from TPM), and solid fraction (SOL) (from particle) were determined from dilute exhaust particles collected on 47 mm Teflon-coated woven glass fiber filters. Coincidentally, particles were collected on 508 x 508 mm Teflon-coated non-woven glass fiber filters, and vapor-phase samples were collected on XAD-2 resin. The SOF and VOC for chemical and biological characterization were obtained by Soxhlet extraction of samples with dichloromethane (DCM). Hydrocarbon mass balances were developed to evaluate the efficiency of the sampling system. Use of the ceramic traps caused no change in engine total hydrocarbon (HC) levels at Mode 4 but decreases in TPM, SOF, and NO2 were noted. In terms of HC emissions only, the percentage of SOF was significantly reduced, but the percentage of VOC was unchanged. For Mode 5, the engine HC levels were significantly reduced but the proportions of HC components, i.e. the percentage of SOF and the percentage of VOC, did not change significantly. Engine emission levels of TPM, SOF, and nitrogen dioxide were also significantly reduced at Mode 5. At both Modes 4 and 5, use of the ceramic particle traps caused an increase in the direct-acting (TA98) mutagenicity of the SOF and a decrease in the activity of the VOC.

  18. Impact of Particle Size of Ceramic Granule Blends on Mechanical Strength and Porosity of 3D Printed Scaffolds

    Directory of Open Access Journals (Sweden)

    Sebastian Spath

    2015-07-01

    Full Text Available 3D printing is a promising method for the fabrication of scaffolds in the field of bone tissue engineering. To date, the mechanical strength of 3D printed ceramic scaffolds is not sufficient for a variety of applications in the reconstructive surgery. Mechanical strength is directly in relation with the porosity of the 3D printed scaffolds. The porosity is directly influenced by particle size and particle-size distribution of the raw material. To investigate this impact, a hydroxyapatite granule blend with a wide particle size distribution was fractioned by sieving. The specific fractions and bimodal mixtures of the sieved granule blend were used to 3D print specimens. It has been shown that an optimized arrangement of fractions with large and small particles can provide 3D printed specimens with good mechanical strength due to a higher packing density. An increase of mechanical strength can possibly expand the application area of 3D printed hydroxyapatite scaffolds.

  19. Cold Spray Coating of Submicronic Ceramic Particles on Poly(vinyl alcohol) in Dry and Hydrogel States

    Science.gov (United States)

    Moreau, David; Borit, François; Corté, Laurent; Guipont, Vincent

    2017-06-01

    We report an approach using cold spray technology to coat poly(vinyl alcohol) (PVA) in polymer and hydrogel states with hydroxyapatite (HA). Using porous aggregated HA powder, we hypothesized that fragmentation of the powder upon cold spray could lead to formation of a ceramic coating on the surface of the PVA substrate. However, direct spraying of this powder led to complete destruction of the swollen PVA hydrogel substrate. As an alternative, HA coatings were successfully produced by spraying onto dry PVA substrates prior to swelling in water. Dense homogeneous HA coatings composed of submicron particles were obtained using rather low-energy spraying parameters (temperature 200-250 °C, pressure 1-3 MPa). Coated PVA substrates could swell in water without removal of the ceramic layer to form HA-coated hydrogels. Microscopic observations and in situ measurements were used to explain how local heating and impact of sprayed aggregates induced surface roughening and strong binding of HA particles to the molten PVA substrate. Such an approach could lead to design of ceramic coatings whose roughness and crystallinity can be finely adjusted to improve interfacing with biological tissues.

  20. Metal matrix composite of an iron aluminide and ceramic particles and method thereof

    Science.gov (United States)

    Schneibel, Joachim H.

    1997-01-01

    A metal matrix composite comprising an iron aluminide binder phase and a ceramic particulate phase such as titanium diboride, zirconium diboride, titanium carbide and tungsten carbide is made by heating a mixture of iron aluminide powder and particulates of one of the ceramics such as titanium diboride, zirconium diboride, titanium carbide and tungsten carbide in a alumina crucible at about 1450.degree. C. for about 15 minutes in an evacuated furnace and cooling the mixture to room temperature. The ceramic particulates comprise greater than 40 volume percent to about 99 volume percent of the metal matrix composite.

  1. Particle migration using local variation of the viscosity (LVOV) model in flow of a non-Newtonian fluid for ceramic tape casting

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Spangenberg, Jon; Hattel, Jesper Henri

    2016-01-01

    behaviour is assumed in the simulation of the ceramic slurry flow.A local variation of the viscosity (LVOV) model as a function of the particle volume fraction is introduced and taken into account in the advection and the settling of the particles inthe flow field. The results show that using the LVOV model...

  2. Formulation and biological actions of nano-bioglass ceramic particles doped with Calcarea phosphorica for bone tissue engineering.

    Science.gov (United States)

    Dinesh Kumar, S; Mohamed Abudhahir, K; Selvamurugan, N; Vimalraj, S; Murugesan, R; Srinivasan, N; Moorthi, A

    2018-02-01

    The improvisation of the treatment procedures for treating the various kind of bone defects such as, bone or dental trauma and for diseases such as osteoporosis, osteomyelitis etc., need the suitable and promising biomaterials with resemblance of bone components. Bioactive glass ceramic (BGC) has recently acquired great attention as the most promising biomaterials; hence it has been widely applied as a filler material for bone tissue regeneration. Because it elicts specific biological responses after implantation in addition more potential in formation of strong interface with both hard and soft tissues by dissolution of calcium and phosphate ions. Hence, the current focus in treating the bone defects by orchestrating the biomaterial in combination of alternative medicine such as homeopathic remedies with biomaterials to prevent the adverse effects at minimal concentrations. So the current study was focused on constructing the nano-bioglass ceramic particles (nBGC) doped with novel homeopathic remedy Calcarea phosphorica for dental and bone therapeutic implants. The nBGC particles were synthesized by sol-gel method and reinforced with commercially available Calcarea phosphorica. The synthesized particles were characterized by SEM, DLS, EDS, FT-IR, and XRD studies. The SEM and DLS were shown the size of the particles at nano scale, also the EDS, and FT-IR investigations indicated that the Calcarea phosphorica was integrated with nBGC particles and also the crystalline nature of particles was confirmed by XRD studies. Both nBGC and Calcarea phosphorica doped nBGC (CP-nBGC) were found to be non toxic to mouse mesenchymal stem cells at lower concentrations and also illustrated the better bone forming ability in vitro. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Joining of aluminium matrix composites by using solders with ceramic reinforcement particles; Weichlote mit keramischen Verstaerkungspartikeln zum Fuegen von Aluminiummatrix-Verbundwerkstoffen

    Energy Technology Data Exchange (ETDEWEB)

    Wielage, B.; Hoyer, I.; Weis, S. [Technische Univ. Chemnitz (Germany)

    2007-07-01

    Ultrasonic soldering was found to be an effective technique for joining of aluminium matrix composites. No fluxes were required. The solders were Sn base allows which have a low melting point below 300 C and minimize the thermal load during joining. To improve the mechanical properties of the solders, ceramic reinforcing components were used, either by mechanical alloying of solder and particles using HEM or by wetting the ceramic component using the surfactant Ti. (orig.)

  4. Improvement in the Design of Metal-Ceramic High Voltage Feedthroughs for use in High Energy Particle Accelerators

    CERN Document Server

    Weterings, W

    1999-01-01

    Large high-voltage devices operate in particle accelerators to steer charged particles in the desired direction. Solid and hollow rods of sintered alumina are used as insulating supports and high-voltage feedthroughs to power the electrodes of these electrostatic systems. The performance of the systems is often limited by voltage breakdown along the surface of the ceramic insulator (so-called surface flashover) or discharge between feedthrough and vacuum tank, which can lead to significant disruptions in terms of overall machine efficiency. Available results on the influence of the mechanical preparation, thermal history and particular cleaning techniques on commercially obtainable alumina samples have been studied in order to investigate possibilities for better preparation methodology of the insulating supports. Also the influence of the relative position of the feedthrough inside the vacuum tank on the high-voltage breakdown behaviour has been studied. This paper describes the theoretical and practical bac...

  5. Effect of kaolin particle size and loading on the characteristics of kaolin ceramic support prepared via phase inversion technique

    Directory of Open Access Journals (Sweden)

    Siti Khadijah Hubadillah

    2016-06-01

    Full Text Available In this study, low cost ceramic supports were prepared from kaolin via phase inversion technique with two kaolin particle sizes, which are 0.04–0.6 μm (denoted as type A and 10–15 μm (denoted as type B, at different kaolin contents ranging from 14 to 39 wt.%, sintered at 1200 °C. The effect of kaolin particle sizes as well as kaolin contents on membrane structure, pore size distribution, porosity, mechanical strength, surface roughness and gas permeation of the support were investigated. The support was prepared using kaolin type A induced asymmetric structure by combining macroporous voids and sponge-like structure in the support with pore size of 0.38 μm and 1.05 μm, respectively, and exhibited ideal porosity (27.7%, great mechanical strength (98.9 MPa and excellent gas permeation. Preliminary study shows that the kaolin ceramic support in this work is potential to gas separation application at lower cost.

  6. Research on sludge-fly ash ceramic particles (SFCP) for synthetic and municipal wastewater treatment in biological aerated filter (BAF).

    Science.gov (United States)

    Zhao, Yaqin; Yue, Qinyan; Li, Renbo; Yue, Min; Han, Shuxin; Gao, Baoyu; Li, Qian; Yu, Hui

    2009-11-01

    Sludge-fly ash ceramic particles (SFCP) and clay ceramic particles (CCP) were employed in two lab-scale up-flow biological aerated filters (BAF) for wastewater treatment to investigate the availability of SFCP used as biofilm support compared with CCP. For synthetic wastewater, under the selected hydraulic retention times (HRT) of 1.5, 0.75 and 0.37 h, respectively, the removal efficiencies of chemical oxygen demand (COD(Cr)) and ammonium nitrogen (NH(4)(+)-N) in SFCP reactor were all higher than those of CCP reactor all through the media height. Moreover, better capabilities responding to loading shock and faster recovery after short intermittence were observed in the SFCP reactor compared with the CCP reactor. For municipal wastewater treatment, which was carried out under HRT of 0.75 h, air-liquid ratio of 7.5 and backwashing period of 48 h, the SFCP reactor also performed better than the CCP reactor, especially for the removal of NH(4)(+)-N.

  7. The separation efficiency of ceramic barrier filters determined at high temperatures by optical particle size and concentration measurement

    Energy Technology Data Exchange (ETDEWEB)

    Hemmer, G.; Umhauer, H.; Kasper, G. [Univ. Karlsruhe, Inst. fuer Mechanische Verfahrenstechnik und Mechanik, Karlsruhe (Germany); Berbner, S. [Freudenberg Nonwovens, Filtration Div., Hopkinsville, KY (United States)

    1999-07-01

    Based on the experiences of earlier investigations a special optical particle counter was developed capable of recording size and quantity (concentration) of the particles directly within a given gas particle stream under the prevailing conditions (true in-situ measurements at high temperatures). In addition to earlier investigations [1], a second type of ceramic filter media with much smaller porosity and a membrane layer on the filtration side was tested. The candles with a length of 1.5 m which are used in industrial applications were mounted in the same hot gas filtration unit already used before. Measurements on the clean gas side at temperatures of up to 1000 C have been conducted using a fraction of quartz particles as test dust. The particle size ranged between 0.3 {mu}m and 10 {mu}m. Filtration velocity (1.5 cm/s) and final pressure drop of dust cake {delta}p (1000 Pa) were kept constant. As a main result the fractional efficiency as function of temperature is discussed and compared with that obtained before for a filter media of type I: The fractional efficiency values of filter type II are at least 100 times higher than that of filter type I. (orig.)

  8. Submicrometer grating light bar for a color-separation backlight.

    Science.gov (United States)

    Liu, Chun-Wei; Lee, Chi-Hung; Yang, Tzu-Chun; Ting, Chia-Jen; Lin, Tsung-Hsin; Lin, Shih-Chieh

    2013-05-20

    A light bar patterned using a submicrometer grating was designed to replace conventional dye color filters for color liquid crystal displays. The light bar generates color rays by transmitting them from side-lit color light-emitting diodes through the submicrometer grating. These angular color rays are then redirected by a V-grooved light guide, and then converged by a lens array and mapped to corresponding subpixel positions to efficiently display color images. The results show that 106% of the National Television System Committee (NTSC) color space in a blue-green-red-green (B-G-R-G) repeating pattern display pixel layout can be achieved.

  9. Reaction of iodine atoms with submicrometer squalane and squalene droplets: mechanistic insights into heterogeneous reactions.

    Science.gov (United States)

    Popolan-Vaida, Denisia M; Wilson, Kevin R; Leone, Stephen R

    2014-11-13

    The gas-phase reaction of iodine atoms with hydrocarbon molecules is energetically unfavorable, and there is no direct evidence for iodinated product formation by either H abstraction or I addition reactions at ambient temperature. Here we consider the possible heterogeneous reaction of I atoms with submicrometer droplets composed of a saturated alkane, squalane (Sq), and an unsaturated alkene, squalene (Sqe). The investigations are performed in an atmospheric pressure photochemical flow tube reactor in conjunction with a vacuum ultraviolet photoionization aerosol mass spectrometer and a scanning mobility particle sizer. Squalane, a branched alkane, is unreactive toward I atoms within the signal-to-noise, and an upper limit of the effective reactive uptake coefficient is estimated to be γI(Sq) ≤ 8.58 × 10(–7). In contrast, the reaction of I atoms with unsaturated submicrometer squalene droplets results in observable iodinated squalene products. The effective reactive uptake coefficient of I atom with squalene particles is determined to be γI(Sqe) = (1.20 ± 0.52) × 10(–4) at an average I concentration of 1.5 × 10(14) molecules·cm(–3).

  10. Impact of Chinese anthropogenic emissions on submicrometer aerosol concentration at Mt. Tateyama, Japan

    Directory of Open Access Journals (Sweden)

    H. Iida

    2009-12-01

    Full Text Available Rapid Asian economic development might engender secondary impacts of atmospheric aerosol particles over the western Pacific after conversion of gaseous pollutants such as SO2. To elucidate changes in aerosol concentrations in leeward areas undergoing remarkable industrialization, the number-size distributions of submicrometer (0.3–1.0 μm aerosols were measured at Murododaira (36.6° N, 137.6° E, 2450 m a.s.l. on the western flank of Mount Tateyama in central Japan during January 1999–February 2009. Nighttime data obtained from 2400 to 0500 were used to analyze free-tropospheric aerosol concentration. Monthly average volume concentrations were calculated for months with >50% daily data coverage. Volume concentrations of submicrometer aerosols were high in spring to early summer and low in winter. Significant increasing trends at 95% confidence levels were found for volume concentrations in winter–spring. Simulated monthly anthropogenic aerosol concentrations at Mt. Tateyama from results of regional aerosol modeling with emission inventory up to 2005 showed seasonal variation and winter–spring increasing trends similar to those of observed aerosol concentration. According to the model analyses, the contribution of anthropogenic aerosol concentrations derived from China was high during winter–spring (60–80% of total anthropogenic aerosols at Mt. Tateyama. This accords with the increasing trend observed for winter–spring. Because SO42− is the dominant component of total anthropogenic aerosols, these results suggest that increasing anthropogenic emissions, especially for SO2, in China, engender enhancement of submicrometer-diameter aerosols over Japan during winter–spring.

  11. Formation and Order Enhancement of submicrometer and nanoscale features in thin films

    Science.gov (United States)

    Lau, Cindy Yee Cin

    The wide applications of two-dimensionally ordered submicrometer features have stimulated the development of cheap and fast fabrication techniques throughout the years. We showed that electrohydrodynamic patterning, which is known to produce ordered pillar arrays on polymer thin film at micrometer scale, could be extended to create submicrometer features as small as 351 +/- 78 nm quickly and economically. However, the dielectric breakdown of polymer imposed a fundamental limit on further reducing the feature size to nanoscale. We overcame the limited resolution by bottom-up colloidal assemblies which used nanoparticles between 49.8 +/- 8.7 nm and 117.6 +/- 6.7 nm as building blocks. By employing flow-coating deposition, we were able to control the deposited amount and achieve large area of uniform colloidal film easily. However, the single crystalline domain of a close-packed monolayer remained limited due to the restricted time for ordering through lateral capillary pressure before the particles were in contact. That motivated the deposition of initially ordered colloidal dispersions, attained through deionizing the solutions to extend electrostatic double layers for long-range repulsion. Although the deposited amount agreed reasonably well with our model adapted for a power-law fluid, the shear-thinning viscosity and final structure both revealed that the initial order was destroyed at high shear. On the other hand, the particle order was partially sustained during low shear depositions, yet the domain size was not particularly extensive. We attributed the limited order to the high compressibility of double layer during the evaporation phase. To improve the order of a colloidal monolayer, we investigated the effect of excess free ligands on 8.0 +/- 0.3 nm gold nanoparticles deposited by the Langmuir-Blodgett technique. We showed that the excess ligands, oleylamine, not only improved the order of particles that were deposited together with them, but could also

  12. An investigation into the effect of a ceramic particle trap on the chemical mutagens in diesel exhaust.

    Science.gov (United States)

    Bagley, S T; Dorie, L D; Leddy, D G; Johnson, J H

    1987-01-01

    Diesel exhaust particles and vapor phase samples were collected from the diluted (15:1) exhaust of a 10.4 L displacement medium-duty engine (Caterpillar 3208), operated under EPA steady-state cycle Modes 4 and 5 conditions for load (50 and 75 percent, respectively) and speed (1680 rpm). Baseline (uncontrolled) emissions were compared to the exhaust modified by the use of an uncatalyzed monolithic ceramic trap (Corning). The Salmonella/microsome mutagenicity bioassay (Ames Test) was used to direct the course of chemical analyses. Total particulate matter (TPM), soluble organic fraction (SOF) (from TPM), sulfate fraction (SO4) (from TPM), and solid fraction (SOL) (from particle) were determined from dilute exhaust particles collected on 47 mm Teflon-coated woven glass fiber filters. Coincidentally, particles were collected on 508 x 508 mm Teflon-coated non-woven glass fiber filters, and vapor-phase samples were collected on XAD-2 resin. The SOF and VOC for chemical and biological characterization were obtained by Soxhlet extraction of samples with dichloromethane (DCM). Hydrocarbon mass balances were developed to evaluate the efficiency of the sampling system. Use of the ceramic traps caused no change in engine total hydrocarbon (HC) levels at Mode 4 but decreases in TPM, SOF, and NO2 were noted. In terms of HC emissions only, the percentage of SOF was significantly reduced, but the percentage of VOC was unchanged. For Mode 5, the engine HC levels were significantly reduced but the proportions of HC components, i.e. the percentage of SOF and the percentage of VOC, did not change significantly. Engine emission levels of TPM, SOF, and nitrogen dioxide (NO2) were also significantly reduced at Mode 5. At both Modes 4 and 5, use of the ceramic particle traps caused an increase in the direct-acting (TA98) mutagenicity (revertants/microgram) of the SOF and a decrease in the activity of the VOC. The traps caused a 70 percent reduction of TPM at Mode 4 but only a 45 percent

  13. Behavior of ceramic particles at the solid-liquid metal interface in metal matrix composites

    Science.gov (United States)

    Stefanescu, D. M.; Dhindaw, B. K.; Kacar, S. A.; Moitra, A.

    1988-01-01

    Directional solidification results were obtained in order to investigate particle behavior at the solid-liquid interface in Al-2 pct Mg (cellular interface) and Al-6.1 pct Ni (eutectic interface) alloys. It is found that particles can be entrapped in the solid if adequate solidification rates and temperature gradients are used. Model results showed critical velocity values slightly higher than those obtained experimentally.

  14. Estimation of Biocompatibility of Nano-Sized Ceramic Particles with Osteoblasts, Osteosarcomas and Hepatocytes by Static and Time-Lapse Observation.

    Science.gov (United States)

    Abe, Shigeaki; Seitoku, Eri; Iwadera, Nobuki; Hamba, Yusuke; Yamagata, Shuichi; Akasaka, Tsukasa; Kusaka, Teruo; Inoue, Satoshi; Yawaka, Yasutaka; Iida, Junichiro; Sano, Hidehiko; Yonezawa, Tetsu; Yoshida, Yasuhiro

    2016-03-01

    We assessed the biocompatibility of nano-sized ceramic particles with several cells types. Though these particles have less than 100 nm in diameter, they act as submicron-sized particles in saline by aggregation that was estimated using laser diffraction particle size analysis (LDS). they act as submicro-sized particles in saline by aggregation based on laser diffraction particle size analysis (LDS). Several types of cells (osteoblasts, osteosarcoma and hepatocyte cells) were exposed to these particles and their cytocompatibility was estimated. Not only the cytotoxic assay but also their static and dynamic morphology under nanoparticles exposure were investigated. The intercellular uptake of particles was determined using a confocal fluorescence microscope. The particles used in this study did not inhibit cellular activity or growth even when their concentrations were high. Only copper oxide particles caused acute cytotoxicity depending on the particle size. The cytotoxicity assay, dynamic behavior of the nanoparticle-exposed cells and their examination under a confocal fluorescence microscope suggests that the irritative reaction was induced by contact between the cells and particles, whereas eluted copper ions are not dominant factor. These results indicate that nano-sized particles used in this study have excellent biocompatibility except copper oxide ones.

  15. Secondary submicrometer impact cratering on the surface of asteroid 25143 Itokawa

    Science.gov (United States)

    Harries, Dennis; Yakame, Shogo; Karouji, Yuzuru; Uesugi, Masayuki; Langenhorst, Falko

    2016-09-01

    Particle RA-QD02-0265 returned by the Hayabusa spacecraft from near-Earth asteroid 25143 Itokawa displayed a unique abundance of submicrometer-sized (≤500 nm) impact craters, which are rarely observed among the Hayabusa samples. The particle consists of intensely twinned diopside that was subjected to a large-scale shock event before exposure to the space environment on the surface of 25143 Itokawa. Intense (sub-)micrometer-scale impact cratering may suggest a long surface exposure and, hence, a long residence time of regolith material on the surface of small asteroids, bearing implications for the dynamical evolution of these bodies. However, our combined FE-SEM and FIB/TEM study shows that the degree of solar wind-induced space weathering and the accumulation of solar flare tracks are not exceptionally different from other Hayabusa particles with surface exposure ages estimated to be less than 1 ka. A 500 nm wide crater on the surface of RA-QD02-0265 exhibits microstructural damage to a depth of 400 nm below its floor and contains residues of Fe-Ni metal, excluding a formation by space craft exhausts or curatorial handling. The geometrical clustering among the 15 craters is unlikely random, and we conclude that the craters have formed through the impacts of secondary projectiles (at least partially Fe-Ni metal) created in a nearby (micro-)impact event. Besides structural damage by the solar wind and deposition of impact-generated melts and vapors, secondary impact cratering on the submicrometer-scale is another potential mechanism to modify the spectral properties of individual regolith grains. The lack of extensively exposed regolith grains supports a dynamic regolith on the surface of 25143 Itokawa.

  16. Particle size distribution of typical ceramic raw materials by laser granulometry

    Science.gov (United States)

    Wojnarovitsne, I. H.; Lenkel, M.

    1984-01-01

    The principles of the method are explained and the working of the CILAS 715 laser granulometer is described. The particle size distributions of milled glazes, quartz, feldspar and china clay were determined by this instrument and by Andreasen sedimentation. The agreement was good for isometric particles, but the china clay appears finer by sedimentation, because the platelets arrange themselves horizontally during sedimentation, while in the laser granulometer preferred orientation is prevented by circulation between the sample holder and the vibrated and stirred reservoir of the slip.

  17. Improvement in retention of solid fission products in HTGR fuel particles by ceramic kernel additives

    Energy Technology Data Exchange (ETDEWEB)

    Foerthmann, R.; Groos, E.; Gruebmeier, H.

    1975-08-15

    Increased requirements concerning the retention of long-lived solid fission products in fuel elements for use in advanced High Temperature Gas-cooled Reactors led to the development of coated particles with improved fission product retention which represent an alternative to silicon carbide-coated fuel particles. Two irradiation experiments have shown that the release of strontium, barium, and caesium from pyrocarbon-coated particles can be reduced by orders of magnitude if the oxide kernel contains alumina-silica additives. It was detected by electron microprobe analysis that the improved retention of the mentioned fission products in the fuel kernel is caused by formation of the stable aluminosilicates SrAl2Si2O8, BaAl2Si2O8and CsAlSi2O6 in the additional alumina-silica phase of the kernel.

  18. Fatigue behavior in water of Y-TZP zirconia ceramics after abrasion with 30 µm silica-coated alumina particles

    Science.gov (United States)

    Scherrer, Susanne S.; Cattani-Lorente, Maria; Vittecoq, Eric; de Mestral, François; Griggs, Jason A.; Wiskott, H.W. Anselm

    2011-01-01

    Objective The use of a 30 µm alumina–silica coated particle sand (CoJet™ Sand, 3M Espe), has shown to enhance the adhesion of resin cements to Y-TZP. The question is whether or not sandblasting 30 µm particles does negatively affect the fatigue limit (S–N curves) and the cumulative survival of Y-TZP ceramics. Method Four zirconia materials tested were: Zeno (ZW) (Wieland), Everest ZS (KV) (KaVo), Lava white (LV) and Lava colored (LVB) (3M Espe). Fatigue testing (S–N) was performed on 66 bar of 3 mm × 5 mm × 40 mm with beveled edges for each zirconia material provided by the manufacturers. One half of the specimens were CoJet sandblasted in the middle of the tensile side on a surface of 5 mm × 6 mm. Cyclic fatigue (N = 30/group) (sinusoidal loading/unloading at 10 Hz between 10% and 100% load) was performed in 3-point-bending in a water tank. Stress levels were lowered from the initial static value (average of N = 3) until surviving 1 million cycles. Fatigue limits were determined from trend lines. Kaplan–Meier survival analysis was performed to determine the failure stress at the median percentile survival level for 1 million of cycles before and after sandblasting. The statistical analyses used the log-rank test. Characterization of the critical flaw was performed by SEM for the majority of the failed specimens. Results The fatigue limits “as received” (ctr) were: LV = 720 MPa, LVB = 600 MPa, KV = 560 MPa, ZW = 470 MPa. The fatigue limits “after CoJet sandblasting” were: LV = 840 MPa, LVB = 788 MPa, KV = 645 MPa, ZW = 540 MPa. The increase in fatigue limit after sandblasting was 15% for Zeno (ZW) and Everest (KV), 17% for Lava (LV) and 31% for Lava colored (LVB). The KM median survival stresses in MPa were: ZW(ctr) = 549 (543–555), ZW(s) = 587 (545–629), KV(ctr) = 593 (579–607), KV(s) = 676 (655–697), LVB(ctr) = 635 (578–692), LVB(s) = 809 (787–831), LV(ctr) = 743 (729–757), LV(s) = 908 (840–976). Log-rank tests were

  19. Sub-micrometer resolution proximity X-ray microscope with digital image registration.

    Science.gov (United States)

    Chkhalo, N I; Pestov, A E; Salashchenko, N N; Sherbakov, A V; Skorokhodov, E V; Svechnikov, M V

    2015-06-01

    A compact laboratory proximity soft X-ray microscope providing submicrometer spatial resolution and digital image registration is described. The microscope consists of a laser-plasma soft X-ray radiation source, a Schwarzschild objective to illuminate the test sample, and a two-coordinate detector for image registration. Radiation, which passes through the sample under study, generates an absorption image on the front surface of the detector. Optical ceramic YAG:Ce was used to convert the X-rays into visible light. An image was transferred from the scintillator to a charge-coupled device camera with a Mitutoyo Plan Apo series lens. The detector's design allows the use of lenses with numerical apertures of NA = 0.14, 0.28, and 0.55 without changing the dimensions and arrangement of the elements of the device. This design allows one to change the magnification, spatial resolution, and field of view of the X-ray microscope. A spatial resolution better than 0.7 μm and an energy conversion efficiency of the X-ray radiation with a wavelength of 13.5 nm into visible light collected by the detector of 7.2% were achieved with the largest aperture lens.

  20. Particle layering in the ceramic-metal thin film Pt-Al2O3

    Science.gov (United States)

    Gibaud, A.; Hazra, S.; Sella, C.; Laffez, P.; Désert, A.; Naudon, A.; van Tendeloo, G.

    2001-05-01

    Experiments performed by x-ray reflectivity, grazing incidence small angle x-ray scattering (GISAXS), and transmission electron microscopy (TEM) on a cosputtered nanocermet thin film of Pt-Al2O3 are presented. It is shown that the morphology of such a heterogeneous material can be well interpreted by combining the information obtained from the three techniques. In particular, the layering of metal nanoparticles in the immediate vicinity of the substrate is clearly evidenced. GISAXS results are interpreted via a model which yields spherical nanoparticles of diameter 2R=3.1 nm, separated on the average by a distance of 5.8 nm. The evidence for the layering of particles close to the substrate is deduced from the analysis of the specular reflectivity and probed directly by TEM.

  1. Complexity of the relationships between the sintering-temperature-dependent grain size, airborne-particle abrasion, ageing and strength of 3Y-TZP ceramics.

    Science.gov (United States)

    Cotič, Jasna; Jevnikar, Peter; Kocjan, Andraž; Kosmač, Tomaž

    2016-04-01

    This study was designed to explore the complex relationships between the sintering-temperature-dependent grain size, airborne-particle abrasion, ageing and strength of 3Y-TZP ceramics. Biomedical grade 3Y-TZP powder was used to fabricate 180 discs. Half of them were sintered at 1400°C for 2h and half at 1500°C for 2h. A total of 18 groups of 10 were formed and subjected to the fully crossed experimental protocol of airborne-particle abrasion with Al2O3 at 2.5bar (no abrasion, 50μm, 110μm) and accelerated ageing at 134°C (no ageing, 12h, 48h). The relative amount of monoclinic phase was determined with XRD. The biaxial flexural strength was measured and statistically analyzed using the three-way ANOVA followed by predetermined contrasts and Tukey's HSD test (α=0.05). The low-temperature-sintered, fine-grained ceramic exhibited an excellent ageing resistance, while the high-temperature-sintered, coarse-grained ceramic experienced a higher surface strengthening and a substantially improved ageing resistance with respect to the airborne-particle abrasion. The overall performance of this material was superior. Our results show that the sintering temperature has a minor effect on the flexural strength, but it plays a crucial role in the surface strengthening and the ageing behaviour of 3Y-TZP dental ceramics. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. On the Stability of c-BN-Reinforcing Particles in Ceramic Matrix Materials

    Directory of Open Access Journals (Sweden)

    Anne-Kathrin Wolfrum

    2018-02-01

    Full Text Available Cubic boron nitride (c-BN composites produced at high pressures and temperatures are widely used as cutting tool materials. The advent of new, effective pressure-assisted densification methods, such as spark plasma sintering (SPS, has stimulated attempts to produce these composites at low pressures. Under low-pressure conditions, however, transformation of c-BN to the soft hexagonal BN (h-BN phase can occur, with a strong deterioration in hardness and wear. In the present work, the influence of secondary phases (B2O3, Si3N4, and oxide glasses on the transformation of c-BN was studied in the temperature range between 1100 °C and 1575 °C. The different heat treated c-BN particles and c-BN composites were analyzed by SEM, X-ray diffraction, and Raman spectroscopy. The transformation mechanism was found to be kinetically controlled solution–diffusion–precipitation. Given a sufficiently low liquid phase viscosity, the transformation could be observed at temperatures as low as 1200 °C for the c-BN–glass composites. In contrast, no transformation was found at temperatures up to 1575 °C when no liquid oxide phase is present in the composite. The results were compared with previous studies concerning the c-BN stability and the c-BN phase diagram.

  3. Statistical analysis and parameterization of the hygroscopic growth of the sub-micrometer urban background aerosol in Beijing

    Science.gov (United States)

    Wang, Yu; Wu, Zhijun; Ma, Nan; Wu, Yusheng; Zeng, Limin; Zhao, Chunsheng; Wiedensohler, Alfred

    2018-02-01

    The take-up of water of aerosol particles plays an important role in heavy haze formation over North China Plain, since it is related with particle mass concentration, visibility degradation, and particle chemistry. In the present study, we investigated the size-resolved hygroscopic growth factor (HGF) of sub-micrometer aerosol particles (smaller than 350 nm) on a basis of 9-month Hygroscopicity-Tandem Differential Mobility Analyzer measurement in the urban background atmosphere of Beijing. The mean hygroscopicity parameter (κ) values derived from averaging over the entire sampling period for particles of 50 nm, 75 nm, 100 nm, 150 nm, 250 nm, and 350 nm in diameters were 0.14 ± 0.07, 0.17 ± 0.05, 0.18 ± 0.06, 0.20 ± 0.07, 0.21 ± 0.09, and 0.23 ± 0.12, respectively, indicating the dominance of organics in the sub-micrometer urban aerosols. In the spring, summer, and autumn, the number fraction of hydrophilic particles increased with increasing particle size, resulting in an increasing trend of overall particle hygroscopicity with enhanced particle size. Differently, the overall mean κ values peaked in the range of 75-150 nm and decreased for particles larger than 150 nm in diameter during wintertime. Such size-dependency of κ in winter was related to the strong primary particle emissions from coal combustion during domestic heating period. The number fraction of hydrophobic particles such as freshly emitted soot decreased with increasing PM2.5 mass concentration, indicating aged and internal mixed particles were dominant in the severe particulate matter pollution. Parameterization schemes of the HGF as a function of relative humidity (RH) and particle size between 50 and 350 nm were determined for different seasons and pollution levels. The HGFs calculated from the parameterizations agree well with the measured HGFs at 20-90% RH. The parameterizations can be applied to determine the hygroscopic growth of aerosol particles at ambient conditions for the area

  4. Effect of airborne-particle abrasion and mechanico-thermal cycling on the flexural strength of glass ceramic fused to gold or cobalt-chromium alloy.

    Science.gov (United States)

    Oliveira de Vasconcellos, Luis Gustavo; Silva, Lucas H; Reis de Vasconcellos, Luana Marotta; Balducci, Ivan; Takahashi, Fernando E; Bottino, Marco Antonio

    2011-10-01

    To evaluate the effect of airborne-particle abrasion and mechanico-thermal cycling on the flexural strength of a ceramic fused to cobalt-chromium alloy or gold alloy. Metallic bars (n = 120) were made (25 mm × 3 mm × 0.5 mm): 60 with gold alloy and 60 with Co-Cr. At the central area of the bars (8 mm × 3 mm), a layer of opaque ceramic and then two layers of glass ceramic (Vita VM13, Vita Zahnfabrick) were fired onto it (thickness: 1 mm). Ten specimens from each alloy group were randomly allocated to a surface treatment [(tungsten bur or air-particle abrasion (APA) with Al(2) O(3) at 10 mm or 20 mm away)] and mechanico-thermal cycling (no cycling or mechanically loaded 20,000 cycles; 10 N distilled water at 37°C and then thermocycled 3000 cycles; 5°C to 55°C, dwell time 30 seconds) combination. Those specimens that did not undergo mechanico-thermal cycling were stored in water (37°C) for 24 hours. Bond strength was measured using a three-point bend test, according to ISO 9693. After the flexural strength test, failure types were noted. The data were analyzed using three factor-ANOVA and Tukey's test (α= 0.05). There were no significant differences between the flexural bond strength of gold and Co-Cr groups (42.64 ± 8.25 and 43.39 ± 10.89 MPa, respectively). APA 10 and 20 mm away surface treatment (45.86 ± 9.31 and 46.38 ± 8.89 MPa, respectively) had similar mean flexural strength values, and both had significantly higher bond strength than tungsten bur treatment (36.81 ± 7.60 MPa). Mechanico-thermal cycling decreased the mean flexural strength values significantly for all six alloy-surface treatment combinations tested when compared to the control groups. The failure type was adhesive in the metal/ceramic interface for specimens surface treated only with the tungsten bur, and mixed for specimens surface treated with APA 10 and 20 mm. Considering the levels adopted in this study, the alloy did not affect the bond strength; APA with Al(2) O(3) at 10 and

  5. Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition

    NARCIS (Netherlands)

    Schmale, J.; Henning, S.; Henzing, B.; Keskinen, H.; Sellegri, K.; Ovadnevaite, J.; Bougiatioti, A.; Kalivitis, N.; Stavroulas, I.; Jefferson, A.; Park, M.; Schlag, P.; Kristensson, A.; Iwamoto, Y.; Pringle, K.; Reddington, C.; Aalto, P.; Äijälä, M.; Baltensperger, U.; Bialek, J.; Birmili, W.; Bukowiecki, N.; Ehn, M.; Fjæraa, A.M.; Fiebig, M.; Frank, G.; Fröhlich, R.; Frumau, A.; Furuya, M.; Hammer, E.; Heikkinen, L.; Herrmann, E.; Holzinger, R.; Hyono, H.; Kanakidou, M.; Kiendler-Scharr, A.; Kinouchi, K.; Kos, G.; Kulmala, M.; Mihalopoulos, N.; Motos, G.; Nenes, A.; O'Dowd, C.; Paramonov, M.; Petäjä, T.; Picard, D.; Poulain, L.; Prévôt, A.S.H.; Slowik, J.; Sonntag, A.; Swietlicki, E.; Svenningsson, B.; Tsurumaru, H.; Wiedensohler, A.; Wittbom, C.; Ogren, J.A.; Matsuki, A.; Yum, S.S.; Myhre, C.L.; Carslaw, K.; Stratmann, F.; Gysel, M.

    2017-01-01

    Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other

  6. Dimensional measurements with submicrometer uncertainty in production environment

    DEFF Research Database (Denmark)

    De Chiffre, L.; Gudnason, M. M.; Madruga, D.

    2015-01-01

    The work concerns a laboratory investigation of a method to achieve dimensional measurements with submicrometer uncertainty under conditions that are typical of a production environment. The method involves the concurrent determination of dimensions and material properties from measurements carried...... out over time. A laboratory set-up was developed comprising a pair of electronic probes mounted on a Zerodur block featuring near zero thermal expansion. Three temperature sensors, data acquisition system, and a temperature regulated plate for heating the workpiece were implemented. Investigations...... gauge blocks along with their uncertainties were estimated directly from the measurements. The length of the two workpieces at the reference temperature of 20 °C was extrapolated from the measurements and compared to certificate values. The investigations have documented that the developed approach...

  7. Three-dimensional structure of brain tissue at submicrometer resolution

    Energy Technology Data Exchange (ETDEWEB)

    Saiga, Rino; Mizutani, Ryuta, E-mail: ryuta@tokai-u.jp [Department of Applied Biochemistry, Tokai University, Hiratsuka, Kanagawa 259-1292 (Japan); Inomoto, Chie; Takekoshi, Susumu; Nakamura, Naoya; Tsuboi, Akio; Osawa, Motoki [Tokai University School of Medicine, Isehara, Kanagawa 259-1193 (Japan); Arai, Makoto; Oshima, Kenichi; Itokawa, Masanari [Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506 (Japan); Uesugi, Kentaro; Takeuchi, Akihisa; Terada, Yasuko; Suzuki, Yoshio [Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Sayo, Hyogo 679-5198 (Japan)

    2016-01-28

    Biological objects are composed of submicrometer structures such as cells and organelles that are essential for their functions. Here, we report on three-dimensional X-ray visualization of cells and organelles at resolutions up to 100 nm by imaging microtomography (micro-CT) equipped with Fresnel zone plate optics. Human cerebral tissue, fruit fly cephalic ganglia, and Escherichia coli bacteria labeled with high atomic-number elements were embedded in epoxy resin and subjected to X-ray microtomography at the BL37XU and BL47XU beamlines of the SPring-8 synchrotron radiation facility. The obtained results indicated that soft tissue structures can be visualized with the imaging microtomography.

  8. Fabrication of mullite-bonded porous SiC ceramics from multilayer-coated SiC particles through sol-gel and in-situ polymerization techniques

    Science.gov (United States)

    Ebrahimpour, Omid

    In this work, mullite-bonded porous silicon carbide (SiC) ceramics were prepared via a reaction bonding technique with the assistance of a sol-gel technique or in-situ polymerization as well as a combination of these techniques. In a typical procedure, SiC particles were first coated by alumina using calcined powder and alumina sol via a sol-gel technique followed by drying and passing through a screen. Subsequently, they were coated with the desired amount of polyethylene via an in-situ polymerization technique in a slurry phase reactor using a Ziegler-Natta catalyst. Afterward, the coated powders were dried again and passed through a screen before being pressed into a rectangular mold to make a green body. During the heating process, the polyethylene was burnt out to form pores at a temperature of about 500°C. Increasing the temperature above 800°C led to the partial oxidation of SiC particles to silica. At higher temperatures (above 1400°C) derived silica reacted with alumina to form mullite, which bonds SiC particles together. The porous SiC specimens were characterized with various techniques. The first part of the project was devoted to investigating the oxidation of SiC particles using a Thermogravimetric analysis (TGA) apparatus. The effects of particle size (micro and nano) and oxidation temperature (910°C--1010°C) as well as the initial mass of SiC particles in TGA on the oxidation behaviour of SiC powders were evaluated. To illustrate the oxidation rate of SiC in the packed bed state, a new kinetic model, which takes into account all of the diffusion steps (bulk, inter and intra particle diffusion) and surface oxidation rate, was proposed. Furthermore, the oxidation of SiC particles was analyzed by the X-ray Diffraction (XRD) technique. The effect of different alumina sources (calcined Al2O 3, alumina sol or a combination of the two) on the mechanical, physical, and crystalline structure of mullite-bonded porous SiC ceramics was studied in the

  9. Effect of nepheline syenite particle size on diametrical compression strength and reliability of extruded ceramic Raschig rings used in packed towers

    Energy Technology Data Exchange (ETDEWEB)

    Salem, A.; Rostami, N.

    2013-06-01

    In order to understand the effect of nepheline syenite particle size on physico-chemical properties of ceramic Raschig rings, the fluxing agent was grinded at different milling times. The compositions were prepared by blending the illitic-kaolinitic clay and pre-grinded particles. The rings were shaped by a laboratory extruder and then were sintered at 1200 degree centigrade. The mechanical reliability of sintered specimens was mathematically described by Weibull theory and the effect of pre-grinding of fluxing agent on Weibull modulus was evaluated by measuring the diametrical compression strength. Weibull modulus and strength were the criteria for selecting the suitable particle size range of nepheline syenite. It was found that the pre-grinding of nepheline syenite acts as fairly strong parameter on microstructure of rings. The investigation concludes that reliable rings can be fabricated if the particle size of nepheline syenite is arranged between 53 and 75 {mu}m. This enhancement in reliability is valuable in packed towers. (Author)

  10. Effect of nepheline syenite particle size on diametrical compression strength and reliability of extruded ceramic Raschig rings used in packed towers

    Energy Technology Data Exchange (ETDEWEB)

    Salem, A.; Rostami, N.

    2013-05-01

    In order to understand the effect of nepheline syenite particle size on physico-chemical properties of ceramic Raschig rings, the fluxing agent was grinded at different milling times. The compositions were prepared by blending the illitic-kaolinitic clay and pre-grinded particles. The rings were shaped by a laboratory extruder and then were sintered at 1200 degree centigrade. The mechanical reliability of sintered specimens was mathematically described by Weibull theory and the effect of pre-grinding of fluxing agent on Weibull modulus was evaluated by measuring the diametrical compression strength. Weibull modulus and strength were the criteria for selecting the suitable particle size range of nepheline syenite. It was found that the pre-grinding of nepheline syenite acts as fairly strong parameter on microstructure of rings. The investigation concludes that reliable rings can be fabricated if the particle size of nepheline syenite is arranged between 53 and 75 {mu}m. This enhancement in reliability is valuable in packed towers. (Author) 17 refs.

  11. Elaboration of silicon carbides nano particles (SiC): from the powder synthesis to the sintered ceramic; Elaboration de ceramiques nanostructurees en carbure de silicium (SiC): de la synthese de poudre a la ceramique frittee

    Energy Technology Data Exchange (ETDEWEB)

    Reau, A. [CEA Saclay, Dept. des Materiaux pour le Nucleaire (DEN/DANS/DMN/SRMA), 91 - Gif-sur-Yvette (France)

    2008-07-01

    Materials for the reactor cores of the fourth generation will need materials supporting high temperatures with fast neutrons flux. SiC{sub f}/SiC ceramics are proposed. One of the possible elaboration process is to fill SiC fiber piece with nano particles SiC powder and to strengthen by sintering. The aim of this thesis is to obtain a nano structured SiC ceramic as a reference for the SiC{sub f}/SiC composite development and to study the influence of the fabrication parameters. (A.L.B.)

  12. Supported microporous ceramic membranes

    Science.gov (United States)

    Webster, Elizabeth; Anderson, Marc

    1993-01-01

    A method for permformation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms.

  13. Ceramic fiber filter technology

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, B.L.; Janney, M.A.

    1996-06-01

    Fibrous filters have been used for centuries to protect individuals from dust, disease, smoke, and other gases or particulates. In the 1970s and 1980s ceramic filters were developed for filtration of hot exhaust gases from diesel engines. Tubular, or candle, filters have been made to remove particles from gases in pressurized fluidized-bed combustion and gasification-combined-cycle power plants. Very efficient filtration is necessary in power plants to protect the turbine blades. The limited lifespan of ceramic candle filters has been a major obstacle in their development. The present work is focused on forming fibrous ceramic filters using a papermaking technique. These filters are highly porous and therefore very lightweight. The papermaking process consists of filtering a slurry of ceramic fibers through a steel screen to form paper. Papermaking and the selection of materials will be discussed, as well as preliminary results describing the geometry of papers and relative strengths.

  14. Simulating aerosol microphysics with the ECHAM4/MADE GCM – Part II: Results from a first multiannual simulation of the submicrometer aerosol

    Directory of Open Access Journals (Sweden)

    A. Lauer

    2006-01-01

    Full Text Available First results of a multiannual integration with the new global aerosol model system ECHAM4/MADE are presented. This model system enables simulations of the particle number concentration and size-distribution, which is a fundamental innovation compared to previous global model studies considering aerosol mass cycles only. The data calculated by the model provide detailed insights into the properties of the global submicrometer aerosol regarding global burden, chemical composition, atmospheric residence time, particle number concentration and size-distribution. The aerosol components considered by the model are sulfate (SO4, nitrate (NO3, ammonium (NH4, black carbon (BC, organic matter (OM, mineral dust, sea salt and aerosol water. The simulated climatological annual mean global atmospheric burdens (residence times of the dominant submicrometer aerosol components are 2.25 Tg (4.5 d for SO4, 0.46 Tg (4.5 d for NH4, 0.26 Tg (6.6 d for BC, and 1.77 Tg (6.5 d for OM. The contributions of individual processes such as emission, nucleation, condensation or dry and wet deposition to the global sources and sinks of specific aerosol components and particle number concentration are quantified. Based on this analysis, the significance of aerosol microphysical processes (nucleation, condensation, coagulation is evaluated by comparison to the importance of other processes relevant for the submicrometer aerosol on the global scale. The results reveal that aerosol microphysics are essential for the simulation of the particle number concentration and important but not vital for the simulation of particle mass concentration. Hence aerosol microphysics should be taken into account in simulations of atmospheric processes showing a significant dependence on aerosol particle number concentration. The analysis of the vertical variation of the microphysical net production and net depletion rates performed for particle number concentration, sulfate mass and black carbon

  15. Fatigue behavior of Ti6Al4V and 316 LVM blasted with ceramic particles of interest for medical devices.

    Science.gov (United States)

    Barriuso, S; Chao, J; Jiménez, J A; García, S; González-Carrasco, J L

    2014-02-01

    Grit blasting is used as a cost-effective method to increase the surface roughness of metallic biomaterials, as Ti6Al4V and 316 LVM, to enhance the osteointegration, fixation and stability of implants. Samples of these two alloys were blasted by using alumina and zirconia particles, yielding rough (up to Ra~8μm) and nearly smooth (up to Ra~1μm) surfaces, respectively. In this work, we investigate the sub-surface induced microstructural effects and its correlation with the mechanical properties, with special emphasis in the fatigue behavior. Blasting with zirconia particles increases the fatigue resistance whereas the opposite effect is observed using alumina ones. As in a conventional shot penning process, the use of rounded zirconia particles for blasting led to the development of residual compressive stresses at the surface layer, without zones of stress concentrators. Alumina particles are harder and have an angular shape, which confers a higher capability to abrade the surface, but also a high rate of breaking down on impact. The higher roughness and the presence of a high amount of embedded alumina particles make the blasted alloy prone to crack nucleation. Interestingly, the beneficial or detrimental role of blasting is more intense for the Ti6Al4V alloy than for the 316 steel. It is proposed that this behavior is related to their different strain hardening exponents and the higher mass fraction of particles contaminating the surface. The low value of this exponent for the Ti6Al4V alloy justifies the expected low sub-surface hardening during the severe plastic deformation, enhancing its capability to soft during cyclic loading. © 2013 Published by Elsevier Ltd.

  16. Real-world traffic emission factors of gases and particles measured in a road tunnel in Stockholm, Sweden

    National Research Council Canada - National Science Library

    Kristensson, Adam; Johansson, Christer; Westerholm, Roger; Swietlicki, Erik; Gidhagen, Lars; Wideqvist, Ulla; Vesely, Vaclav

    2004-01-01

    .... These include 49 different polycyclic aromatic hydrocarbons (PAH), CO, NOX, benzene, toluene, xylenes, aldehydes, elements and inorganic/organic carbon contained in particles, the sub-micrometer aerosol number size distribution, PM2.5 and PM10...

  17. Laser melt injection of hard ceramic particles into Al and Ti alloys - processing, microstructure and mechanical behaviour

    NARCIS (Netherlands)

    Ocelik, V.; Nijman, S.; van Ingen, R.; Oliveira, U.; de Hosson, J.T.M.; Brebbia, CA; DeHosson, JTM; Nishida, SI

    2003-01-01

    The conditions for a successful Laser Melt Injection (LMI) of SiC and WC particles into the melt pool of Al8Si and Ti6A14V alloys were studied experimentally and theoretically by FEM calculations. The laser employed is a high power Nd:YAG. The formation of a relatively thick aluminium oxide layer on

  18. Effect of nepheline syenite particle size on diametrical compression strength and reliability of extruded ceramic Raschig rings used in packed towers

    Directory of Open Access Journals (Sweden)

    Salem, Amin

    2013-04-01

    Full Text Available In order to understand the effect of nepheline syenite particle size on physico-chemical properties of ceramic Raschig rings, the fluxing agent was grinded at different milling times. The compositions were prepared by blending the illitic-kaolinitic clay and pre-grinded particles. The rings were shaped by a laboratory extruder and then were sintered at 1200 ºC. The mechanical reliability of sintered specimens was mathematically described by Weibull theory and the effect of pre-grinding of fluxing agent on Weibull modulus was evaluated by measuring the diametrical compression strength. Weibull modulus and strength were the criteria for selecting the suitable particle size range of nepheline syenite. It was found that the pre-grinding of nepheline syenite acts as fairly strong parameter on microstructure of rings. The investigation concludes that reliable rings can be fabricated if the particle size of nepheline syenite is arranged between 53 and 75 μm. This enhancement in reliability is valuable in packed towers.Para conocer el efecto del tamaño de partícula de nefelina sienita sobre las propiedades fisicoquímicas de los anillos Raschig cerámicos, este fundente fue molido a diferentes tiempos. Las composiciones se prepararon mediante la mezcla de la arcilla caolinítica illitica y las partículas pre-molidas. Los anillos se obtuvieron en una extrusora de laboratorio y luego fueron sinterizados a 1200 ºC. La fiabilidad mecánica de las muestras sinterizadas se describe matemáticamente por la teoría de Weibull y el efecto de pre-molienda del fundente en el módulo de Weibull se evaluó midiendo la resistencia a la compresión diametral. El módulo de Weibull y la resistencia fueron los criterios para seleccionar el rango de tamaño de partícula adecuado de nefelina sienita para la fabricación de los anillos que se determinó estaba entre 53 y 75 μm comprobándose que influye considerablemente en la microestructura de los mismos. La

  19. M&A For Lithography Of Sparse Arrays Of Sub-Micrometer Features

    Science.gov (United States)

    Brueck, Steven R.J.; Chen, Xiaolan; Zaidi, Saleem; Devine, Daniel J.

    1998-06-02

    Methods and apparatuses are disclosed for the exposure of sparse hole and/or mesa arrays with line:space ratios of 1:3 or greater and sub-micrometer hole and/or mesa diameters in a layer of photosensitive material atop a layered material. Methods disclosed include: double exposure interferometric lithography pairs in which only those areas near the overlapping maxima of each single-period exposure pair receive a clearing exposure dose; double interferometric lithography exposure pairs with additional processing steps to transfer the array from a first single-period interferometric lithography exposure pair into an intermediate mask layer and a second single-period interferometric lithography exposure to further select a subset of the first array of holes; a double exposure of a single period interferometric lithography exposure pair to define a dense array of sub-micrometer holes and an optical lithography exposure in which only those holes near maxima of both exposures receive a clearing exposure dose; combination of a single-period interferometric exposure pair, processing to transfer resulting dense array of sub-micrometer holes into an intermediate etch mask, and an optical lithography exposure to select a subset of initial array to form a sparse array; combination of an optical exposure, transfer of exposure pattern into an intermediate mask layer, and a single-period interferometric lithography exposure pair; three-beam interferometric exposure pairs to form sparse arrays of sub-micrometer holes; five- and four-beam interferometric exposures to form a sparse array of sub-micrometer holes in a single exposure. Apparatuses disclosed include arrangements for the three-beam, five-beam and four-beam interferometric exposures.

  20. Improving the strength of ceramics by controlling the interparticle forces and rheology of the ceramic suspensions

    CERN Document Server

    Chou, Y P

    2001-01-01

    This thesis describes a study of the modification of the interparticle forces of colloidal ceramic particles in aqueous suspensions in order to improve the microstructural homogeneity, and hence the reliability and mechanical performances, of subsequently formed ceramic compacts. A concentrated stable fine ceramic powder suspension has been shown to be able to generate a higher density of a ceramic product with better mechanical, and also electrical, electrochemical and optical, properties of the ceramic body. This is because in a colloidally stable suspension there are no aggregates and so defect formation, which is responsible for the ceramic body performance below its theoretical maximum, is reduced. In order to achieve this, it is necessary to form a well dispersed ceramic suspension by ensuring the interparticle forces between the particles are repulsive, with as a high a loading with particles as possible. By examining the rheological behaviour and the results of Atomic Force Microscope, the dispersion ...

  1. Ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

  2. Thermal shock resistance ceramic insulator

    Science.gov (United States)

    Morgan, Chester S.; Johnson, William R.

    1980-01-01

    Thermal shock resistant cermet insulators containing 0.1-20 volume % metal present as a dispersed phase. The insulators are prepared by a process comprising the steps of (a) providing a first solid phase mixture of a ceramic powder and a metal precursor; (b) heating the first solid phase mixture above the minimum decomposition temperature of the metal precursor for no longer than 30 minutes and to a temperature sufficiently above the decomposition temperature to cause the selective decomposition of the metal precursor to the metal to provide a second solid phase mixture comprising particles of ceramic having discrete metal particles adhering to their surfaces, said metal particles having a mean diameter no more than 1/2 the mean diameter of the ceramic particles, and (c) densifying the second solid phase mixture to provide a cermet insulator having 0.1-20 volume % metal present as a dispersed phase.

  3. Fatigue behavior in water of Y-TZP zirconia ceramics after abrasion with 30 μm silica-coated alumina particles.

    Science.gov (United States)

    Scherrer, Susanne S; Cattani-Lorente, Maria; Vittecoq, Eric; de Mestral, François; Griggs, Jason A; Wiskott, H W Anselm

    2011-02-01

    The use of a 30 μm alumina-silica coated particle sand (CoJet™ Sand, 3M Espe), has shown to enhance the adhesion of resin cements to Y-TZP. The question is whether or not sandblasting 30 μm particles does negatively affect the fatigue limit (S-N curves) and the cumulative survival of Y-TZP ceramics. Four zirconia materials tested were: Zeno (ZW) (Wieland), Everest ZS (KV) (KaVo), Lava white (LV) and Lava colored (LVB) (3M Espe). Fatigue testing (S-N) was performed on 66bar of 3 mm × 5 mm × 40 mm with beveled edges for each zirconia material provided by the manufacturers. One half of the specimens were CoJet sandblasted in the middle of the tensile side on a surface of 5 mm × 6 mm. Cyclic fatigue (N=30/group) (sinusoidal loading/unloading at 10 Hz between 10% and 100% load) was performed in 3-point-bending in a water tank. Stress levels were lowered from the initial static value (average of N=3) until surviving 1 million cycles. Fatigue limits were determined from trend lines. Kaplan-Meier survival analysis was performed to determine the failure stress at the median percentile survival level for 1 million of cycles before and after sandblasting. The statistical analyses used the log-rank test. Characterization of the critical flaw was performed by SEM for the majority of the failed specimens. The fatigue limits "as received" (ctr) were: LV=720 MPa, LVB=600 MPa, KV=560 MPa, ZW=470 MPa. The fatigue limits "after CoJet sandblasting" were: LV=840 MPa, LVB=788 MPa, KV=645 MPa, ZW=540 MPa. The increase in fatigue limit after sandblasting was 15% for Zeno (ZW) and Everest (KV), 17% for Lava (LV) and 31% for Lava colored (LVB). The KM median survival stresses in MPa were: ZW(ctr)=549 (543-555), ZW(s)=587 (545-629), KV(ctr)=593 (579-607), KV(s)=676 (655-697), LVB(ctr)=635 (578-692), LVB(s)=809 (787-831), LV(ctr)=743 (729-757), LV(s)=908 (840-976). Log-rank tests were significantly different (pceramic materials and can therefore be recommended for adhesive cementation

  4. [Ceramic posts].

    Science.gov (United States)

    Mainjot, Amélie; Legros, Caroline; Vanheusden, Alain

    2006-01-01

    As a result of ceramics and all-ceram technologies development esthetic inlay core and abutments flooded the market. Their tooth-colored appearance enhances restoration biomimetism principally on the marginal gingiva area. This article reviews indications and types of cores designed for natural teeth and implants.

  5. Injection molding of nanopatterned surfaces in the sub-micrometer range with induction heating aid

    DEFF Research Database (Denmark)

    Menotti, Stefano; Hansen, Hans Nørgaard; Bissacco, Giuliano

    2014-01-01

    Replication of sub-micrometer structures by injection molding leads to special requirements for the mold in order to ensure proper replica and acceptable cycle time. This paper investigates the applicability of induction heating embedded into the mold for the improvement of nanopattern replication....... A tool insert having a surface containing functional geometries in the sub-micrometer range was produced using aluminum anodization and nickel electroplating. In order to provide elevated mold temperatures necessary for the complete replica of the pattern, a new mold setup was developed, which allows...... rapid heating of the cavity wall using an induction heating system. Temperature was measured using a thermocouple placed in the mold insert. The system was used to heat up the cavity wall with heating rates of up to 10 K/s. Acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) were used...

  6. Study and evaluation of atmospheric pollution in Spain: necessary measures arising from the EC Directive on PM10 and PM2.5 particles in the Ceramic industry

    Directory of Open Access Journals (Sweden)

    Rodríguez, S.

    2000-02-01

    Full Text Available The European Commission Directive, 1999/30/EC, approved on the 22nd of April 1999, on atmospheric particles establishes a standard that is more stringent than the current one. This Directive proposes the monitoring of particles lower than 10 μm (PM10, thoracic particles based on health impact criteria. The proposed EC limits are 40 μgPM10.m-3 and 20 μgPM10.m-3 as annual means in 2005 and 2010, respectively. In accordance with the European Commission (EC, the future PM10 limits will be revised in 2003 if the European States can demonstrate that the exceedances of the new limits are attributed to natural inputs. The exceedances due to natural inputs are more frequent in Mediterranean countries due to the re-suspension of natural soil particles and to the higher frequency of Saharan air mass intrusions. This study summarises the preliminary results obtained from two research projects in Spain focused on: 1 establishing the criteria for the discrimination of natural/anthropogenic inputs of PM10; 2 identifying the events when the proposed limits are exceeded by natural inputs and 3 determining the most suitable monitoring parameter, PM10 or PM2.5, in order to avoid natural interference. Given the importance of the ceramic industry in Castelló, special attention will be placed on the preliminary results obtained this area.La Directiva de la comisión Europea, 1999/30/CE, aprobada el 22 de Abril de 1999, referida a partículas atmosféricas en suspensión, establece una normativa más estricta que la vigente. Esta normativa propone el control de las partículas inferiores a 10 μm (PM10, partículas torácicas basándose en criterios de impacto en la salud. Según esta directiva no se podrán superar medias diarias anuales de 40 μgPM10.m-3 en el 2005 y de 20 μgPM10.m-3 en el 2010. La directiva contempla la revisión de los límites normativos y de los parámetros de control en el 2003, pudiendo variar estos en el caso de que los Estados miembros

  7. Properties of ceramic-reinforced aluminium matrix composites - a review

    National Research Council Canada - National Science Library

    Das, Dipti Kanta; Mishra, Purna Chandra; Singh, Saranjit; Thakur, Ratish Kumar

    2014-01-01

    .... The properties discussed include microstructural, optical, physical and mechanical behaviour of ceramic-reinforced aluminium matrix composites and effects of reinforcement fraction, particle size...

  8. Engineering ceramics

    CERN Document Server

    Bengisu, Murat

    2001-01-01

    This is a comprehensive book applying especially to junior and senior engineering students pursuing Materials Science/ Engineering, Ceramic Engineering and Mechanical Engineering degrees. It is also a reference book for other disciplines such as Chemical Engineering, Biomedical Engineering, Nuclear Engineering and Environmental Engineering. Important properties of most engineering ceramics are given in detailed tables. Many current and possible applications of engineering ceramics are described, which can be used as a guide for materials selection and for potential future research. While covering all relevant information regarding raw materials, processing properties, characterization and applications of engineering ceramics, the book also summarizes most recent innovations and developments in this field as a result of extensive literature search.

  9. Tetragonal and cubic zirconia multilayered ceramic constructs created by EPD.

    Science.gov (United States)

    Mochales, Carolina; Frank, Stefan; Zehbe, Rolf; Traykova, Tania; Fleckenstein, Christine; Maerten, Anke; Fleck, Claudia; Mueller, Wolf-Dieter

    2013-02-14

    The interest in electrophoretic deposition (EPD) for nanomaterials and ceramics production has widely increased due to the versatility of this technique to effectively combine different materials in unique shapes and structures. We successfully established an EPD layering process with submicrometer sized powders of Y-TZP with different mol percentages of yttrium oxide (3 and 8%) and produced multilayers of alternating tetragonal and cubic phases with a clearly defined interface. The rationale behind the design of these multilayer constructs was to optimize the properties of the final ceramic by combining the high mechanical toughness of the tetragonal phase of zirconia together with the high ionic conductivity of its cubic phase. In this work, a preliminary study of the mechanical properties of these constructs proved the good mechanical integrity of the multilayered constructs obtained as well as crack deflection in the interface between tetragonal and cubic zirconia layers.

  10. The role of jet and film drops in controlling the mixing state of submicron sea spray aerosol particles.

    Science.gov (United States)

    Wang, Xiaofei; Deane, Grant B; Moore, Kathryn A; Ryder, Olivia S; Stokes, M Dale; Beall, Charlotte M; Collins, Douglas B; Santander, Mitchell V; Burrows, Susannah M; Sultana, Camille M; Prather, Kimberly A

    2017-07-03

    The oceans represent a significant global source of atmospheric aerosols. Sea spray aerosol (SSA) particles comprise sea salts and organic species in varying proportions. In addition to size, the overall composition of SSA particles determines how effectively they can form cloud droplets and ice crystals. Thus, understanding the factors controlling SSA composition is critical to predicting aerosol impacts on clouds and climate. It is often assumed that submicrometer SSAs are mainly formed by film drops produced from bursting bubble-cap films, which become enriched with hydrophobic organic species contained within the sea surface microlayer. In contrast, jet drops formed from the base of bursting bubbles are postulated to mainly produce larger supermicrometer particles from bulk seawater, which comprises largely salts and water-soluble organic species. However, here we demonstrate that jet drops produce up to 43% of total submicrometer SSA number concentrations, and that the fraction of SSA produced by jet drops can be modulated by marine biological activity. We show that the chemical composition, organic volume fraction, and ice nucleating ability of submicrometer particles from jet drops differ from those formed from film drops. Thus, the chemical composition of a substantial fraction of submicrometer particles will not be controlled by the composition of the sea surface microlayer, a major assumption in previous studies. This finding has significant ramifications for understanding the factors controlling the mixing state of submicrometer SSA particles and must be taken into consideration when predicting SSA impacts on clouds and climate.

  11. The role of jet and film drops in controlling the mixing state of submicron sea spray aerosol particles

    Science.gov (United States)

    Wang, Xiaofei; Deane, Grant B.; Moore, Kathryn A.; Ryder, Olivia S.; Stokes, M. Dale; Beall, Charlotte M.; Collins, Douglas B.; Santander, Mitchell V.; Burrows, Susannah M.; Sultana, Camille M.; Prather, Kimberly A.

    2017-07-01

    The oceans represent a significant global source of atmospheric aerosols. Sea spray aerosol (SSA) particles comprise sea salts and organic species in varying proportions. In addition to size, the overall composition of SSA particles determines how effectively they can form cloud droplets and ice crystals. Thus, understanding the factors controlling SSA composition is critical to predicting aerosol impacts on clouds and climate. It is often assumed that submicrometer SSAs are mainly formed by film drops produced from bursting bubble-cap films, which become enriched with hydrophobic organic species contained within the sea surface microlayer. In contrast, jet drops formed from the base of bursting bubbles are postulated to mainly produce larger supermicrometer particles from bulk seawater, which comprises largely salts and water-soluble organic species. However, here we demonstrate that jet drops produce up to 43% of total submicrometer SSA number concentrations, and that the fraction of SSA produced by jet drops can be modulated by marine biological activity. We show that the chemical composition, organic volume fraction, and ice nucleating ability of submicrometer particles from jet drops differ from those formed from film drops. Thus, the chemical composition of a substantial fraction of submicrometer particles will not be controlled by the composition of the sea surface microlayer, a major assumption in previous studies. This finding has significant ramifications for understanding the factors controlling the mixing state of submicrometer SSA particles and must be taken into consideration when predicting SSA impacts on clouds and climate.

  12. What every surgeon should know about Ceramic-on-Ceramic bearings in young patients

    Science.gov (United States)

    Hernigou, Philippe; Roubineau, François; Bouthors, Charlie; Flouzat-Lachaniette, Charles-Henri

    2016-01-01

    Based on the exceptional tribological behaviour and on the relatively low biological activity of ceramic particles, Ceramic-on-Ceramic (CoC) total hip arthroplasty (THA) presents significant advantages CoC bearings decrease wear and osteolysis, the cumulative long-term risk of dislocation, muscle atrophy, and head-neck taper corrosion. However, there are still concerns regarding the best technique for implantation of ceramic hips to avoid fracture, squeaking, and revision of ceramic hips with fracture of a component. We recommend that surgeons weigh the potential advantages and disadvantages of current CoC THA in comparison with other bearing surfaces when considering young very active patients who are candidates for THA. Cite this article: Hernigou P, Roubineau F, Bouthors C, Flouzat-Lachaniette C-H. What every surgeon should know about Ceramic-on-Ceramic bearings in young patients. EFORT Open Rev 2016;1:107-111. DOI: 10.1302/2058-5241.1.000027. PMID:28461936

  13. Synthesis of Micro/Nano Crystalline Ceramics

    Science.gov (United States)

    Mathew, Philip; Isac, Sheelakumari; Abraham, Rosalin; Isac, Jayakumari

    2008-04-01

    As a matter of fact almost every industrial production line, office and home is dependant on ceramic materials. Newly designed devices incorporate ceramic materials because of their useful chemical, electrical, mechanical, thermal and structural properties. The effectiveness of a large system depends critically on its ceramic components. That is ceramics are important, first because they comprise a large basic industry and second because their properties are essential for many applications. Ceramics are more stable than metals both in chemical and thermal environments. In this work the authors describes a method for the preparation of PBT ceramics material from lead oxide (PbO), barium carbonate and titanium oxide based on pre-calcinations of oxides. The results were analyzed by X-ray Diffraction (XRD), Infrared Spectroscopy (IR) and TGA. XRD and SEM studies revealed that its particle size is in nanometer range. Dielectric studies were conducted at a frequency range of 100 KHz to 13 MHz. Mechanical properties were calculated.

  14. Influência da distribuição granulométrica na estabilidade dimensional de placas cerâmicas de base vermelha Influence of particle size distribution on the dimensional stability of red ceramic tiles

    Directory of Open Access Journals (Sweden)

    A. C. A. Prado

    2008-12-01

    Full Text Available As propriedades do revestimento cerâmico queimado estão intrinsecamente ligadas às características da massa, dentre estas se encontram o tamanho, a distribuição, o formato e o arranjo das partículas. O efeito da distribuição granulométrica de partículas sobre a estabilidade dimensional de placas cerâmicas para revestimentos de base vermelha foi estudado em três massas, todas continham no mínimo 57% de material advindo da Formação Corumbataí. Foram estudadas duas distribuições granulométricas - uma parecida com aquelas usadas no Pólo Cerâmico de Santa Gertrudes e, outra, com uma massa de grés. De uma maneira geral, granulações mais grossas, semelhantes à massa de Santa Gertrudes, variaram menos dimensionalmente quando as placas apresentaram médias e altas porosidades (absorção de água entre 3,0 e 10,0%. Já, granulações mais finas, similares a massas de grés, foram necessárias para a produção de placas de baixa absorção (menor que 3,0%.The properties of final ceramic tiles are related with the mass characteristics, among them the size, shape, distribution and arrange of particles. The effect of particle size distribution on dimensional stability of red ceramic tiles was studied in three masses; all of them composed with, at minimum, 57% of Corumbataí Formation's materials. Two particle size distributions were investigated: the first was similar to the masses that are used in the Santa Gertrudes Ceramic Pole's factories and the other was similar to the stoneware mass. In general, masses with larger particle sizes, similar to that of Santa Gertrudes, had greater dimensional stability in the products with 3 to 10% of water absorption. On the other hand, in the manufacture of low porosity tiles (water absorption capacity < 3% it is recommended the use of smaller grain size.

  15. Nanopowders M{sub 2}O{sub 3} (M = Y, La, Yb, Nd) with spherical particles and laser ceramics based on them

    Energy Technology Data Exchange (ETDEWEB)

    Bagayev, Sergei N; Kaminskii, Alexandr A; Kopylov, Yu L; Kravchenko, V B; Tolmachev, A V; Shemet, V V; Yavetskii, R P

    2013-03-31

    We have considered the problems of agglomeration of yttrium aluminium garnet (YAG) nanopowders prepared by chemical co-precipitation of precursors from aqueous solutions and subsequent calcination. To fabricate YAG and Y{sub 2}O{sub 3} laser ceramic samples with high optical transmittance and reproducible characteristics, we have developed a method for producing non-agglomerated nanopowders of pure and doped Y{sub 2}O{sub 3} by homogeneous chemical precipitation. Nanopowders Y{sub 2}O{sub 3} with La and Yb as well as mixtures of Y{sub 2}O{sub 3} : Nd and several commercial nanopowders of aluminium oxide have been compacted; optimised compacting technique have been selected; ceramic samples (Y, La, Yb){sub 2}O{sub 3} and YAG : Nd with high optical transmittance at a wavelength of 1 {mu}m have been produced by solid-phase synthesis. (extreme light fields and their applications)

  16. Steady- and Transient-State Analyses of Fully Ceramic Microencapsulated Fuel with Randomly Dispersed Tristructural Isotropic Particles via Two-Temperature Homogenized Model—I: Theory and Method

    Directory of Open Access Journals (Sweden)

    Yoonhee Lee

    2016-06-01

    Full Text Available As a type of accident-tolerant fuel, fully ceramic microencapsulated (FCM fuel was proposed after the Fukushima accident in Japan. The FCM fuel consists of tristructural isotropic particles randomly dispersed in a silicon carbide (SiC matrix. For a fuel element with such high heterogeneity, we have proposed a two-temperature homogenized model using the particle transport Monte Carlo method for the heat conduction problem. This model distinguishes between fuel-kernel and SiC matrix temperatures. Moreover, the obtained temperature profiles are more realistic than those of other models. In Part I of the paper, homogenized parameters for the FCM fuel in which tristructural isotropic particles are randomly dispersed in the fine lattice stochastic structure are obtained by (1 matching steady-state analytic solutions of the model with the results of particle transport Monte Carlo method for heat conduction problems, and (2 preserving total enthalpies in fuel kernels and SiC matrix. The homogenized parameters have two desirable properties: (1 they are insensitive to boundary conditions such as coolant bulk temperatures and thickness of cladding, and (2 they are independent of operating power density. By performing the Monte Carlo calculations with the temperature-dependent thermal properties of the constituent materials of the FCM fuel, temperature-dependent homogenized parameters are obtained.

  17. Sub-micrometer adhesion modulation on polymer surfaces containing gratings produced by two-beam interference

    Energy Technology Data Exchange (ETDEWEB)

    Csete, M. [Department of Optics and Quantum Electronics, University of Szeged, Dom ter 9, H-6720 Szeged (Hungary)]. E-mail: mcsete@sol.cc.u-szeged.hu; Kresz, N. [Department of Optics and Quantum Electronics, University of Szeged, Dom ter 9, H-6720 Szeged (Hungary); Vass, Cs. [Department of Optics and Quantum Electronics, University of Szeged, Dom ter 9, H-6720 Szeged (Hungary); Kurdi, G. [Research Group on Laser Physics, University of Szeged, Dom ter 9, H-6720 Szeged (Hungary); Heiner, Zs. [Department of Optics and Quantum Electronics, University of Szeged, Dom ter 9, H-6720 Szeged (Hungary); Deli, M. [Laboratory of Molecular Neurobiology, Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Temesvari krt. 62, H-6726 Szeged (Hungary); Bor, Zs. [Department of Optics and Quantum Electronics, University of Szeged, Dom ter 9, H-6720 Szeged (Hungary); Marti, O. [Department of Experimental Physics, University of Ulm, Albert Einstein Allee 11, D-89069 Ulm (Germany)

    2005-12-15

    Grating-like structures having a period of 416 nm were produced on the surface of poly-carbonate films by two-beam interference realized by the fourth harmonic of Nd:Yag laser. The period of the structures was half of that the applied master grating, the ratio of the width of the valleys to the period was tuned by the intensity, the depth of the modulation was increased by the number of laser pulses. Pulsed force mode atomic force microscopy was applied to study the topography and the adhesion on structured surfaces with sub-micrometer resolution. The adhesion modulation caused by the topography was calculated along line cross-sections of the AFM pictures taking into account the tip and surface geometry. The separation of the effects of the topography and the laser-induced material changes proved that the adhesion is increased at the areas illuminated by laser beam having a fluence above the melting threshold. The laser-induced material changes cause an additional adhesion increase at the valleys of the structure. It was shown that the adherence of albumin results in dense packing on poly-carbonate surface parts having sub-micrometer periodic adhesion modulation.

  18. Fabrication of transparent ceramics using nanoparticles

    Science.gov (United States)

    Cherepy, Nerine J; Tillotson, Thomas M; Kuntz, Joshua D; Payne, Stephen A

    2012-09-18

    A method of fabrication of a transparent ceramic using nanoparticles synthesized via organic acid complexation-combustion includes providing metal salts, dissolving said metal salts to produce an aqueous salt solution, adding an organic chelating agent to produce a complexed-metal sol, heating said complexed-metal sol to produce a gel, drying said gel to produce a powder, combusting said powder to produce nano-particles, calcining said nano-particles to produce oxide nano-particles, forming said oxide nano-particles into a green body, and sintering said green body to produce the transparent ceramic.

  19. Infrared Optical Properties of β-Spodumene Solid Solution Glass-Ceramic for Fiber-Optic Devices

    Science.gov (United States)

    Sakamoto, Akihiko; Yamamoto, Shigeru

    2006-09-01

    The IR optical properties of an opaque β-spodumene solid solution (s.s.) glass-ceramic for fiber-optic devices were studied in relation to its refractive indices in both crystalline and glass phases. We investigated the refractive indices of both phases on the basis of IR transmittance change due to the structural relaxation of the glass phase. The refractive indices of this β-spodumene s.s. glass-ceramic at a wavelength of 1550 nm in the crystalline and glass phases were first determined to be 1.530 and 1.495, respectively. It was found from the refractive index data that the optical scattering intensity of this glass-ceramic approximately follows the Rayleigh-Gans model. We also demonstrated that the inner diameter of an opaque glass-ceramic capillary used in optical fiber connectors can be optically measured with a sub-micrometer accuracy using an IR laser.

  20. Ceramic Seal.

    Energy Technology Data Exchange (ETDEWEB)

    Smartt, Heidi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Romero, Juan A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Custer, Joyce Olsen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hymel, Ross W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Krementz, Dan [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Gobin, Derek [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Harpring, Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Martinez-Rodriguez, Michael [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Varble, Don [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); DiMaio, Jeff [Tetramer Technologies, Pendleton, SC (United States); Hudson, Stephen [Tetramer Technologies, Pendleton, SC (United States)

    2016-11-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  1. ceramic pigment

    Indian Academy of Sciences (India)

    In contrast, the relatively poor blue colour obtained by dispersing Co2SiO4 into ceramic glazes is mainly attributed to the evolution of Co2+ initially in octahedral coordination of olivine structure to tetrahedral coordination of glassy phase. On the other hand, regarding the growing concern on. Co costs and environmental ...

  2. Thermoelectric properties of Si/CoSi2 sub-micrometer composites prepared by melt-spinning technique

    Science.gov (United States)

    Xie, Jun; Ohishi, Yuji; Ichikawa, Satoshi; Muta, Hiroaki; Kurosaki, Ken; Yamanaka, Shinsuke

    2017-05-01

    We here report on the influence of CoSi2 precipitates on the thermoelectric properties of heavily doped p-type Si. A simple self-assembly process using a melt-spinning technique followed by spark plasma sintering is introduced to prepare bulk Si/CoSi2 composites with a nominal composition of (Si0.99B0.01)95Co5. Scanning and transmission electron microscopy observations present clear evidence of a sub-micrometer CoSi2 phase with a size ranging from 50 to 500 nm. These sub-micrometer precipitates resulted in a retention of the high electrical performance of heavily doped Si, while simultaneously reducing thermal conductivity by over 20% compared to a coarse CoSi2 phase (1-10 μm) in a comparative sample prepared by arc melting and spark plasma sintering. As a result, a figure of merit ZT value of 0.21 at 1073 K was achieved in the sub-micrometer Si/CoSi2, an increase of 16% compared with the ZT value for homogeneous p-type Si with a similar carrier concentration. This suggests that the self-assembled sub-micrometer inclusions effectively enhanced the thermoelectric performance of Si-based thermoelectric materials.

  3. Electro-optical and dielectric characterization of submicrometer-sized PDLC films

    Science.gov (United States)

    Krishna Koduru, Hari

    2017-01-01

    This report concerns thin films (25 µm thickness) of polymer-dispersed liquid crystal (PDLC) composites having submicrometer-sized nematic liquid crystal domains. Such PDLC films were prepared by performing photo-induced phase separation of mixed soft material composed from the room-temperature nematic liquid crystal 4-n-heptyl cyanobiphenyl (7CB) and photo-curable polymer NOA-65. Being of interest for electro-optical (EO) and other applications driven by alternating-current electric field, the produced composites were studied by EO measurements and complex impedance spectroscopy. For the examined soft-solid composite material with a large content of submicro-confined nematic, was obtained information about the dielectric permittivity and molecular dynamics, useful for practice.

  4. From micro to nano: properties and potential applications of micro- and nano-filled polymer ceramic composites in microsystem technology.

    Science.gov (United States)

    Hanemann, T; Boehm, J; Henzi, P; Honnef, K; Litfin, K; Ritzhaupt-Kleissl, E; Hausselt, J

    2004-08-01

    In microsystem technology, four important material classes are established either for the generation or the replication of microstructured surfaces: silicon, polymers, metals and ceramics. Composite materials consisting of a polymer matrix and ceramic fillers show improved thermomechanical properties in comparison to polymers and can be introduced as a new additional material class. The substitution of micro-sized ceramic fillers by nano-sized ceramics in composites has a strong influence on the composite's physical properties: the reduction of ceramic particle size down to the nanometre scale results in an improved sinter activity owing to the large surface area. The fabrication of dense ceramics is simplified and can be used for a rapid prototyping of microstructured ceramic parts. The addition of nano-sized ceramics with particle sizes of composites with modified refractive indices for use in polymer waveguides. The influence of the ceramic particle size, the ceramic content and different dispersion methods on the composite's physical properties are discussed.

  5. Monolithic ceramics

    Science.gov (United States)

    Herbell, Thomas P.; Sanders, William A.

    1992-01-01

    A development history and current development status evaluation are presented for SiC and Si3N4 monolithic ceramics. In the absence of widely sought improvements in these materials' toughness, and associated reliability in structural applications, uses will remain restricted to components in noncritical, nonman-rated aerospace applications such as cruise missile and drone gas turbine engine components. In such high temperature engine-section components, projected costs lie below those associated with superalloy-based short-life/expendable engines. Advancements are required in processing technology for the sake of fewer and smaller microstructural flaws.

  6. Hygroscopicity of the submicrometer aerosol at the high-alpine site Jungfraujoch, 3580 m a.s.l., Switzerland

    Directory of Open Access Journals (Sweden)

    S. Sjogren

    2008-09-01

    Full Text Available Data from measurements of hygroscopic growth of submicrometer aerosol with a hygroscopicity tandem differential mobility analyzer (HTDMA during four campaigns at the high alpine research station Jungfraujoch, Switzerland, are presented. The campaigns took place during the years 2000, 2002, 2004 and 2005, each lasting approximately one month. Hygroscopic growth factors (GF, i.e. the relative change in particle diameter from dry diameter, D0, to diameter measured at higher relative humidity, RH are presented for three distinct air mass types, namely for: 1 free tropospheric winter conditions, 2 planetary boundary layer influenced air masses (during a summer period and 3 Saharan dust events (SDE. The GF values at 85% RH (D0=100 nm were 1.40±0.11 and 1.29±0.08 for the first two situations while for SDE a bimodal GF distribution was often found. No phase changes were observed when the RH was varied between 10–90%, and the continuous water uptake could be well described with a single-parameter empirical model. The frequency distributions of the average hygroscopic growth factors and the width of the retrieved growth factor distributions (indicating whether the aerosol is internally or externally mixed are presented, which can be used for modeling purposes.

    Measurements of size resolved chemical composition were performed with an aerosol mass spectrometer in parallel to the GF measurements. This made it possible to estimate the apparent ensemble mean GF of the organics (GForg using inverse ZSR (Zdanovskii-Stokes-Robinson modeling. GForg was found to be ~1.20 at aw=0.85, which is at the upper end of previous laboratory and field data though still in agreement with the highly aged and oxidized nature of the Jungfraujoch aerosol.

  7. Durabilidade de peças cerâmicas vermelhas com adição de rejeito de rocha ornamental isenta de granalha Durability of red ceramic samples with addition of ornamental rock waste free of steel particles

    Directory of Open Access Journals (Sweden)

    D. V. Rodrigues

    2012-09-01

    Full Text Available Para avaliação da degradação acelerada em laboratório sofrida pelos corpos de prova de cerâmica vermelha com adição de rejeito de rocha ornamental isento de granalha, foi utilizado um equipamento que lixivia com água quente e fria em tempos controlados, e também, congela a amostra em até -4 ºC. Os corpos de prova cerâmicos foram confeccionados com até 10% em massa de rejeito de rocha ornamental a seco, e em seguida, umedecidos e moldados por extrusão. Os materiais produzidos foram calcinados nas temperaturas de 700 ºC, 800 ºC e 900 ºC. Após 1060 h de degradação acelerada em equipamento de laboratório, analisaram-se as propriedades cerâmicas do material. Os resultados das resistências mecânicas foram comparados através da distribuição de Weibull, antes e depois da degradação. Nota-se que o material com adição de 10% de rejeito de rocha ornamental na massa cerâmica é mais confiável quando queimada a 900 ºC após a degradação, quando comparados com as amostras sem adição de rejeito, proporcionando maior durabilidade.For the evaluation of the accelerated degradation in laboratory of red ceramic specimens with addition of ornamental rock waste free from steel particles, an equipment that leach with hot and cool water and time control, and also freezing the specimen at -4 ºC was used,. The ceramic samples were made with up to 10 wt.% of the dry ornamental rock waste, and after humidifying and molding by extrusion. The specimens were fired at 700 ºC, 800 ºC and 900 ºC. After 1060 h of accelerated degradation lab test, ceramic properties were evaluated. The results of the strength were compared for Weibull distribution, before and after degradation. The specimens with addition of 10 wt.% waste is more durable and reliable when fired to 900 ºC after the degradation.

  8. Do surface treatments affect the optical properties of ceramic veneers?

    Science.gov (United States)

    Turgut, Sedanur; Bağış, Bora; Korkmaz, Fatih Mehmet; Tamam, Evsen

    2014-09-01

    Surface treatments may affect the optical properties of ceramic veneers before cementation. The purpose of this study was to evaluate whether various surface treatments affect the optical properties of different types of ceramic veneers. Disk-shaped ceramic veneers (N=280) were prepared from the IPS e.max Press, e.max CAD, Empress Esthetic, e.max Ceram, and Inline ceramic systems with 0.5-mm and 1.0-mm thicknesses. The ceramics were divided into 4 groups: no surface treatments; etched with hydrofluoric acid; airborne-particle abraded with 30-μm Al2O3; and irradiated with erbium:yttrium-aluminum-garnet laser. A translucent shade of resin was chosen for cementation. Color parameters were examined with a colorimeter. Statistical analyses were done with 3-way ANOVA and the Bonferroni test (P=.05). Significant interactions were noted between the surface treatments, ceramic type, and thickness for ΔE values (P=.01), and no significant interactions were noted for L* (P=.773), a* (P=.984), and b* (P=.998). The greatest color change occurred after airborne-particle abrasion with 0.5-mm-thick e.max Press (2.9 ΔE). Significant differences in ΔE values were found among the hydrofluoric acid, airborne-particle abrasion, and laser groups for 0.5-mm-thick ceramics, except IPS Inline, and among the hydrofluoric acid, airborne-particle abrasion, and laser groups for 1.0-mm-thick ceramics, except Empress Esthetic ceramics. The color change of the ceramics increased after the surface treatments, particularly as the ceramics became thinner. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  9. The effect of the TiC particle size on the preferred oxidation temperature for self-healing of oxide ceramic matrix materials

    NARCIS (Netherlands)

    Boatemaa, L.; Brouwer, J.C.; van der Zwaag, S.; Sloof, W.G.

    2018-01-01

    The effect of particle size on the oxidation kinetics of TiC powders is studied. Different sizes of TiC powder ranging from nanometre to submillimetre sizes are investigated. The samples are heated at different heating rates from room temperature up to 1200 °C in dry synthetic air. The Kissinger

  10. Effect of airborne particle abrasion protocols on surface topography of Y-TZP ceramic Efeito do protocolo de jateamento com partículas na topografia da superfície de uma cerâmica Y-TZP

    Directory of Open Access Journals (Sweden)

    J. R. C. Queiroz

    2012-06-01

    Full Text Available This study aimed to evaluate Y-TZP surface after different airborne particle abrasion protocols. Seventy-six Y-TZP ceramic blocks (5×4×4 mm³ were sintered and polished. Specimens were randomly divided into 19 groups (n=4 according to control group and 3 factors: a protocol duration (2 and 4 s; b particle size (30 µm, alumina coated silica particle; 45 µm, alumina particle; and 145 µm, alumina particle and; c pressure (1.5, 2.5 and 4.5 bar. Airborne particle abrasion was performed following a strict protocol. For qualitative and quantitative results, topography surfaces were analyzed in a digital optical profilometer (Interference Microscopic, using different roughness parameters (Ra, Rq, Rz, X-crossing, Mr1, Mr2 and Sdr and 3D images. Surface roughness also was analyzed following the primer and silane applications on Y-TZP surfaces. One-way ANOVA revealed that treatments (application period, particle size and pressure of particle blasting provided significant difference for all roughness parameters. The Tukey test determined that the significant differences between groups were different among roughness parameters. In qualitative analysis, the bonding agent application reduced roughness, filing the valleys in the surface. The protocols performed in this study verified that application period, particle size and pressure influenced the topographic pattern and amplitude of roughness.O objetivo deste estudo foi avaliar a superfície de uma cerâmica à base de zircônia tetragonal estabilizada por ítria (Y-TZP após diferentes protocolos de jateamento com partículas. Setenta e seis blocos cerâmicos de Y-TZP (5 x 4 x 4 mm³ foram sinterizados e polidos. As amostras foram randomicamente divididas em 19 grupos (n=4 sendo um controle e 18 grupos utilizando 3 fatores: a tempo (2 e 4 s; b tamanho de partícula (30 µm - partículas de alumina revestida por sílica; 45 µm - partículas de alumina; 145 µm - partículas de alumina e; c pressão (1

  11. Characterization of dual-phase steel microstructure by combined submicrometer EBSD and EPMA carbon measurements.

    Science.gov (United States)

    Pinard, Philippe T; Schwedt, Alexander; Ramazani, Ali; Prahl, Ulrich; Richter, Silvia

    2013-08-01

    Electron backscatter diffraction (EBSD) and electron probe microanalysis (EPMA) measurements are combined to characterize an industrial produced dual-phase steel containing some bainite fraction. High-resolution carbon mappings acquired on a field emission electron microprobe are utilized to validate and improve the identification of the constituents (ferrite, martensite, and bainite) performed by EBSD using the image quality and kernel average misorientation. The combination eliminates the ambiguity between the identification of bainite and transformation-induced dislocation zones, encountered if only the kernel average misorientation is considered. The detection of carbon in high misorientation regions confirms the presence of bainite. These results are corroborated by secondary electron images after nital etching. Limitations of this combined method due to differences between the spatial resolution of EBSD and EPMA are assessed. Moreover, a quantification procedure adapted to carbon analysis is presented and used to measure the carbon concentration in martensite and bainite on a submicrometer scale. From measurements on reference materials, this method gives an accuracy of 0.02 wt% C and a precision better than 0.05 wt% C despite unavoidable effects of hydrocarbon contamination.

  12. Evolution of Submicrometer Organic Aerosols during a Complete Residential Coal Combustion Process.

    Science.gov (United States)

    Zhou, Wei; Jiang, Jingkun; Duan, Lei; Hao, Jiming

    2016-07-19

    In the absence of particulate matter (PM) control devices, residential coal combustion contributes significantly to ambient PM pollution. Characterizing PM emissions from residential coal combustion with high time resolution is beneficial for developing control policies and evaluating the environmental impact of PM. This study reports the evolution of submicrometer organic aerosols (OA) during a complete residential coal combustion process, that is, from fire start to fire extinction. Three commonly used coal types (bituminous, anthracite, and semicoke coals) were evaluated in a typical residential stove in China. For all three types of coal, the OA emission exhibited distinct characteristics in the four stages, that is, ignition, fierce combustion, relatively stable combustion, and ember combustion. OA emissions during the ignition stage accounted for 58.2-85.4% of the total OA emission of a complete combustion process. The OA concentration decreased rapidly during the fierce combustion stage and remained low during the relatively stable combustion stage. During these two stages, a significant ion peak of m/z 73 from organic acids were observed. The degree of oxidation of the OA increased from the first stage to the last stage. Implications for ambient OA source-apportionment and residential PM emission characterization and control are discussed.

  13. Single molecule analysis of bacterial polymerase chain reaction products in submicrometer fluidic channels.

    Science.gov (United States)

    Stavis, Samuel M; Corgié, Stéphane C; Cipriany, Benjamin R; Craighead, Harold G; Walker, Larry P

    2007-09-20

    Laser induced fluorescence in submicrometer fluidic channels was used to characterize the synthesis of polymerase chain reaction (PCR) products from a model bacterial system in order to explore the advantages and limitations of on chip real time single molecule PCR analysis. Single oligonucleotide universal bacterial primers and PCR amplicons from the 16S rDNA of Thermobifida fusca (325 bp) were directly detected at all phases of the reaction with low sample consumption and without post-amplification purification or size screening. Primers were fluorescently labeled with single Alexa Fluor 488 or Alexa Fluor 594 fluorophores, resulting in double labeled, two color amplicons. PCR products were driven electrokinetically through a fused silica channel with a 250 nm by 500 nm rectangular cross section. Lasers with 488 nm and 568 nm wavelengths were focused and overlapped on the channel for fluorescence excitation. All molecules entering the channel were rapidly and uniformly analyzed. Photon burst analysis was used to detect and identify individual primers and amplicons, and fluorescence correlation and cross-correlation spectroscopy were used to account for analyte flow speed. Conventional gel and capillary electrophoresis were also used to characterize the PCR amplification, and the results of differences in detection sensitivity and analyte discrimination were examined. Limits were imposed by the purity and labeling efficiency of the PCR reagents, which must be improved in parallel with increases in detection sensitivity.

  14. A linear piezoelectric stepper motor with submicrometer step size and centimeter travel range.

    Science.gov (United States)

    Judy, J W; Polla, D L; Robbins, W P

    1990-01-01

    A linear stepper motor capable of submicrometer controlled movement has been constructed using the piezoelectric material lead zirconate titanate (PZT). This motor consists of a 25.4-mmx12.7-mmx1.6-mm piezoelectric driving element connected between a glider base and an attached load. The device is inset in a trench to constrain motion to one dimension. An electrode on the bottom of the glider is used with an electrode on the top of the trench to implement an electrostatic clamp. This clamp enables the stepper motor to climb slopes of up to 12 degrees , whereas without the clamp only slopes of 6 degrees or less are tolerated. A linear inertial sliding motion can be achieved by expanding and contracting the piezoelectric bar, but the addition of the electrostatic clamp enhances the movement capabilities of the glider by the periodic clamping and unclamping of the glider. Glider velocities of 5.7-476 mum/s are measured by timing the movement of the glider over a 1.0-mm portion of the track through an optical microscope. Displacement steps of 0.07-1.1 mum are calculated by dividing the measured glider velocity by the frequency of the applied voltage pulses. Displacement step size and glider velocity are controlled by the application of PZT extension voltages ranging from +/-(60-340) V.

  15. High Gain Submicrometer Optical Amplifier at Near-Infrared Communication Band.

    Science.gov (United States)

    Wang, Xiaoxia; Zhuang, Xiujuan; Yang, Sen; Chen, Yu; Zhang, Qinglin; Zhu, Xiaoli; Zhou, Hong; Guo, Pengfei; Liang, Junwu; Huang, Yu; Pan, Anlian; Duan, Xiangfeng

    2015-07-10

    Nanoscale near-infrared optical amplification is important but remains a challenge to achieve. Here we report a unique design of silicon and erbium silicate core-shell nanowires for high gain submicrometer optical amplification in the near-infrared communication band. The high refraction index silicon core is used to tightly confine the optical field within the submicron structures, and the single crystalline erbium-ytterbium silicates shell is used as the highly efficient gain medium. Both theoretical and experimental results show that, by systematically tuning the core diameter and shell thickness, a large portion of the optical power can be selectively confined to the erbium silicate shell gain medium to enable a low loss waveguide and high gain optical amplifier. Experimental results further demonstrate that an optimized core-shell nanowire can exhibit an excellent net gain up to 31  dB mm(-1), which is more than 20 times larger than the previously reported best results on the micron-scale optical amplifiers.

  16. Deposition efficiency optimization in cold spraying of metal-ceramic powder mixtures

    Science.gov (United States)

    Klinkov, S. V.; Kosarev, V. F.

    2017-10-01

    In the present paper, results of optimization of the cold spray deposition process of a metal-ceramic powder mixture involving impacts of ceramic particles onto coating surface are reported. In the optimization study, a two-probability model was used to take into account the surface activation induced by the ceramic component of the mixture. The dependence of mixture deposition efficiency on the concentration and size of ceramic particles was analysed to identify the ranges of both parameters in which the effect due to ceramic particles on the mixture deposition efficiency was positive. The dependences of the optimum size and concentration of ceramic particles, and also the maximum gain in deposition efficiency, on the probability of adhesion of metal particles to non-activated coating surface were obtained.

  17. Thermal oxidation of medical Ti6Al4V blasted with ceramic particles: Effects on the microstructure, residual stresses and mechanical properties.

    Science.gov (United States)

    Lieblich, M; Barriuso, S; Multigner, M; González-Doncel, G; González-Carrasco, J L

    2016-02-01

    Roughening of Ti6Al4V by blasting with alumina or zirconia particles improves the mechanical fixation of implants by increasing the surface area available for bone/implant apposition. Additional thermal oxidation treatments of the blasted alloy have already shown to be a complementary low-cost solution to enhancing the in vitro biocompatibility and corrosion resistance of the alloy. In this work, the effects of oxidation treatment on a grit blasted Ti6Al4V biomedical alloy have been analysed in order to understand the net effect of the combined treatments on the alloy fatigue properties. Synchrotron radiation diffraction experiments have been performed to measure residual stresses before and after the treatments and microstructural and hardness changes have been determined. Although blasting of Ti6Al4V with small spherical zirconia particles increases the alloy fatigue resistance with respect to unblasted specimens, fatigue strength after oxidation decreases below the unblasted value, irrespective of the type of particle used for blasting. Moreover, at 700°C the as-blasted compressive residual stresses (700MPa) are not only fully relaxed but even moderate tensile residual stresses, of about 120MPa, are found beneath the blasted surfaces. Contrary to expectations, a moderate increase in hardness occurs towards the blasted surface after oxidation treatments. This can be attributed to the fact that grit blasting modifies the crystallographic texture of the Ti6Al4V shifting it to a random texture, which affects the hardness values as shown by additional experiments on cold rolled samples. The results indicate that the oxidation treatment performed to improve biocompatibility and corrosion resistance of grit blasted Ti6Al4V should be carried out with caution since the alloy fatigue strength can be critically diminished below the value required for high load-bearing components. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Verification of ceramic structures

    NARCIS (Netherlands)

    Behar-Lafenetre, S.; Cornillon, L.; Rancurel, M.; Graaf, D. de; Hartmann, P.; Coe, G.; Laine, B.

    2012-01-01

    In the framework of the "Mechanical Design and Verification Methodologies for Ceramic Structures" contract [1] awarded by ESA, Thales Alenia Space has investigated literature and practices in affiliated industries to propose a methodological guideline for verification of ceramic spacecraft and

  19. Ceramic Laser Materials

    Directory of Open Access Journals (Sweden)

    Guillermo Villalobos

    2012-02-01

    Full Text Available Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.

  20. Joining Ceramics By Brazing

    Science.gov (United States)

    Chiaramonte, Francis P.; Sudsina, Michael W.

    1992-01-01

    Certain ceramic materials tightly bond together by brazing with suitable alloys. Enables fabrication of parts of wide variety of shapes from smaller initial pieces of ceramics produced directly in only limited variety of shapes.

  1. X-Ray Nanofocus CT: Visualising Of Internal 3D-Structures With Submicrometer Resolution

    Science.gov (United States)

    Weinekoetter, Christian

    2008-09-01

    High-resolution X-ray Computed Tomography (CT) allows the visualization and failure analysis of the internal micro structure of objects—even if they have complicated 3D-structures where 2D X-ray microscopy would give unclear information. During the past several years, computed tomography has progressed to higher resolution and quicker reconstruction of the 3D-volume. Most recently it even allows a three-dimensional look into the inside of materials with submicron resolution. With the use of nanofocus® tube technology, nanoCT®-systems are pushing forward into application fields that were exclusive to high cost and rare available synchrotron techniques. The study was performed with the new nanotom, a very compact laboratory system which allows the analysis of samples up to 120 mm in diameter and weighing up to 1 kg with exceptional voxel-resolution down to volumes, the nanotom® includes a variety of effective software tools to reduce ring-artefacts and correct beam hardenings or drift effects which occurred during data acquisition. The resulting CT volume data set can be displayed in various ways, for example by virtual slicing and sectional views in any direction of the volume. By the fact that this requires only a mouse click, this technique will substitute destructive mechanical slicing and cutting in many applications. The initial CT results obtained with the nanotom® demonstrate that it is now possible to analyze the three-dimensional micro structure of materials and small objects with submicrometer resolution. Any internal difference in material, density or porosity within a sample can be visualized and data like distances can be measured. NanoCT® widely expands the spectrum of detectable micro-structures. The nanotom® opens a new dimension of 3D-microanalysis and will replace more destructive methods—saving costs and time per sample inspected.

  2. MECHANICAL STRENGTH OF HIGHLY POROUS CERAMICS

    NARCIS (Netherlands)

    VANDENBORN, IC; SANTEN, A; HOEKSTRA, HD; DEHOSSON, JTM; Born, I.C. van den

    1991-01-01

    This paper reports on the mechanical strength of highly porous ceramics in terms of the Weibull and Duxbury-Leath distributions. More than 1000 side-crushing strength tests on silica-catalyst carriers of various particle sizes have been performed in series. Within a series, preparation conditions

  3. Sintering characteristics of nano-ceramic coatings

    NARCIS (Netherlands)

    De Hosson, JTM; Popma, R

    2003-01-01

    This paper concentrates on sintering characteristics of nano-sized ceramic SiO2 particles. The sintering process is studied as a function of temperature using a conventional furnace and using a laser beam. The underlying idea is to combine the nanoceramic sol-gel concept with inkjet technology and

  4. Thermal conductivity analysis of SiC ceramics and fully ceramic microencapsulated fuel composites

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeon-Geun, E-mail: hglee@kaeri.re.kr [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon (Korea, Republic of); Kim, Daejong [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Seung Jae [KEPCO Nuclear Fuel, 242, Daedeok-daero, Yuseong-gu, Daejeon (Korea, Republic of); Park, Ji Yeon; Kim, Weon-Ju [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon (Korea, Republic of)

    2017-01-15

    Highlights: • Thermal conductivity of SiC ceramics and FCM pellets was measured and discussed. • Thermal conductivity of FCM pellets was analyzed by the Maxwell-Eucken equation. • Effective thermal conductivity of TRISO particles applied in this study was assumed. - Abstract: The thermal conductivity of SiC ceramics and FCM fuel composites, consisting of a SiC matrix and TRISO coated particles, was measured and analyzed. SiC ceramics and FCM pellets were fabricated by hot press sintering with Al{sub 2}O{sub 3} and Y{sub 2}O{sub 3} sintering additives. Several factors that influence thermal conductivity, specifically the content of sintering additives for SiC ceramics and the volume fraction of TRISO particles and the matrix thermal conductivity of FCM pellets, were investigated. The thermal conductivity values of samples were analyzed on the basis of their microstructure and the arrangement of TRISO particles. The thermal conductivity of the FCM pellets was compared to that predicted by the Maxwell-Eucken equation and the thermal conductivity of TRISO coated particles was calculated. The thermal conductivity of FCM pellets in various sintering conditions was in close agreement to that predicted by the Maxwell-Eucken equation with the fitted thermal conductivity value of TRISO particles.

  5. Creep in ceramics

    CERN Document Server

    Pelleg, Joshua

    2017-01-01

    This textbook is one of its kind, since there are no other books on Creep in Ceramics. The book consist of two parts: A and B. In part A general knowledge of creep in ceramics is considered, while part B specifies creep in technologically important ceramics. Part B covers creep in oxide ceramics, carnides and nitrides. While covering all relevant information regarding raw materials and characterization of creep in ceramics, the book also summarizes most recent innovations and developments in this field as a result of extensive literature search.

  6. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  7. Ceramic gas turbine shroud

    Science.gov (United States)

    Shi, Jun; Green, Kevin E.

    2014-07-22

    An example gas turbine engine shroud includes a first annular ceramic wall having an inner side for resisting high temperature turbine engine gasses and an outer side with a plurality of radial slots. A second annular metallic wall is positioned radially outwardly of and enclosing the first annular ceramic wall and has a plurality of tabs in communication with the slot of the first annular ceramic wall. The tabs of the second annular metallic wall and slots of the first annular ceramic wall are in communication such that the first annular ceramic wall and second annular metallic wall are affixed.

  8. Physical properties of the sub-micrometer aerosol over the Amazon rain forest during the wet-to-dry season transition - comparison of modeled and measured CCN concentrations

    Directory of Open Access Journals (Sweden)

    J. Rissler

    2004-01-01

    Full Text Available Sub-micrometer atmospheric aerosol particles were studied in the Amazon region, 125 km northeast of Manaus, Brazil (-1°55.2'S, 59°28.1'W. The measurements were performed during the wet-to-dry transition period, 4-28 July 2001 as part of the LBA (Large-Scale Biosphere Atmosphere Experiment in Amazonia CLAIRE-2001 (Cooperative LBA Airborne Regional Experiment experiment. The number size distribution was measured with two parallel differential mobility analyzers, the hygroscopic growth at 90% RH with a Hygroscopic Tandem Mobility Analyzer (H-TDMA and the concentrations of cloud condensation nuclei (CCN with a cloud condensation nuclei counter. A model was developed that uses the H-TDMA data to predict the number of soluble molecules or ions in the individual particles and the corresponding minimum particle diameter for activation into a cloud droplet at a certain supersaturation. Integrating the number size distribution above this diameter, CCN concentrations were predicted with a time resolution of 10 min and compared to the measured concentrations. During the study period, three different air masses were identified and compared: clean background, air influenced by aged biomass burning, and moderately polluted air from recent local biomass burning. For the clean period 2001, similar number size distributions and hygroscopic behavior were observed as during the wet season at the same site in 1998, with mostly internally mixed particles of low diameter growth factor (~1.3 taken from dry to 90% RH. During the periods influenced by biomass burning the hygroscopic growth changed slightly, but the largest difference was seen in the number size distribution. The CCN model was found to be successful in predicting the measured CCN concentrations, typically within 25%. A sensitivity study showed relatively small dependence on the assumption of which model salt that was used to predict CCN concentrations from H-TDMA data. One strength of using H-TDMA data

  9. Electrospray ionizer for mass spectrometry of aerosol particles

    Energy Technology Data Exchange (ETDEWEB)

    He, Siqin; Hogan, Chris; Li, Lin; Liu, Benjamin Y. H.; Naqwi, Amir; Romay, Francisco

    2017-09-19

    A device and method are disclosed to apply ESI-based mass spectroscopy to submicrometer and nanometer scale aerosol particles. Unipolar ionization is utilized to charge the particles in order to collect them electrostatically on the tip of a tungsten rod. Subsequently, the species composing the collected particles are dissolved by making a liquid flow over the tungsten rod. This liquid with dissolved aerosol contents is formed into highly charged droplets, which release unfragmented ions for mass spectroscopy, such as time-of-flight mass spectroscopy. The device is configured to operate in a switching mode, wherein aerosol deposition occurs while solvent delivery is turned off and vice versa.

  10. Sub-Micrometer Magnetic Nanocomposites: Insights into the Effect of Magnetic Nanoparticles Interactions on the Optimization of SAR and MRI Performance.

    Science.gov (United States)

    Grillo, Renato; Gallo, Juan; Stroppa, Daniel G; Carbó-Argibay, Enrique; Lima, Renata; Fraceto, Leonardo F; Bañobre-López, Manuel

    2016-10-05

    There is increasing interest in the development of new magnetic polymeric carriers for biomedical applications such as trigger-controlled drug release, magnetic hyperthermia (MH) for the treatment of cancer, and as contrast agents in magnetic resonance imaging (MRI). This work describes the synthesis of sub-micrometer and magnetic polymer nanocomposite capsules (MPNCs) by combining in one single platform the biodegradable polymer poly-ε-caprolactone (PCL) and different concentrations of ∼8 nm oleic acid (OA)-functionalized magnetite nanoparticles (Fe3O4@OA), employing the oil-in-water emulsion/solvent evaporation method. The MPNCs showed a significant increase in particle size from ∼400 to ∼800 nm as the magnetic loading in the organic-inorganic hybrids increases from 1.0% to 10%. The MPNCs presented high incorporation efficiency of Fe3O4@OA nanoparticles, good colloidal stability, and super-paramagnetic properties. Interestingly, electron microscopy results showed that the Fe3O4@OA nanoparticles were preferentially located at the surface of the capsules. Evaluation of the magnetic properties showed that the saturation magnetization and the blocking temperature of the MPNCs samples increased as a function of the Fe3O4@OA loading. All the MPNCs exhibited heating when subjected to MH, and showed good specific absorption rates. Use of the formulations decreased the longitudinal (T1) and transverse (T2) relaxation times of water protons' nuclei, with excellent transverse relaxivity (r2) values, especially in the case of the formulation with lowest Fe3O4@OA loading. Furthermore, the MPNCs-cell interaction was studied, and MPNCs showed lower cellular toxicity to normal cells compared to cancer cells. These findings help in understanding the relationships between magnetic nanoparticles and polymeric capsules, opening perspectives for their potential clinical uses as simultaneous heating sources and imaging probes in MH and MRI, respectively.

  11. Scatterometry for semiconductor sub-micrometer and nanometer critical dimension metrology

    Science.gov (United States)

    Al-Assaad, Rayan M.

    Scatterometry1 is one optical measurement technique that has been explored extensively for semiconductor sub-micrometer dimensional metrology. The technique refers to the measurements of reflected power upon the interaction of an incident beam with some periodic surface (grating). The characteristics of the diffractive surface affect directly the acquired measurements. Therefore it is possible to resolve some information about the grating line profile and dimensions from the measurements, which is referred to as the inverse scatterometry problem. As technology is continuously pushing lithographic processes to sub-nanometer precision2, aspects of the inverse scatterometry problem related to the accurate estimation and modeling of errors and the enhancement of the optimization methods become of great importance. For this purpose the effects of measurement errors on the estimated grating profile are analyzed in this dissertation and optimization methods are proposed to improve the accuracies in the estimated geometrical parameters for various grating profiles in real experimental conditions. A technique based on the information content analysis of the measurement data is further suggested to reduce the number of measurements required without the loss in the solution accuracies resulting in lower cost and more suitable real time implementation. Theoretical and experimental results are presented to validate these studies where the solutions to the profile parameters are accomplished by implementing a linear regression technique3. In addition a new scheme is proposed to address resolving more difficult profile parameters with sub-wavelength dimensions (sub-100 nm) that are until now subject to ongoing investigation with inconclusive results. The proposed approach consists of using a large number of angular reflectance measurements with linearly polarized TM incidence. In the case where the profile dimensions are many times smaller than the light wavelength, the parameter

  12. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    Science and Technology of Ceramics. 2. Functional Ceramics. Sheela Ramasesha. In Part 11 we saw that ceramics could be broadly classified as traditional and advanced ceramics. Traditional ceramics are those made from naturally occurring materials like clays and minerals without requiring much refinement. In this part ...

  13. Crystallization of high-strength fine-sized leucite glass-ceramics.

    Science.gov (United States)

    Chen, X; Chadwick, T C; Wilson, R M; Hill, R; Cattell, M J

    2010-12-01

    Manufacturing of leucite glass-ceramics often leads to materials with inhomogeneous microstructures. Crystal-glass thermal mismatches which produce microcracking around larger crystals-agglomerates are associated with reduced mechanical properties. The hypotheses were that fine (ceramics were characterized by XRD, SEM, and Dilatometry. Experimental (A, M1A and M2A) and commercial glass-ceramics were tested by the BFS test. Experimental glass-ceramics showed an increased leucite crystal number and decreased crystal size with glass particle size reduction. Leucite glass-ceramics (ceramics M1A and M2A had higher mean BFS and characteristic strength than the IPS Empress Esthetic glass-ceramic (p translucent leucite glass-ceramics were synthesized and produced high mean BFS.

  14. Development of an ordered array of optoelectrochemical individually readable sensors with submicrometer dimensions: application to remote electrochemiluminescence imaging.

    Science.gov (United States)

    Chovin, Arnaud; Garrigue, Patrick; Vinatier, Philippe; Sojic, Neso

    2004-01-15

    A novel array of optoelectrochemical submicrometer sensors for remote electrochemiluminescence (ECL) imaging is presented. This device was fabricated by chemical etching of a coherent optical fiber bundle to produce a nanotip array. The surface of the etched bundle was sputter-coated with a thin layer of indium tin oxide in order to create a transparent and electrically conductive surface that is insulated eventually by a new electrophoretic paint except for the apex of the tip. These fabrication steps produced an ordered array of optoelectrochemical sensors with submicrometer dimensions that retains the optical fiber bundle architecture. The electrochemical behavior of the sensor array was independently characterized by cyclic voltammetry and ECL experiments. The steady-state current indicates that the sensors are diffusively independent. This sensor array was further studied with a co-reactant ECL model system, such as Ru(bpy)(3)(2+)/TPrA. We clearly observed an ordered array of individual ECL micrometer spots, which corresponds to the sensor array structure. While the sensors of the array are not individually addressable electrochemically, we could establish that the sensors are optically independent and individually readable. Finally, we show that remote ECL imaging is performed quantitatively through the optoelectrochemical sensor array itself.

  15. The friction and wear of ceramic/ceramic and ceramic/metal combinations in sliding contact

    Energy Technology Data Exchange (ETDEWEB)

    Sliney, H.E.; Dellacorte, C. (NASA Lewis Research Center, Cleveland, OH (United States))

    1994-07-01

    The tribological characteristics of ceramics sliding on ceramics are compared to those of ceramics sliding on a nickel-based turbine alloy. The friction and wear of oxide ceramics and silicon-based ceramics in air at temperatures from room ambient to 900 C (in a few cases to 1200 C) were measured for a hemispherically-tipped pin on a flat sliding contact geometry. In general, especially at high temperature, friction and wear were lower for ceramic/metal combinations than for ceramic/ceramic combinations. The better tribological performance for ceramic/metal combinations is attributed primarily to the lubricious nature of the oxidized surface of the metal.

  16. Mass transfer effects in hygroscopic measurements of aerosol particles

    Directory of Open Access Journals (Sweden)

    M. N. Chan

    2005-01-01

    Full Text Available The tandem differential mobility analyzer (TDMA has been widely utilized to measure the hygroscopicity of laboratory-generated and atmospheric submicrometer particles. An important concern in investigating the hygroscopicity of the particles is if the particles have attained equilibrium state in the measurements. We present a literature survey to investigate the mass transfer effects in hygroscopicity measurements. In most TDMA studies, a residence time in the order of seconds is used for humidification (or dehumidification. NaCl and (NH42SO4 particles are usually used to verify the equilibrium measurements during this residence time, which is presumed to be sufficient for other particles. There have been observations that not all types of submicrometer particles, including atmospheric particles, attain their equilibrium sizes within this time scale. We recommend that experimentation with different residence times be conducted and that the residence time should be explicitly stated in future TDMA measurements. Mass transfer effects may also exist in the measurements of other properties related to the water uptake of atmospheric particles such as relative humidity dependent light scattering coefficients and cloud condensation nuclei activity.

  17. NDE of ceramics and ceramic composites

    Science.gov (United States)

    Vary, Alex A.; Klima, Stanley J.

    Although nondestructive evaluation (NDE) techniques for ceramics are fairly well developed, they are difficult to apply in many cases for high probability detection of the minute flaws that can cause failure in monolithic ceramics. Conventional NDE techniques are available for monolithic and fiber reinforced ceramic matrix composites, but more exact quantitative techniques needed are still being investigated and developed. Needs range from flaw detection to below 100 micron levels in monolithic ceramics to global imaging of fiber architecture and matrix densification anomalies in ceramic composites. NDE techniques that will ultimately be applicable to production and quality control of ceramic structures are still emerging from the lab. Needs are different depending on the processing stage, fabrication method, and nature of the finished product. NDE techniques are being developed in concert with materials processing research where they can provide feedback information to processing development and quality improvement. NDE techniques also serve as research tools for materials characterization and for understanding failure processes, e.g., during thermomechanical testing.

  18. Antibacterial ceramic for sandbox. Sunabayo kokin ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, K. (Ishizuka Glass Co. Ltd. Nagoya (Japan))

    1993-10-01

    Sands in sandboxes in parks have been called into question of being contaminated by colon bacilli and spawns from ascarides. This paper introduces an antibacterial ceramic for sandbox developed as a new material effective to help reduce the contamination. The ceramic uses natural sand as the main raw material, which is added with borax and silver to contain silver ions that have bacteria and fungus resistance and deodorizing effect. The ceramic has an average grain size ranging from 0.5 mm to 0.7 mm, and is so devised as to match specific gravity, grain size and shape of the sand, hence no separation and segregation can occur. The result of weatherability and antibacterial strength tests on sand for a sandbox mixed with the ceramic at 1% suggests that its efficacy lasts for about three years. Its actual use is under observation. Its efficacy has been verified in a test that measures a survival factor of spawns from dog ascardides contacted with aqueous solution containing the ceramic at 1%. Safety and sanitation tests have proved the ceramic a highly safe product that conforms to the food sanitation law. 5 refs., 3 figs., 3 tabs.

  19. Ceramic laser materials

    Science.gov (United States)

    Ikesue, Akio; Aung, Yan Lin

    2008-12-01

    The word 'ceramics' is derived from the Greek keramos, meaning pottery and porcelain. The opaque and translucent cement and clay often used in tableware are not appropriate for optical applications because of the high content of optical scattering sources, that is, defects. Recently, scientists have shown that by eliminating the defects, a new, refined ceramic material - polycrystalline ceramic - can be produced. This advanced ceramic material offers practical laser generation and is anticipated to be a highly attractive alternative to conventional glass and single-crystal laser technologies in the future. Here we review the history of the development of ceramic lasers, the principle of laser generation based on this material, some typical results achieved with ceramic lasers so far, and discuss the potential future outlook for the field.

  20. Particle Size Distribution in Aluminum Manufacturing Facilities

    Science.gov (United States)

    Liu, Sa; Noth, Elizabeth M.; Dixon-Ernst, Christine; Eisen, Ellen A.; Cullen, Mark R.; Hammond, S. Katharine

    2015-01-01

    As part of exposure assessment for an ongoing epidemiologic study of heart disease and fine particle exposures in aluminum industry, area particle samples were collected in production facilities to assess instrument reliability and particle size distribution at different process areas. Personal modular impactors (PMI) and Minimicro-orifice uniform deposition impactors (MiniMOUDI) were used. The coefficient of variation (CV) of co-located samples was used to evaluate the reproducibility of the samplers. PM2.5 measured by PMI was compared to PM2.5 calculated from MiniMOUDI data. Mass median aerodynamic diameter (MMAD) and concentrations of sub-micrometer (PM1.0) and quasi-ultrafine (PM0.56) particles were evaluated to characterize particle size distribution. Most of CVs were less than 30%. The slope of the linear regression of PMI_PM2.5 versus MiniMOUDI_PM2.5 was 1.03 mg/m3 per mg/m3 (± 0.05), with correlation coefficient of 0.97 (± 0.01). Particle size distribution varied substantively in smelters, whereas it was less variable in fabrication units with significantly smaller MMADs (arithmetic mean of MMADs: 2.59 μm in smelters vs. 1.31 μm in fabrication units, p = 0.001). Although the total particle concentration was more than two times higher in the smelters than in the fabrication units, the fraction of PM10 which was PM1.0 or PM0.56 was significantly lower in the smelters than in the fabrication units (p < 0.001). Consequently, the concentrations of sub-micrometer and quasi-ultrafine particles were similar in these two types of facilities. It would appear, studies evaluating ultrafine particle exposure in aluminum industry should focus on not only the smelters, but also the fabrication facilities. PMID:26478760

  1. Analyses of fine paste ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sabloff, J A [ed.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics. (DLC)

  2. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 2. Science and Technology of Ceramics - Advanced Ceramics: Structural Ceramics and Glasses. Sheela K Ramasesha. Series Article Volume 5 Issue 2 February 2000 pp 4-11 ...

  3. Nanofunctionalized zirconia and barium sulfate particles as bone cement additives.

    Science.gov (United States)

    Gillani, Riaz; Ercan, Batur; Qiao, Alex; Webster, Thomas J

    2010-02-02

    Zirconia (ZrO(2)) and barium sulfate (BaSO(4)) particles were introduced into a methyl methacrylate monomer (MMA) solution with polymethyl methacrylate (PMMA) beads during polymerization to develop the following novel bone cements: bone cements with unfunctionalized ZrO(2) micron particles, bone cements with unfunctionalized ZrO(2) nanoparticles, bone cements with ZrO(2) nanoparticles functionalized with 3-(trimethoxysilyl)propyl methacrylate (TMS), bone cements with unfunctionalized BaSO(4) micron particles, bone cements with unfunctionalized BaSO(4) nanoparticles, and bone cements with BaSO(4) nanoparticles functionalized with TMS. Results demonstrated that in vitro osteoblast (bone-forming cell) densities were greater on bone cements containing BaSO(4) ceramic particles after four hours compared to control unmodified bone cements. Osteoblast densities were also greater on bone cements containing all of the ceramic particles after 24 hours compared to unmodified bone cements, particularly those bone cements containing nanofunctionalized ceramic particles. Bone cements containing ceramic particles demonstrated significantly altered mechanical properties; specifically, under tensile loading, plain bone cements and bone cements containing unfunctionalized ceramic particles exhibited brittle failure modes whereas bone cements containing nanofunctionalized ceramic particles exhibited plastic failure modes. Finally, all bone cements containing ceramic particles possessed greater radio-opacity than unmodified bone cements. In summary, the results of this study demonstrated a positive impact on the properties of traditional bone cements for orthopedic applications with the addition of unfunctionalized and TMS functionalized ceramic nanoparticles.

  4. Continuous Fiber Ceramic Composites

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

  5. Measuring Fracture Times Of Ceramics

    Science.gov (United States)

    Shlichta, Paul J.; Bister, Leo; Bickler, Donald G.

    1989-01-01

    Electrical measurements complement or replace fast cinematography. Electronic system measures microsecond time intervals between impacts of projectiles on ceramic tiles and fracture tiles. Used in research on ceramics and ceramic-based composite materials such as armor. Hardness and low density of ceramics enable them to disintegrate projectiles more efficiently than metals. Projectile approaches ceramic tile specimen. Penetrating foil squares of triggering device activate display and recording instruments. As ceramic and resistive film break oscilloscope plots increase in electrical resistance of film.

  6. Storing Waste in Ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Bourcier, W L; Sickafus, K

    2004-07-20

    form is designed, the atomic environment of the radionuclides is chosen to maximize chemical durability. Elements such as zirconium and phosphorus can be included in the waste form that react with and make some radionuclides less soluble and therefore less likely to be released. The long-term performance assessment of radionuclide containment requires the development of models for each part of the barrier system. It is almost certainly easier to model the corrosion and alteration of waste forms than it is to develop coupled hydrologic, chemical, and geophysical models of radionuclide transport away from a repository. Therefore, much time and effort has been spent optimizing the chemical durability of both glass and ceramic waste forms for radionuclide containment. This has not been an easy task. Three problems in particular posed the greatest challenges. The first is that radionuclides decay, transmuting into daughter elements that may have different chemical properties. These new elements might degrade the existing mineral by making it unstable. A good waste form that works well for uranium may work poorly for lead, its final decay product. The second problem is that the radioactive decay itself damages the solid over time. Radioactive decay is an energetic process in which ejected particles and the recoiling nucleus disrupt the surrounding atoms. A single alpha-decay event can displace thousands of atoms in the surrounding volume. We know from laboratory measurements that radionuclides are more easily released from radiation-damaged structures than from materials that do not sustain radiation damage. The third problem is that radioactive waste, particularly the high level waste from reprocessing of spent nuclear fuel to extract plutonium and uranium, contains a variety of elements with widely varying chemistry. The waste form must incorporate the radionuclides, as well as non-radioactive elements such as silicon and sodium that are present in the waste stream as a

  7. Method of making molten carbonate fuel cell ceramic matrix tape

    Science.gov (United States)

    Maricle, Donald L.; Putnam, Gary C.; Stewart, Jr., Robert C.

    1984-10-23

    A method of making a thin, flexible, pliable matrix material for a molten carbonate fuel cell is described. The method comprises admixing particles inert in the molten carbonate environment with an organic polymer binder and ceramic particle. The composition is applied to a mold surface and dried, and the formed compliant matrix material removed.

  8. Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    The Ceramic Technology Project was developed by the USDOE Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the USDOE and NASA advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. These programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. A five-year project plan was developed with extensive input from private industry. In July 1990 the original plan was updated through the estimated completion of development in 1993. The objective is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities.

  9. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-02-01

    This is the fifth quarterly report on a new study to develop a ceramic membrane/metal joint. Results of wetting experiments on commercially available Nickel based brazing alloys on perovskite surfaces are described. Additionally, experimental and numerical investigations on the strength of concentric ceramic/metal joints are presented.

  10. Ceramic heat exchanger

    Science.gov (United States)

    LaHaye, P.G.; Rahman, F.H.; Lebeau, T.P.; Severin, B.K.

    1998-06-16

    A tube containment system is disclosed. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture. 6 figs.

  11. Introducing asymmetric functionality into MOFs via the generation of metallic Janus MOF particles.

    Science.gov (United States)

    Ayala, Abraham; Carbonell, Carlos; Imaz, Inhar; Maspoch, Daniel

    2016-04-14

    Herein we report a versatile methodology for engineering metallic Janus MOF particles based on desymmetrization at interfaces, whereby each MOF particle is partially coated with a desired metal. We demonstrate that it enables the fabrication of homogeneous Janus MOF particles according to the MOF (ZIF-8, UiO-66 or UiO-66-SH), the metal (Au, Co or Pt), the MOF particle size (from the micrometer to the submicrometer regime) and the metal-film thickness (from 5 nm to 50 nm) employed. We anticipate that our strategy could be applied to impart new functionalities to MOFs, including asymmetric functionalization, magnetic-guidance and motorization.

  12. Fabrication and characterization of spark plasma sintered Ce:LuAG ceramic for scintillation application

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. Arun; Senthilselvan, J., E-mail: jsselvan@hotmail.com [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai–600 025, Tamil Nadu (India)

    2016-05-23

    Rare earth Cerium doped Lutetium Aluminum Garnet (Ce:LuAG) ceramics are widely used as phosphor material in medical imaging and high-energy physics. Due to its technological importance, an attempt has been made to fabricate Ce:LuAG ceramics by using spark plasma sintering (SPS) technique. XRD patterns of SPS sintered Ce:LuAG ceramics reveals a mixed LuAG and CeO{sub 2} (antisite defect) phases. The microstructures of SPS sintered Ce:LuAG ceramics shows limited densification, inappropriate compaction of particles and existence of residual pores, voids between the grain boundaries affects the transparency of Ce:LuAG ceramics. Relative density and hardness of post sintered Ce:LuAG ceramic is also determined. The effect of Ce{sup 3+} doping concentration and sintering temperature on optical luminescence behavior of Ce:LuAG ceramic is presented.

  13. Minimal compliance design for metal–ceramic composites with lamellar microstructures

    DEFF Research Database (Denmark)

    Piat, R.; Sinchuk, Y.; Vasoya, M.

    2011-01-01

    of lamellar domains. With local ceramic volume fraction and lamella orientation chosen as the design variables, a minimum compliance optimization problem is solved based on topology optimization and finite element methods for metal–ceramic samples with different geometries and boundary conditions....... Micromechanical models are applied for the calculation of the effective elastic properties of the composites. Optimized local lamella orientations and ceramic contents are calculated, and the difference between the initial (specimen with constant ceramic content and orientation) and the optimized designs......Metal–ceramic composites produced by melt infiltration of ceramic preforms are studied in an optimal design context. The ceramic preforms are manufactured through a process of freeze-casting of Al2O3 particle suspension. The microstructure of these composites can be presented as distributions...

  14. Plasma Synthesis and Sintering of Advanced Ceramics

    Science.gov (United States)

    1990-09-15

    glow discharge, corona discharge, RF or microwave discharge, etc.) and the electron concentration in the plasma are important. The efficiency of... corona discharge, and the low pressure capacitively or inductively coupled RF discharge. It is probable that a low pressure microwave discharge would also...Rhodes, "Agglomerate and Particle Size Effects on Sintering Yttria- Stabilized Zirconia ", J. Am. Ceram. Soc., 64 [1] 19-22 (1981). 4. T. S. Yeh and M

  15. Remodeling of injectable, low-viscosity polymer/ceramic bone grafts in a sheep femoral defect model.

    Science.gov (United States)

    Talley, Anne D; McEnery, Madison A; Kalpakci, Kerem N; Zienkiewicz, Katarzyna J; Shimko, Daniel A; Guelcher, Scott A

    2017-11-01

    Ceramic/polymer composite bone grafts offer the potential advantage of combining the osteoconductivity of ceramic component with the ductility of polymeric component, resulting in a graft that meets many of the desired properties for bone void fillers (BVF). However, the relative contributions of the polymer and ceramic components to bone healing are not well understood. In this study, we compared remodeling of low-viscosity (LV) ceramic/poly(ester urethane) composites to a ceramic BVF control in a sheep femoral condyle plug defect model. LV composites incorporating either ceramic (LV/CM) or allograft bone (LV/A) particles were evaluated. We hypothesized that LV/CM composites which have the advantageous handling properties of injectability, flowability, and settability would heal comparably to the CM control, which was evaluated for up to 2 years to study its long-term degradation properties. Remodeling of LV/CM was comparable to that observed for the CM control, as evidenced by new bone formation on the surface of the ceramic particles. At early time points (4 months), LV/CM composites healed similar to the ceramic clinical control, while LV/A components showed more variable healing due to osteoclast-mediated resorption of the allograft particles. At longer time points (12-15 months), healing of LV/CM composites was more variable due to the nonhomogeneous distribution and lower concentration of the ceramic particles compared to the ceramic clinical control. Resorption of the ceramic particles was almost complete at 2 years. This study highlights the importance of optimizing the loading and distribution of ceramic particles in polymer/ceramic composites to maximize bone healing. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2333-2343, 2017. © 2016 Wiley Periodicals, Inc.

  16. Effect of Surface Treatments on Leakage of Zirconium Oxide Ceramics

    Directory of Open Access Journals (Sweden)

    Göknil Alkan Demetoğlu

    2016-08-01

    Full Text Available Objective: The aim of this pilot study was to compare the effects of pretreatments on leakage of zirconia ceramics. Materials and Methods: The speciments divided into 6 groups that were subsequently treated as follows: group 1, no treatment (control; group 2, the ceramic surfaces were airborne-particle abraded with 110 μm aluminum-oxide (Al2O3 particles; group 3, after abrasion of the surfaces with 110 μm Al2O3 particles, silica coating using 30 μm (Al2O3 particles modified by silica (rocatec system and application of the silane coupling agent (espe-sil; group 4, ceramic surfaces irritated with neodymium-doped yttrium aluminium garnet (Nd:YAG laser [fidelis plus 3 foton (Ljubljana, Slovenia] at 20 hz, 100 mj, 2 w, 100 μs; group 5, ceramic surfaces irritated with Nd:YAG laser at fidelis plus 3 fotona (Ljubljana, Slovenia at 20 hz, 100 mj, 2 w, 100 μs; group 6; application of a zirconia primer (z-prime plus bisco, IL, USA agent. And all ceramics tested for leakage. Results: For marginal leakage, score 0 was found in all groups. Conclusion: No significant differences were found in marginal leakage under all conditions.

  17. The precursors effects on biomimetic hydroxyapatite ceramic powders.

    Science.gov (United States)

    Yoruç, Afife Binnaz Hazar; Aydınoğlu, Aysu

    2017-06-01

    In this study, effects of the starting material on chemical, physical, and biological properties of biomimetic hydroxyapatite ceramic powders (BHA) were investigated. Characterization and chemical analysis of BHA powders were performed by using XRD, FT-IR, and ICP-AES. Microstructural features such as size and morphology of the resulting BHA powders were characterized by using BET, nano particle sizer, pycnometer, and SEM. Additionally, biological properties of the BHA ceramic powders were also investigated by using water-soluble tetrazolium salts test (WST-1). According to the chemical analysis of BHA ceramic powders, chemical structures of ceramics which are prepared under different conditions and by using different starting materials show differences. Ceramic powders which are produced at 80°C are mainly composed of hydroxyapatite, dental hydroxyapatite (contain Na and Mg elements in addition to Ca), and calcium phosphate sulfide. However, these structures are altered at high temperatures such as 900°C depending on the features of starting materials and form various calcium phosphate ceramics and/or their mixtures such as Na-Mg-hydroxyapatite, hydroxyapatite, Mg-Whitlockit, and chloroapatite. In vitro cytotoxicity studies showed that amorphous ceramics produced at 80°C and ceramics containing chloroapatite structure as main or secondary phases were found to be extremely cytotoxic. Furthermore, cell culture studies showed that highly crystalline pure hydroxyapatite structures were extremely cytotoxic due to their high crystallinity values. Consequently, the current study indicates that the selection of starting materials which can be used in the production of calcium phosphate ceramics is very important. It is possible to produce calcium phosphate ceramics which have sufficient biocompatibility at physiological pH values and by using appropriate starting materials. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Characterization and evaluation of ceramic properties of clay used in structural ceramics; Caracterizacao e avaliacao das propriedades ceramicas de argila utilizada em ceramica estrutural

    Energy Technology Data Exchange (ETDEWEB)

    Reis, A.S., E-mail: alessandrar@ifes.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia do Espirito Santo (IFES), Colatina, ES (Brazil); Oliveira, J.N.; Della-Sagrillo, V.P. [Instituto Federal de Educacao, Ciencia e Tecnologia do Espirito Santo (IFES), Vitoria, ES (Brazil); Valenzuela-Diaz, F.R. [Universidade de Sao Paulo (PMT/EP/USP), Sao Paulo, SP (Brazil)

    2014-07-01

    The clay used in the manufacture of structural ceramic products must meet quality requirements that are influenced by their chemical, physical, mineralogical and microstructural characteristics, which control the ceramic properties of the final products. This paper aims to characterize the clay used in the manufacture of ceramic roof tiles and bricks. The clay was characterized through XRF, XRD, thermogravimetry and differential thermal analysis, Atterberg limits and particle size distribution. Specimens were shaped, dried at 110°C, and burned at 900 deg C in an industrial kiln. After that, they were submitted to tests of water absorption, apparent porosity, bulk density and flexural strength. The results show that the chemical composition of clay has significant amount of silica and alumina and adequate levels of kaolinite for use in structural ceramic. The ceramic properties evaluated in the specimens partially meet the requirements of the Brazilian standard-clays for structural ceramics. (author)

  19. Anionic Conducting Oxide Ceramics

    National Research Council Canada - National Science Library

    Dunn, Bruce

    1998-01-01

    This program has emphasized the interrelationships among synthesis, microstructure and properties for oxygen ion conducting ceramics based on copper-substituted bismuth vanadate (Bi V Cu O ), known as BICUVOX...

  20. Making Ceramic Cameras

    Science.gov (United States)

    Squibb, Matt

    2009-01-01

    This article describes how to make a clay camera. This idea of creating functional cameras from clay allows students to experience ceramics, photography, and painting all in one unit. (Contains 1 resource and 3 online resources.)

  1. Light emitting ceramic device

    Science.gov (United States)

    Valentine, Paul; Edwards, Doreen D.; Walker, Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

    2010-05-18

    A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, is herein claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

  2. Bonded carbon or ceramic fiber composite filter vent for radioactive waste

    Science.gov (United States)

    Brassell, Gilbert W.; Brugger, Ronald P.

    1985-02-19

    Carbon bonded carbon fiber composites as well as ceramic or carbon bonded ceramic fiber composites are very useful as filters which can separate particulate matter from gas streams entraining the same. These filters have particular application to the filtering of radioactive particles, e.g., they can act as vents for containers of radioactive waste material.

  3. Technology Implementation Plan. Fully Ceramic Microencapsulated Fuel for Commercial Light Water Reactor Application

    Energy Technology Data Exchange (ETDEWEB)

    Snead, Lance Lewis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Powers, Jeffrey J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Worrall, Andrew [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Snead, Mary A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-01

    This report is an overview of the implementation plan for ORNL's fully ceramic microencapsulated (FCM) light water reactor fuel. The fully ceramic microencapsulated fuel consists of tristructural isotropic (TRISO) particles embedded inside a fully dense SiC matrix and is intended for utilization in commercial light water reactor application.

  4. Porous ceramic membranes

    OpenAIRE

    Biesheuvel, P. M.; Biesheuvel, Pieter Maarten

    2000-01-01

    Synthetic membranes are increasingly used for energy-efficient separation of liquid and gaseous mixtures in household applications, environmental technology and the chemical and energy industry. Besides, membranes are used in component-specific sensors in gas and liquid streams, preferably combined with micro-electronic devices. Ceramic membranes have a large potential over their polymer counterparts for applications at high temperature, pressure and in aggressive environments. Ceramic membra...

  5. Sub-micrometer 20MeV protons or 45MeV lithium spot irradiation enhances yields of dicentric chromosomes due to clustering of DNA double-strand breaks.

    Science.gov (United States)

    Schmid, T E; Friedland, W; Greubel, C; Girst, S; Reindl, J; Siebenwirth, C; Ilicic, K; Schmid, E; Multhoff, G; Schmitt, E; Kundrát, P; Dollinger, G

    2015-11-01

    In conventional experiments on biological effects of radiation types of diverse quality, micrometer-scale double-strand break (DSB) clustering is inherently interlinked with clustering of energy deposition events on nanometer scale relevant for DSB induction. Due to this limitation, the role of the micrometer and nanometer scales in diverse biological endpoints cannot be fully separated. To address this issue, hybrid human-hamster AL cells have been irradiated with 45MeV (60keV/μm) lithium ions or 20MeV (2.6keV/μm) protons quasi-homogeneously distributed or focused to 0.5×1μm(2) spots on regular matrix patterns (point distances up to 10.6×10.6μm), with pre-defined particle numbers per spot to provide the same mean dose of 1.7Gy. The yields of dicentrics and their distribution among cells have been scored. In parallel, track-structure based simulations of DSB induction and chromosome aberration formation with PARTRAC have been performed. The results show that the sub-micrometer beam focusing does not enhance DSB yields, but significantly affects the DSB distribution within the nucleus and increases the chance to form DSB pairs in close proximity, which may lead to increased yields of chromosome aberrations. Indeed, the experiments show that focusing 20 lithium ions or 451 protons per spot on a 10.6μm grid induces two or three times more dicentrics, respectively, than a quasi-homogenous irradiation. The simulations reproduce the data in part, but in part suggest more complex behavior such as saturation or overkill not seen in the experiments. The direct experimental demonstration that sub-micrometer clustering of DSB plays a critical role in the induction of dicentrics improves the knowledge on the mechanisms by which these lethal lesions arise, and indicates how the assumptions of the biophysical model could be improved. It also provides a better understanding of the increased biological effectiveness of high-LET radiation. Copyright © 2015 Elsevier B.V. All

  6. Dielectric silicone elastomers with mixed ceramic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Stiubianu, George, E-mail: george.stiubianu@icmpp.ro [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Bele, Adrian; Cazacu, Maria; Racles, Carmen; Vlad, Stelian [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Ignat, Mircea [National R& D Institute for Electrical Engineering ICPE-CA Bucharest, Splaiul Unirii 313, District 3, Bucharest 030138 (Romania)

    2015-11-15

    Highlights: • Composite ceramics nanoparticles (MCN) with zirconium dioxide and lead zirconate. • Dielectric elastomer films wDith PDMS matrix and MCN as dielectric filler. • Hydrophobic character—water resistant and good flexibility specific to siloxanes. • Increased value of dielectric constant with the content of MCN in dielectric films. • Increased energy output from uniaxial deformation of the dielectric elastomer films. - Abstract: A ceramic material consisting in a zirconium dioxide-lead zirconate mixture has been obtained by precipitation method, its composition being proved by wide angle X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The average diameter of the ceramic particles ranged between 50 and 100 nm, as revealed by transmission electron microscopy images. These were surface treated and used as filler for a high molecular mass polydimethylsiloxane-α,ω-diol (Mn = 450,000) prepared in laboratory, the resulted composites being further processed as films and crosslinked. A condensation procedure, unusual for polydimethylsiloxane having such high molecular mass, with a trifunctional silane was approached for the crosslinking. The effect of filler content on electrical and mechanical properties of the resulted materials was studied and it was found that the dielectric permittivity of nanocomposites increased in line with the concentration of ceramic nanoparticles.

  7. The friction and wear of ceramic/ceramic and ceramic/metal combinations in sliding contracts

    Energy Technology Data Exchange (ETDEWEB)

    Sliney, H.E.; Dellacorte, C. [NASA Lewis Research Center, Cleveland, OH (United States)

    1994-07-01

    The tribological characteristics of ceramics sliding on ceramics are compared to those of ceramics sliding on a nickel-based turbine alloy. The friction and wear of oxide ceramics and silicon-based ceramics in air at temperatures from room ambient to 900{degrees}C (in a few cases to 1200{degrees}C) were measured for a hemispherically-tipped pin on a flat sliding contract geometry. In general, especially at high temperature, friction and wear were lower for ceramic/metal combinations than for ceramic/ceramic combinations. The better tribological performance for ceramic/metal combinations is attributed primarily to the lubricious nature of the oxidized surface of the metal. 12 refs., 6 figs., 1 tab.

  8. Filtração de aerossóis em altas temperaturas utilizando filtros cerâmicos de dupla camada: influência do diâmetro de partícula na eficiência de coleta Filtration of aerosols at high temperatures using a double layer ceramic filter: influence of the particle diameter in the collection efficiency

    Directory of Open Access Journals (Sweden)

    N. L de Freitas

    2004-12-01

    Full Text Available Neste trabalho foram utilizados filtros cerâmicos para filtração de aerossóis, constituídos por dupla camada, onde a primeira camada é formada por um suporte celular de elevada porosidade com diâmetro de poro controlado e a segunda formada por uma película filtrante. A camada suporte foi obtida pela técnica de replicação cerâmica de espuma poliuretânica, por meio da impregnação de uma suspensão aquosa de Al2O3. Foram utilizados suportes de 45 e 75 poros/polegada. A membrana filtrante (Al2O3 e argila foi a mesma para ambos os suportes, sendo composta por uma massa granular cerâmica de baixa porosidade. Os experimentos de filtração foram realizados em temperaturas de 25 a 700 ºC onde mediu-se a capacidade dos filtros de limpar um aerossol de partículas finas polidispersas (diâmetro mediano de 4,6 µm e calculou-se a eficiência de coleta para diâmetros de partícula entre 0,4 e 8,5 µm. Os resultados mostraram que a eficiência diminuiu com o aumento da temperatura e aumentou com o diâmetro da partícula.In this work, ceramic filters were used for aerosol filtration. The filters were constituted by two layers, where the first layer was formed by of a highly porous ceramic support with controlled pore size and the second layer constituted by a fine membrane. The ceramic support was obtained from polymeric foams utilizing a technique of alumina impregnation. The supports had 45 and 75 pores per inch (ppi. The membrane (a mixture of alumina and clay was the same for the two supports, with much smaller pore sizes. The filtration experiments were accomplished at temperatures varying from 25 to 700 ºC, where the ability of the filters for cleaning an aerosol constituted by fine particles (median diameter of 4.6 µm was measured. The collection efficiency was calculated for particle diameters between 0.4 and 8.5 µm. The results showed that the collection efficiency decreased with the increase of the temperature and increased

  9. Contribution from indoor sources to particle number and mass concentrations in residential houses

    Science.gov (United States)

    He, Congrong; Morawska, Lidia; Hitchins, Jane; Gilbert, Dale

    As part of a large study investigating indoor air in residential houses in Brisbane, Australia, the purpose of this work was to quantify emission characteristics of indoor particle sources in 15 houses. Submicrometer particle number and approximation of PM 2.5 concentrations were measured simultaneously for more than 48 h in the kitchen of all the houses by using a condensation particle counter (CPC) and a photometer (DustTrak), respectively. In addition, characterizations of particles resulting from cooking conducted in an identical way in all the houses were measured by using a scanning mobility particle sizer (SMPS), an aerodynamic particle sizer (APS) and a DustTrak. All the events of elevated particle concentrations were linked to indoor activities using house occupants diary entries, and catalogued into 21 different types of indoor activities. This enabled quantification of the effect of indoor sources on indoor particle concentrations as well as quantification of emission rates from the sources. For example, the study found that frying, grilling, stove use, toasting, cooking pizza, cooking, candle vaporizing eucalyptus oil and fan heater use, could elevate the indoor submicrometer particle number concentration levels by more than five times, while PM 2.5 concentrations could be up to 3, 30 and 90 times higher than the background levels during smoking, frying and grilling, respectively.

  10. The effect of nanometric zirconia particle additives on microstructure and mechanical properties of dense alumina

    Directory of Open Access Journals (Sweden)

    Lukasz Zych

    2009-09-01

    Full Text Available Zirconia additives have favourable influence on mechanical properties of dense alumina polycrystals. It results from the martensitic transformation of tetragonal zirconia particles into monoclinic symmetry at the crack tip propagating through a material. Usually applied zirconia particles were of sub-micrometer or micrometer sizes. In the present work nanometric zirconia particles prepared by hydrothermal crystallization technique were introduced into the alumina matrix. Both, zirconia and alumina powders were homogenized in an aqueous suspension of pH selected on the basis of the zeta (ξ potential measurements. It was found that this factor influences greatly strength of the resulting powder agglomerates and hence mechanical properties of the sintered material.

  11. Effects of process variables on the properties of YBa2Cu3O(7-x) ceramics formed by investment casting

    Science.gov (United States)

    Hooker, M. W.; Taylor, T. D.; Leigh, H. D.; Wise, S. A.; Buckley, J. D.; Vasquez, P.; Buck, G. M.; Hicks, L. P.

    1993-01-01

    An investment casting process has been developed to produce net-shape, superconducting ceramics. In this work, a factorial experiment was performed to determine the critical process parameters for producing cast YBa2Cu3O7 ceramics with optimum properties. An analysis of variance procedure indicated that the key variables in casting superconductive ceramics are the particle size distribution and sintering temperature. Additionally, the interactions between the sintering temperature and the other process parameters (e.g., particle size distribution and the use of silver dopants) were also found to influence the density, porosity, and critical current density of the fired ceramics.

  12. Testing method for ceramic armour and bare ceramic tiles

    NARCIS (Netherlands)

    Carton, E.P.; Roebroeks, G.H.J.J.

    2016-01-01

    TNO developed an alternative, more configuration independent ceramic test method than the Depth-of-Penetration test method. In this alternative test ceramic tiles and ceramic based armour are evaluated as target without a semi-infinite backing layer. An energy approach is chosen to evaluate and rank

  13. Testing method for ceramic armor and bare ceramic tiles

    NARCIS (Netherlands)

    Carton, E.P.; Roebroeks, G.H.J.J.

    2014-01-01

    TNO has developed an alternative, more configuration independent ceramic test method than the standard Depth-of-Penetration test method. In this test ceramic tiles and ceramic based armor are evaluated as target without a semi-infinite backing layer. An energy approach is chosen to evaluate and rank

  14. Cooled Ceramic Turbine Vane Project

    Data.gov (United States)

    National Aeronautics and Space Administration — N&R Engineering will investigate the feasibility of cooled ceramics, such as ceramic matrix composite (CMC) turbine blade concepts that can decrease specific...

  15. Submicrometer Hollow Bioglass Cones Deposited by Radio Frequency Magnetron Sputtering: Formation Mechanism, Properties, and Prospective Biomedical Applications.

    Science.gov (United States)

    Popa, A C; Stan, G E; Besleaga, C; Ion, L; Maraloiu, V A; Tulyaganov, D U; Ferreira, J M F

    2016-02-01

    This work reports on the unprecedented magnetron sputtering deposition of submicrometric hollow cones of bioactive glass at low temperature in the absence of any template or catalyst. The influence of sputtering conditions on the formation and development of bioglass cones was studied. It was shown that larger populations of well-developed cones could be achieved by increasing the argon sputtering pressure. A mechanism describing the growth of bioglass hollow cones is presented, offering the links for process control and reproducibility of the cone features. The composition, structure, and morphology of the as-synthesized hollow cones were investigated by energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), grazing incidence geometry X-ray diffraction (GIXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM)-selected area electron diffraction (SAED). The in vitro biological performance, assessed by degradation tests (ISO 10993-14) and cytocompatibility assays (ISO 10993-5) in endothelial cell cultures, was excellent. This allied with resorbability and the unique morphological features make the submicrometer hollow cones interesting candidate material devices for focal transitory permeabilization of the blood-brain barrier in the treatment of carcinoma and neurodegenerative disorders.

  16. A method to transfer an individual graphene flake to a target position with a precision of sub-micrometer

    Science.gov (United States)

    Wang, Yubing; Yin, Weihong; Han, Qin; Yang, Xiaohong; Ye, Han; Lü, Qianqian; Yin, Dongdong

    2017-04-01

    Graphene field-effect transistors have been intensively studied. However, in order to fabricate devices with more complicated structures, such as the integration with waveguide and other two-dimensional materials, we need to transfer the exfoliated graphene samples to a target position. Due to the small area of exfoliated graphene and its random distribution, the transfer method requires rather high precision. In this paper, we systematically study a method to selectively transfer mechanically exfoliated graphene samples to a target position with a precision of sub-micrometer. To characterize the doping level of this method, we transfer graphene flakes to pre-patterned metal electrodes, forming graphene field-effect transistors. The hole doping of graphene is calculated to be 2.16 × {10}12{{{cm}}}-2. In addition, we fabricate a waveguide-integrated multilayer graphene photodetector to demonstrate the viability and accuracy of this method. A photocurrent as high as 0.4 μA is obtained, corresponding to a photoresponsivity of 0.48 mA/W. The device performs uniformly in nine illumination cycles. Project supported by the National Key Research and Development Program of China (No. 2016YFB0402404), the High-Tech Research and Development Program of China (Nos. 2013AA031401, 2015AA016902, 2015AA016904), and the National Natural Foundation of China (Nos. 61674136, 61176053, 61274069, 61435002).

  17. Interactions of mineral dust with pollution and clouds: An individual-particle TEM study of atmospheric aerosol from Saudi Arabia

    Science.gov (United States)

    Pósfai, Mihály; Axisa, Duncan; Tompa, Éva; Freney, Evelyn; Bruintjes, Roelof; Buseck, Peter R.

    2013-03-01

    Aerosol particles from desert dust interact with clouds and influence climate on regional and global scales. The Riyadh (Saudi Arabia) aerosol campaign was initiated to study the effects of dust particles on cloud droplet nucleation and cloud properties. Here we report the results of individual-particle studies of samples that were collected from an aircraft in April 2007. We used analytical transmission electron microscopy, including energy-dispersive X-ray spectrometry, electron diffraction, and imaging techniques for the morphological, chemical, and structural characterization of the particles. Dust storms and regional background conditions were encountered during four days of sampling. Under dusty conditions, the coarse (supermicrometer) fraction resembles freshly crushed rock. The particles are almost exclusively mineral dust grains and include common rock-forming minerals, among which clay minerals, particularly smectites, are most abundant. Unaltered calcite grains also occur, indicating no significant atmospheric processing. The particles have no visible coatings but some contain traces of sulfur. The fine (submicrometer) fraction is dominated by particles of anthropogenic origin, primarily ammonium sulfate (with variable organic coating and some with soot inclusions) and combustion-derived particles (mostly soot). In addition, submicrometer, iron-bearing clay particles also occur, many of which are internally mixed with ammonium sulfate, soot, or both. We studied the relationships between the properties of the aerosol and the droplet microphysics of cumulus clouds that formed above the aerosol layer. Under dusty conditions, when a large concentration of coarse-fraction mineral particles was in the aerosol, cloud drop concentrations were lower and droplet diameters larger than under regional background conditions, when the aerosol was dominated by submicrometer sulfate particles.

  18. Mechanical properties of ceramics

    CERN Document Server

    Pelleg, Joshua

    2014-01-01

    This book discusses the mechanical properties of ceramics and aims to provide both a solid background for undergraduate students, as well as serving as a text to bring practicing engineers up to date with the latest developments in this topic so they can use and apply these to their actual engineering work.  Generally, ceramics are made by moistening a mixture of clays, casting it into desired shapes and then firing it to a high temperature, a process known as 'vitrification'. The relatively late development of metallurgy was contingent on the availability of ceramics and the know-how to mold them into the appropriate forms. Because of the characteristics of ceramics, they offer great advantages over metals in specific applications in which hardness, wear resistance and chemical stability at high temperatures are essential. Clearly, modern ceramics manufacturing has come a long way from the early clay-processing fabrication method, and the last two decades have seen the development of sophisticated technique...

  19. Diffusion in ceramics

    CERN Document Server

    Pelleg, Joshua

    2016-01-01

    This textbook provides an introduction to changes that occur in solids such as ceramics, mainly at high temperatures, which are diffusion controlled, as well as presenting research data. Such changes are related to the kinetics of various reactions such as precipitation, oxidation and phase transformations, but are also related to some mechanical changes, such as creep. The book is composed of two parts, beginning with a look at the basics of diffusion according to Fick's Laws. Solutions of Fick’s second law for constant D, diffusion in grain boundaries and dislocations are presented along with a look at the atomistic approach for the random motion of atoms. In the second part, the author discusses diffusion in several technologically important ceramics. The ceramics selected are monolithic single phase ones, including: A12O3, SiC, MgO, ZrO2 and Si3N4. Of these, three refer to oxide ceramics (alumina, magnesia and zirconia). Carbide based ceramics are represented by the technologically very important Si-ca...

  20. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  1. Method of making metal matrix composites reinforced with ceramic particulates

    Science.gov (United States)

    Cornie, James A.; Kattamis, Theodoulos; Chambers, Brent V.; Bond, Bruce E.; Varela, Raul H.

    1989-01-01

    Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys.

  2. Method of making metal matrix composites reinforced with ceramic particulates

    Science.gov (United States)

    Cornie, J.A.; Kattamis, T.; Chambers, B.V.; Bond, B.E.; Varela, R.H.

    1989-08-01

    Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys. 2 figs.

  3. Moldagem por injeção em baixa pressão de peças complexas de cerâmicas avançadas produzidas com pós submicrométricos Low-pressure injection molding of complex parts of advanced ceramic produced with fine powder

    Directory of Open Access Journals (Sweden)

    J. E. Zorzi

    2004-09-01

    Full Text Available A moldagem por injeção em baixa pressão (MIBP tem constituído, nos últimos anos, uma excelente alternativa para a produção de pequenos lotes de peças cerâmicas diversificadas e com formas complexas. Esta técnica de conformação é relativamente simples e barata, mas apresenta diversos problemas na etapa de extração dos ligantes, principalmente quando o pó cerâmico é muito fino e as peças possuem grande seção transversal. Neste trabalho é descrita uma metodologia específica para a produção de peças cerâmicas por moldagem por injeção a baixa pressão de alumina submicrométrica (0,4 mim, incluindo a formulação da mistura para injeção, bem como detalhes do processo de extração dos ligantes orgânicos utilizados na moldagem. Para o desenvolvimento deste processo fez-se necessário (i entender melhor o processo de MIBP, (ii desenvolver a formulação da mistura de pó cerâmico e aditivos orgânicos, (iii confeccionar moldes adequados para a injeção a baixas pressões e (iv otimizar os parâmetros de injeção. A metodologia desenvolvida neste trabalho, possibilita a confecção de peças cerâmicas complexas, com seção transversal relativamente grande, permitindo uma produção robusta de pequenos lotes de peças cerâmicas diversificadas com ótima qualidade e excelente reprodutibilidade.In the past years, low-pressure injection molding (LPIM has been a good alternative for the production of small batches of diversified complex shapes ceramic parts. This molding technique is relatively simple and cheap, but presents several problems related to debinding, especially for fine ceramic particle, and large cross-section ceramic pieces. In this work, we present a metodology for the production of ceramic parts based on the LPIM of submicrometer-sized alumina powder (0.4 mum. The binder formulation is described, as well as the details of the debinding stage. For the development of this process it was necessary (i to

  4. Processing and Characterization of Multiphase Ceramic Composites

    Science.gov (United States)

    Men, Danju

    Multiphase ceramic composites structure design has advantages for many applications. It is not only an effective way of limiting grain growth which allows for fine-grain size superplasticity at elevated temperatures, but also a combination of various desirable properties can be obtained from different phases, which otherwise cannot be found in one single phase material. The goal of this research is to select, design and optimize multiphase ceramic systems for mainly two purposes: shape forming and inert matrix nuclear fuel. These ceramic composites feature the machinability of monazite (LaPO 4) due to weak interfacial bonding with other oxides, the superplasticity of 3 mol% tetragonal zirconia (3Y-TZP), and the high hardness and strength of Al2O3 and MgAl2O4. These materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical behavior at room temperature was characterized for the elastic modulus, hardness and fracture toughness. They were fabricated and demonstrated to have deformation rates in the superplastic range of at high temperatures and easy machinability at room temperature using conventional tools. An issue with conventional nuclear fuel, UO2, is its very low thermal conductivity that causes high central temperatures, which can lead to melting and cracking during reactor operation. The solution can be found in multiphase ceramic composites, by combining nuclear fuel particles in a heat conducting phase with high thermal conductivity and other phases that absorb fission byproducts while maintaining good radiation stability. In the current research, proposed multiphase ceramic composite materials were designed and radiation damage was characterized by scanning and transmission electron microscopy (TEM). Gold irradiation was used to represent the primary knock-on atoms damage caused by neutrons. Xenon irradiation was used to represent the fission product damage. Magnetoplumbite, was the most susceptible to

  5. Relationships between submicrometer particulate air pollution and air mass history in Beijing, China, 2004 2006

    Science.gov (United States)

    Wehner, B.; Birmili, W.; Ditas, F.; Wu, Z.; Hu, M.; Liu, X.; Mao, J.; Sugimoto, N.; Wiedensohler, A.

    2008-10-01

    The Chinese capital Beijing is one of the global megacities where the effects of rapid economic growth have led to complex air pollution problems that are not well understood. In this study, ambient particle number size distributions in Beijing between 2004 and 2006 are analysed as a function of regional meteorological transport. An essential result is that the particle size distribution in Beijing depends to large extent on the history of the synoptic scale air masses. A first approach based on manual back trajectory classification yielded differences in particulate matter mass concentration by a factor of two between four different air mass categories, including three main wind directions plus the case of stagnant air masses. A back trajectory cluster analysis refined these results, yielding a total of six trajectory clusters. Besides the large scale wind direction, the transportation speed of an air mass was found to play an essential role on the PM concentrations in Beijing. Slow-moving air masses were shown to be associated with an effective accumulation of surface-based anthropogenic emissions due to both, an increased residence time over densely populated land, and their higher degree of vertical stability. For the six back trajectory clusters, differences in PM1 mass concentrations by a factor of 3.5, in the mean air mass speed by a factor of 6, and in atmospheric visibility by a factor of 4 were found. The main conclusion is that the air quality in Beijing is not only degraded by anthropogenic aerosol sources from within the megacity, but also by sources across the entire Northwest China plain depending on the meteorological situation.

  6. Relationships between submicrometer particulate air pollution and air mass history in Beijing, China, 2004-2006

    Science.gov (United States)

    Wehner, B.; Birmili, W.; Ditas, F.; Wu, Z.; Hu, M.; Liu, X.; Mao, J.; Sugimoto, N.; Wiedensohler, A.

    2008-06-01

    The Chinese capital Beijing is one of the global megacities where the effects of rapid economic growth have led to complex air pollution problems that are not well understood. In this study, ambient particle number size distributions in Beijing between 2004 and 2006 are analysed as a function of regional meteorological transport. An essential result is that the particle size distribution in Beijing depends to large extent on the history of the synoptic scale air masses. A first approach based on manual back trajectory classification yielded differences in particulate matter mass concentration (PM1 and PM10) by a factor of two between four different air mass categories, including three main wind directions plus the case of stagnant air masses. A back trajectory cluster analysis refined these results, yielding a total of six trajectory clusters. Besides the large scale wind direction, the transportation speed of an air mass was found to play an essential role on the PM concentrations in Beijing. Slow-moving air masses were shown to be associated with an effective accumulation of surface-based anthropogenic emissions due to both, an increased residence time over densely populated land, and their higher degree of vertical stability. For the six back trajectory clusters, differences in PM1 mass concentrations by a factor of 3.5, in the mean air mass speed by a factor of 6, and in atmospheric visibility by a factor of 4 were found. The main conclusion is that the air quality in Beijing is not only degraded by anthropogenic aerosol sources from within the megacity, but also by sources across the entire Northwest China plain depending on the meteorological situation.

  7. Production of ceramics from coal fly ash

    Directory of Open Access Journals (Sweden)

    Angjusheva Biljana

    2012-01-01

    Full Text Available Dense ceramics are produced from fly ash from REK Bitola, Republic of Macedonia. Four types of fly ash from electro filters and one from the collected zone with particles < 0.063 mm were the subject of this research. Consolidation was achieved by pressing (P= 133 MPa and sintering (950, 1000, 1050 and 11000C and heating rates of 3 and 100/min. Densification was realized by liquid phase sintering and solid state reaction where diopside [Ca(Mg,Al(Si,Al2O6] was formed. Ceramics with optimal properties (porosity 2.96±0.5%, bending strength - 47.01±2 MPa, compressive strength - 170 ±5 MPa was produced at 1100ºC using the heating rate of 10ºC/min.

  8. Effect of Impact Angle on Ceramic Deposition Behavior in Composite Cold Spray: A Finite-Element Study

    Science.gov (United States)

    Chakrabarty, Rohan; Song, Jun

    2017-10-01

    During the cold spraying of particle-reinforced metal matrix composite coatings (ceramic and metal particles mixture) on metal substrates, ceramic particles may either get embedded in the substrate/deposited coating or may rebound from the substrate surface. In this study, the dependence of the ceramic rebounding phenomenon on the spray angle and its effect on substrate erosion have been analyzed using finite-element analysis. From the numerical simulations, it was found that the ceramic particle density and substrate material strength played the major roles in determining the embedding and ceramic retention behavior. Substrate material erosion also influenced the ceramic retention, and the material loss increased as the impact angles decreased from normal. In general, the results concluded that decreasing the impact angle promoted the retention possibility of ceramics in the substrate. This study provides new theoretical insights into the effect of spray angles on the ceramic retention and suggests a new route toward optimizing the spraying process to increase the ceramic retention in composite coatings cold spray.

  9. High flow ceramic pot filters

    NARCIS (Netherlands)

    van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

    2017-01-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more

  10. Impact of Wildfire Emissions on Chloride and Bromide Depletion in Marine Aerosol Particles.

    Science.gov (United States)

    Braun, Rachel A; Dadashazar, Hossein; MacDonald, Alexander B; Aldhaif, Abdulamonam M; Maudlin, Lindsay C; Crosbie, Ewan; Aghdam, Mojtaba Azadi; Hossein Mardi, Ali; Sorooshian, Armin

    2017-08-15

    This work examines particulate chloride (Cl-) and bromide (Br-) depletion in marine aerosol particles influenced by wildfires at a coastal California site in the summers of 2013 and 2016. Chloride exhibited a dominant coarse mode due to sea salt influence, with substantially diminished concentrations during fire periods as compared to nonfire periods. Bromide exhibited a peak in the submicrometer range during fire and nonfire periods, with an additional supermicrometer peak in the latter periods. Chloride and Br- depletions were enhanced during fire periods as compared to nonfire periods. The highest observed %Cl- depletion occurred in the submicrometer range, with maximum values of 98.9% (0.32-0.56 μm) and 85.6% (0.56-1 μm) during fire and nonfire periods, respectively. The highest %Br- depletion occurred in the supermicrometer range during fire and nonfire periods with peak depletion between 1.8-3.2 μm (78.8% and 58.6%, respectively). When accounting for the neutralization of sulfate by ammonium, organic acid particles showed the greatest influence on Cl- depletion in the submicrometer range. These results have implications for aerosol hygroscopicity and radiative forcing in areas with wildfire influence owing to depletion effects on composition.

  11. Verification of Ceramic Structures

    Science.gov (United States)

    Behar-Lafenetre, Stephanie; Cornillon, Laurence; Rancurel, Michael; De Graaf, Dennis; Hartmann, Peter; Coe, Graham; Laine, Benoit

    2012-07-01

    In the framework of the “Mechanical Design and Verification Methodologies for Ceramic Structures” contract [1] awarded by ESA, Thales Alenia Space has investigated literature and practices in affiliated industries to propose a methodological guideline for verification of ceramic spacecraft and instrument structures. It has been written in order to be applicable to most types of ceramic or glass-ceramic materials - typically Cesic®, HBCesic®, Silicon Nitride, Silicon Carbide and ZERODUR®. The proposed guideline describes the activities to be performed at material level in order to cover all the specific aspects of ceramics (Weibull distribution, brittle behaviour, sub-critical crack growth). Elementary tests and their post-processing methods are described, and recommendations for optimization of the test plan are given in order to have a consistent database. The application of this method is shown on an example in a dedicated article [7]. Then the verification activities to be performed at system level are described. This includes classical verification activities based on relevant standard (ECSS Verification [4]), plus specific analytical, testing and inspection features. The analysis methodology takes into account the specific behaviour of ceramic materials, especially the statistical distribution of failures (Weibull) and the method to transfer it from elementary data to a full-scale structure. The demonstration of the efficiency of this method is described in a dedicated article [8]. The verification is completed by classical full-scale testing activities. Indications about proof testing, case of use and implementation are given and specific inspection and protection measures are described. These additional activities are necessary to ensure the required reliability. The aim of the guideline is to describe how to reach the same reliability level as for structures made of more classical materials (metals, composites).

  12. Impact design methods for ceramic components in gas turbine engines

    Science.gov (United States)

    Song, J.; Cuccio, J.; Kington, H.

    1991-01-01

    Methods currently under development to design ceramic turbine components with improved impact resistance are presented. Two different modes of impact damage are identified and characterized, i.e., structural damage and local damage. The entire computation is incorporated into the EPIC computer code. Model capability is demonstrated by simulating instrumented plate impact and particle impact tests.

  13. Characterization of Conventional and High-Translucency Y-TZP Dental Ceramics Submitted to Air Abrasion.

    Science.gov (United States)

    Tostes, Bhenya Ottoni; Guimarães, Renato Bastos; Noronha-Filho, Jaime Dutra; Botelho, Glauco Dos Santos; Guimarães, José Guilherme Antunes; Silva, Eduardo Moreira da

    2017-01-01

    This study evaluated the effect of air-abrasion on t®m phase transformation, roughness, topography and the elemental composition of three Y-TZP (Yttria-stabilized tetragonal zirconia polycrystal) dental ceramics: two conventional (Lava Frame and IPS ZirCad) and one with high-translucency (Lava Plus). Plates obtained from sintered blocks of each ceramic were divided into four groups: AS (as-sintered); 30 (air-abrasion with 30 mm Si-coated Al2O3 particles); 50 (air-abrasion with 50 mm Al2O3 particles) and 150 (air-abrasion with 150 mm Al2O3 particles). After the treatments, the plates were submitted to X-ray diffractometry; 3-D profilometry and SEM/EDS. The AS surfaces were composed of Zr and t phases. All treatments produced t®m phase transformation in the ceramics. The diameter of air-abrasion particles influenced the roughness (150>50>30>AS) and the topography. SEM analysis showed that the three treatments produced groove-shaped microretentions on the ceramic surfaces, which increased with the diameter of air-abrasion particles. EDS showed a decrease in Zr content along with the emergence of O and Al elements after air-abrasion. Presence of Si was also detected on the plates air-abraded with 30 mm Si-coated Al2O3 particles. It was concluded that irrespective of the type and diameter of the particles, air-abrasion produced t®m phase transformation, increased the roughness and changed the elemental composition of the three Y-TZP dental ceramics. Lava Plus also behaved similarly to the conventional Y-TZP ceramics, indicating that this high translucency ceramic could be more suitable to build monolithic ceramic restorations in the aesthetic restorative dentistry field.

  14. Preparation of Polyamide-6 Submicrometer-Sized Spheres by In Situ Polymerization.

    Science.gov (United States)

    Zhao, Xingke; Xia, Housheng; Fu, Xubing; Duan, Jianping; Yang, Guisheng

    2015-11-01

    Polyamide-6 (PA6) submicron-sized spheres are prepared by two steps: (1) anionic ring-opening polymerization of ε-caprolactam in the presence of poly(ethylene glycol)-block-poly-(propylene glycol)-block-poly(ethylene glycol)(PEG-b-PPG-b-PEG) and (2) separation of PA6 spheres by dissolving PEG-b-PPG-b-PEG from the prepared blends. The PA6 microspheres obtained are regular spherical, with diameter ranging from 200 nm to 2 μm and narrow size distribution, as confirmed by scanning electron microscopy. By comparison with PA6/PS and PA6/PEG systems, it is denominated that the PEG blocks in PEG-b-PPG-b-PEG can effectively reduce the surface tension of PA6 droplets and further decrease the diameter of the PA6 microspheres. The PPG block in PEG-b-PPG-b-PEG can prevent the PA6 droplets coalescing with each other, and isolated spherical particles can be obtained finally. The phase inversion of the PA6/PEG-b-PPG-b-PEG blends occurs at very low PEG-b-PPG-b-PEG content; the PEG-b-PPG-b-PEG phase can be removed by water easily. The whole experiment can be finished in a short time (approximately in half an hour) without using any organic solvents; it is an efficient strategy for the preparation of submicron-sized PA6 microspheres. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Flame assisted synthesis of catalytic ceramic membranes

    DEFF Research Database (Denmark)

    Johansen, Johnny; Mosleh, Majid; Johannessen, Tue

    2004-01-01

    technology it is possible to make supported catalysts, composite metal oxides, catalytically active surfaces, and porous ceramic membranes. Membrane layers can be formed by using a porous substrate tube (or surface) as a nano-particle filter. The aerosol gas from the flame is led through a porous substrate......Membranes consisting of one or more metal oxides can be synthesized by flame pyrolysis. The general principle behind flame pyrolysis is the decomposition and oxidation of evaporated organo-metallic precursors in a flame, thereby forming metal oxide monomers. Because of the extreme supersaturation...... created in the flame, the monomers will nucleate homogeneously and agglomerate to form aggregates of large ensembles of monomers. The aggregates will then sinter together to form single particles. If the flame temperature and the residence time are sufficiently high, the formed oxide particles...

  16. Ceramic/metal nanocomposites by lyophilization: Processing and HRTEM study

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Gonzalez, C.F. [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo - UO - Principado de Asturias - PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain); Agouram, S. [Department of Applied Physics and Electromagnetism, Universitat de Valencia, 46100 Burjassot (Spain); Torrecillas, R. [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo -UO - Principado de Asturias- PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain); Moya, J.S. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (ICMM-CSIC), Cantoblanco, 28049 Madrid (Spain); Lopez-Esteban, S., E-mail: s.lopez@cinn.es [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo - UO - Principado de Asturias - PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer A cryogenic route has been used to obtain ceramic/metal nanostructured powders. Black-Right-Pointing-Pointer The powders present good homogeneity and dispersion of metal. Black-Right-Pointing-Pointer The metal nanoparticle size distributions are centred in 17-35 nm. Black-Right-Pointing-Pointer Both phases, ceramic and metal, present a high degree of crystallinity. Black-Right-Pointing-Pointer Good metal/ceramic interfaces due to epitaxial growth, studied by HRTEM. -- Abstract: This work describes a wet-processing route based on spray-freezing and subsequent lyophilization designed to obtain nanostructured ceramic/metal powders. Starting from the ceramic powder and the corresponding metal salt, a water-based suspension is sprayed on liquid nitrogen. The frozen powders are subsequently freeze-dried, calcined and reduced. The material was analyzed using X-ray diffraction analysis at all stages. High resolution transmission electron microscopy studies showed a uniform distribution of metal nanoparticles on the ceramic grain surfaces, good interfaces and high crystallinity, with an average metal particle size in the nanometric range.

  17. Investigation of Locally Made Ceramic Filter for Household Water Treatment

    Directory of Open Access Journals (Sweden)

    Awaluddin Nurmiyanto

    2012-06-01

    Full Text Available This research have objective to develop and evaluate the performance of ceramic filter in using locally available material at Yogyakarta. Ceramic filter are made by pressing a mixture of clay, discarded pottery (grog and combustible material (coconut fiber into the molder. Curving processes are then applied to form tubular shape before firing it using kiln (1005°C. Filtration test were performed gravitationally by flowing well water into ceramic filter. Filtered water quality was complying with Indonesia drinking water quality standard (E.Coli and turbidity although it has low filtration rate (0,461 L/Hr. The most optimum ceramic filter in turbidity and bacterial removal was composition number 10 {clay+coconut fiber 4,5%(w/w+grog 5%(w/w} that have average turbidity removal 88,2%, and average E. Coli removal 100%. N2 adsorption-desorption result on ceramic filter number 10 showed 0,04μm pore size, and 4,32m2/g pore surface area. The result from the XRD (X-ray diffractometer indicates crystal structure of calcite and quartz on ceramic filter surface. Energy Dispersive X-ray (EDX analysis showed Carbon compound as the most material constituent within the filter. Whereas micro’s photo using SEM (scanning electron microscopic and TEM (transmitted electron microscopic showed filter surface consists of stacked aggregates, separated by more randomly oriented particles.

  18. Tick-proof ceramics. Bo dani ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Shimono, F. (Ishizuka Glass Co. Ltd., Nagoya (Japan))

    1993-07-01

    Ishizuka Glass has developed SiO2-B2O3-R2O(RO) based tick-proof ceramics (trade name; Segrocera) in cooperation with Yamato Chemical Industry, insecticide maker. This article is a report on effectiveness of this ceramics. Ticks living indoors are roughly divided into two kinds, namely ticks living in a house itself and ticks which enter the house by parasitizing on animals and plants, and Segrocera has been developed aiming at the former ticks which, irrespective of its kind, need the temperature of 20-30[degree]C and the moisture of 60% or more as its breeding conditions. The tick-proof effect of Segrocera is as excellent as 90-99% and even after keeping its specimen at 75RH for 12 months, it has shown the ratio of inhibiting ticks' breeding of 98-99%. In comparison with that the effect of other tick-proof agent, pyrethroids-based aerosol is limited up to 24 hours, it is the feature of Segrocera that its life is considerably longer. Safety of Segrocera is also very high. 2 refs., 1 fig., 7 tabs.

  19. Transformation Toughening of Ceramics

    Science.gov (United States)

    1992-03-01

    chanical twing of ualaneeting Ceramica at High Temperatures. ILondo, Patigue-crack growth in overaged and partially stabi- U.K., 198.""IS. Itoribe... Ceramica " Chapter 18 In Mechanical Prop- ŗR. M. !AcMeeding and A. 0. Evans, ’Mechanics of Transformation ertles of Engineering Ceramics. Edited by W.W

  20. Microporous alumina ceramic membranes

    Science.gov (United States)

    Anderson, Marc A.; Sheng, Guangyao

    1993-01-01

    Several methods are disclosed for the preparation microporous alumina ceramic membranes. For the first time, porous alumina membranes are made which have mean pore sizes less than 100 Angstroms and substantially no pores larger than that size. The methods are based on improved sol-gel techniques.

  1. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendfra Nagabhushana

    2001-07-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  2. The Role of Ceramics in a Resurgent Nuclear Industry

    Energy Technology Data Exchange (ETDEWEB)

    Marra, J

    2006-02-28

    With fuel oil and natural gas prices near record highs and worldwide energy demands increasing at an alarming rate, there is growing interest in revitalization of the nuclear power industry within the United States and across the globe. Ceramic materials have long played a very important part in the commercial nuclear industry with applications throughout the entire fuel cycle; from fuel fabrication to waste stabilization. As the international community begins to look at advanced fuel cycles that minimize waste and increase proliferation resistance, ceramic materials will play an even larger role. Many of the advanced reactor concepts being evaluated operate at high-temperature requiring the use of durable, heat-resistant materials. Ceramic fuels are being investigated for a variety of Generation IV reactor concepts. These include the traditional TRISO-coated particles as well as advanced inert-matrix fuels. In order to minimize wastes and legacy materials, ceramic processes are also being applied to fuel reprocessing operations. Ceramic materials continue to provide a vital contribution in ''closing the fuel cycle'' by stabilization of associated low-level and high-level wastes in highly durable grout, ceramics, and glass. In the next five years, programs that are currently in the conceptual phase will begin laboratory- and engineering-scale demonstrations. This will require production-scale demonstrations of several ceramic technologies from fuel form development to advanced stabilization methods. Within the next five to ten years, these demonstrations will move to even larger scales and will also include radioactive demonstrations of these advanced technologies. These radioactive demonstrations are critical to program success and will require advances in ceramic materials associated with nuclear energy applications.

  3. Ceramic Laser Materials

    Energy Technology Data Exchange (ETDEWEB)

    Soules, T F; Clapsaddle, B J; Landingham, R L; Schaffers, K I

    2005-02-15

    Transparent ceramic materials have several major advantages over single crystals in laser applications, not the least of which is the ability to make large aperture parts in a robust manufacturing process. After more than a decade of working on making transparent YAG:Nd, Japanese workers have recently succeeded in demonstrating samples that performed as laser gain media as well as their single crystal counterparts. Since then several laser materials have been made and evaluated. For these reasons, developing ceramic laser materials is the most exciting and futuristic materials topic in today's major solid-state laser conferences. We have established a good working relationship with Konoshima Ltd., the Japanese producer of the best ceramic laser materials, and have procured and evaluated slabs designed by us for use in our high-powered SSHCL. Our measurements indicate that these materials will work in the SSHCL, and we have nearly completed retrofitting the SSHCL with four of the largest transparent ceramic YAG:Nd slabs in existence. We have also begun our own effort to make this material and have produced samples with various degrees of transparency/translucency. We are in the process of carrying out an extensive design-of-experiments to establish the significant process variables for making transparent YAG. Finally because transparent ceramics afford much greater flexibility in the design of lasers, we have been exploring the potential for much larger apertures, new materials, for example for the Mercury laser, other designs for SSHL, such as, edge pumping designs, slabs with built in ASE suppression, etc. This work has just beginning.

  4. Ceramic tubesheet design analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mallett, R.H.; Swindeman, R.W.

    1996-06-01

    A transport combustor is being commissioned at the Southern Services facility in Wilsonville, Alabama to provide a gaseous product for the assessment of hot-gas filtering systems. One of the barrier filters incorporates a ceramic tubesheet to support candle filters. The ceramic tubesheet, designed and manufactured by Industrial Filter and Pump Manufacturing Company (EF&PM), is unique and offers distinct advantages over metallic systems in terms of density, resistance to corrosion, and resistance to creep at operating temperatures above 815{degrees}C (1500{degrees}F). Nevertheless, the operational requirements of the ceramic tubesheet are severe. The tubesheet is almost 1.5 m in (55 in.) in diameter, has many penetrations, and must support the weight of the ceramic filters, coal ash accumulation, and a pressure drop (one atmosphere). Further, thermal stresses related to steady state and transient conditions will occur. To gain a better understanding of the structural performance limitations, a contract was placed with Mallett Technology, Inc. to perform a thermal and structural analysis of the tubesheet design. The design analysis specification and a preliminary design analysis were completed in the early part of 1995. The analyses indicated that modifications to the design were necessary to reduce thermal stress, and it was necessary to complete the redesign before the final thermal/mechanical analysis could be undertaken. The preliminary analysis identified the need to confirm that the physical and mechanical properties data used in the design were representative of the material in the tubesheet. Subsequently, few exploratory tests were performed at ORNL to evaluate the ceramic structural material.

  5. Seasonal variation of atmospheric particle number concentrations, new particle formation and atmospheric oxidation capacity at the high Arctic site Villum Research Station, Station Nord

    DEFF Research Database (Denmark)

    Nguyen, Quynh T.; Glasius, Marianne; Sørensen, Lise L.

    2016-01-01

    This work presents an analysis of the physical properties of sub-micrometer aerosol particles measured at the high Arctic site Villum Research Station, Station Nord (VRS), northeast Greenland, between July 2010 and February 2013. The study focuses on particle number concentrations, particle number...... size distributions and the occurrence of new particle formation (NPF) events and their seasonality in the high Arctic, where observations and characterization of such aerosol particle properties and corresponding events are rare and understanding of related processes is lacking. A clear accumulation...... of the NPF events, while no positive correlation was observed. Calculations of air mass back trajectories using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for the NPF event days suggested that the onset or interruption of events could possibly be explained by changes in air...

  6. Fabrication of high-alloy powders consisting of spherical particles from ultradispersed components

    Science.gov (United States)

    Samokhin, A. V.; Fadeev, A. A.; Sinayskiy, M. A.; Alekseev, N. V.; Tsvetkov, Yu. V.; Arzhatkina, O. A.

    2017-07-01

    It is shown that powders of a model high alloy consisting of spherical particles 25-50 μm in size can be synthesized from a starting ultradispersed powder, which is made of a mixture of the alloy components and is fabricated by the magnesiothermal reduction of metal chlorides in the potassium chloride melt. The synthesis includes the stages of microgranulation of an ultradispersed powder, heat treatment of microgranules, classification of the microgranules with the separation of microgranule fraction of 25-50 μm, spheroidization of the separated fraction in a thermal plasma flow, and classification with the separation of a fraction of micro- and submicrometer-sized particles.

  7. Ceramic-on-ceramic total hip arthroplasty early dislocation rate.

    Science.gov (United States)

    Colwell, Clifford W; Hozack, William J; Mesko, J Wesley; D'Antonio, James A; Bierbaum, Benjamin E; Capello, William N; Jaffe, William L; Mai, Kenny T

    2007-12-01

    Wear debris from metal-on-polyethylene articulation in conventional total hip arthroplasty can limit the implant's longevity. Modern ceramic material with high wear resistance and low fracture risk has the potential to extend the lifetime of total hip arthroplasty, which makes the procedure potentially more suitable for young, active patients. Concerns with brittle ceramic material include fracture risk, the "squeak" phenomenon, and potentially a higher dislocation rate secondary to limited neck lengths and liner options. We therefore determined the early dislocation rate in modern ceramic-on-ceramic total hip arthroplasty. In 1635 total hip arthroplasties performed over the 9-year period (1996-2005), we observed three anterior and 15 posterior dislocations (1.1%). All were treated successfully, one with a revision and 17 with closed reduction under general anesthesia. Ceramic-on-ceramic total hip arthroplasty can be a good alternative bearing surface with a low dislocation rate.

  8. Novel Processing of Ceramics with Polymorphic Control

    Science.gov (United States)

    Jodhani, Gagan

    Polymorphism is an important phenomenon exhibited by many materials, including ceramic oxides. The availability of multiple structural configurations for the same chemical composition opens the pathway to a large number of phases with distinct properties. The formation of the crystal structures can be directly correlated to the processing temperature and/or pressure as well as the particle size for nanomaterials. This work focuses on the tailored synthesis of the desired polymorphs of binary and ternary metal oxides through nanoscale processes with emphasis on flame spray pyrolysis. Flame spray pyrolysis (FSP) is a scalable nano-manufacturing process used for the synthesis of oxide based ceramics. The advantage of this process lies in ease of operation and inexpensive processing as well as the uniformity in the particle size distribution of the products. It is a rapid solidification process involving the atomization of precursor using high temperature gradients and low residence times in the flame. Thus, metastable polymorphs have successfully been synthesized by FSP. Although a wide variety of studies have been conducted on the synthesis and applications of ceramics via FSP there has been scarce knowledge on the actual dynamics of crystal structure formation during the process. Various solution parameters were studied to understand the particle and crystal structure formation for the FSP powders. The process parameters were kept the same; 1.5 slm methane and 3.0 slm O2 was used as fuel for the flame, 5slm oxygen was used as dispersion gas and the precursor was fed at 5ml/min. MoO3 was synthesized using different concentrations of precursor and the particle sizes obtained were correlated to the materials parameters such as solution concentration and amount of organic precursor solvent. Another study was conducted on formation of WO3 polymorphs using organic precursor salts dissolved in organic solvent. The solution was prepared to obtain low particle sizes and to

  9. Highly porous ceramic oxide aerogels having improved flexibility

    Science.gov (United States)

    Meador, Mary Ann B. (Inventor); Nguyen, Baochau N. (Inventor)

    2012-01-01

    Ceramic oxide aerogels incorporating periodically dispersed flexible linkages are provided. The flexible linkages impart greater flexibility than the native aerogels without those linkages, and have been shown to reduce or eliminate the need for supercritical CO.sub.2-mediated drying of the corresponding wet gels. The gels may also be polymer cross-linked via organic polymer chains that are attached to and extend from surface-bound functional groups provided or present over the internal surfaces of a mesoporous ceramic oxide particle network via appropriate chemical reactions.

  10. Slip-casting alumina ceramics for crown and bridge restorations.

    Science.gov (United States)

    Pröbster, L; Diehl, J

    1992-01-01

    The In-Ceram technique uses alumina ceramics and glass in a two-step firing procedure to create a high-strength core material for single-tooth restorations as well as small fixed partial dentures. Fine-grain alumina particles are sintered to form a porous substructure, which is infiltrated with molten glass. The combination of these two processes gives the material its outstanding properties. The sintering process is almost without shrinkage, providing an excellent fit, while the glass infiltration leaves practically no porosities, resulting in high strength.

  11. Catalyzed Ceramic Burner Material

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, Amy S., Dr.

    2012-06-29

    period in accomplishing these objectives. Our work in the area of Pd-based, methane oxidation catalysts has led to the development of highly active catalysts with relatively low loadings of Pd metal using proprietary coating methods. The thermal stability of these Pd-based catalysts were characterized using SEM and BET analyses, further demonstrating that certain catalyst supports offer enhanced stability toward both PdO decomposition and/or thermal sintering/growth of Pd particles. When applied to commercially available fiber mesh substrates (both metallic and ceramic) and tested in an open-air burner, these catalyst-support chemistries showed modest improvements in the NOx emissions and radiant output compared to uncatalyzed substrates. More significant, though, was the performance of the catalyst-support chemistries on novel media substrates. These substrates were developed to overcome the limitations that are present with commercially available substrate designs and increase the gas-catalyst contact time. When catalyzed, these substrates demonstrated a 65-75% reduction in NOx emissions across the firing range when tested in an open air burner. In testing in a residential boiler, this translated into NOx emissions of <15 ppm over the 15-150 kBtu/hr firing range.

  12. Bond strength between zirconium ceramic and dual resinous cement

    Directory of Open Access Journals (Sweden)

    João Galan Junior

    2010-04-01

    Full Text Available Objective: To assess the influence of different surface treatments on the bond strength between the resinous cement Panavia F (Kuraray Co. Ltd., Osaka, Japan and the structure of In-Ceram YZ (Vita Zahnfabrik, Bad Säckingen, Germany. Methods: Fifteen ceramic blocks were assessed: Group 1, finishing with abrasive paper; Group 2, finishing, airborne Al2O3 particle abrasion and silanization; Group 3, finishing, airborne particle abrasion, silicatization and silanization. After treatment, the blocks received cementation of resin composite cylinders with Panavia F (Kuraray Co. Ltd., Osaka, Japan and were submitted to the shear bond strength test in a universal testing machine. Results: The results were statistically analyzed (ANOVA and multiple comparison Student-Newman-Keuls test: Group 1 (9.66 ± 1.67 MPa < Group 2 (16.61 ± 3.38 MPa = Group 3 (19.23 ± 5.69 MPa, with p = 0.007. Conclusion: The structures of the In-Ceram YZ system (Vita Zahnfabrik, Bad Säckingen, Germany associated with Panavia F (Kuraray Co. Ltd., Osaka, Japan require previous etching to achieve greater bond strength between the ceramic and cement, and this treatment may be performed with airborne particle abrasion I or traditional silicatization, both followed by silanization.

  13. Composite material having controlled coefficient of thermal expansion with oxidic ceramics and procedure for the obtainment thereof

    OpenAIRE

    Torrecillas, Ramón; García Moreno, Olga; Fernández, Adolfo

    2009-01-01

    [EN] The present invention relates to a composite material comprising a ceramic component, characterized in having a negative coefficient of thennal expansion, and oxidic ceramic particles, to the procedure for the obtainment thereof, and to the uses thereof in microelectronics, precision optics, aeronautics and aerospace.

  14. Grain boundaries in ceramics and ceramic-metal interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, D.R.; Wolf, D.

    1986-01-01

    Three interfaces exist: the crystal-crystal grain boundary in very pure single-phase ceramics, the crystal-glass-crystal grain boundary in most single-phase and polyphase ceramics, and the ceramic-metal interface. It is needed to correlate their structure and adhesion/failure. Methods for studying the bonding, interfacial structure, and fracture and adhesion are discussed, and recommendations are given. 42 refs. (DLC)

  15. PARTICLE CONCENTRATIONS IN A CHURCH DURING DIFFERENT WEATHER CONDITIONS – A CASE STUDY

    Directory of Open Access Journals (Sweden)

    Bernard Polednik

    2016-11-01

    Full Text Available The purpose of this study is to report particle number (PN and particle mass (PM concentration changes in the church during three 60-minute Masses held on a cloudy, sunny and rainy day. At each Mass with a similar number of participants the same number of candles was lit and incense was burned. The highest average PN1 and PM1 concentrations of submicrometer particles which respectively amounted to 23.9 pt/cm3 and 241.1 µg/m3 were obtained for the Mass held on a rainy day. During that Mass the maximum PN1 and PM1 concentrations (amounting to 59.4×103 pt/cm3 and 632 µg/m3 were respectively about 15 and 39 times higher than the church background levels. The greatest number of submicrometer particles (about 18.5×109 was inhaled by an average participant of the Mass held on a sunny day and it was approximately 7 times higher than the number that would have been inhaled at the same time outdoors. The greatest mass of such particles (about 195.4 µg was inhaled by an average participant of the Mass held on a rainy day and it was approximately 8 times higher than the mass of particles that would have been inhaled outdoors during the same time.

  16. Coated particles for lithium battery cathodes

    Science.gov (United States)

    Singh, Mohit; Eitouni, Hany Basam; Pratt, Russell Clayton; Mullin, Scott Allen; Wang, Xiao-Liang

    2017-07-18

    Particles of cathodic materials are coated with polymer to prevent direct contact between the particles and the surrounding electrolyte. The polymers are held in place either by a) growing the polymers from initiators covalently bound to the particle, b) attachment of the already-formed polymers by covalently linking to functional groups attached to the particle, or c) electrostatic interactions resulting from incorporation of cationic or anionic groups in the polymer chain. Carbon or ceramic coatings may first be formed on the surfaces of the particles before the particles are coated with polymer. The polymer coating is both electronically and ionically conductive.

  17. Ceramic hot-gas filter

    Science.gov (United States)

    Connolly, Elizabeth Sokolinski; Forsythe, George Daniel; Domanski, Daniel Matthew; Chambers, Jeffrey Allen; Rajendran, Govindasamy Paramasivam

    1999-01-01

    A ceramic hot-gas candle filter having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during backpulse cleaning and is resistant to chemical degradation at high temperatures.

  18. Seal between metal and ceramic conduits

    Energy Technology Data Exchange (ETDEWEB)

    Underwood, Richard Paul; Tentarelli, Stephen Clyde

    2015-02-03

    A seal between a ceramic conduit and a metal conduit of an ion transport membrane device consisting of a sealing surface of ceramic conduit, a sealing surface of ceramic conduit, a single gasket body, and a single compliant interlayer.

  19. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  20. Development of Sesquioxide Ceramic for High Energy Lasers

    Science.gov (United States)

    2015-05-25

    Ceramic Matrix Composites , Ceramics ...important. 15. SUBJECT TERMS Laser Materials Processing, Ceramic Matrix Composites , Ceramics 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF... ceramic processing, optimizing the processing requires time and resources. Once the fabrication process is established, composition adjustment

  1. Tailored Ceramics for Laser Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, Joel [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2007-12-10

    Transparent ceramics match or exceed the performance of single-crystal materials in laser applications, with a more-robust fabrication process. Controlling the distribution of optical dopants in transparent ceramics would allow qualitative improvements in amplifier slab design by allowing gain and loss to be varied within the material. My work aims to achieve a controlled pattern or gradient of dopant prior to sintering, in order to produce tailored ceramics.

  2. Laser Micromachining of Ceramics

    OpenAIRE

    SCITI, Diletta; Bellosi, Alida

    2011-01-01

    Laser surface processing of ceramics is an area of considerable technological importance for several structural, tribological, optical and electronic applications. The laser beam behaves as a heat source that induces a temperature rise on the surface and within the bulk of the material. Depending on laser parameters and material characteristics, lasers can be used for fabricating microholes at designated locations, for cutting, scribing, for surface modifications In this work different types ...

  3. Statistic><Ceramics

    DEFF Research Database (Denmark)

    Hansen, Flemming Tvede

    2008-01-01

    Co-organizer for and participant at the exhibition: Statistic><Ceramics The Röhsska Museum of Design and Decorative Arts; Gothenborg 5/2-16/3 2008 Museum fur Kunst und Gewerbe, Hamburg 3/4-27/4 2008......Co-organizer for and participant at the exhibition: Statistic>2-16/3 2008 Museum fur Kunst und Gewerbe, Hamburg 3/4-27/4 2008...

  4. Ceramic stationary gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Roode, M. van [Solar Turbines Inc., San Diego, CA (United States)

    1995-10-01

    The performance of current industrial gas turbines is limited by the temperature and strength capabilities of the metallic structural materials in the engine hot section. Because of their superior high-temperature strength and durability, ceramics can be used as structural materials for hot section components (blades, nozzles, combustor liners) in innovative designs at increased turbine firing temperatures. The benefits include the ability to increase the turbine inlet temperature (TIT) to about 1200{degrees}C ({approx}2200{degrees}F) or more with uncooled ceramics. It has been projected that fully optimized stationary gas turbines would have a {approx}20 percent gain in thermal efficiency and {approx}40 percent gain in output power in simple cycle compared to all metal-engines with air-cooled components. Annual fuel savings in cogeneration in the U.S. would be on the order of 0.2 Quad by 2010. Emissions reductions to under 10 ppmv NO{sub x} are also forecast. This paper describes the progress on a three-phase, 6-year program sponsored by the U.S. Department of Energy, Office of Industrial Technologies, to achieve significant performance improvements and emissions reductions in stationary gas turbines by replacing metallic hot section components with ceramic parts. Progress is being reported for the period September 1, 1994, through September 30, 1995.

  5. Dental ceramics: a current review.

    Science.gov (United States)

    Lawson, Nathaniel C; Burgess, John O

    2014-03-01

    Ceramics are used for many dental applications and are characterized in various ways, including by their hardness, brittleness, thermal and electrical insulation, and biocompatibility. The ceramics most commonly used in dentistry are oxides, particularly silicon dioxide (SiO2), or silica; aluminum oxide (Al2O3), or alumina; and zirconium dioxide (ZrO2), or zirconia. This article reviews the microstructure of current dental ceramic materials and how it relates to their mechanical properties, clinical techniques, and optical properties. Typical ceramics currently in use are described, and their clinically relevant properties such as strength, fracture, polishability, and wear are compared. Cementation methods are also discussed.

  6. Evaluation of Surface Treatment Methods on the Bond Strength of Zirconia Ceramics Systems, Resin Cements and Tooth Surface

    Directory of Open Access Journals (Sweden)

    Akkuş Emek

    2015-07-01

    Full Text Available Objectives: To compare the effects of airborne-particle abrasion (APA and tribochemical silica coating (TSC surface treatment methods on the shear bond strength of zirconia ceramics systems, resin cements and tooth surface

  7. Effects of Kaolin particle size and annealing temperature on the ...

    African Journals Online (AJOL)

    ... large contact area presented by the insulating kaolin particles resulting in reduction of the number of zinc particle-particle contact. The results from this study will help in the development of conducting ceramics which could find use in chemical industries as electrodes in environments not conducive for metallic electrodes.

  8. Fracture strength of three all-ceramic systems: Top-Ceram compared with IPS-Empress and In-Ceram.

    Science.gov (United States)

    Quran, Firas Al; Haj-Ali, Reem

    2012-03-01

    The purpose of this study was to investigate the fracture loads and mode of failure of all-ceramic crowns fabricated using Top-Ceram and compare it with all-ceramic crowns fabricated from well-established systems: IPS-Empress II, In-Ceram. Thirty all-ceramic crowns were fabricated; 10 IPS-Empress II, 10 In-Ceram alumina and 10 Top-Ceram. Instron testing machine was used to measure the loads required to introduce fracture of each crown. Mean fracture load for In-Ceram alumina [941.8 (± 221.66) N] was significantly (p > 0.05) higher than those of Top-Ceram and IPS-Empress II. There was no statistically significant difference between Top-Ceram and IPS-Empress II mean fracture loads; 696.20 (+222.20) and 534 (+110.84) N respectively. Core fracture pattern was highest seen in Top- Ceram specimens.

  9. Fabrication of sub-micrometer PMOSFETs with sub-100 nm p sup + -n shallow junctions using Group III dual ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, C.-M. (Intel Corp., Santa Clara, CA (USA)); Steckl, A.J. (Cincinnati Univ., OH (USA). Dept. of Electrical and Computer Engineering)

    1990-04-01

    Fabrication of sub-micrometer PMOSFETs with sub-100 nm p{sup +}-n source/drain junctions using all Group III ({sup 69}Ga, {sup 115}In, {sup 11}B, {sup 49}BF{sub 2}) dual ion implantation is reported. We have obtained low leakage p{sup +}-n shallow junctions with a depth less than 70 nm by implanting various combinations of Group III species in conjunction with low temperature rapid thermal annealing (25/3 keV Ga/B implant annealed at 600{sup 0}C for 30 s; 50/5 keV and 30/3 keV, In/B implants annealed at 900{sup 0}C for 10 s). Sub-micrometer (0.6-0.95 {mu}m) PMOSFETs have been fabricated with this technique. The Ga/B-implanted transistors exhibit a subthreshold slope of 95-105 mV/decade and yield a maximum transconductance of 35-45 mS/mm. The corresponding values for the In/B-implanted FETs are 100-110 mV/decade and 30-40 mS/mm. (author).

  10. Wear and creep of highly crosslinked polyethylene against cobalt chrome and ceramic femoral heads.

    Science.gov (United States)

    Galvin, A L; Jennings, L M; Tipper, J L; Ingham, E; Fisher, J

    2010-10-01

    The wear and creep characteristics of highly crosslinked ultrahigh-molecular-weight polyethylene (UHMWPE) articulating against large-diameter (36mm) ceramic and cobalt chrome femoral heads have been investigated in a physiological anatomical hip joint simulator for 10 million cycles. The crosslinked UHMWPE/ceramic combination showed higher volume deformation due to creep plus wear during the first 2 million cycles, and a steady-state wear rate 40 per cent lower than that of the crosslinked UHMWPE/cobalt chrome combination. Wear particles were isolated and characterized from the hip simulator lubricants. The wear particles were similar in size and morphology for both head materials. The particle isolation methodology used could not detect a statistically significant difference between the particles produced by the cobalt chrome and alumina ceramic femoral heads.

  11. Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2007-01-01

    A family of glass/ceramic composite materials has been investigated for use as sealants in planar solid oxide fuel cells. These materials are modified versions of a barium calcium aluminosilicate glass developed previously for the same purpose. The composition of the glass in mole percentages is 35BaO + 15CaO + 5Al2O3 + 10B2O3 + 35SiO2. The glass seal was found to be susceptible to cracking during thermal cycling of the fuel cells. The goal in formulating the glass/ ceramic composite materials was to (1) retain the physical and chemical advantages that led to the prior selection of the barium calcium aluminosilicate glass as the sealant while (2) increasing strength and fracture toughness so as to reduce the tendency toward cracking. Each of the composite formulations consists of the glass plus either of two ceramic reinforcements in a proportion between 0 and 30 mole percent. One of the ceramic reinforcements consists of alumina platelets; the other one consists of particles of yttria-stabilized zirconia wherein the yttria content is 3 mole percent (3YSZ). In preparation for experiments, panels of the glass/ceramic composites were hot-pressed and machined into test bars.

  12. Pre-Hispanic ceramics analyzed using PIXE and radiographic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Lima, S.C., E-mail: sclima@mae.usp.br [Museu de Arqueologia e Etnologia da Universidade de Sao Paulo, Cidade Universitaria, Sao Paulo, SP (Brazil); Rizzutto, M.A., E-mail: rizzutto@if.usp.br [Instituto de Fisica, Universidade de Sao Paulo, Cidade Universitaria, Sao Paulo, SP (Brazil); Added, N.; Barbosa, M.D.L.; Trindade, G.F. [Instituto de Fisica, Universidade de Sao Paulo, Cidade Universitaria, Sao Paulo, SP (Brazil); Fleming, M.I.D.A. [Museu de Arqueologia e Etnologia da Universidade de Sao Paulo, Cidade Universitaria, Sao Paulo, SP (Brazil)

    2011-12-15

    Ceramics objects are the most common artifacts found during excavation of archaeological sites and often depicts cultural habits and manufacturing technologies of the culture. The determination of macroscopic and microscopic characteristics of the ceramic objects such as the ceramic porosity, addition of tempers in the clay, main chemical components and the trace elements present in the ceramic can reveal many aspects about the manufacturing processes used by the culture, its degree of development, the provenance of the raw materials and the exchange networks. Also the radiography can help to investigate the manufactured processes, the size of the tempers used and the conservation status of the artifacts. In this present work two non-destructive techniques, radiography and PIXE (Particle Induced X-ray Emission) were used to characterize one set of thirty-six pre-Hispanic ceramic pieces from the Chimu Culture conserved in the Museu de Arqueologia e Etnologia (MAE/USP). The PIXE analyses performed in the external beam setup at LAMFI (Laboratorio de Analise de Materiais por Feixes Ionicos) allowed measure the principal chemical elements such as Al, Si, K, Ti, Fe and Ca, present in this group of pieces. X-ray imagings allowed identify the manufacture processes, the granularity of the tempers used, as well as the similarity and the differences between the pieces studied.

  13. Pre-Hispanic ceramics analyzed using PIXE and radiographic techniques

    Science.gov (United States)

    Lima, S. C.; Rizzutto, M. A.; Added, N.; Barbosa, M. D. L.; Trindade, G. F.; Fleming, M. I. D. A.

    2011-12-01

    Ceramics objects are the most common artifacts found during excavation of archaeological sites and often depicts cultural habits and manufacturing technologies of the culture. The determination of macroscopic and microscopic characteristics of the ceramic objects such as the ceramic porosity, addition of tempers in the clay, main chemical components and the trace elements present in the ceramic can reveal many aspects about the manufacturing processes used by the culture, its degree of development, the provenance of the raw materials and the exchange networks. Also the radiography can help to investigate the manufactured processes, the size of the tempers used and the conservation status of the artifacts. In this present work two non-destructive techniques, radiography and PIXE (Particle Induced X-ray Emission) were used to characterize one set of thirty-six pre-Hispanic ceramic pieces from the Chimu Culture conserved in the Museu de Arqueologia e Etnologia (MAE/USP). The PIXE analyses performed in the external beam setup at LAMFI (Laboratório de Análise de Materiais por Feixes Iônicos) allowed measure the principal chemical elements such as Al, Si, K, Ti, Fe and Ca, present in this group of pieces. X-ray imagings allowed identify the manufacture processes, the granularity of the tempers used, as well as the similarity and the differences between the pieces studied.

  14. Method of preparing porous, rigid ceramic separators for an electrochemical cell. [Patent application

    Science.gov (United States)

    Bandyopadhyay, G.; Dusek, J.T.

    Porous, rigid separators for electrochemical cells are prepared by first calcining particles of ceramic material at temperatures above about 1200/sup 0/C for a sufficient period of time to reduce the sinterability of the particles. A ceramic powder that has not been calcined is blended with the original powder to control the porosity of the completed separator. The ceramic blend is then pressed into a sheet of the desired shape and sintered at a temperature somewhat lower than the calcination temperature. Separator sheets of about 1 to 2.5 mm thickness and 30 to 70% porosity can be prepared by this technique. Ceramics such as yttria, magnesium oxide, and magnesium-aluminium oxide have advantageously been used to form separators by this method.

  15. Particle Pollution

    Science.gov (United States)

    ... Your Health Particle Pollution Public Health Issues Particle Pollution Recommend on Facebook Tweet Share Compartir Particle pollution — ... see them in the air. Where does particle pollution come from? Particle pollution can come from two ...

  16. Crystallization of high-strength nano-scale leucite glass-ceramics.

    Science.gov (United States)

    Theocharopoulos, A; Chen, X; Wilson, R M; Hill, R; Cattell, M J

    2013-11-01

    Fine-grained, high strength, translucent leucite dental glass-ceramics are synthesized via controlled crystallization of finely milled glass powders. The objectives of this study were to utilize high speed planetary milling of an aluminosilicate glass for controlled surface crystallization of nano-scale leucite glass-ceramics and to test the biaxial flexural strength. An aluminosilicate glass was synthesized, attritor or planetary milled and heat-treated. Glasses and glass-ceramics were characterized using particle size analysis, X-ray diffraction and scanning electron microscopy. Experimental (fine and nanoscale) and commercial (Ceramco-3, IPS Empress Esthetic) leucite glass-ceramics were tested using the biaxial flexural strength (BFS) test. Gaussian and Weibull statistics were applied. Experimental planetary milled glass-ceramics showed an increased leucite crystal number and nano-scale median crystal sizes (0.048-0.055 μm(2)) as a result of glass particle size reduction and heat treatments. Experimental materials had significantly (p0.05) strength difference. All other groups' mean BFS and characteristic strengths were found to be significantly different (pglass-ceramics with high flexural strength. These materials may help to reduce problems associated with brittle fracture of all-ceramic restorations and give reduced enamel wear. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. A novel method for isolation and recovery of ceramic nanoparticles and metal wear debris from serum lubricants at ultra-low wear rates.

    Science.gov (United States)

    Lal, S; Hall, R M; Tipper, J L

    2016-09-15

    Ceramics have been used to deliver significant improvements in the wear properties of orthopaedic bearing materials, which has made it challenging to isolate wear debris from simulator lubricants. Ceramics such as silicon nitride, as well as ceramic-like surface coatings on metal substrates have been explored as potential alternatives to conventional implant materials. Current isolation methods were designed for isolating conventional metal, UHMWPE and ceramic wear debris. In this paper, we describe a methodology for isolation and recovery of ceramic or ceramic-like coating particles and metal wear particles from serum lubricants under ultra-low and low wear performance. Enzymatic digestion was used to digest the serum proteins and sodium polytungstate was used as a novel density gradient medium to isolate particles from proteins and other contaminants by ultracentrifugation. This method demonstrated over 80% recovery of particles and did not alter the size or morphology of ceramic and metal particles during the isolation process. Improvements in resistance to wear and mechanical damage of the articulating surfaces have a large influence on longevity and reliability of joint replacement devices. Modern ceramics have demonstrated ultra-low wear rates for hard-on-hard total hip replacements. Generation of very low concentrations of wear debris in simulator lubricants has made it challenging to isolate the particles for characterisation and further analysis. We have introduced a novel method to isolate ceramic and metal particles from serum-based lubricants using enzymatic digestion and novel sodium polytungstate gradients. This is the first study to demonstrate the recovery of ceramic and metal particles from serum lubricants at lowest detectable in vitro wear rates reported in literature. Copyright © 2016. Published by Elsevier Ltd.

  18. Lightweight high performance ceramic material

    Science.gov (United States)

    Nunn, Stephen D [Knoxville, TN

    2008-09-02

    A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.

  19. Ceramics in nuclear waste management

    Energy Technology Data Exchange (ETDEWEB)

    Chikalla, T D; Mendel, J E [eds.

    1979-05-01

    Seventy-three papers are included, arranged under the following section headings: national programs for the disposal of radioactive wastes, waste from stability and characterization, glass processing, ceramic processing, ceramic and glass processing, leaching of waste materials, properties of nuclear waste forms, and immobilization of special radioactive wastes. Separate abstracts were prepared for all the papers. (DLC)

  20. Micromolding for ceramic microneedle arrays

    NARCIS (Netherlands)

    van Nieuwkasteele-Bystrova, Svetlana Nikolajevna; Lüttge, Regina

    2011-01-01

    The fabrication process of ceramic microneedle arrays (MNAs) is presented. This includes the manufacturing of an SU-8/Si-master, its double replication resulting in a PDMS mold for production by micromolding and ceramic sintering. The robustness of the replicated structures was tested by means of

  1. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 8. Science and Technology of Ceramics - Traditional Ceramics. Sheela K Ramasesha. Series Article Volume 4 Issue 8 August 1999 pp 16-24. Fulltext. Click here to view fulltext PDF. Permanent link:

  2. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 12. Science and Technology of Ceramics - Functional Ceramics. Sheela K Ramasesha. Series Article Volume 4 Issue 12 December 1999 pp 21-30. Fulltext. Click here to view fulltext PDF. Permanent link:

  3. Low thermal expansion glass ceramics

    CERN Document Server

    1995-01-01

    This book is one of a series reporting on international research and development activities conducted by the Schott group of companies With the series, Schott aims to provide an overview of its activities for scientists, engineers, and managers from all branches of industry worldwide where glasses and glass ceramics are of interest Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated This volume describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization Thus glass ceramics with thermal c...

  4. Ceramic membrane development in NGK

    Science.gov (United States)

    Araki, Kiyoshi; Sakai, Hitoshi

    2011-05-01

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R&D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  5. Particle Size Distribution in Aluminum Manufacturing Facilities.

    Science.gov (United States)

    Liu, Sa; Noth, Elizabeth M; Dixon-Ernst, Christine; Eisen, Ellen A; Cullen, Mark R; Hammond, S Katharine

    2014-10-01

    As part of exposure assessment for an ongoing epidemiologic study of heart disease and fine particle exposures in aluminum industry, area particle samples were collected in production facilities to assess instrument reliability and particle size distribution at different process areas. Personal modular impactors (PMI) and Minimicro-orifice uniform deposition impactors (MiniMOUDI) were used. The coefficient of variation (CV) of co-located samples was used to evaluate the reproducibility of the samplers. PM2.5 measured by PMI was compared to PM2.5 calculated from MiniMOUDI data. Mass median aerodynamic diameter (MMAD) and concentrations of sub-micrometer (PM1.0) and quasi-ultrafine (PM0.56) particles were evaluated to characterize particle size distribution. Most of CVs were less than 30%. The slope of the linear regression of PMI_PM2.5 versus MiniMOUDI_PM2.5 was 1.03 mg/m3 per mg/m3 (± 0.05), with correlation coefficient of 0.97 (± 0.01). Particle size distribution varied substantively in smelters, whereas it was less variable in fabrication units with significantly smaller MMADs (arithmetic mean of MMADs: 2.59 μm in smelters vs. 1.31 μm in fabrication units, p = 0.001). Although the total particle concentration was more than two times higher in the smelters than in the fabrication units, the fraction of PM10 which was PM1.0 or PM0.56 was significantly lower in the smelters than in the fabrication units (p particles were similar in these two types of facilities. It would appear, studies evaluating ultrafine particle exposure in aluminum industry should focus on not only the smelters, but also the fabrication facilities.

  6. Method of forming a ceramic matrix composite and a ceramic matrix component

    Science.gov (United States)

    de Diego, Peter; Zhang, James

    2017-05-30

    A method of forming a ceramic matrix composite component includes providing a formed ceramic member having a cavity, filling at least a portion of the cavity with a ceramic foam. The ceramic foam is deposited on a barrier layer covering at least one internal passage of the cavity. The method includes processing the formed ceramic member and ceramic foam to obtain a ceramic matrix composite component. Also provided is a method of forming a ceramic matrix composite blade and a ceramic matrix composite component.

  7. Particle processing technology

    Science.gov (United States)

    Yoshio, Sakka

    2014-02-01

    includes two papers on the fabrication of mechanically reliable nanocomposites by dispersing graphene into a ceramic matrix, and on supercapacitors with high energy densities in a Co(OH)2 system decorated with graphene and carbon nanotubes. As a novel preparation method of oxide films, the fabrication of alumina films with laminated structures by ac anodization is reviewed. Moreover a new type of nanosheet has been fabricated by the exfoliation of layered, ternary transition-metal carbide and nitride compounds, known as Mn + 1AXn phases (or MAX phases) where M is an early transition metal, such as Ti or Nb, A is an A group element, such as Si or Al, X is carbon and/or nitrogen and n = 1-3 [4]. Among the MAX phases, those containing Mo have been theoretically calculated by first-principles calculations to be a source for obtaining Mo2C nanosheets with potentially unique properties. As an example of improving bulk ceramic properties, texturing by using a high magnetic field [5] and sintering by the electric current activated/assisted sintering (ECAS) technology [6] have been demonstrated for ultra-high temperature ceramics with high-temperature strength. A project on the development of materials and particle processing for the field of environment and energy has been ongoing at the National Institute for Materials Science since April 2011. This project employs various core competence technologies for particle processing such as ion beam irradiation for nanoparticle fabrication [7], fullerene nanomaterial processing using liquid-liquid interface precipitation [8], a gas reduction nitridation process to obtain Si3N4-based phosphor materials [9], advanced phosphors via novel processing [10, 11], ultra-high pressure technology for processing and in situ analysis [12, 13], colloidal processing in a high magnetic field to obtain laminated, textured ceramics [1, 3, 5], the ECAS process for nanostructuring ceramics [6] and so forth. Here, I would like to introduce some research

  8. Improved performance of diatomite-based dental nanocomposite ceramics using layer-by-layer assembly

    Science.gov (United States)

    Lu, Xiaoli; Xia, Yang; Liu, Mei; Qian, Yunzhu; Zhou, Xuefeng; Gu, Ning; Zhang, Feimin

    2012-01-01

    To fabricate high-strength diatomite-based ceramics for dental applications, the layer-by-layer technique was used to coat diatomite particles with cationic [poly(allylamine hydrochloride)] and anionic [poly(sodium 4-styrenesulfonate)] polymers to improve the dispersion and adsorption of positively charged nano-ZrO2 (zirconia) as a reinforcing agent. The modified diatomite particles had reduced particle size, narrower size distribution, and were well dispersed, with good adsorption of nano-ZrO2. To determine the optimum addition levels for nano-ZrO2, ceramics containing 0, 20, 25, 30, and 35 wt% nano-ZrO2 were sintered and characterized by the three-point bending test and microhardness test. In addition to scanning electron microscopy, propagation phase-contrast synchrotron X-ray microtomography was used to examine the internal structure of the ceramics. The addition of 30 wt% nano-ZrO2 resulted in the highest flexural strength and fracture toughness with reduced porosity. Shear bond strength between the core and veneer of our diatomite ceramics and the most widely used dental ceramics were compared; the shear bond strength value for the diatomite-based ceramics was found to be significantly higher than for other groups (P dental materials. PMID:22619551

  9. Enhanced resolution particle size distributions by multiple angle photon correlation spectroscopy

    Science.gov (United States)

    Bott, Steven E.

    1989-01-01

    Photon correlation spectroscopy (PCS) has become a method of choice for measuring submicrometer particles. It is capable of rapid, accurate measurements of mean particle size. Since the measurements are nonperturbing, it is ideal for monitoring systems undergoing dynamic changes. Despite its widespread acceptance, the information content of PCS measurements for particle size distributions is low and provides limited resolution. A method is presented whereby PCS measurements made at several scattering angles plus the angular distribution of light scattered from the particles are combined in a single simultaneous analysis to effect an enhanced resolution particle size distribution. The efficacy of the method is assessed by recovering size distributions from computer simulated data and by comparisons of conventional PCS measurements of polystyrene spheres with those made by the new method.

  10. Thick ceramic coating technique. Atsuniku ceramic coating gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Sata, N. (Government Industrial Reserach Institute, Tohoku, Sendai (Japan))

    1987-10-15

    This paper describes a thick ceramic coating technique that uses a reactive bonding process. This process coats interior of a metallic cylinder or surface of a metal having optional curvature with thick (2 mm to 3 mm) ceramics composed mainly of alumina. The process features easiness in coating and simplicity of the equipment. Reactive heat generated from thermit reaction melts iron and alumina as the reaction products, and produces molten ceramics which is cooled on the metal surface to deposit and solidify as a ceramics layer, thus completing the synthesis and the coating in one process. Its application fields would include reaction tubes, abrasive fluid tubes, and high-temperature fluid tubes that can utilize the ceramics' resistance to abrasion, corrosion and heat as well as heat insulation. The ceramics layer has a hardness of about Hv 1500 and porosity from 2 to 3%. The bonding strength between the substrate metal and the ceramics layer can achieve 10 MPa to 20 MPa as a result of surface oxidation treatment and cooling treatment given initially to prevent the outer wall temperature from rising. 2 figs.

  11. Water Absorption Behavior of Polystyrene Particles Prepared by Emulsion Polymerization with Nonionic Emulsifiers and Innovative Easy Synthesis of Hollow Particles.

    Science.gov (United States)

    Okubo, Masayoshi; Kobayashi, Hiroshi; Huang, Chujuan; Miyanaga, Eri; Suzuki, Toyoko

    2017-04-11

    Submicrometer-sized raspberry-like polystyrene (PS) particles, which were prepared by emulsion polymerization with polyoxyethylene nonylphenyl ether nonionic emulsifier (Emulgen 910, HLB 12.2) and potassium persulfate initiator, contained 8.5 vol % (relative to the particle) of water and 5.5 wt % (relative to PS) of Emulgen 910 in the inside. The water absorption decreased the glass transition temperature of the PS particles dispersed in an aqueous medium. The wt % (relative to PS) of the incorporated Emulgen 910 increased with increasing initial Emulgen 910 concentration in the emulsion polymerization, but the wt % (relative to the total Emulgen 910 used) of the incorporated Emulgen 910 was constant at approximately 50% independent of the initial concentration. The vol % (relative to particle) of water increased to 46% by heat treatment at 90 °C for 24 h, which was based on further water absorption, and resulted in spherical hollow particles, where the amount of the incorporated Emulgen 910 remarkably decreased in a short treatment and then remained almost constant during the heat treatment. After another 24 h treatment, the percentage of nonhollow particles increased gradually, which was based on the escape of the water domain together with Emulgen 910 from the inside of the particles. On the other hand, spherical PS particles prepared by emulsifier-free emulsion polymerization did not contain water in the inside and were not changed to hollow ones by a similar heat treatment. From these results, an innovative easy method to synthesize hydrophobic hollow PS particles is proposed.

  12. High-temperature corrosion resistance of ceramics and ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.

    1996-06-01

    Ceramics and ceramic composites offer the potential to operate fossil energy systems at the higher temperatures necessary for improved energy efficiency and better environmental control. However, because many fossil fuel-derived processes contain sulfur, chlorine, and carbon, as well as oxygen, degradation from high-temperature corrosion and environmental effects arising from reactions of solids with gases and condensable products is a common life-determining factor in operating systems. Ceramic-based products are not immune to such degradation; adequate corrosion resistance must be assured to exploit the technical and economic potential of such materials. This is normally accomplished by using stable, sound oxides that exist in their bulk form, that naturally grow as surface layers upon exposure to an oxidizing environment, or that are deposited as a coating on a susceptible material. It is therefore important to examine the critical issues with respect to more environmental stability of ceramics that have the potential to be corrosion resistant in particular fossil environments. Key aspects include not only chemical compatibility, but the influence of the environment on the mechanical behavior of the ceramic materials. In addition, for coatings, the mechanical reliability of the ceramic is a key issue in that an otherwise corrosion-resistant surface layer must remain sound and adherent in order to provide protection to the underlying substrate. The purpose of this work is to support the development of advanced ceramics and ceramic composites for applications in fossil environments by examining critical issues related to high-temperature corrosion resistance. More specifically, the overall objective of this task is to examine the chemical compatibility and reliability of potentially corrosion-resistant ceramics being developed as protective overcoats and/or structural materials as parts of other work elements funded by the AR&TD Program.

  13. Ceramic fiber reinforced filter

    Science.gov (United States)

    Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  14. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

    In the present quarter, the possibility of using a more complex interfacial engineering approach to the development of reliable and stable oxygen transport perovskite ceramic membranes/metal seals is discussed. Experiments are presented and ceramic/metal interactions are characterized. Crack growth and fracture toughness of the membrane in the reducing conditions are also discussed. Future work regarding this approach is proposed are evaluated for strength and fracture in oxygen gradient conditions. Oxygen gradients are created in tubular membranes by insulating the inner surface from the reducing environment by platinum foils. Fracture in these test conditions is observed to have a gradient in trans and inter-granular fracture as opposed to pure trans-granular fracture observed in homogeneous conditions. Fracture gradients are reasoned to be due to oxygen gradient set up in the membrane, variation in stoichiometry across the thickness and due to varying decomposition of the parent perovskite. The studies are useful in predicting fracture criterion in actual reactor conditions and in understanding the initial evolution of fracture processes.

  15. Removing Pathogens Using Nano-Ceramic-Fiber Filters

    Science.gov (United States)

    Tepper, Frederick; Kaledin, Leonid

    2005-01-01

    A nano-aluminum-oxide fiber of only 2 nanometers in diameter was used to develop a ceramic-fiber filter. The fibers are electropositive and, when formulated into a filter material (NanoCeram(TradeMark)), would attract electro-negative particles such as bacteria and viruses. The ability to detect and then remove viruses as well as bacteria is of concern in space cabins since they may be carried onboard by space crews. Moreover, an improved filter was desired that would polish the effluent from condensed moisture and wastewater, producing potable drinking water. A laboratory- size filter was developed that was capable of removing greater than 99.9999 percent of bacteria and virus. Such a removal was achieved at flow rates hundreds of times greater than those through ultraporous membranes that remove particles by sieving. Because the pore size of the new filter was rather large as compared to ultraporous membranes, it was found to be more resistant to clogging. Additionally, a full-size cartridge is being developed that is capable of serving a full space crew. During this ongoing effort, research demonstrated that the filter media was a very efficient adsorbent for DNA (deoxyribonucleic acid), RNA (ribonucleic acid), and endotoxins. Since the adsorption is based on the charge of the macromolecules, there is also a potential for separating proteins and other particulates on the basis of their charge differences. The separation of specific proteins is a major new thrust of biotechnology. The principal application of NanoCeram filters is based on their ability to remove viruses from water. The removal of more than 99.9999 percent of viruses was achieved by a NanoCeram polishing filter added to the effluent of an existing filtration device. NanoCeram is commercially available in laboratory-size filter discs and in the form of a syringe filter. The unique characteristic of the filter can be demonstrated by its ability to remove particulate dyes such as Metanyl yellow. Its

  16. Recycling ceramic industry wastes in sound absorbing materials

    Directory of Open Access Journals (Sweden)

    C. Arenas

    2016-10-01

    Full Text Available The scope of this investigation is to develop a material mainly composed (80% w/w of ceramic wastes that can be applied in the manufacture of road traffic noise reducing devices. The characterization of the product has been carried out attending to its acoustic, physical and mechanical properties, by measuring the sound absorption coefficient at normal incidence, the open void ratio, density and compressive strength. Since the sound absorbing behavior of a porous material is related to the size of the pores and the thickness of the specimen tested, the influence of the particle grain size of the ceramic waste and the thickness of the samples tested on the properties of the final product has been analyzed. The results obtained have been compared to a porous concrete made of crushed granite aggregate as a reference commercial material traditionally used in similar applications. Compositions with coarse particles showed greater sound absorption properties than compositions made with finer particles, besides presenting better sound absorption behavior than the reference porous concrete. Therefore, a ceramic waste-based porous concrete can be potentially recycled in the highway noise barriers field.

  17. Deformation of a dental ceramic following adhesive cementation.

    LENUS (Irish Health Repository)

    2010-01-01

    Stress-induced changes imparted in a \\'dentin-bonded-crown\\' material during sintering, annealing, pre-cementation surface modification, and resin coating have been visualized by profilometry. The hypothesis tested was that operative techniques modify the stressing pattern throughout the material thickness. We polished the upper surfaces of 10 ceramic discs to remove surface imperfections before using a contact profilometer (40-nm resolution) to measure the \\'flatness\\'. Discs were re-profiled after annealing and after alumina particle air-abrasion and resin-coating of the \\'fit\\' surface. Polished surfaces were convex, with a mean deflection of 8.4 + or - 1.5 microm. Mean deflection was significantly reduced (P = 0.029) following alumina particle air-abrasion and increased (P < 0.001) on resin-coating. Polishing induced a tensile stress state, resulting in surface convexity. Alumina particle air-abrasion reduced the relative tensile stress state of the contralateral polished surface. Resin-polymerization generated compression within the resin-ceramic \\'hybrid layer\\' and tension in the polished surface and is likely to contribute to the strengthening of ceramics by resin-based cements.

  18. Ceramics in geothermal power plant. Chinetsu hatsuden to ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sanada, N. (Government Industrial Research Institute, Tohoku, Sendai (Japan))

    1991-03-30

    This paper summarizes how ceramics are used in geothermal power plants. Although there are not many cases of using ceramics in geothermal power generation, they are used or discussed of their use where environmental temperature or flow velocity in geothermal fluid is high, or solids are anticipated to get mixed, with an expectation on their superior heat and erosion resistance. Applications may include use of alumina ceramics in nozzles in total flow generation turbines, magnesium oxide insulator cable to suspend a measuring instrument to inspect geothermal beds, titania spraying and covering of carbon steel mirror plates in a power plant separator, and SiC ceramics in bearings for downhole pump motors. The paper also describes several examples of problems in development which have been tackled with to date (including manufacture of metal-alumina pipes using a centrifugal thermit process). 8 refs., 6 figs., 1 tab.

  19. A simple sheathless CE-MS interface with a sub-micrometer electrical contact fracture for sensitive analysis of peptide and protein samples

    DEFF Research Database (Denmark)

    Nguyen, Tam T. T. N.; Petersen, Nickolaj J.; Rand, Kasper Dyrberg

    2016-01-01

    of forming a sub-micrometer fracture directly in the capillary. The simple interface design allowed the generation of a stable ESI spray capable of ionization at low nanoliter flow-rates (45–90 nL/min) for high sensitivity MS analysis of challenging samples like those containing proteins and peptides...... profile was achieved and comparable sequence coverage was obtained by the CE-MS method (73%) compared to a representative UPLC-MS method (77%). The CE-MS interface was subsequently used to analyse a more complex sample of pharmaceutically relevant human proteins including insulin, tissue factor and α......Online coupling of capillary electrophoresis (CE) to electrospray ionization mass spectrometry (MS) has shown considerable potential, however, technical challenges have limited its use. In this study, we have developed a simple and sensitive sheathless CE-MS interface based on the novel concept...

  20. Agglomeration of ceramic powders

    Science.gov (United States)

    Cawley, James D.; Larosa, Judith; Dirkse, Fredrick

    1989-01-01

    A research program directed at a critical comparison of numerical models for power agglomeration with experimental observations is currently underway. Central to this program is the quantitative characterization of the distribution of mass within an agglomerate as a function of time. Current experiments are designed to restrict agglomeration to a surface, which is oriented perpendicular to the force of gravity. These experiments are discussed with reference to: their significance to ceramic processing; artifacts which may be avoided in microgravity experiments; and the comparison of information available in real space (from optical microscopy) to that in reciprocal space (from light scattering). The principle machine requirement appears to be a need to obtain information at small scattering angles.

  1. Creep in electronic ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Routbort, J. L.; Goretta, K. C.; Arellano-Lopez, A. R.

    2000-04-27

    High-temperature creep measurements combined with microstructural investigations can be used to elucidate deformation mechanisms that can be related to the diffusion kinetics and defect chemistry of the minority species. This paper will review the theoretical basis for this correlation and illustrate it with examples from some important electronic ceramics having a perovskite structure. Recent results on BaTiO{sub 3}, (La{sub 1{minus}x}Sr){sub 1{minus}y}MnO{sub 3+{delta}}, YBa{sub 2}Cu{sub 3}O{sub x}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x}, (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} and Sr(Fe,Co){sub 1.5}O{sub x} will be presented.

  2. Role of minerogenic particles in light scattering in lakes and a river in central New York.

    Science.gov (United States)

    Peng, Feng; Effler, Steven W; O'Donnell, David; Perkins, Mary Gail; Weidemann, Alan

    2007-09-10

    The role of minerogenic particles in light scattering in several lakes and a river (total of ten sites) in central New York, which represent a robust range of scattering conditions, was evaluated based on an individual particle analysis technique of scanning electron microscopy interfaced with automated x-ray microanalysis and image analysis (SAX), in situ bulk measurements of particle scattering and backscattering coefficients (bp and bbp), and laboratory analyses of common indicators of scattering. SAX provided characterizations of the elemental x-ray composition, number concentration, particle size distribution (PSD), shape, and projected area concentration of minerogenic particles (PAVm) of sizes>0.4 microm. Mie theory was applied to calculate the minerogenic components of bp (bm) and bbp (bb,m) with SAX data. Differences in PAVm, associated primarily with clay minerals and CaCO3, were responsible for most of the measured differences in both bp and bbp across the study sites. Contributions of the specified minerogenic particle classes to bm were found to correspond approximately to their contributions to PAVm. The estimates of bm represented substantial fractions of bp, whereas those of bb,m were the dominant component of bbp. The representativeness of the estimates of bm and bb,m was supported by their consistency with the bulk measurements. Greater uncertainty prevails for the bb,m estimates than those for bm, associated primarily with reported deviations in particle shapes from sphericity. The PSDs were well represented by the "B" component of the two-component model or a three parameter generalized gamma distribution [Deep-Sea Res. Part I 40, 1459 (1993)]. The widely applied Junge (hyperbolic) function performed poorly in representing the PSDs and the size dependency of light scattering in these systems, by overrepresenting the concentrations of submicrometer particles especially. Submicrometer particles were not important contributors to bm or bb,m.

  3. Sintering behavior of LZSA glass-ceramics

    Directory of Open Access Journals (Sweden)

    Oscar Rubem Klegues Montedo

    2009-06-01

    Full Text Available The LZSA glass-ceramic system (Li2O-ZrO2-SiO2-Al2O 3 shows interesting properties, such as good chemical resistance, low thermal expansion, high abrasion resistance, and a low dielectric constant. However, in order to obtain a high performance material for specific applications, the sintering behavior must be better understood so that the porosity may be reduced and other properties improved. In this context, a sintering investigation for a specific LZSA glass-ceramic system composition was carried out. A 18.8Li2O-8.3ZrO2-64.2SiO2-8.7Al 2O3 glass was prepared by melting the solids, quenching the melt in water, and grinding the resulting solid in order to obtain a powder (3.68 μm average particle diameter. Subsequently, the glass powder was characterized (chemical analysis and determination of thermal properties and the sintering behavior was investigated using optical non-contact dilatometry measurements. The results showed that the crystallization process strongly reduced the sintering in the temperature interval from 785 to 940 °C, and a maximum thermal shrinkage of 15.4% was obtained with operating conditions of 1020 °C and 180 minutes.

  4. Porous ceramic lamellae for orthodontic ceramic brackets: part I: fabrication and characterization.

    Science.gov (United States)

    Arici, S; Minors, C J; Messer, P F

    1997-07-01

    This study was undertaken to test a new and original orthodontic bracket base, consisting of a porous lamella, which was designed to facilitate removal of ceramic brackets from the enamel surface after treatment. In the phase of the study presented here, porous pellets were made by bonding coarse alumina particles (calcined or fused) with mullite, formed by their reaction with fine quartz particles during firing of the mixture at 1700 degrees C. After machining the pellets to the desired shape, nine types of lamellae with different porosities were attached to the brackets using two different adhesive resins, and also bonded to bovine enamel using the same adhesives. The tensile bond strengths for the assemblies were determined so that the lamellae and the bonding adhesive that might be suitable for clinical application could be selected for testing in vitro in the second phase of the study.

  5. Inorganic glass ceramic slip rings

    Science.gov (United States)

    Glossbrenner, E. W.; Cole, S. R.

    1972-01-01

    Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

  6. Low Thermal Expansion Glass Ceramics

    CERN Document Server

    Bach, Hans

    2005-01-01

    This book appears in the authoritative series reporting the international research and development activities conducted by the Schott group of companies. This series provides an overview of Schott's activities for scientists, engineers, and managers from all branches of industry worldwide in which glasses and glass ceramics are of interest. Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated. This new extended edition describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics. The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions. Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization. Thus g...

  7. Recent progress in ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E.

    1998-09-01

    Both fundamental and practical aspects of ceramic joining are understood well enough for many, if not most, applications requiring moderate strengths at room temperature. This paper argues that the two greatest needs in ceramic joining are for techniques to join buried interfaces by selective heating, and methods for joining ceramics for use at temperatures of 800 to 1,200 C. Heating with microwave radiation or with high-energy electron beams has been used to join buried ceramic interfaces, for example SiC to SiC. Joints with varying levels of strength at temperatures of 600 to 1,000 C have been made using four techniques: (1) transient liquid phase bonding; (2) joining with refractory braze alloys; (3) joining with refractory glass compositions; and (4) joining using preceramic polymers. Joint strengths as high as 550 MPa at 1,000 C have been reported for silicon nitride-silicon nitride bonds tested in four-point flexure.

  8. ceramics by differential scanning calorimetry

    Indian Academy of Sciences (India)

    Administrator

    YbxGd2–xZr2O7 (x = 0, 1, 2) ceramics were pressureless-sintered using ceramic powders acquired by chemical-coprecipitation and calcination methods. Heat capacities of YbxGd2–xZr2O7 were measured with a heat flux-type differential scanning calorimetry in the temperature range of 298–1200 K. At 298 K, the heat.

  9. Development of Ceramic Laser Element

    Science.gov (United States)

    2009-11-24

    macro level (OM) . . . P.7 6. Observation in micro level (SEM, EPMA ) . . . P.9 7. Observation in nano-level (HR-TEM...Transmitted polarized microscopy of the transparent ceramic samples. 10 6.2 By SEM and EPMA (electron probe micro analysis) In order to...Gd:YAG Y Al Nd1%Nd:YAG Fig.11 Electron probe micro analysis ( EPMA ) images of the fabricated transparent ceramic samples. 11 7

  10. Nonlinear fracture of concrete and ceramics

    Science.gov (United States)

    Kobayashi, Albert S.; Du, Jia-Ji; Hawkins, Niel M.; Bradt, Richard C.

    1989-01-01

    The nonlinear fracture process zones in an impacted unnotched concrete bend specimen, a prenotched ceramic bend specimen, and an unnotched ceramic/ceramic composite bend specimen were estimated through hybrid experimental numerical analysis. Aggregate bridging in concrete, particulate bridging in ceramics, and fiber bridging in ceramic/ceramic composite are modeled by Barenblatt-type cohesive zones which are incorporated into the finite-element models of the bend specimens. Both generation and propagation analyses are used to estimate the distribution of crack closure stresses in the nonlinear fracture process zones. The finite-element models are then used to simulate fracture tests consisting of rapid crack propagation in an impacted concrete bend specimen, and stable crack growth and strain softening in a ceramic and ceramic/ceramic composite bend specimens.

  11. Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rajendra Bordia

    2009-07-31

    The goal of this project was to explore and develop a novel class of nanoscale reinforced ceramic coatings for high temperature (600-1000 C) corrosion protection of metallic components in a coal-fired environment. It was focused on developing coatings that are easy to process and low cost. The approach was to use high-yield preceramic polymers loaded with nano-size fillers. The complex interplay of the particles in the polymer, their role in controlling shrinkage and phase evolution during thermal treatment, resulting densification and microstructural evolution, mechanical properties and effectiveness as corrosion protection coatings were investigated. Fe-and Ni-based alloys currently used in coal-fired environments do not possess the requisite corrosion and oxidation resistance for next generation of advanced power systems. One example of this is the power plants that use ultra supercritical steam as the working fluid. The increase in thermal efficiency of the plant and decrease in pollutant emissions are only possible by changing the properties of steam from supercritical to ultra supercritical. However, the conditions, 650 C and 34.5 MPa, are too severe and result in higher rate of corrosion due to higher metal temperatures. Coating the metallic components with ceramics that are resistant to corrosion, oxidation and erosion, is an economical and immediate solution to this problem. Good high temperature corrosion protection ceramic coatings for metallic structures must have a set of properties that are difficult to achieve using established processing techniques. The required properties include ease of coating complex shapes, low processing temperatures, thermal expansion match with metallic structures and good mechanical and chemical properties. Nanoscale reinforced composite coatings in which the matrix is derived from preceramic polymers have the potential to meet these requirements. The research was focused on developing suitable material systems and

  12. Core-shell diodes for particle detectors

    Science.gov (United States)

    Jia, Guobin; Plentz, Jonathan; Höger, Ingmar; Dellith, Jan; Dellith, Andrea; Falk, Fritz

    2016-02-01

    High performance particle detectors are needed for fundamental research in high energy physics in the exploration of the Higgs boson, dark matter, anti-matter, gravitational waves and proof of the standard model, which will extend the understanding of our Universe. Future particle detectors should have ultrahigh radiation hardness, low power consumption, high spatial resolution and fast signal response. Unfortunately, some of these properties are counter-influencing for the conventional silicon drift detectors (SDDs), so that they cannot be optimized simultaneously. In this paper, the main issues of conventional SDDs have been analyzed, and a novel core-shell detector design based on micro- and nano-structures etched into Si-wafers is proposed. It is expected to simultaneously reach ultrahigh radiation hardness, low power consumption, fast signal response and high spatial resolution down to the sub-micrometer range, which will probably meet the requirements for the most powerful particle accelerators in the near future. A prototype core-shell detector was fabricated using modern silicon nanotechnology and the functionality was tested using electron-beam-induced current measurements. Such a high performance detector will open many new applications in extreme radiation environments such as high energy physics, astrophysics, high resolution (bio-) imaging and crystallography, which will push these fields beyond their current boundaries.

  13. Factors controlling crystallization of miserite glass-ceramic.

    Science.gov (United States)

    Muhammed, Fenik K; Moorehead, Robert; van Noort, Richard; Pollington, Sarah

    2015-12-01

    The purpose of this study was to investigate a range of variables affecting the synthesis of a miserite glass-ceramic (GC). Miserite glass was synthesized by the melt quench technique. The crystallization kinetics of the glass were determined using Differential Thermal Analysis (DTA). The glasses were ground with dry ball-milling and then sieved to different particle sizes prior to sintering. These particle sizes were submitted to heat treatment regimes in a high temperature furnace to form the GC. The crystal phases of the GC were analyzed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was used to examine the microstructure of the cerammed glass. XRD analysis confirmed that the predominant crystalline phase of the GC was miserite along with a minor crystalline phase of cristobalite only when the particle size is <20 μm and the heat treatment at 1000°C was carried out for 4h and slowly cooled at the furnace rate. For larger particle sizes and faster cooling rates, a pseudowollastonite crystalline phase was produced. Short sintering times produced either a pseudowollastonite or xonotolite crystalline phase. The current study has shown that particle size and heat treatment schedules are major factors in controlling the synthesis of miserite GC. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. Solid state reaction in alumina nanoparticles/LZSA glass-ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Montedo, O.K. [Universidade do Extremo Sul Catarinense (UESC), SC (Brazil); Oliveira, A.N. de; Raupp-Pereira, F. [Universidade Federal de Santa Catarina (UFSC), SC (Brazil)

    2016-07-01

    Full text: The aim of this work is to present results related to solid state reactions on LZSA glass-ceramic composites containing alumina reinforcement nano-particles. A LZSA (Li2O-ZrO2-SiO2-Al2O3) glass-ceramic has been prepared by sintering of powders and characterized. Composites containing 0 to 77 vol.% of alumina nanoparticles (27-43 nm APS, 35 m2.g-1 SSA) and a 16.9Li2O•5.0ZrO2•65.1SiO2•8.6Al2O3 glass-ceramic matrix have been prepared. X-ray diffractometry studies have been performed in order of investigating the solid state reactions occurring in LZSA-based composites. Results of the XRD patterns have been related to the coefficient of thermal expansion (CTE), Young modulus, and dielectric constant, showing that, in comparison with the glass-ceramic composition, the composites showed a decrease of CTE with the alumina concentration increasing, due to the increasing of beta-spodumeness formation (solid solution of beta-spodumene, Li2O.Al2O3.4-10SiO2). The performance of the glass-ceramic was improved with the alumina nano-particles addition, showing potential of using in the preparation of Low Thermal Co-fired Ceramics (LTCC). (author)

  15. Influential parameters on particle exposure of pedestrians in urban microenvironments

    Science.gov (United States)

    Buonanno, G.; Fuoco, F. C.; Stabile, L.

    2011-03-01

    Exposure to particle concentrations in urban areas was evaluated in several studies since airborne particles are considered to bring about adverse health effects. Transportation modes and urban microenvironments account for the highest contributions to the overall daily particle exposure concentration. In the present study an evaluation of the influential parameters affecting particle exposure of pedestrian in urban areas is reported. Street geometry, traffic mode, wind speed and direction effects were analyzed through an experimental campaign performed in different streets of an Italian town. To this purpose a high-resolution time measurement apparatus was used in order to capture the dynamic of the freshly emitted particles. Number, surface area and mass concentrations and distributions were measured continuously along both the sides of street canyons and avenue canyons during 10-minutes walking routes. The combined effect of street geometry and wind direction may contribute strongly to dilute the fresh particles emitted by vehicles. In particular, street canyons are characterized by lower ventilation phenomena which lead to similar concentration values on both the side of the street. Higher wind speed was found to decrease concentrations in the canyon. Traffic mode also seems to influence exposure concentrations. In particular, submicrometer particle mass concentration was higher as the traffic is more congested; otherwise, coarse fraction dominates mass exposure concentration along street characterized by a more fluent traffic, showing a typical resuspension modality.

  16. Structures and properties of alumina-based ceramic for reconstructive oncology

    Science.gov (United States)

    Grigoriev, M. V.; Kulkov, S. N.

    2016-08-01

    The microstructure of alumina ceramics based on powders with a varying grain size has been investigated. Both commercial alumina powders and those fabricated by denitration of aluminum salts in high-frequency discharge plasma were used. It is shown that the variation of the sintering temperature and morphology of the initial powders of the particles leads to a change of the pore structure of ceramics from pore isolated clusters to a structure consisting of a ceramic skeleton and a large pore space. Changing the type of pore structure occurs at about 50% of porosity. The ceramic pore size distribution is bimodal. Dependencies final density vs initial density are linear; at the same time with increasing temperature, inclination of changes from positive to negative, indicating the change of sealing mechanisms. Extrapolation of these curves showed that they intersect with the values of density of about 2 g/cm3, which indicates the possibility of producing non-shrink ceramics. It is shown that the strength increases with increasing nanocrystalline alumina content in powder mixture. A change in the character the pore structure is accompanied by a sharp decrease in strength, which corresponds to the percolation transition in ceramics. These results showed that it is possible to obtain ceramic materials with the structure and properties similar to natural bone.

  17. Support Services for Ceramic Fiber-Ceramic Matrix Composites

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, J.P.

    2000-06-06

    Structural and functional materials used in solid- and liquid-fueled energy systems are subject to gas- and condensed-phase corrosion and erosion by entrained particles. For a given material, its temperature and the composition of the corrodents determine the corrosion rates, while gas flow conditions and particle aerodynamic diameters determine erosion rates. Because there are several mechanisms by which corrodents deposit on a surface, the corrodent composition depends not only on the composition of the fuel, but also on the temperature of the material and the size range of the particles being deposited. In general, it is difficult to simulate under controlled laboratory conditions all of the possible corrosion and erosion mechanisms to which a material may be exposed in an energy system. Therefore, with funding from the Advanced Research Materials Program, the University of North Dakota Energy & Environmental Research Center (EERC) is coordinating with NCC Engineering and the National Energy Technology Laboratory (NETL) to provide researchers with no-cost opportunities to expose materials in pilot-scale systems to conditions of corrosion and erosion similar to those occurring in commercial power systems. The EERC has two pilot-scale solid-fuel systems available for exposure of materials coupons. The slagging furnace system (SFS) was built under the DOE Combustion 2000 Program as a testing facility for advanced heat exchanger subsystems. It is a 2.5-MMBtu/hr (2.6 x 10{sup 6} kJ/hr) solid-fuel combustion system with exit temperatures of 2700 to 2900 F to ensure that the ash in the main combustor is molten and flowing. Sample coupons may be exposed in the system either within the slagging zone or near the convective air heater at 1800 F (980 C). In addition, a pilot-scale entrained-bed gasifier system known as the transport reactor development unit (TRDU) is available. Also operating at approximately 2.5 MMBtu/hr (2.6 x 10{sup 6} kJ/hr), it is a pressurized unit

  18. Shear bond strength between veneering ceramics and ceria-stabilized zirconia/alumina.

    Science.gov (United States)

    Fischer, Jens; Stawarczyk, Bogna; Sailer, Irena; Hämmerle, Christoph H F

    2010-05-01

    Ceria-stabilized tetragonal ZrO(2)/Al(2)O(3) nanocomposite (Ce-TZP/A) offers superior properties compared to yttria-stabilized zirconia (Y-TZP). However, the bond quality to veneering ceramics has not been investigated. The purpose of this study was to evaluate the bond strength of different veneering ceramics to Ce-TZP/A. Cubes of Ce-TZP/A (NANOZR) (edge length, 10 mm) were layered with veneering ceramics (5 mm in thickness) with or without application of a liner and sheared at the interface. The effect of different surface treatments (polished with 3-mum diamond paste or airborne-particle abraded) was evaluated with 1 veneering ceramic (Cerabien ZR). Shear bond strength of 5 additional veneering ceramics (IPS e.max, Initial ZR, Triceram, Vintage ZR, or VITA VM 9) to polished Ce-TZP/A was measured (n=10). Polished Y-TZP (Hint-ELs ZrO(2) HIP) veneered with 2 ceramics (Cerabien ZR, Vintage ZR) served as the control. Mean shear bond strength values (MPa) were calculated. The means were statistically analyzed with 2-way ANOVA for the effect of surface treatment and liner, 2-way ANOVA for the effect of different veneering ceramic brands and liner, and 3-way ANOVA for the effect of substrate, veneering ceramic brands, and liner, as well as 1-way ANOVA for the differences between the veneering ceramics. A post hoc Scheffé test was used (alpha=.05). The effects of surface treatment (P=.007) or application of liner (Pveneering ceramics showed bond strength values with means ranging between 14.2 +/-1.7 MPa (IPS e.max with liner) and 27.5 +/-4.2 MPa (VITA VM 9). A significant difference was found between the results of shear bond tests with Y-TZP and Ce-TZP/A (P=.022). The application of a liner on Y-TZP had no significant effect. Airborne-particle abrasion is not necessary to enhance the shear bond strength of the evaluated veneering ceramics to Ce-TZP/A. Liners impair the shear bond strength of veneering ceramics to Ce-TZP/A.

  19. Laser and Particle Guiding Micro-Elements for Particle Accelerators

    CERN Document Server

    Plettner, Tomas; Spencer, James; Wisdom, Jeffrey

    2005-01-01

    Laser driven particle accelerators based on the current generation of lasers will require sub-micron control of the laser field as well as precise beam guiding. Hence the fabrication techniques that allow integrating both elements into an accelerator-on-chip format become critical for the success of such particle accelerators. Micromachining technology for silicon has been shown to be one such feasible technology in PAC2003 but with a variety of complications on the laser side. Fortunately, in recent years the fabrication of transparent ceramics has become an interesting technology that could be applied for laser-particle accelerators in several ways. We discuss this area, its advantages such as the range of materials it provides and various ways to implement it followed by some different test examples that have been considered. One important goal of this approach is an integrated system that could avoid the necessity of having to inject either laser or particle pulses into these structures.

  20. Synthesis of highly sinterable Yb: SrF2 nanopowders for transparent ceramics

    Science.gov (United States)

    Li, Weiwei; Huang, Haijun; Mei, Bingchu; Song, Jinghong

    2018-01-01

    In this paper, ytterbium doped strontium fluoride (Yb: SrF2) nanoparticles were synthesized by direct precipitation method. High-speed centrifugation was used to separate high sintering activity of nanopowders from powders with hard aggregated and large size. Using powders at different parts of the centrifugal tube as starting powders, Yb: SrF2 transparent ceramics was fabricated by hot pressed (HP) method for the first time. Effects of morphology and particle size on the sinterability of Yb: SrF2 nanopowders were investigated. The transmittance reached 77% at the wavelength of 1200 nm and pores stilled remained in the ceramics. The spectroscopic and thermal properties of Yb: SrF2 transparent ceramics were also investigated. This paper provides an effective way to obtain well dispersed and high sinterability nanoparticles for SrF2 ceramics sintering.

  1. Study of Direct Bonding Ceramics with Metal Using Sn2La Solder

    Directory of Open Access Journals (Sweden)

    Roman Koleňák

    2015-01-01

    Full Text Available The aim of this research was to study the direct bonding of ceramic materials, mainly Al2O3 and selected metals, with primary attention given to Cu substrate. Soldering was performed with Sn-based solder alloyed with 2% La. We found that the bond formation between Sn2La solder and Al2O3 occurs at the activation of lanthanum phases in solder by ultrasound. Lanthanum in the solder becomes oxidised in air during the soldering process. However, due to ultrasonic activation, the lanthanum particles are distributed to the boundary with ceramic material. A uniformly thin layer containing La, 1.5 µm in thickness, is formed on the boundary with Al2O3 material, ensuring both wetting and joint formation. The shear strength with Al2O3 ceramics is 7.5 MPa. Increased strength to 13.5 MPa was observed with SiC ceramics.

  2. Carbon-ceramic composites from coal tar pitch and clays: application as electrocatalyst support

    Energy Technology Data Exchange (ETDEWEB)

    Montilla, F.; Morallon, E.; Vazquez, J.L.; Alcaniz-Monge, J.; Cazorla-Amoros, D.

    2002-07-01

    Carbon-ceramic composites were prepared and characterised by different techniques (electron microscopy, X-ray microanalysis, X-ray diffraction and cyclic voltammetry). The effect on the conductivity of the thermal treatment temperature of the composites and the structure of the starting ceramic were analysed. The results demonstrate that the layered structure of the clay determines their conductivity. The composites prepared are conductors and the conductivity increases to a maximum with increasing thermal treatment. Platinum was successfully deposited on the carbon-ceramic composite by chemical and electrochemical methods. A better distribution of platinum and smaller particle sizes are obtained by the electrochemical method. The direct electrooxidation of methanol in acid medium was studied on platinum-modified carbon-ceramic electrodes.

  3. Effect of Particle Size and Impact Velocity on Collision Behaviors Between Nano-Scale TiN Particles: MD Simulation.

    Science.gov (United States)

    Yao, Hai-Long; Hu, Xiao-Zhen; Yang, Guan-Jun

    2018-06-01

    Inter-particle bonding formation which determines qualities of nano-scale ceramic coatings is influenced by particle collision behaviors during high velocity collision processes. In this study, collision behaviors between nano-scale TiN particles with different diameters were illuminated by using Molecular Dynamics simulation through controlling impact velocities. Results show that nano-scale TiN particles exhibit three states depending on particle sizes and impact velocities, i.e., bonding, bonding with localized fracturing, and rebounding. These TiN particles states are summarized into a parameter selection map providing an overview of the conditions in terms of particle sizes and velocities. Microstructure results show that localized atoms displacement and partial fracture around the impact region are main reasons for bonding formation of nano-scale ceramic particles, which shows differences from conventional particles refining and amorphization. A relationship between the adhesion energy and the rebound energy is established to understand bonding formation mechanism for nano-scale TiN particle collision. Results show that the energy relationship is depended on the particle sizes and impact velocities, and nano-scale ceramic particles can be bonded together as the adhesion energy being higher than the rebound energy.

  4. Technical Progress Report on Single Pass Flow Through Tests of Ceramic Waste Forms for Plutonium Immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, P; Roberts, S; Bourcier, W

    2000-12-01

    This report updates work on measurements of the dissolution rates of single-phase and multi-phase ceramic waste forms in flow-through reactors at Lawrence Livermore National Laboratory. Previous results were reported in Bourcier (1999). Two types of tests are in progress: (1) tests of baseline pyrochlore-based multiphase ceramics; and (2) tests of single-phase pyrochlore, zirconolite, and brannerite (the three phases that will contain most of the actinides). Tests of the multi-phase material are all being run at 25 C. The single-phase tests are being run at 25, 50, and 75 C. All tests are being performed at ambient pressure. The as-made bulk compositions of the ceramics are given in Table 1. The single pass flow-through test procedure [Knauss, 1986 No.140] allows the powdered ceramic to react with pH buffer solutions traveling upward vertically through the powder. Gentle rocking during the course of the experiment keeps the powder suspended and avoids clumping, and allows the system to behave as a continuously stirred reactor. For each test, a cell is loaded with approximately one gram of the appropriate size fraction of powdered ceramic and reacted with a buffer solution of the desired pH. The buffer solution compositions are given in Table 2. All the ceramics tested were cold pressed and sintered at 1350 C in air, except brannerite, which was sintered at 1350 C in a CO/CO{sub 2} gas mixture. They were then crushed, sieved, rinsed repeatedly in alcohol and distilled water, and the desired particle size fraction collected for the single pass flow-through tests (SPFT). The surface area of the ceramics measured by BET ranged from 0.1-0.35 m{sup 2}/g. The measured surface area values, average particle size, and sample weights for each ceramic test are given in the Appendices.

  5. Influence of air-abrasion on zirconia ceramic bonding using an adhesive composite resin.

    Science.gov (United States)

    Yang, B; Barloi, A; Kern, M

    2010-01-01

    Air-abrasion as bonding conditioning method for zirconia ceramic might compromise the mechanical strength of zirconia restorations. The purpose of this study was to evaluate the influence of surface conditioning parameters, i.e., air-abrasion with reduced pressure or no air-abrasion and priming with adhesive primers on the long-term resin bond strength to zirconia ceramic. Zirconia ceramic disks were polished with 600 grit abrasive paper. Plexiglas tubes filled with composite resin were bonded with RelyX Unicem luting composite resin to the conditioned zirconia disks. Three surface conditions (unconditioned, air-born particle abrasion at 0.05 or 0.25 MPa) and four priming conditions (no priming, priming with Metal/Zirconia Primer, priming with Alloy Primer, priming with Clearfil Ceramic Primer) were tested. Sixteen specimens of each combination were bonded. Subgroups of eight bonded samples were stored in water either for 3 days or 150 days with 37,500 thermocycling. Tensile bond strengths (TBSs) were determined with a universal testing machine at a crosshead speed of 2mm/min. Without priming, RelyX Unicem showed durable bond strength to 0.25 MPa airborne-particle abraded ceramic. When combined with 10-methacryloyloxy-decyl dihydrogenphosphate containing primers, air-abrasion resulted in a durable TBS to zirconia ceramic even at a reduced abrasion pressure. However, combined with Metal/Zirconia Primer air-abrasion did not provide a durable TBS to zirconia ceramic. Using a self-adhesive luting resin composite (RelyX Unicem), air-abrasion at 0.25 MPa or the combination of low pressure air-abrasion and priming with MDP-containing primers seems to be useful to achieve durable long-term bonding to zirconia ceramic.

  6. Nano-Ceramic Coated Plastics

    Science.gov (United States)

    Cho, Junghyun

    2013-01-01

    Plastic products, due to their durability, safety, and low manufacturing cost, are now rapidly replacing cookware items traditionally made of glass and ceramics. Despite this trend, some still prefer relatively expensive and more fragile ceramic/glassware because plastics can deteriorate over time after exposure to foods, which can generate odors, bad appearance, and/or color change. Nano-ceramic coatings can eliminate these drawbacks while still retaining the advantages of the plastic, since the coating only alters the surface of the plastic. The surface coating adds functionality to the plastics such as self-cleaning and disinfectant capabilities that result from a photocatalytic effect of certain ceramic systems. These ceramic coatings can also provide non-stick surfaces and higher temperature capabilities for the base plastics without resorting to ceramic or glass materials. Titanium dioxide (TiO2) and zinc oxide (ZnO) are the candidates for a nano-ceramic coating to deposit on the plastics or plastic films used in cookware and kitchenware. Both are wide-bandgap semiconductors (3.0 to 3.2 eV for TiO2 and 3.2 to 3.3 eV for ZnO), so they exhibit a photocatalytic property under ultraviolet (UV) light. This will lead to decomposition of organic compounds. Decomposed products can be easily washed off by water, so the use of detergents will be minimal. High-crystalline film with large surface area for the reaction is essential to guarantee good photocatalytic performance of these oxides. Low-temperature processing (plastics. One possible way of processing nanoceramic coatings at low temperatures (plastic materials (silicone, Teflon, PET, etc.) that can possess both photocatalytic oxide properties and flexible plastic properties. Processing cost is low and it does not require any expensive equipment investment. Processing can be scalable to current manufacturing infrastructure.

  7. Radiation damage of hollandite in multiphase ceramic waste forms

    Science.gov (United States)

    Clark, Braeden M.; Tumurgoti, Priyatham; Sundaram, S. K.; Amoroso, Jake W.; Marra, James C.; Shutthanandan, Vaithiyalingam; Tang, Ming

    2017-10-01

    Radiation damage was simulated in multiphase titanate-based ceramic waste forms using an ion accelerator to generate high energy alpha particles (He+) and an ion implanter to generate 7 MeV gold (Au3+) particles. X-ray diffraction and transmission electron microscopy were used to characterize the damaged surfaces and nearby regions. Simulated multiphase ceramic waste forms were prepared using two processing methods: spark plasma sintering and melt-processing. Both processing methods produced ceramics with similar phase assemblages consisting of hollandite-, zirconolite/pyrochlore-, and perovskite-type phases. The measured heavy ion (Au3+) penetration depth was less in spark plasma sintered samples than in melt-processed samples. Structural breakdown of the hollandite phase occurred under He+ irradiation indicated by the presence of x-ray diffraction peaks belonging to TiO2, BaTiO5, and other hollandite related phases (Ba2Ti9O20). The composition of the constituent hollandite phase affected the extent of damage induced by Au3+ ions.

  8. Metal-Ceramic composites via “in situ” methods

    Science.gov (United States)

    Florea, R. M.

    2017-08-01

    Several “in situ” methods for obtaining composite materials with ceramic particles were developed in order to overcome some of the inherent problems associated with conventional processes. This paper reviews the obtaining processes of composite materials with a greater emphasis on nitriding and oxidation by directed melting. These obtaining methods provide microstructures with different combinations of metal-ceramic. Metal matrix composites with controlled amounts of dispersed ceramic particles are obtained by “in situ” processes. The composite materials obtained are having different properties by controlling various processing variables such as temperature, time, the reactant phases and the reinforcing material. The properties of the “in situ” obtained materials depend mainly on the matrix and volume fraction of constituent phase. Briefly are reviewed the mechanical properties, hardness mechanisms and possible applications of these composite materials. Nitridation is much more attractive because with the variation of process parameters is obtained a wider range of microstructures and properties. The activation energy for the formation of AlN (A1N ˜ 100 kJ/mole) is smaller than that of oxidation (Al2O3 ˜ 400 kJ/mole) and growth rates (3 × 10-2 gm/cm2/s) are at least three times higher for oxidation.

  9. Investigation of hierarchical structure formation in ceramics with invar effect

    Science.gov (United States)

    Dedova, Elena S.; Shadrin, Vladimir S.; Shutilova, Ekaterina S.; Kulkov, Sergei N.

    2015-10-01

    The structure, phase composition and thermal properties of (Al2O3-20 wt % ZrO2)-ZrW2O8 ceramic composites obtained using nanosized, finely dispersed and coarse-grained initial powders were investigated. On the polished surface of composites homogeneously distributed white particles were observed. The chemical composition of the particles was determined. The phase composition of the composites was represented with corundum, monoclinic ZrO2 and two modifications of ZrW2O8 (tetragonal and cubic) regardless of initial powders morphology. Crystal structure parameters of the material obtained were determined. Linear thermal expansion coefficient values of the composites were determined and compared with those calculated using the mixture rule. The experimental data correlated well with the calculated values of CTE for Al2O3-20 wt % ZrO2 ceramics. The difference in thermal expansion values for composites obtained using initial components with different morphology may be attributed to phase transformations, features of hierarchical structures, internal stresses due to thermal expansion mismatch, which contribute significantly to thermal expansion of the ceramic composites.

  10. Effect of particle size on microstructure and strength of porous spinel ...

    Indian Academy of Sciences (India)

    Abstract. The porous spinel ceramics were prepared from magnesite and bauxite by the pore-forming in situ technique. The characterization of porous spinel ceramics was determined by X-ray diffractometer (XRD), scanning electron microscopy(SEM), mercury porosimetry measurement etc and the effects of particle size on ...

  11. Incorporation of cobalt and nickel metal nano-particles in nano-grain ...

    Indian Academy of Sciences (India)

    Sol-Gel Division, †Glass-Ceramic Coating Division, Central Glass and Ceramic Research Institute, Calcutta 700 032, India. Abstract. Precursor ... films were deposited onto silica glass substrate by the dipping technique. Annealing was ... Nano-grain zirconia; nano particles of cobalt and nickel metals; sol-gel. 1. Introduction.

  12. Ordered ceramic membranes

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M.A.; Hill, C.G. Jr.; Zeltner, W.A.

    1991-10-01

    Ceramic membranes have been formed from colloidal sols coated on porous clay supports. These supported membranes have been characterized in terms of their permeabilities and permselectivities to various aqueous test solutions. The thermal stabilities and pore structures of these membranes have been characterized by preparing unsupported membranes of the correpsonding material and performing N{sub 2} adsorption-desorption and X-ray diffraction studies on these membranes. To date, membranes have been prepared from a variety of oxides, including TiO{sub 2}, SiO{sub 2}, ZrO{sub 2}, and Al{sub 2}O{sub 3}, as well as Zr-, Fe-, and Nb-doped TiO{sub 2}. In many of these membranes pore diameters are less than 2 nm, while in others the pore diameters are between 3 and 5 nm. Procedures for fabricating porous clay supports with reproducible permeabilities for pure water are also discussed. 30 refs., 59 figs., 22 tabs.

  13. Ceramic HEPA Filter Program

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, M A; Bergman, W; Haslam, J; Brown, E P; Sawyer, S; Beaulieu, R; Althouse, P; Meike, A

    2012-04-30

    Potential benefits of ceramic filters in nuclear facilities: (1) Short term benefit for DOE, NRC, and industry - (a) CalPoly HTTU provides unique testing capability to answer questions for DOE - High temperature testing of materials, components, filter, (b) Several DNFSB correspondences and presentations by DNFSB members have highlighted the need for HEPA filter R and D - DNFSB Recommendation 2009-2 highlighted a nuclear facility response to an evaluation basis earthquake followed by a fire (aka shake-n-bake) and CalPoly has capability for a shake-n-bake test; (2) Intermediate term benefit for DOE and industry - (a) Filtration for specialty applications, e.g., explosive applications at Nevada, (b) Spin-off technologies applicable to other commercial industries; and (3) Long term benefit for DOE, NRC, and industry - (a) Across industry, strong desire for better performance filter, (b) Engineering solution to safety problem will improve facility safety and decrease dependence on associated support systems, (c) Large potential life-cycle cost savings, and (d) Facilitates development and deployment of LLNL process innovations to allow continuous ventilation system operation during a fire.

  14. III Advanced Ceramics and Applications Conference

    CERN Document Server

    Gadow, Rainer; Mitic, Vojislav; Obradovic, Nina

    2016-01-01

    This is the Proceedings of III Advanced Ceramics and Applications conference, held in Belgrade, Serbia in 2014. It contains 25 papers on various subjects regarding preparation, characterization and application of advanced ceramic materials.

  15. Reliability of ceramics for heat engine applications

    Science.gov (United States)

    1980-01-01

    The advantages and disadvantages associated with the use of monolithic ceramics in heat engines are discussed. The principle gaps in the state of understanding of ceramic material, failure origins, nondestructive tests as well as life prediction are included.

  16. Panel report on high temperature ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Nolet, T C [ed.

    1979-01-01

    Fundamental research is reported concerning high temperature ceramics for application in turbines, engines, batteries, gasifiers, MHD, fuel cells, heat exchangers, and hot wall combustors. Ceramics microstructure and behavior are included. (FS)

  17. Incorporation of Waste Ceramic Blocks in Structural Ceramics

    Science.gov (United States)

    de Oliveira, Orley Magalhães; das Graças da Silva-Valenzuela, Maria; Andrade, Christiano Gianesi Bastos; Junior, Antonio Hortêncio Munhoz; Valenzuela-Díaz, Francisco Rolando

    In Brazil, Ceramics Industries produce bricks and ceramic tiles in practically all the country. In the southwestern region of Bahia are located some of these industries. A considerable proportion of the material produced do not pass the quality control for not having a uniform visual appearance or have cracks. These burned pieces are generally discarded, resulting in a big quantity of waste. The objective of this work is the characterization of this industrial waste and thus consign them to other industrial applications. Our results demonstrate that the burned waste have potential to be used for incorporation in common clay for structural ceramics, thereby avoiding its disposal in nature and reducing this environmental liability. Experimental bodies were tested with different quantities of waste. The common clay and the burned waste were characterized by XRD, TG/DTA, and SEM. The burned specimens were tested for mechanical strength, water absorption, bulk density, and apparent porosity. An incorporation of 10% of waste furnished the best results.

  18. Unidirectionally Textured CaBi4Ti4O15 Ceramics by the Reactive Templated Grain Growth with an Extrusion

    Science.gov (United States)

    Takeuchi, Tsuguto; Tani, Toshihiko; Saito, Yasuyoshi

    2000-09-01

    Dense CaBi4Ti4O15 (CBT) ceramics with a unique texture were prepared by the reactive templated grain growth (RTGG) method using an extrusion technique. Plate-like Bi4Ti3O12 (BIT) particles, a reactive template for CBT, were mixed with other oxide and carbonate powders and unidirectionally aligned by extrusion. During sintering, oriented CBT grains were formed in situ topotaxially on the oriented BIT particles, and the templated grain growth and their densification eventually fabricated textured CBT ceramics. X-ray diffraction measurements and scanning electron microscopic observations revealed that the plate-like CBT grains were unidirectionally oriented parallel to the extruding direction without uniaxial alignment. Textured CBT ceramics poled in the extruding direction exhibited electromechanical coupling coefficients (k33) and piezoelectric coefficients (d33 and g33) more than two times as large as one of nontextured ceramics with the same composition.

  19. High flow ceramic pot filters.

    Science.gov (United States)

    van Halem, D; van der Laan, H; Soppe, A I A; Heijman, S G J

    2017-11-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6-19 L h-1), but initial LRVs for E. coli of high flow filters was slightly lower than for regular ceramic pot filters. This disadvantage was, however, only temporarily as the clogging in high flow filters had a positive effect on the LRV for E. coli (from below 1 to 2-3 after clogging). Therefore, it can be carefully concluded that regular ceramic pot filters perform better initially, but after clogging, the high flow filters have a higher flow rate as well as a higher LRV for E. coli. To improve the initial performance of new high flow filters, it is recommended to further utilize residence time of the water in the receptacle, since additional E. coli inactivation was observed during overnight storage. Although a relationship was observed between flow rate and LRV of MS2 bacteriophages, both regular and high flow filters were unable to reach over 2 LRV. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Effect of porous glass-ceramic fillers on mechanical properties of light-cured dental resin composites.

    Science.gov (United States)

    Liu, Yong; Tan, Yanni; Lei, Ting; Xiang, Qijun; Han, Yunjuan; Huang, Baiyun

    2009-06-01

    The aim of this work was to study the effect of porous particles on the mechanical properties of dental resin composites. Two kinds of glass-ceramic powders with different calcium-mica to fluorapatite ratio were used as inorganic fillers for light-cured dental resin composites. The glass-ceramic particles were etched to introduce porous structures. The microstructures of particles and the fractography of dental composites were observed using SEM/EDS. The crystalline phases in the fillers were determined by XRD. The specific surface areas (SBET) of porous fillers were tested to show the degree of porosity. 6 samples were prepared for each bending strength test, which was conducted in a Mechanical Testing System. The results show that the bending strength does not vary monotonically with the porosity of the particles. For the glass-ceramics with a high nominal calcium-mica to fluorapatite ratio, the dental resin filled with porous particles has a higher strength than that filled with dense particles; however, for the glass-ceramics with a low nominal calcium-mica to fluorapatite ratio, the dental resin filled with porous particles has a lower strength. The study indicates that the porosity itself is not a decisive factor for strengthening of dental resin composites. The composition of the glass-ceramic particles and the porous structure are also essential factors influencing the mechanical strength. The investigation on the effect of porous glass-ceramic fillers will provide more understanding on the mechanical properties of dental resin composites and will help with the design of new dental restorative materials.

  1. Ceramic cutting tools materials, development and performance

    CERN Document Server

    Whitney, E Dow

    1994-01-01

    Interest in ceramics as a high speed cutting tool material is based primarily on favorable material properties. As a class of materials, ceramics possess high melting points, excellent hardness and good wear resistance. Unlike most metals, hardness levels in ceramics generally remain high at elevated temperatures which means that cutting tip integrity is relatively unaffected at high cutting speeds. Ceramics are also chemically inert against most workmetals.

  2. Emerging Ceramic-based Materials for Dentistry

    Science.gov (United States)

    Denry, I.; Kelly, J.R.

    2014-01-01

    Our goal is to give an overview of a selection of emerging ceramics and issues for dental or biomedical applications, with emphasis on specific challenges associated with full-contour zirconia ceramics, and a brief synopsis on new machinable glass-ceramics and ceramic-based interpenetrating phase composites. Selected fabrication techniques relevant to dental or biomedical applications such as microwave sintering, spark plasma sintering, and additive manufacturing are also reviewed. Where appropriate, the authors have added their opinions and guidance. PMID:25274751

  3. Nd:Y 2O 3 nanopowders for laser ceramics

    Science.gov (United States)

    Kopylov, Yu. L.; Kravchenko, V. B.; Komarov, A. A.; Lebedeva, Z. M.; Shemet, V. V.

    2007-06-01

    Nanopowders of Nd-doped yttrium oxide were obtained by chemical co-precipitation method using nitrate salts solutions and different precipitant agents - urea, ammonium carbonate and oxalic acid. Precursor and oxide particles agglomeration, particle form, particle size and specific surface area depend critically upon experimental conditions. Plates and rods were formed with hydroxycarbonate and oxalates precipitation correspondingly, whereas hydroxynitrates gave more uniform spherical particles' shapes. Calcination at 900-1200 °C gave oxide powders with specific area in the range 15-50 m 2/g. High energy ball milling was used to decrease grain agglomeration. Powders with around 100 nm size were used to prepare pellets by slip casting into porous moulds using PMMA or PAA additives to reduce viscosity of the slurries with high powder contents. The pellets density around 0.48-0.52 of the theoretical value was obtained. Vacuum sintering of the pellets at 1700-1800 °C gave transparent ceramic samples with grain size between 10 and 50 μm. The most serious defects in the ceramics are closed pores which reduce their transparency.

  4. Polygamous particles

    OpenAIRE

    Wu, Kun-Ta; Feng, Lang; Sha, Ruojie; Dreyfus, Rémi; Grosberg, Alexander Y.; Seeman, Nadrian C.; Chaikin, Paul M.

    2012-01-01

    DNA is increasingly used as an important tool in programming the self-assembly of micrometer- and nanometer-scale particles. This is largely due to the highly specific thermoreversible interaction of cDNA strands, which, when placed on different particles, have been used to bind precise pairs in aggregates and crystals. However, DNA functionalized particles will only reach their true potential for particle assembly when each particle can address and bind to many different kinds of particles. ...

  5. Durability of feldspathic veneering ceramic on glass-infiltrated alumina ceramics after long-term thermocycling.

    Science.gov (United States)

    Mesquita, A M M; Ozcan, M; Souza, R O A; Kojima, A N; Nishioka, R S; Kimpara, E T; Bottino, M A

    2010-01-01

    This study compared the bond strength durability of a feldspathic veneering ceramic to glass-infiltrated reinforced ceramics in dry and aged conditions. Disc shaped (thickness: 4 mm, diameter: 4 mm) of glass-infiltrated alumina (In-Ceram Alumina) and glass-infiltrated alumina reinforced by zirconia (In-Ceram Zirconia) core ceramic specimens (N=48, N=12 per groups) were constructed according to the manufacturers' recommendations. Veneering ceramic (VITA VM7) was fired onto the core ceramics using a mold. The core-veneering ceramic assemblies were randomly divided into two conditions and tested either immediately after specimen preparation (Dry) or following 30000 thermocycling (5-55 ºC±1; dwell time: 30 seconds). Shear bond strength test was performed in a universal testing machine (cross-head speed: 1 mm/min). Failure modes were analyzed using optical microscope (x20). The bond strength data (MPa) were analyzed using ANOVA (α=0.05). Thermocycling did not decrease the bond strength results for both In-Ceram Alumina (30.6±8.2 MPa; P=0.2053) and In-Ceram zirconia (32.6±9 MPa; P=0.3987) core ceramic-feldspathic veneering ceramic combinations when compared to non-aged conditions (28.1±6.4 MPa, 29.7±7.3 MPa, respectively). There were also no significant differences between adhesion of the veneering ceramic to either In-Ceram Alumina or In-Ceram Zirconia ceramics (P=0.3289). Failure types were predominantly a mixture of adhesive failure between the veneering and the core ceramic together with cohesive fracture of the veneering ceramic. Long-term thermocycling aging conditions did not impair the adhesion of the veneering ceramic to the glass-infiltrated alumina core ceramics tested.

  6. Vacuum chamber for containing particle beams

    Science.gov (United States)

    Harvey, A.

    1985-11-26

    A vacuum chamber for containing a charged particle beam in a rapidly changing magnetic environment comprises a ceramic pipe with conducting strips oriented along the longitudinal axis of the pipe and with circumferential conducting bands oriented perpendicular to the longitudinal axis but joined with a single longitudinal electrical connection. When both strips and bands are on the outside of the ceramic pipe, insulated from each other, a high-resistance conductive layer such as nickel can be coated on the inside of the pipe.

  7. Ablation Resistant Zirconium and Hafnium Ceramics

    Science.gov (United States)

    Bull, Jeffrey (Inventor); White, Michael J. (Inventor); Kaufman, Larry (Inventor)

    1998-01-01

    High temperature ablation resistant ceramic composites have been made. These ceramics are composites of zirconium diboride and zirconium carbide with silicon carbide, hafnium diboride and hafnium carbide with silicon carbide and ceramic composites which contain mixed diborides and/or carbides of zirconium and hafnium. along with silicon carbide.

  8. Ceramic microfabrication by rapid prototyping process chains

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    fast and inexpensive supply for polymer master models and a ceramic shaping method that enables the replication of the RP model into multiple ceramic materials within a short time. (Knitter et al 1999). 2. Rapid prototyping process chains. The manufacturing of ceramic microparts presented here set out with the 3D-CAD ...

  9. Instructional Resources. The Significance of Form: Ceramics.

    Science.gov (United States)

    Zawatsky, Carole; And Others

    1989-01-01

    Presents four lesson plans designed to teach K-12 students about ceramics and the artists using the medium. Each lesson is centered around one ceramic piece: (1) "Wall Clock," by the Chantilly Porcelain Factory; (2) "Poppy Vase," by Adelaide Robineau; (3) "Laughing Eyes," by Pablo Picasso; and (4) "Ceramic Drum Jar," by Tsayutitsa. (GEA)

  10. Evaluation of mechanical properties and structural changes of ceramic filter materials for hot gas cleaning under simulated process conditions

    OpenAIRE

    Westerheide, R.; Wehd, C. von der; Rehak, P.; Adler, J.

    2002-01-01

    In the combined cycle technology for advanced coal fired power plants at high temperatures up to 950 °C the removal of particles from the stream to the gas turbine is carried out with ceramic filter elements. These elements consist often of siliceous bonded coarse grained silicon carbide. A stable long term operation of the filter elements leads to the demands on good resistance towards thermal, mechanical and chemical loading. The structure of ceramic filter elements consists usually of a hi...

  11. Dynamic properties of ceramic materials

    Energy Technology Data Exchange (ETDEWEB)

    Grady, D.E. [Sandia National Labs., Albuquerque, NM (United States). Experimental Impact Physics Dept.

    1995-02-01

    The present study offers new data and analysis on the transient shock strength and equation-of-state properties of ceramics. Various dynamic data on nine high strength ceramics are provided with wave profile measurements, through velocity interferometry techniques, the principal observable. Compressive failure in the shock wave front, with emphasis on brittle versus ductile mechanisms of deformation, is examined in some detail. Extensive spall strength data are provided and related to the theoretical spall strength, and to energy-based theories of the spall process. Failure waves, as a mechanism of deformation in the transient shock process, are examined. Strength and equation-of-state analysis of shock data on silicon carbide, boron carbide, tungsten carbide, silicon dioxide and aluminum nitride is presented with particular emphasis on phase transition properties for the latter two. Wave profile measurements on selected ceramics are investigated for evidence of rate sensitive elastic precursor decay in the shock front failure process.

  12. [Effect of a chemical primer on the bond strength of a zirconia ceramic with self-adhesive resin cement].

    Science.gov (United States)

    Zhang, Hong; Jing, Ye; Nie, Rongrong; Meng, Xiangfeng

    2015-10-01

    To evaluate the bond strength and durability of a self-adhesive resin cement with a zirconia ceramic pretreated by a zirconia primer. Zirconia ceramic (Vita Inceram YZ) plates with a thickness of 2.5 mm were fired, polished, and then cleaned. Half of the polished ceramic plates were sandblasted with 50 μm alumina particles at 0.3 MPa for 20 s. The surface compound weight ratios were measured via X-ray fluorescence microscopy. The polished and sandblasted ceramic plates were directly bonded with self-adhesive resin cement (Biscem) or were pretreated by a zirconia primer (Z Primer Plus) before bonding with Biscem. The specimens of each test group were divided into two subgroups (n=10) and subjected to the shear test after 0 and 10,000 thermal cycles. The data were analyzed via three-way ANOVA. After air abrasion, 8.27% weight ratio of alumina attached to the zirconia surface. Compared with air abrasion, primer treatment more significantly improved the primary resin bond strength of the zirconia ceramic. The primary resin bond strength of the zirconia ceramic with no primer treatment was not affected by thermocycling (P>0.05). However, the primary resin bond strength of the zirconia ceramic with primer treatment was significantly decreased by thermocycling (Pzirconia ceramics. However, the bond interface of the primer is not stable and rapidly degraded during thermocycling.

  13. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; N. Nagabhushana

    2003-08-07

    In the present quarter, experiments are presented on ceramic/metal interactions of Zirconia/ Ni-B-Si system and with a thin Ti coating deposited on zirconia surface. Existing facilities were modified for evaluation of environmental assisted slow crack growth and creep in flexural mode. Processing of perovskites of LSC, LSF and LSCF composition were continued for evaluation of mechanical properties as a function of environment. These studies in parallel to those on the LSFCO composition is expect to yield important information on questions such as the role of cation segregation and the stability of the perovskite structure on crack initiation vs. crack growth. Studies have been continued on the La{sub 1-x}Sr{sub x}FeO{sub 3-d} composition using neutron diffraction and TGA studies. A transition from p-type to n-type of conductor was observed at relative low pO{sub 2}, at which the majority carriers changed from the holes to electrons because of the valence state decreases in Fe due to the further loss of oxygen. Investigation on the thermodynamic properties of the membrane materials are continued to develop a complete model for the membrane transport. Data obtained at 850 C show that the stoichiometry in La{sub 0.2}Sr{sub 0.8}Fe{sub 0.8}Cr{sub 0.2}O{sub 3-x} vary from {approx}2.85 to 2.6 over the pressure range studied. From the stoichiometry a lower limit of 2.6 corresponding to the reduction of all Fe{sup 4+} to Fe{sup 3+} and no reduction of Cr{sup 3+} is expected.

  14. Proton conducting cerate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Coffey, G.W.; Pederson, L.R.; Armstrong, T.R.; Bates, J.L.; Weber, W.J. [Pacific Northwest Lab., Richland, WA (United States)

    1995-08-01

    Cerate perovskites of the general formula AM{sub x}Ce{sub 1-x}O{sub 3-{delta}}, where A = Sr or Ba and where M = Gd, Nd, Y, Yb or other rare earth dopant, are known to conduct a protonic current. Such materials may be useful as the electrolyte in a solid oxide fuel cell operating at intermediate temperatures, as an electrochemical hydrogen separation membrane, or as a hydrogen sensor. Conduction mechanisms in these materials were evaluated using dc cyclic voltammetry and mass spectrometry, allowing currents and activation energies for proton, electron, and oxygen ion contributions to the total current to be determined. For SrYb{sub 0.05}Ce{sub 0.95}O{sub 3-{delta}}, one of the best and most environmentally stable compositions, proton conduction followed two different mechanisms: a low temperature process, characterized by an activation energy of 0.42{+-}0.04 eV, and a high temperature process, characterized by an activation energy of 1.38{+-}0.13 eV. It is believed that the low temperature process is dominated by grain boundary conduction while bulk conduction is responsible for the high temperature process. The activation energy for oxygen ion conduction (0.97{+-}0.10 eV) agrees well with other oxygen conductors, while that for electronic conduction, 0.90{+-}0.09 eV, is affected by a temperature-dependent electron carrier concentration. Evaluated by direct measurement of mass flux through a dense ceramic with an applied dc field, oxygen ions were determined to be the majority charge carrier except at the lowest temperatures, followed by electrons and then protons.

  15. Ceramic catalyst materials

    Energy Technology Data Exchange (ETDEWEB)

    Sault, A.G.; Gardner, T.J. [Sandia National Laboratories, Albuquerque, NM (United States); Hanprasopwattanna, A.; Reardon, J.; Datye, A.K. [Univ. of New Mexico, Albuquerque, NM (United States)

    1995-08-01

    Hydrous titanium oxide (HTO) ion-exchange materials show great potential as ceramic catalyst supports due to an inherently high ion-exchange capacity which allows facile loading of catalytically active transition metal ions, and an ability to be cast as thin films on virtually any substrate. By coating titania and HTO materials onto inexpensive, high surface area substrates such as silica and alumina, the economics of using these materials is greatly improved, particularly for the HTO materials, which are substantially more expensive in the bulk form than other oxide supports. In addition, the development of thin film forms of these materials allows the catalytic and mechanical properties of the final catalyst formulation to be separately engineered. In order to fully realize the potential of thin film forms of titania and HTO, improved methods for the deposition and characterization of titania and HTO films on high surface area substrates are being developed. By varying deposition procedures, titania film thickness and substrate coverage can be varied from the submonolayer range to multilayer thicknesses on both silica and alumina. HTO films can also be formed, but the quality and reproducibility of these films is not nearly as good as for pure titania films. The films are characterized using a combination of isopropanol dehydration rate measurements, point of zero charge (PZC) measurements, BET surface area, transmission electron microscopy (TEM), and elemental analysis. In order to assess the effects of changes in film morphology on catalytic activity, the films are being loaded with MoO{sub 3} using either incipient wetness impregnation or ion-exchange of heptamolybdate anions followed by calcining. The MoO{sub 3} is then sulfided to form MOS{sub 2}, and tested for catalytic activity using pyrene hydrogenation and dibenzothiophene (DBT) desulfurization, model reactions that simulate reactions occurring during coal liquefaction.

  16. Laser-driven particle acceleration towards radiobiology and medicine

    CERN Document Server

    2016-01-01

    This book deals with the new method of laser-driven acceleration for application to radiation biophysics and medicine. It provides multidisciplinary contributions from world leading scientist in order to assess the state of the art of innovative tools for radiation biology research and medical applications of ionizing radiation. The book contains insightful contributions on highly topical aspects of spatio-temporal radiation biophysics, evolving over several orders of magnitude, typically from femtosecond and sub-micrometer scales. Particular attention is devoted to the emerging technology of laser-driven particle accelerators and their applicatio to spatio-temporal radiation biology and medical physics, customization of non-conventional and selective radiotherapy and optimized radioprotection protocols.

  17. NANOSTRUCTURED CERAMICS AND COMPOSITES FOR REFRACTORY APPLICATIONS IN COAL GASIFICATION

    Energy Technology Data Exchange (ETDEWEB)

    Paul Brown

    2005-01-31

    A class of ceramics, capable of exhibiting low coefficients of thermal expansion and catalytic properties was investigated. Investigations were directed towards nanoengineering of NZP ceramics and NZP-based composites by chemical means by controlling their compositions and processing variables. NaZr{sub 2}(PO{sub 4}){sub 3} (NZP) was synthesized by combining water-soluble precursors leading to the precipitation of a gel that was dried, calcined, pressed into pellets, then fired at 850 C. Without chemical additives, the resulting ceramic comprised pores ranging in size from approximately 25 to 50 nm and a surface area of about 30m{sup 2}/g. Hydroxyapatite, which has a needle-like morphology, was mechanically mixed with the calcined gel to template NZP crystallization. What resulted was a coarsening of the pore structure and a decrease in surface area. When copper nitrate was added to the solution during synthesis, the resulting ceramic underwent shrinkage upon firing as well as an increase in strength. HAp and copper additions combined resulted in 40% volume shrinkage and a doubling of the tensile strength to 16MPa. A very different type of porosity was achieved when silica was partly substituted for phosphorous in the NZP structure. Na{sub 3}Zr{sub 2}(Si{sub 2}P)O{sub 12} (NASCION) was synthesized in the same manner as NZP, but the fired ceramic possessed a reticulated pore structure comprising large cavities ranging in size from 5 to 50 {micro}m. The NASCION ceramic either shrank or expanded upon firing depending on when the silica was added during synthesis. When the silica precursor (amorphous, precipitated silica) was added before the calcining step, the pressed pellets expanded during firing, whereas they shrank when the silica was added after the gel was calcined. The observed dilation increased with increasing calcining temperature and particle size, up to 26%. The contraction of the ceramic when fired increased with increasing calcining temperature and a

  18. Calibration of aerosol instruments in a wide particle size range

    Energy Technology Data Exchange (ETDEWEB)

    Yli-Ojanpera, J.

    2012-07-01

    Aerosol particles have an important role in many scientific and technological issues. Aerosol particle measurements are widely applied for example in clean room technology, in atmospheric measurements and in studying the Particulate Matter (PM) emissions from traffic and industry. This thesis concentrates on developing new aerosol instrumentation both for measurement and calibration purposes. On the measurement side, the driving force has been the urgent need for instruments that have a fast time response and are able to measure nanoparticles with reasonable accuracy. In this respect, the nanoparticle resolution of the Electrical Low Pressure Impactor (ELPI, Dekati Ltd.) was improved by designing, manufacturing and implementing a new impactor stage (cutpoint 16.7 nm) to the ELPI cascade impactor. The new impactor stage divides the particle size range measured by the filter stage (7-30 nm) between the new stage and the filter stage. As a result, the nanoparticle resolution of the ELPI was improved. This made the device more suitable, for example, for vehicle engine emission measurements. The new stage is currently being sold as a part of the new ELPI+ instrument, which is an improved version of the original ELPI. On the calibration side, the main driving force behind aerosol instrument development has been the lack of calibration standards available for calibrating the number concentration responses of the instruments in the sub-micrometer size range. In this size range, the most common method to calibrate an instrument is to use a differential mobility analyzer (DMA), for obtaining monodisperse particles for the calibration, and a Faraday cup aerosol electrometer (FCAE), for measuring the reference number concentration. Even though, in principle, the DMA allows size selection up to 1 {mu}m in diameter, the calibrations are usually limited to particles below 100 nm because of the multiple charging of particles. To solve this problem, a new concept for realizing a

  19. Stereolithography: A new method for processing dental ceramics by additive computer-aided manufacturing.

    Science.gov (United States)

    Dehurtevent, Marion; Robberecht, Lieven; Hornez, Jean-Christophe; Thuault, Anthony; Deveaux, Etienne; Béhin, Pascal

    2017-05-01

    The aim of this study was to compare the physical and mechanical properties of stereolithography (SLA)- manufactured alumina ceramics of different composition to those of subtractive- manufactured ceramics and to produce suitable dental crown frameworks. The physical and mechanical properties of a control and six experimental SLA ceramics prepared from slurries with small (S) and large (L) particles (0.46±0.03 and 1.56±0.04μm, respectively) and three dry matter contents (70%, 75%, 80%) were evaluated by dynamic rheometry, hydrostatic weighing, three3-point flexural strength measurements, and Weibull analyses, and by the micrometrics measurement of shrinkage ratio before and after the heat treatments. S75 was the only small particle slurry with a significantly higher viscosity than L70. The viscosity of the S80 slurry made it impossible to take rheological measurements. The viscosities of the S75 and S80 slurries caused deformations in the printed layers during SLA manufacturing and were excluded from further consideration. SLA samples with low dry matter content had significantly lower and densityflexural strengths. Only SLA samples with a large particle size and high dry matter content (L75 and L80) were similar in density and flexural strength to the subtractive- manufactured samples. The 95% confidence intervals of the Weibull modulus of the L80 ceramic were higher (no overlap fraction) than those of the L75 ceramic and were similar to the control (overlap fraction). The Weibull characteristics of L80 ceramic were higher than those of L75 ceramic and the control. SLA can be used to process suitable crown frameworks but shows results in anisotropic shrinkage. The hH High particle size and dry matter content of the L80 slurry allowed made it possible to produce a reliable ceramic by SLA manufacturing with an anisotropic shrinkage, and a density, and flexural strength similar to those of a subtractive-manufactured ceramic. SLA allowed made it possible to build

  20. Ceramic components for MHD electrode

    Science.gov (United States)

    Marchant, D.D.

    A ceramic component which exhibits electrical conductivity down to near room temperatures has the formula: Hf/sub x/In/sub y/A/sub z/O/sub 2/ where x = 0.1 to 0.4, y = 0.3 to 0.6, z = 0.1 to 0.4 and A is a lanthanide rare earth or yttrium. The component is suitable for use in the fabrication of MHD electrodes or as the current leadout portion of a composite electrode with other ceramic components.

  1. Ceramic veneers with minimum preparation

    Science.gov (United States)

    da Cunha, Leonardo Fernandes; Reis, Rachelle; Santana, Lino; Romanini, Jose Carlos; Carvalho, Ricardo Marins; Furuse, Adilson Yoshio

    2013-01-01

    The aim of this article is to describe the possibility of improving dental esthetics with low-thickness glass ceramics without major tooth preparation for patients with small to moderate anterior dental wear and little discoloration. For this purpose, a carefully defined treatment planning and a good communication between the clinician and the dental technician helped to maximize enamel preservation, and offered a good treatment option. Moreover, besides restoring esthetics, the restorative treatment also improved the function of the anterior guidance. It can be concluded that the conservative use of minimum thickness ceramic laminate veneers may provide satisfactory esthetic outcomes while preserving the dental structure. PMID:24932126

  2. Grain growth kinetics of textured-BaTiO3 ceramics

    Indian Academy of Sciences (India)

    Administrator

    based ceramics (Kimura and. Yoshida 2006; Shoji et al 2009), which properly attributed to the round matrix grain morphology of BT particles. Figure 5(a–f) shows XRD patterns of BT-textured ce- ramics sintered at 1250 °C for different soaking times.

  3. Grain-size effects on thermal properties of BaTiO3 ceramics

    Indian Academy of Sciences (India)

    Administrator

    fine non-agglomerated powder with a narrow particle size distribution and an appropriate densification method to minimize the grain growth are required. In our experi- ment, the raw BaTiO3 powder with the grain sizes of 10 and 100 nm were synthesized by chemical processing. (Li et al 2002). Dense BaTiO3 ceramics with ...

  4. A Brief Research Review for Improvement Methods the Wettability between Ceramic Reinforcement Particulate and Aluminium Matrix Composites

    Science.gov (United States)

    Razzaq, Alaa Mohammed; Majid, Dayang Laila Abang Abdul; Ishak, M. R.; B, Uday M.

    2017-05-01

    The development of new methods for addition fine ceramic powders to Al aluminium alloy melts, which would lead to more uniform distribution and effective incorporation of the reinforcement particles into the aluminium matrix alloy. Recently the materials engineering research has moved to composite materials from monolithic, adapting to the global need for lightweight, low cost, quality, and high performance advanced materials. Among the different methods, stir casting is one of the simplest ways of making aluminium matrix composites. However, it suffers from poor distribution and combination of the reinforcement ceramic particles in the metal matrix. These problems become significantly effect to reduce reinforcement size, more agglomeration and tendency with less wettability for the ceramic particles in the melt process. Many researchers have carried out different studies on the wettability between the metal matrix and dispersion phase, which includes added wettability agents, fluxes, preheating the reinforcement particles, coating the reinforcement particles, and use composting techniques. The enhancement of wettability of ceramic particles by the molten matrix alloy and the reinforcement particles distribution improvement in the solidified matrix is the main objective for many studies that will be discussed in this paper.

  5. Bond strength of the porcelain repair system to all-ceramic copings and porcelain.

    Science.gov (United States)

    Lee, Sang J; Cheong, Chan Wook; Wright, Robert F; Chang, Brian M

    2014-02-01

    The purpose of this study was to investigate the shear bond strength of the porcelain repair system on alumina and zirconia core ceramics, comparing this strength with that of veneering porcelain. Veneering ceramic (n = 12), alumina core (n = 24), and zirconia core (n = 24) blocks measuring 10 × 5 × 5 mm(3) were fabricated. Veneering ceramic blocks were used as the control. Alumina and zirconia core blocks were divided into 2 groups (n = 12 each), and a slot (2 × 2 × 4 mm(3)) filled with veneering ceramics was prepared into one of the alumina and zirconia core groups (n = 12). Followed by surface treatments of micro-abrasion with 30 μm alumina particles, etching with 35% phosphoric acid and silane primer and bond, composite resin blocks (2 × 2 × 2 mm(3)) were built up and light polymerized onto the treated surfaces by 3 configurations: (a) composite blocks bonded onto veneering ceramic surface alone, (b) composite blocks bonded onto alumina core or zirconia core surfaces, (c) a 50% surface area of the composite blocks bonded to veneering ceramics and the other 50% surface area of the composite blocks to alumina core or zirconia core surfaces. The shear bond strength of the composite to each specimen was tested by a universal testing machine at a 0.5 mm/min crosshead speed. The shear bond strength was analyzed by unpaired t-tests for within the configuration groups and ANOVA for among the different configuration groups. When the mean shear bond strength was compared within groups of the same configuration, there were no statistically significant differences. Comparison of the shear bond strength among groups of different configurations revealed statistically significant differences. The mean shear bond strength of composite onto 100% veneering ceramic surface and composite onto 50% veneering 50% all-ceramic cores was statistically higher than that of composite onto 100% all-ceramic cores; however, the differences of the shear bond strength of composite bonded

  6. Alumina matrix ceramic-nickel composites formed by centrifugal slip casting

    Directory of Open Access Journals (Sweden)

    Justyna Zygmuntowicz

    2015-12-01

    Full Text Available The paper is focused on the possibility of fabricating the alumina matrix ceramic-nickel composites with gradient concentration of metal particles. Centrifugal slip casting method was chosen for the composite fabrication. This method allows fabrication of the graded distribution of nickel particles in the hollow cylinder composites. The horizontal rotation axis was applied. The samples were characterized by XRD, SEM and quantitative description of the microstructure. The macroscopic as well as SEM observations of the prepared composites confirmed the gradient concentration of Ni particles in the composite materials. The application of the centrifugal slip casting method allows for the graded distribution of metal particles in the samples.

  7. Laser and Particle Guiding Micro-Elements for Particle Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Plettner, T.; Gaume, R.; Wisdom, J.; /Stanford U., Phys. Dept.; Spencer, J.; /SLAC

    2005-06-07

    Laser driven particle accelerators require sub-micron control of the laser field as well as precise electron-beam guiding so fabrication techniques that allow integrating both elements into an accelerator-on-chip format become critical for the success of such next generation machines. Micromachining technology for silicon has been shown to be one such feasible technology in PAC2003[1] but with a variety of complications on the laser side. However, fabrication of transparent ceramics has become an interesting technology that could be applied for laser-particle accelerators in several ways. We discuss the advantages such as the range of materials available and ways to implement them followed by some different test examples we been considered. One important goal is an integrated system that avoids having to inject either laser or particle pulses into these structures.

  8. Cellular structure of the healthy and keratoconic human cornea imaged in-vivo with sub-micrometer axial resolution OCT(Conference Presentation)

    Science.gov (United States)

    Bizheva, Kostadinka; Tan, Bingyao; Mason, Erik; Carter, Kirsten; Haines, Lacey; Sorbara, Luigina

    2017-02-01

    Keratoconus causes progressive morphological changes in the corneal epithelium (EPI), Bowman's membrane (BM) and anterior stroma. However, it is still not well understood if KC originates in the corneal epithelium and propagates to the anterior stroma through disruptions of the BM, or vice versa. In this study we used a sub-micrometer axial resolution OCT system to image in-vivo the cellular structure of the EPI layer and the fibrous structure of the BM and the anterior stroma in mild to advanced keratoconics, as well as healthy subjects. The imaging study was approved by the University of Waterloo Human Research Ethics Committee. The OCT system operates in the 800 nm spectral region at 34 kHz image acquisition rate and provides 0.95 um axial and < 2 um lateral resolution in corneal tissue, which is sufficient to visualize the cellular structure of the corneal epithelium and the fibrous structure of the BM. In some subjects, localized thinning and thickening of the EPI layer was observed, while there was no visible damage to the BM or anterior stroma. In other subjects, localized breakage of the stromal collagen fibrils was observed with no significant morphological changes of the corneal EPI.

  9. Fabrication and characterization of fully ceramic microencapsulated fuels

    Energy Technology Data Exchange (ETDEWEB)

    Terrani, K.A., E-mail: kurt.terrani@gmail.com [Fuel Cycle and Isotopes Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Kiggans, J.O.; Katoh, Y. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Shimoda, K. [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Montgomery, F.C.; Armstrong, B.L.; Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Hinoki, T. [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Hunn, J.D. [Fuel Cycle and Isotopes Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Snead, L.L. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2012-07-15

    The current generation of fully ceramic microencapsulated fuels, consisting of Tristructural Isotropic fuel particles embedded in a silicon carbide matrix, is fabricated by hot pressing. Matrix powder feedstock is comprised of alumina-yttria additives thoroughly mixed with silicon carbide nanopowder using polyethyleneimine as a dispersing agent. Fuel compacts are fabricated by hot pressing the powder-fuel particle mixture at a temperature of 1800-1900 Degree-Sign C using compaction pressures of 10-20 MPa. Detailed microstructural characterization of the final fuel compacts shows that oxide additives are limited in extent and are distributed uniformly at silicon carbide grain boundaries, at triple joints between silicon carbide grains, and at the fuel particle-matrix interface.

  10. Fabrication and characterization of fully ceramic microencapsulated fuels

    Science.gov (United States)

    Terrani, K. A.; Kiggans, J. O.; Katoh, Y.; Shimoda, K.; Montgomery, F. C.; Armstrong, B. L.; Parish, C. M.; Hinoki, T.; Hunn, J. D.; Snead, L. L.

    2012-07-01

    The current generation of fully ceramic microencapsulated fuels, consisting of Tristructural Isotropic fuel particles embedded in a silicon carbide matrix, is fabricated by hot pressing. Matrix powder feedstock is comprised of alumina-yttria additives thoroughly mixed with silicon carbide nanopowder using polyethyleneimine as a dispersing agent. Fuel compacts are fabricated by hot pressing the powder-fuel particle mixture at a temperature of 1800-1900 °C using compaction pressures of 10-20 MPa. Detailed microstructural characterization of the final fuel compacts shows that oxide additives are limited in extent and are distributed uniformly at silicon carbide grain boundaries, at triple joints between silicon carbide grains, and at the fuel particle-matrix interface.

  11. [Study of relationship between powder-size gradation and mechanical properties of Zirconia toughened glass infiltrated nanometer-ceramic composite powder].

    Science.gov (United States)

    Chai, Feng; Xu, Ling; Liao, Yun-mao; Chao, Yong-lie

    2003-07-01

    The fabrication of all-ceramic dental restorations is challenged by ceramics' relatively low flexural strength and intrinsic poor resistance to fracture. This paper aimed at investigating the relationships between powder-size gradation and mechanical properties of Zirconia toughened glass infiltrated nanometer-ceramic composite (Al(2)O(3)-nZrO(2)). Al(2)O(3)-nZrO(2) ceramics powder (W) was processed by combination methods of chemical co-precipitation and ball milling with addition of different powder-sized ZrO(2). Field-emission scanning electron microscopy was used to determine the particle size distribution and characterize the particle morphology of powders. The matrix compacts were made by slip-casting technique and sintered to 1,450 degrees C and flexural strength and the fracture toughness of them were measured. 1. The particle distribution of Al(2)O(3)-nZrO(2) ceramics powder ranges from 0.02 - 3.5 micro m and among them the superfine particles almost accounted for 20%. 2. The ceramic matrix samples with addition of nZrO(2) (W) showed much higher flexural strength (115.434 +/- 5.319) MPa and fracture toughness (2.04 +/- 0.10) MPa m(1/2) than those of pure Al(2)O(3) ceramics (62.763 +/- 7.220 MPa; 1.16 +/- 0.02 MPa m(1/2)). The particle size of additive ZrO(2) may impose influences on mechanical properties of Al(2)O(3)-nZrO(2) ceramics matrix. Good homogeneity and reasonable powder-size gradation of ceramic powder can improve the mechanical properties of material.

  12. Fabrication and characterization of biomimetic ceramic/polymer composite materials for dental restoration.

    Science.gov (United States)

    Petrini, Morena; Ferrante, Maurizio; Su, Bo

    2013-04-01

    Conventional dental composites with randomly dispersed inorganic particles within a polymer matrix fail to recapitulate the aligned and anisotropic structure of the dentin and enamel. The aim of the study was to produce a biomimetic composite consisting of a ceramic preform with graded and continuously aligned open pores, infiltrated with epoxy resin. The freeze casting technique was used to obtain the hierarchically structured architecture of the ceramic preforms. Optical and scanning electron microscopy (SEM) and differential thermal analysis and thermogravimetry (TG-DTA) were used to characterize the samples. Three point bending test and compression test were also performed. All analysis confirmed that the biomimetic composite was characterized by a multi-level hierarchical structure along the freezing direction. In the bottom layers close to the cooling plate (up to 2mm thick), a randomly packed ceramic with closed pores were formed, which resulted in incomplete infiltration with resin and resultant poor mechanical propertiesof the composite. Above 2mm, all ceramic samples showed an aligned structure with an increasing lamellae spacing (wavelength) and a decreasing wall thickness. Mechanical tests showed that the properties of the composites made from ceramic preforms above 2mm from cooling plate are similar to those of the dentin. The fabrication processing reported in this work offers a viable route for the fabrication of biomimetic composites, which could be potentially used in a range of dental restorations to compete with the current dental composites and ceramics. Copyright © 2012 Academy of Dental Materials. All rights reserved.

  13. Industrial ceramics in Spain

    Directory of Open Access Journals (Sweden)

    Regueiro, M.

    2000-02-01

    Full Text Available The Spanish ceramic industry has experienced a amazing growth in the last four years. Such expansion has affected all sector, but has been particularly noteworthy in those directly related to construction: tiles. glazes, bricks and roof tiles. A combination of an extraordinary exporting effort, together with a record figure in new housing projects (415 000 houses in 1999, are responsible for such outburst. Other sectors, such as refractories have undergone significant growths due to the high rate of steel production increase, also in historical record figures (15m t in 1999. All this sectors doubled altogether the growing rate of their main European competitors. Raw material production has had an even more effervescent trend, almost doubling 1995 production. Such dynamic growth has been associated to a remarkable quality increase and to an unparalleled technological innovation process.

    La industria española de la cerámica ha experimentado un notable crecimiento en los últimos cuatro años; expansión que ha alcanzado a todos los sectores, pero que ha sido especialmente notable en los mas directamente asociados a la construcción: revestimientos, esmaltes, tejas y ladrillos. La combinación de un extraordinario esfuerzo exportador unido a las cifras récord en la viviendas iniciadas, 415 000 en 1999, justifican este auge. Otros sectores como refractarios han experimentado crecimientos significativos ante el ritmo elevado en la producción de acero, que alcanzó asimismo un récord histórico, 15 Mt en 1999. Para el conjunto de estos sectores el ritmo de crecimiento ha duplicado el de los principales competidores europeos. La producción de materias primas han experimentado un dinamismo aún mas elevado duplicándose prácticamente las cifras respecto a 1995. Este crecimiento ha estado asociado a un notable incremento en la calidad y en los procesos de innovación tecnológica.

  14. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; N. Nagabhushana; Thomas W. Eagar; Harold R. Larson; Raymundo Arroyave; X.-D Zhou; Y.-W. Shin; H.U. Anderson; Nigel Browning; Alan Jacobson; C.A. Mims

    2003-11-01

    The present quarterly report describes some of the initial studies on newer compositions and also includes newer approaches to address various materials issues such as in metal-ceramic sealing. The current quarter's research has also focused on developing a comprehensive reliability model for predicting the structural behavior of the membranes in realistic conditions. In parallel to industry provided compositions, models membranes have been evaluated in varying environment. Of importance is the behavior of flaws and generation of new flaws aiding in fracture. Fracture mechanics parameters such as crack tip stresses are generated to characterize the influence of environment. Room temperature slow crack growth studies have also been initiated in industry provided compositions. The electrical conductivity and defect chemistry of an A site deficient compound (La{sub 0.55}Sr{sub 0.35}FeO{sub 3}) was studied. A higher conductivity was observed for La{sub 0.55}Sr{sub 0.35}FeO{sub 3} than that of La{sub 0.60}Sr{sub 0.40}FeO{sub 3} and La{sub 0.80}Sr{sub 0.20}FeO{sub 3}. Defect chemistry analysis showed that it was primarily contributed by a higher carrier concentration in La{sub 0.55}Sr{sub 0.35}FeO{sub 3}. Moreover, the ability for oxygen vacancy generation is much higher in La{sub 0.55}Sr{sub 0.35}FeO{sub 3} as well, which indicates a lower bonding strength between Fe-O and a possible higher catalytic activity for La{sub 0.55}Sr{sub 0.35}FeO{sub 3}. The program continued to investigate the thermodynamic properties (stability and phase separation behavior) and total conductivity of prototype membrane materials. The data are needed together with the kinetic information to develop a complete model for the membrane transport. Previous report listed initial measurements on a sample of La{sub 0.2}Sr{sub 0.8}Fe{sub 0.55}Ti{sub 0.45}O{sub 3-x} prepared in-house by Praxair. Subsequently, a second sample of powder from a larger batch of sample were characterized and compared

  15. Casting of particle-based hollow shapes

    Science.gov (United States)

    Menchhofer, Paul

    1995-01-01

    A method for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product.

  16. Deformation Behavior of Sub-micron and Micron Sized Alumina Particles in Compression.

    Energy Technology Data Exchange (ETDEWEB)

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay; Mook, William; Boyce, Brad; Kotula, Paul Gabriel; McKenzie, Bonnie Beth; Bufford, Daniel Charles; Hall, Aaron Christopher.

    2014-09-01

    The ability to integrate ceramics with other materials has been limited due to high temperature (>800degC) ceramic processing. Recently, researchers demonstrated a novel process , aerosol deposition (AD), to fabricate ceramic films at room temperature (RT). In this process, sub - micro n sized ceramic particles are accelerated by pressurized gas, impacted on the substrate, plastically deformed, and form a dense film under vacuum. This AD process eliminates high temperature processing thereby enabling new coatings and device integration, in which ceramics can be deposited on metals, plastics, and glass. However, k nowledge in fundamental mechanisms for ceramic particle s to deform and form a dense ceramic film is still needed and is essential in advancing this novel RT technology. In this wo rk, a combination of experimentation and atomistic simulation was used to determine the deformation behavior of sub - micron sized ceramic particle s ; this is the first fundamental step needed to explain coating formation in the AD process . High purity, singl e crystal, alpha alumina particles with nominal size s of 0.3 um and 3.0 um were examined. Particle characterization, using transmission electron microscopy (TEM ), showed that the 0.3 u m particles were relatively defect - free single crystals whereas 3.0 u m p articles were highly defective single crystals or particles contained low angle grain boundaries. Sub - micron sized Al 2 O 3 particles exhibited ductile failure in compression. In situ compression experiments showed 0.3um particles deformed plastically, fractured, and became polycrystalline. Moreover, dislocation activit y was observed within the se particles during compression . These sub - micron sized Al 2 O 3 particles exhibited large accum ulated strain (2 - 3 times those of micron - sized particles) before first fracture. I n agreement with the findings from experimentation , a tomistic simulation s of nano - Al 2 O 3 particles showed dislocation slip and

  17. Evaluation of clayey masses compositions starting from the residue incorporation of the red ceramic industry to obtain tubular ceramic membranes; Avaliacao das composicoes de massas argilosas a partir da incorporacao de residuo da industria de ceramica vermelha na obtencao de membranas ceramicas tubulares

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Adriano Lima da; Chaves, Alexsandra Cristina; Luna, Carlos Bruno Barreto; Neves, Gelmires de Araujo; Lira, Helio de Lucena, E-mail: adrianolimadasilva@hotmail.com, E-mail: alexsandra.chaves@ifap.edu.br, E-mail: brunobarretodemaufcg@hotmail.com, E-mail: gelmires@ufcg.edu.br, E-mail: helio@ufcg.edu.br [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

    2017-01-15

    The inappropriate residue disposal of red ceramic industry is very high. Nowadays, one of the major challenges is the investigation of processes to obtain alternative materials, enabling the use of these residues to manufacture new materials. This work's objective is to study clayey masses' compositions starting from the residue incorporation of the red ceramic industry to be used in tubular ceramic membranes. Two compositions of ceramic masses were established, composition A (50% of residue) and composition B (70% of residue). Granulometric analysis of the ceramic masses presented an average size of particles, what indicates membranes in the microfiltration scale. Another observed factor is related to the increase of residue amount, what favored a decrease in the ceramic mass' plasticity. A rise in the apparent porosity was also observed, probably because of a possible growing in the bigger pores numbers, due to the sintering high temperature and the elevation of residue quantity itself. (author)

  18. Doubled-ended ceramic thyratron

    CERN Multimedia

    1974-01-01

    The double-ended ceramic thyratron CX 1171 B, with its coaxial voltage divider for the SPS. Such a switch, paralleled by three ignitrons in series forms the "thyragnitron" arrangement, and can switch 10 kA, 25 ms pulses, with very fast rise times.

  19. Optical scattering in glass ceramics

    NARCIS (Netherlands)

    Mattarelli, M.; Montagna, M.; Verrocchio, P.

    2008-01-01

    The transparency of glass ceramics with nanocrystals is generally higher than that expected from the theory of Rayleigh scattering. We attribute this ultra-transparency to the spatial correlation of the nanoparticles. The structure factor is calculated for a simple model system, the random

  20. Gas Separations using Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Paul KT Liu

    2005-01-13

    This project has been oriented toward the development of a commercially viable ceramic membrane for high temperature gas separations. A technically and commercially viable high temperature gas separation membrane and process has been developed under this project. The lab and field tests have demonstrated the operational stability, both performance and material, of the gas separation thin film, deposited upon the ceramic membrane developed. This performance reliability is built upon the ceramic membrane developed under this project as a substrate for elevated temperature operation. A comprehensive product development approach has been taken to produce an economically viable ceramic substrate, gas selective thin film and the module required to house the innovative membranes for the elevated temperature operation. Field tests have been performed to demonstrate the technical and commercial viability for (i) energy and water recovery from boiler flue gases, and (ii) hydrogen recovery from refinery waste streams using the membrane/module product developed under this project. Active commercializations effort teaming with key industrial OEMs and end users is currently underway for these applications. In addition, the gas separation membrane developed under this project has demonstrated its economical viability for the CO2 removal from subquality natural gas and landfill gas, although performance stability at the elevated temperature remains to be confirmed in the field.

  1. Energy storage properties and relaxor behavior of lead-free Ba1-xSm2x/3Zr0.15Ti0.85O3 ceramics.

    Science.gov (United States)

    Sun, Zheng; Li, Lingxia; Yu, Shihui; Kang, Xinyu; Chen, Siliang

    2017-10-24

    Lead-free Ba1-xSm2x/3Zr0.15Ti0.85O3 (BSZT) ceramics were synthesized by a solid state reaction route. The microstructure, dielectric relaxor behavior and energy storage properties of BSZT ceramics were studied. The growth of grain size was suppressed with the increase of Sm addition and kept in the submicrometer scale. Successive substitution of Sm(3+) for Ba(2+) disrupted the long-range dipole and promoted the increase of polar nano-region (PNR) size, resulting in the enhanced degree of relaxor behavior. The increasing PNR size also lead to the slimmer hysteresis loops and improved the energy storage efficiency. Furthermore, high saturated polarization (Pmax) and low remnant polarization (Pr) were obtained due to the formation of defect dipoles, which facilitated the switch of PNRs and contributed to the enhancement of energy storage density. The x = 0.003 sample was found to exhibit a higher energy storage density of 1.15 J cm(-3) and an energy storage efficiency of 92%. The result revealed that the BSZT ceramics may be a good candidate for energy storage application.

  2. Effects of surface-finishing protocols on the roughness, color change, and translucency of different ceramic systems.

    Science.gov (United States)

    Akar, Gülcan Coşkun; Pekkan, Gürel; Çal, Ebru; Eskitaşçıoğlu, Gürcan; Özcan, Mutlu

    2014-08-01

    Surface-finishing protocols have a mechanical impact on ceramic surfaces that could eventually affect surface topography and light scattering. An optimum protocol is needed to avoid damaging the optical properties of ceramics. The purpose of this study was to determine the effects of different surface-finishing protocols on the surface roughness, color change, and translucency of ceramic and metal ceramic restorations. Standardized disk-shaped specimens (1.5 × 10 mm, n=128) were fabricated from 3 different ceramic core materials (aluminum oxide [Al2O3]-AL, zirconium oxide [ZrO2]-ZR, lithium disilicate [Li2Si2O5]-LIT), veneered (V) with dentin ceramics (n=32 per group), and placed in the following groups: ALV, ZRV, and LITV. The metal ceramic group acted as the control (n=32). Four different surface-finishing methods were tested. Airborne-particle abrasion with 50 μm Al2O3, polishing with adjustment kit, polishing with adjustment kit plus diamond polishing paste, and autoglazing (n=8 subgroup) were applied on the veneering ceramics. The specimens were analyzed with a profilometer for surface roughness, and color change and translucency were measured with a clinical spectrophotometer. Statistical analyses were performed with 1-way ANOVA and the Tukey honest significant difference tests (α=.05). Specimens treated with the airborne particle abrasion method showed significantly higher mean profilometer for surface roughness values in all groups (P.05). With the diamond polishing paste method, lower surface roughness values were achieved in the ZRV and metal ceramic groups acted as the control groups. Different surface-finishing methods affected the color change of the ceramic systems, except for ZRV. Surface-finishing protocols significantly affected the translucency values of the ALV, LITV, and metal ceramic groups (P<.05). No single surface-finishing protocol can be recommended to obtain the smoothest surface and the least color change without affecting

  3. Effect of laser welding on the titanium ceramic tensile bond strength

    Directory of Open Access Journals (Sweden)

    Rodrigo Galo

    2011-08-01

    Full Text Available Titanium reacts strongly with elements, mainly oxygen at high temperature. The high temperature of titanium laser welding modifies the surface, and may interfere on the metal-ceramic tensile bond strength. OBJECTIVE: The influence of laser welding on the titanium-ceramic bonding has not yet been established. The purpose of this in vitro study was to analyze the influence of laser welding applied to commercially pure titanium (CpTi substructure on the bond strength of commercial ceramic. The influence of airborne particle abrasion (Al2O3 conditions was also studied. MATERIAL AND METHODS: Forty CpTi cylindrical rods (3 mm x 60 mm were cast and divided into 2 groups: with laser welding (L and without laser welding (WL. Each group was divided in 4 subgroups, according to the size of the particles used in airborne particle abrasion: A - Al2O3 (250 µm; B - Al2O3 (180 µm; C - Al2O3 (110 µm; D - Al2O3 (50 µm. Ceramic rings were fused around the CpTi rods. Specimens were invested and their tensile strength was measured at fracture with a universal testing machine at a crosshead speed of 2.0 mm/min and 200 kgf load cell. Statistical analysis was carried out with analysis of variance and compared using the independent t test (p<0.05. RESULTS: Significant differences were found among all subgroups (p<0.05. The highest and the lowest bond strength means were recorded in subgroups WLC (52.62 MPa and LD (24.02 MPa, respectively. CONCLUSION: Airborne particle abrasion yielded significantly lower bond strength as the Al2O3 particle size decreased. Mechanical retention decreased in the laser-welded specimens, i.e. the metal-ceramic tensile bond strength was lower.

  4. Solid-particle erosion of aluminum/particulate ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Goretta, K.C.; Wu, W.; Routbort, J.L. (Argonne National Lab., IL (USA)); Rohatgi, P.K. (Wisconsin Univ., Milwaukee, WI (USA))

    1990-06-01

    Impact erosion of 2014 aluminum, 2014 aluminum + 20 vol % particulate silicon carbide, and 2014 aluminum + 20 vol % particulate aluminum oxide has been studied at room temperature. The alloys were tested in the as-received and heat-treated conditions. Experiments were conducted with aluminum oxide abrasive in vacuum in a slinger-type apparatus over a range of abrasive size, velocity, and angle of impact. Erosion rates were influenced by reinforcement and heat treatment. Reduced ductility, both overall and local, attributed to reinforcement or heat treatment, caused, under most conditions, more rapid erosion of the composites. The data suggest that erosion rate can be minimized by proper microstructural control, involving reducing reinforcement segregation and the amount of intermetallic compounds. 37 refs., 7 figs.

  5. Ceramic matrix composite article and process of fabricating a ceramic matrix composite article

    Science.gov (United States)

    Cairo, Ronald Robert; DiMascio, Paul Stephen; Parolini, Jason Robert

    2016-01-12

    A ceramic matrix composite article and a process of fabricating a ceramic matrix composite are disclosed. The ceramic matrix composite article includes a matrix distribution pattern formed by a manifold and ceramic matrix composite plies laid up on the matrix distribution pattern, includes the manifold, or a combination thereof. The manifold includes one or more matrix distribution channels operably connected to a delivery interface, the delivery interface configured for providing matrix material to one or more of the ceramic matrix composite plies. The process includes providing the manifold, forming the matrix distribution pattern by transporting the matrix material through the manifold, and contacting the ceramic matrix composite plies with the matrix material.

  6. Mechanical properties of ceramic-polymer nanocomposites

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available Nano crystalline powders of Barium Sodium Niobate (BNN with the composition Ba3–2x Na4+x R Nb10 O30 with (R stands for rare earth = 0, x = 0 have been prepared by conventional ceramic technique. Barium Sodium Niobate can form a wide range of solid solutions, incorporating rare earth and alkali, alkaline earth elements with different compositions. The powder belonged to tungsten bronze type structure with tetragonal symmetry and lattice constants a = b = 1.2421 nm and c = 0.3903 nm. XRD (X-ray Diffraction SEM (Scanning Electron Microscope and AFM (Atomic Force Microscope studies revealed that the particle size is in the nanometer range. Composites are prepared by mixing powders of BNN with polystyrene at different volume fractions of the BNN. Melt mixing technique is carried out in a Brabender Plasticoder at a rotor speed of 60 rpm (rotations per minute for composite preparation. Mechanical properties such as stress-strain behavior, Young’s modulus, tensile strength, strain at break etc. are evaluated. Addition of filler enhances the mechanical properties of the polymer such as Young’s modulus and tensile strength. The composites showed the trend of perfect adhesion between the filler and the polymer. The filler particles are distributed relatively uniform fashion in all composites and the particles are almost spherical in shape with irregular boundaries. To explore more carefully the degree of interfacial adhesion between the two phases, the results are analyzed by using models featuring adhesion parameter. The experimental results are compared with theoretical predictions.

  7. Ceramic superconductor/metal composite materials employing the superconducting proximity effect

    Science.gov (United States)

    Holcomb, Matthew J.

    2002-01-01

    Superconducting composite materials having particles of superconducting material disposed in a metal matrix material with a high electron-boson coupling coefficient (.lambda.). The superconducting particles can comprise any type of superconductor including Laves phase materials, Chevrel phase materials, A15 compounds, and perovskite cuprate ceramics. The particles preferably have dimensions of about 10-500 nanometers. The particles preferably have dimensions larger than the superconducting coherence length of the superconducting material. The metal matrix material has a .lambda. greater than 0.2, preferably the .lambda. is much higher than 0.2. The metal matrix material is a good proximity superconductor due to its high .lambda.. When cooled, the superconductor particles cause the metal matrix material to become superconducting due to the proximity effect. In cases where the particles and the metal matrix material are chemically incompatible (i.e., reactive in a way that destroys superconductivity), the particles are provided with a thin protective metal coating. The coating is chemically compatible with the particles and metal matrix material. High Temperature Superconducting (HTS) cuprate ceramic particles are reactive and therefore require a coating of a noble metal resistant to oxidation (e.g., silver, gold). The proximity effect extends through the metal coating. With certain superconductors, non-noble metals can be used for the coating.

  8. Recent progress on synthesis of ceramics core/shell nanostructures

    Directory of Open Access Journals (Sweden)

    Vladimir V. Srdić

    2013-06-01

    Full Text Available Thin surface layers on fine particles were found to substantially change their functionalities and properties, such as chemical reactivity, thermal stability, catalytic activity, dispersibility, or optical, magnetic and electronic properties. Because of that, the core/shell nanostructures have opened up research opportunities in almost all areas of science and engineering, including medicine, catalysis, biotechnology, chemistry, optics, electronics, energy storage, etc. Immense efforts have been implied to produce and investigate different core/shell systems, and thereby, various synthesis techniques have been developed. In this review, we report adetailed overview of different synthesis techniques used for preparation of various ceramics core/shell nanostructures with tunable size and tailored structure.

  9. Consolidated waste forms: glass marbles and ceramic pellets

    Energy Technology Data Exchange (ETDEWEB)

    Treat, R.L.; Rusin, J.M.

    1982-05-01

    Glass marbles and ceramic pellets have been developed at Pacific Northwest Laboratory as part of the multibarrier concept for immobilizing high-level radioactive waste. These consolidated waste forms served as substrates for the application of various inert coatings and as ideal-sized particles for encapsulation in protective matrices. Marble and pellet formulations were based on existing defense wastes at Savannah River Plant and proposed commercial wastes. To produce marbles, glass is poured from a melter in a continuous stream into a marble-making device. Marbles were produced at PNL on a vibratory marble machine at rates as high as 60 kg/h. Other marble-making concepts were also investigated. The marble process, including a lead-encapsulation step, was judged as one of the more feasible processes for immobilizing high-level wastes. To produce ceramic pellets, a series of processing steps are required, which include: spray calcining - to dry liquid wastes to a powder; disc pelletizing - to convert waste powders to spherical pellets; sintering - to densify pellets and cause desired crystal formation. These processing steps are quite complex, and thereby render the ceramic pellet process as one of the least feasible processes for immobilizing high-level wastes.

  10. Use of basaltic waste as red ceramic raw material

    Directory of Open Access Journals (Sweden)

    T. M. Mendes

    Full Text Available Abstract Nowadays, environmental codes restrict the emission of particulate matters, which result in these residues being collected by plant filters. This basaltic waste came from construction aggregate plants located in the Metropolitan Region of Londrina (State of Paraná, Brazil. Initially, the basaltic waste was submitted to sieving (< 75 μm and the powder obtained was characterized in terms of density and particle size distribution. The plasticity of ceramic mass containing 0%, 10%, 20%, 30%, 40% and 50% of basaltic waste was measured by Atterberg method. The chemical composition of ceramic formulations containing 0% and 20% of basaltic waste was determined by X-ray fluorescence. The prismatic samples were molded by extrusion and fired at 850 °C. The specimens were also tested to determine density, water absorption, drying and firing shrinkages, flexural strength, and Young's modulus. Microstructure evaluation was conducted by scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry. Basaltic powder has similar physical and chemical characteristics when compared to other raw materials, and contributes to ceramic processing by reducing drying and firing shrinkage. Mechanical performance of mixtures containing basaltic powder is equivalent to mixtures without waste. Microstructural aspects such as pore size distribution were modified by basaltic powder; albite phase related to basaltic powder was identified by X-ray diffraction.

  11. Translucency of dental ceramics with different thicknesses.

    Science.gov (United States)

    Wang, Fu; Takahashi, Hidekazu; Iwasaki, Naohiko

    2013-07-01

    The increased use of esthetic restorations requires an improved understanding of the translucent characteristics of ceramic materials. Ceramic translucency has been considered to be dependent on composition and thickness, but less information is available about the translucent characteristics of these materials, especially at different thicknesses. The purpose of this study was to investigate the relationship between translucency and the thickness of different dental ceramics. Six disk-shaped specimens of 8 glass ceramics (IPS e.max Press HO, MO, LT, HT, IPS e.max CAD LT, MO, AvanteZ Dentin, and Trans) and 5 specimens of 5 zirconia ceramics (Cercon Base, Zenotec Zr Bridge, Lava Standard, Lava Standard FS3, and Lava Plus High Translucency) were prepared following the manufacturers' instructions and ground to a predetermined thickness with a grinding machine. A spectrophotometer was used to measure the translucency parameters (TP) of the glass ceramics, which ranged from 2.0 to 0.6 mm, and of the zirconia ceramics, which ranged from 1.0 to 0.4 mm. The relationship between the thickness and TP of each material was evaluated using a regression analysis (α=.05). The TP values of the glass ceramics ranged from 2.2 to 25.3 and the zirconia ceramics from 5.5 to 15.1. There was an increase in the TP with a decrease in thickness, but the amount of change was material dependent. An exponential relationship with statistical significance (Pceramics and zirconia ceramics. The translucency of dental ceramics was significantly influenced by both material and thickness. The translucency of all materials increased exponentially as the thickness decreased. All of the zirconia ceramics evaluated in the present study showed some degree of translucency, which was less sensitive to thickness compared to that of the glass ceramics. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  12. Detection of nano- and micro-sized particles in routine biopsy material - pilot study.

    Science.gov (United States)

    Dvorackova, Jana; Bielnikova, Hana; Kukutschova, Jana; Peikertova, Pavlina; Filip, Peter; Zelenik, Karol; Kominek, Pavel; Uvirova, Magdalena; Pradna, Jana; Cermakova, Zuzana; Dvoracek, Igor

    2015-03-01

    Nanotechnology is receiving enormous funding. Very little however is known about the health dangers of this technology so far. Chronic tonsillitis is one of a number of diseases called idiopathic. Among other factors, the tonsils are exposed to suspended particles in inhaled air including nano particles. The objective of this study was to detect and evaluate metallic particles in human tonsil tissue diagnosed with chronic tonsillitis and in amniotic fluid as a comparison. . Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) was used for identification of solid particles in a total of 64 samples of routinely analyzed biopsy and cytologic material. Almost all samples were found to contain solid particles of various metals. The most frequent, regardless of diagnosis, were iron, chromium, nickel and aluminium. The size, determined using SEM, varied from around 500 nm to 25 µm. The majority formed aggregates of several micrometers in size but there were a significant number of smaller (sub-micrometer or nano-sized) particles present. The incidence of metallic particles was similar in child and adult tissues. The difference was in composition: the presence of several metals in adults was due to occupational exposure. The presence of metallic particles in pathologically altered tissues may signal an alternative causation of some diseases. The ethiopathogenic explanation of these diseases associated with the presence of nano-sized particles in the organism has emerged into a new field of pathology, nanopathology.

  13. Thermal, mechanical and electrical properties of polyanaline based ceramic nano-composites

    Science.gov (United States)

    Sohail, M.; Khan, M. S.; Khattak, N. S.

    2016-08-01

    Micro/nanohybrid materials have vast applications due to their great potentialities in the field of nanoscience and nanotechnology. Herein we report an investigation on the fabrication and physicochemical characterization of ceramic (Fe0.01La0.01Al0.5Zn0.98O) and hybrid ceramic-polyaniline nano-composits. Ceramic nano-particles were prepared by sol-gel technique while optimizing the molar ratios of the constituent's metal nitrates. The prepared inorganic particles were then embedded in the polymer matrix via one-pot blending method. The prepared ceramic particles and their composites with polyaniline were analysed under FT- IR, SEM and TGA. The presence of some chemical species was observed at the interface of the compositing materials. TGA analysis showed the thermal stability of the composite material. Frequency dependent dielectric properties were analysed and it was found that conducting polyaniline has an additional effect on the electrical behaviour of the composite. Rheology study showed enhanced mechanical properties of composite material as compared to their constituting counterparts.

  14. Advanced ceramic materials for next-generation nuclear applications

    Science.gov (United States)

    Marra, John

    2011-10-01

    The nuclear industry is at the eye of a 'perfect storm' with fuel oil and natural gas prices near record highs, worldwide energy demands increasing at an alarming rate, and increased concerns about greenhouse gas (GHG) emissions that have caused many to look negatively at long-term use of fossil fuels. This convergence of factors has led to a growing interest in revitalization of the nuclear power industry within the United States and across the globe. Many are surprised to learn that nuclear power provides approximately 20% of the electrical power in the US and approximately 16% of the world-wide electric power. With the above factors in mind, world-wide over 130 new reactor projects are being considered with approximately 25 new permit applications in the US. Materials have long played a very important role in the nuclear industry with applications throughout the entire fuel cycle; from fuel fabrication to waste stabilization. As the international community begins to look at advanced reactor systems and fuel cycles that minimize waste and increase proliferation resistance, materials will play an even larger role. Many of the advanced reactor concepts being evaluated operate at high-temperature requiring the use of durable, heat-resistant materials. Advanced metallic and ceramic fuels are being investigated for a variety of Generation IV reactor concepts. These include the traditional TRISO-coated particles, advanced alloy fuels for 'deep-burn' applications, as well as advanced inert-matrix fuels. In order to minimize wastes and legacy materials, a number of fuel reprocessing operations are being investigated. Advanced materials continue to provide a vital contribution in 'closing the fuel cycle' by stabilization of associated low-level and high-level wastes in highly durable cements, ceramics, and glasses. Beyond this fission energy application, fusion energy will demand advanced materials capable of withstanding the extreme environments of high

  15. Ceramic fiber reinforced glass-ceramic matrix composite

    Science.gov (United States)

    Bansal, Narottam P. (Inventor)

    1993-01-01

    A slurry of BSAS glass powders is cast into tapes which are cut to predetermined sizes. Mats of continuous chemical vapor deposition (CVD)-SiC fibers are alternately stacked with these matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite which is heated to burn out organic constituents. The remaining interim material is then hot-pressed to form a BSAS glass-ceramic fiber-reinforced composite.

  16. Particle detectors

    CERN Multimedia

    CERN. Geneva

    1999-01-01

    Introduction, interaction of radiation with matter measurement of momentum of charged particles, of energy of e/gamma, hadrons, identification of particles. Design of HEP detectors. Principle of operation and performance of tracking sub-detectors, calorimeters and muon system.

  17. Hot Superplastic Powder Forging for Transparent nanocrystalline Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, W. Roger

    2006-05-22

    The program explored a completely new, economical method of manufacturing nanocrystalline ceramics, Hot Superplastic Powder Forging (HSPF). The goal of the work was the development of nanocrystalline/low porosity optically transparent zirconia/alumina. The high optical transparency should result from lack of grain boundary scattering since grains will be smaller than one tenth the wavelength of light and from elimination of porosity. An important technological potential for this process is manufacturing of envelopes for high-pressure sodium vapor lamps. The technique for fabricating monolithic nanocrystalline material does not begin with powder whose particle diameter is <100 nm as is commonly done. Instead it begins with powder whose particle diameter is on the order of 10-100 microns but contains nanocrystalline crystallites <<100 nm. Spherical particles are quenched from a melt and heat treated to achieve the desired microstructure. Under a moderate pressure within a die or a mold at temperatures of 1100C to 1300C densification is by plastic flow of superplastic particles. A nanocrystalline microstructure results, though some features are greater than 100nm. It was found, for instance, that in the fully dense Al2O3-ZrO2 eutectic specimens that a bicontinuous microstructure exists containing <100 nm ZrO2 particles in a matrix of Al2O3 grains extending over 1-2 microns. Crystallization, growth, phase development and creep during hot pressing and forging were studied for several compositions and so provided some details on development of polycrystalline microstructure from heating quenched ceramics.

  18. Evaluation of Monolithic Ceramics and Ceramic Thermal Barrier Coatings for Diesel Engine Applications

    National Research Council Canada - National Science Library

    Swab, Jeffrey J

    2001-01-01

    The Metals and Ceramics Research Branch (MCRB) of the Weapons and Materials Research Directorate is providing ceramic material characterization and evaluation to the Tank Automotive Research, Development, and Engineering Center (TARDEC...

  19. Optical properties of base dentin ceramics for all-ceramic restorations.

    OpenAIRE

    Shiraishi, Takanobu; Wood, Duncan J.; Shinozaki, Nobuya; Van Noort, Richard

    2011-01-01

    The study was conducted to compare the optical parameters of VM7(®) M-shade base dentin ceramics (VITA, Germany) for all ceramic restorations to the chemical composition across the 3D-MASTER(®) shade system.

  20. Separators - Technology review: Ceramic based separators for secondary batteries

    Science.gov (United States)

    Nestler, Tina; Schmid, Robert; Münchgesang, Wolfram; Bazhenov, Vasilii; Schilm, Jochen; Leisegang, Tilmann; Meyer, Dirk C.

    2014-06-01

    Besides a continuous increase of the worldwide use of electricity, the electric energy storage technology market is a growing sector. At the latest since the German energy transition ("Energiewende") was announced, technological solutions for the storage of renewable energy have been intensively studied. Storage technologies in various forms are commercially available. A widespread technology is the electrochemical cell. Here the cost per kWh, e. g. determined by energy density, production process and cycle life, is of main interest. Commonly, an electrochemical cell consists of an anode and a cathode that are separated by an ion permeable or ion conductive membrane - the separator - as one of the main components. Many applications use polymeric separators whose pores are filled with liquid electrolyte, providing high power densities. However, problems arise from different failure mechanisms during cell operation, which can affect the integrity and functionality of these separators. In the case of excessive heating or mechanical damage, the polymeric separators become an incalculable security risk. Furthermore, the growth of metallic dendrites between the electrodes leads to unwanted short circuits. In order to minimize these risks, temperature stable and non-flammable ceramic particles can be added, forming so-called composite separators. Full ceramic separators, in turn, are currently commercially used only for high-temperature operation systems, due to their comparably low ion conductivity at room temperature. However, as security and lifetime demands increase, these materials turn into focus also for future room temperature applications. Hence, growing research effort is being spent on the improvement of the ion conductivity of these ceramic solid electrolyte materials, acting as separator and electrolyte at the same time. Starting with a short overview of available separator technologies and the separator market, this review focuses on ceramic-based separators

  1. Effect of silica fiber on the mechanical and chemical behavior of alumina-based ceramic core material

    Directory of Open Access Journals (Sweden)

    Weiguo Jiang

    2017-12-01

    Full Text Available In order to improve the chemical leachability, the alumina-based ceramic core material with the silica fiber was injected and sintered at 1100 °C/4 h, 1200 °C/4 h, 1300 °C/4 h and 1400 °C/4 h, respectively. The micrographs of ceramic core materials at sintered and leached state were characterized by scanning electron microscopy (SEM. The phase composition of ceramic core material after sintering and the leaching product after leaching were detected by X-ray diffraction (XRD. The porosity, room temperature bend strength, creep property at elevated temperature and the leaching rate in aqueous caustic solution were studied. The experimental results show that the ceramic core material with silica fiber obtain a fair balance between mechanical and chemical properties at sintering of 1300 °C/4 h. Specifically, the leach rate of ceramic core material with silica fiber is increased apparently. High leaching surface and weak adhesive strength between agglomerated alumina particles are the reasons that responsible for the ceramic core material with silica fiber be leaching fast than that of the ceramic core material without fiber.

  2. Particle dynamics and particle-cell interaction in microfluidic systems

    Science.gov (United States)

    Stamm, Matthew T.

    Particle-laden flow in a microchannel resulting in aggregation of microparticles was investigated to determine the dependence of the cluster growth rate on the following parameters: suspension void fraction, shear strain rate, and channel-height to particle-diameter ratio. The growth rate of an average cluster was found to increase linearly with suspension void fraction, and to obey a power-law relationships with shear strain rate as S 0.9 and channel-height to particle-diameter ratio as (h/d )--3.5. Ceramic liposomal nanoparticles and silica microparticles were functionalized with antibodies that act as targeting ligands. The bio-functionality and physical integrity of the cerasomes were characterized. Surface functionalization allows cerasomes to deliver drugs with selectivity and specificity that is not possible using standard liposomes. The functionalized particle-target cell binding process was characterized using BT-20 breast cancer cells. Two microfluidic systems were used; one with both species in suspension, the other with cells immobilized inside a microchannel and particle suspension as the mobile phase. Effects of incubation time, particle concentration, and shear strain rate on particle-cell binding were investigated. With both species in suspension, the particle-cell binding process was found to be reasonably well-described by a first-order model. Particle desorption and cellular loss of binding affinity in time were found to be negligible; cell-particle-cell interaction was identified as the limiting mechanism in particle-cell binding. Findings suggest that separation of a bound particle from a cell may be detrimental to cellular binding affinity. Cell-particle-cell interactions were prevented by immobilizing cells inside a microchannel. The initial stage of particle-cell binding was investigated and was again found to be reasonably well-described by a first-order model. For both systems, the time constant was found to be inversely proportional to

  3. Ceramics as biomaterials for dental restoration.

    Science.gov (United States)

    Höland, Wolfram; Schweiger, Marcel; Watzke, Ronny; Peschke, Arnd; Kappert, Heinrich

    2008-11-01

    Sintered ceramics and glass-ceramics are widely used as biomaterials for dental restoration, especially as dental inlays, onlays, veneers, crowns or bridges. Biomaterials were developed either to veneer metal frameworks or to produce metal-free dental restorations. Different types of glass-ceramics and ceramics are available and necessary today to fulfill customers' needs (patients, dentists and dental technicians) regarding the properties of the biomaterials and the processing of the products. All of these different types of biomaterials already cover the entire range of indications of dental restorations. Today, patients are increasingly interested in metal-free restoration. Glass-ceramics are particularly suitable for fabricating inlays, crowns and small bridges, as these materials achieve very strong, esthetic results. High-strength ceramics are preferred in situations where the material is exposed to high masticatory forces.

  4. Process for making ceramic hot gas filter

    Science.gov (United States)

    Connolly, Elizabeth Sokolinski; Forsythe, George Daniel; Domanski, Daniel Matthew; Chambers, Jeffrey Allen; Rajendran, Govindasamy Paramasivam

    2001-01-01

    A ceramic hot-gas candle filter having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during backpulse cleaning and is resistant to chemical degradation at high temperatures.

  5. BasePetroCeram: a database for petrographic and geochemical analysis of archaeological ceramics

    OpenAIRE

    Barreau, Jean-Baptiste; Gehres, Benjamin

    2015-01-01

    International audience; Based on ceramics petrographic and geochemical studies, "BasePetroCeram" project aims to reference petrographic and geochemical analysis of archaeological ceramics from France. In the form of a secure database associated with a web interface, this tool allows a stronger recognition of ceramic bodies, as well as exchanges over long distances, but also collaboration of research teams and emergence of new issues. From a technical point of view, the web framework used is F...

  6. Salt splitting with ceramic membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kurath, D. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-10-01

    The purpose of this task is to develop ceramic membrane technologies for salt splitting of radioactively contaminated sodium salt solutions. This technology has the potential to reduce the low-level waste (LLW) disposal volume, the pH and sodium hydroxide content for subsequent processing steps, the sodium content of interstitial liquid in high-level waste (HLW) sludges, and provide sodium hydroxide free of aluminum for recycle within processing plants at the DOE complex. Potential deployment sites include Hanford, Savannah River, and Idaho National Engineering Laboratory (INEL). The technical approach consists of electrochemical separation of sodium ions from the salt solution using sodium (Na) Super Ion Conductors (NaSICON). As the name implies, sodium ions are transported rapidly through these ceramic crystals even at room temperatures.

  7. Silsesquioxane-derived ceramic fibres

    Science.gov (United States)

    Hurwitz, F. I.; Farmer, S. C.; Terepka, F. M.; Leonhardt, T. A.

    1991-01-01

    Fibers formed from blends of silsesquioxane polymers were characterized to study the pyrolytic conversion of these precursors to ceramics. The morphology of fibers pyrolyzed to 1400 C revealed primarily amorphous glasses whose conversion to beta-SiC is a function of both blend composition and pyrolysis conditions. Formation of beta-SiC crystallites within the glassy phase is favored by higher than stoichiometric C/Si ratios, while carbothermal reduction of Si-O bonds to form SiC with loss of SiO and CO occurs at higher methyl/phenylpropyl silsesquioxane (lower C/Si) ratios. As the carbothermal reduction is assumed to be diffusion controlled, the fibers can serve as model systems to gain understanding of the silsesquioxane pyrolysis behavior, and therefore are useful in the development of polysilsesquioxane-derived ceramic matrices and coatings as well.

  8. Ceramics: Durability and radiation effects

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, R.C.; Lutze, W. [Univ. of New Mexico, Albuquerque, NM (United States); Weber, W.J. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-05-01

    At present, there are three seriously considered options for the disposition of excess weapons plutonium: (1) incorporation, partial burn-up and direct disposal of MOX-fuel; (2) vitrification with defense waste and disposal as glass {open_quotes}logs{close_quotes}; (3) deep borehole disposal. The first two options provide a safeguard due to the high activity of fission products in the irradiated fuel and the defense waste. The latter option has only been examined in a preliminary manner, and the exact form of the plutonium has not been identified. In this paper, we review the potential for the immobilization of plutonium in highly durable crystalline ceramics apatite, pyrochlore, zirconolite, monazite and zircon. Based on available data, we propose zircon as the preferred crystalline ceramic for the permanent disposition of excess weapons plutonium.

  9. Manufacturing tailored property ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Ewsuk, K.G. [Sandia National Labs., Albuquerque, NM (United States). Ceramic Processing Science Dept.; Harrison, L.W. [E.I. du Pont de Nemours and Co., Inc., Wilmington, DE (United States). Central Research and Development Dept.

    1994-11-14

    Composite materials are desirable for many advanced engineering applications where the properties of a single phase material cannot meet all of the service requirements; however, existing process technology has limited the development and commercialization of composites. Lack of reproducible sintering to high density is one of the major obstacles to commercializing ceramic composites. Final-stage, non-reactive liquid phase sintering (NLPS) theory provides metrics for sinterability that can be used as guidelines to design and manufacture dense ceramic-filled-glass (CFG) composites. Additionally, within the constraints defined by the NLPS theory, sum-property models can be used to predict CFG composite properties, and to design composites with properties tailored to specific applications. By integrating composite process models with composite property models, processable, application-tailored CFG composites for microelectronics packaging have been designed and fabricated.

  10. Mullite Ceramics at Extreme Conditions

    Science.gov (United States)

    Kalita, Patricia; Cornelius, Andrew; Lipinska, Kris; Hemmers, Oliver; Sinogeikin, Stanislav; Fisher, Reinhard; Schneider, Hartmut

    2013-03-01

    Mullite is perhaps one of the most important phases in both traditional and advanced ceramics and thus one of the most widely studied ceramic phases. Even though the thermo-elastic behavior of mullites have been studied extensively (spectroscopy, diffraction, dilatometry, theoretical simulations), there are only few studies into the effects of pressure on mullites. This work aims at filling this gap by examining the role of oxygen vacancies on the mechanical stability and on the bulk modulus of mullite-type structures. DAAD, German Research Council, DFG No FI442/14-1. DOE-NNSA DE-FC08-01NV14049. DOE-BES, DOE-NNSA, NSF, DOD -TACOM, the W.M. Keck Found. DOE-BES, W-31-109-ENG-38.

  11. Experiences with voice to design ceramics

    DEFF Research Database (Denmark)

    Hansen, Flemming Tvede; Jensen, Kristoffer

    2014-01-01

    This article presents SoundShaping, a system to create ceramics from the human voice and thus how digital technology makes new possibilities in ceramic craft. The article is about how experiential knowledge that the craftsmen gains in a direct physical and tactile interaction with a responding....... The shape is output to a 3D printer to make ceramic results. The system demonstrates the close connection between digital technology and craft practice. Several experiments and reflections demonstrate the validity of this work....

  12. Tantalum-Based Ceramics for Refractory Composites

    Science.gov (United States)

    Stewart, David A.; Leiser, Daniel; DiFiore, Robert; Kalvala, Victor

    2006-01-01

    A family of tantalum-based ceramics has been invented as ingredients of high-temperature composite insulating tiles. These materials are suitable for coating and/or permeating the outer layers of rigid porous (foam-like or fibrous) ceramic substrates to (1) render the resulting composite ceramic tiles impervious to hot gases and (2) enable the tiles to survive high heat fluxes at temperatures that can exceed 3,000 F ( 1,600 C).

  13. Low-thermal expansion infrared glass ceramics

    Science.gov (United States)

    Lam, Philip

    2009-05-01

    L2 Tech, Inc. is in development of an innovative infrared-transparent glass ceramic material with low-thermal expansion (ZrW2O8) which has Negative Thermal Expansion (NTE). The glass phase is the infrared-transparent germanate glass which has positive thermal expansion (PTE). Then glass ceramic material has a balanced thermal expansion of near zero. The crystal structure is cubic and the thermal expansion of the glass ceramic is isotropic or equal in all directions.

  14. Synthesis of luminescent ceramics from alumina nanopowder

    Science.gov (United States)

    Kortov, V.; Kiryakov, A.; Ananchenko, D.; Zvonarev, S.

    2015-11-01

    The effect of the conditions of high-temperature synthesis in a reducing medium on the density, area and cathodoluminescence of ceramics made of compacted α-Al2O3 powder is the focus of this work. The dependence of the luminescence intensity on the temperature and duration of the synthesis of ceramics is presented. The optimal parameters for synthesis of luminescent ceramics from alumina nanopowder are defined.

  15. Micro-morphological changes prior to adhesive bonding: high-alumina and glassy-matrix ceramics

    Directory of Open Access Journals (Sweden)

    Marco Cícero Bottino

    2008-06-01

    Full Text Available The aim of this study was to qualitatively demonstrate surface micro-morphological changes after the employment of different surface conditioning methods on high-alumina and glassy-matrix dental ceramics. Three disc-shaped high-alumina specimens (In-Ceram Alumina, INC and 4 glassy-matrix ceramic specimens (Vitadur Alpha, V (diameter: 5 mm and height: 5 mm were manufactured. INC specimens were submitted to 3 different surface conditioning methods: INC1 - Polishing with silicon carbide papers (SiC; INC2 - Chairside air-borne particle abrasion (50 µm Al2O3; INC3 - Chairside silica coating (CoJet; 30 µm SiOx. Vitadur Alpha (V specimens were subjected to 4 different surface conditioning methods: V1 - Polishing with SiC papers; V2 - HF acid etching; V3 - Chairside air-borne particle abrasion (50 µm Al2O3; V4 - Chairside silica coating (30 µm SiOx. Following completion of the surface conditioning methods, the specimens were analyzed using SEM. After polishing with SiC, the surfaces of V specimens remained relatively smooth while those of INC exhibited topographic irregularities. Chairside air-abrasion with either aluminum oxide or silica particles produced retentive patterns on both INC and V specimens, with smoother patterns observed after silica coating. V specimens etched with HF presented a highly porous surface. Chairside tribochemical silica coating resulted in smoother surfaces with particles embedded on the surface even after air-blasting. Surface conditioning using air-borne particle abrasion with either 50 µm alumina or 30 µm silica particles exhibited qualitatively comparable rough surfaces for both INC and V. HF acid gel created the most micro-retentive surface for the glassy-matrix ceramic tested.

  16. Multiphase-Multifunctional Ceramic Coatings

    Science.gov (United States)

    2013-06-30

    Ceramic Coatings Performing Organization names: Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional – Unidad Queretaro...University of California, Santa Barbara Principal Investigator / Organization: Dr . Luis Gerardo Trápaga Martínez CINVESTAV-Querétaro Principal...Investigator US collaboration / Organization: Dr . Carlos G. Levi University of California, Santa Barbara Reporting Period Final Dates covered

  17. Evaluation of bond strength of various margin ceramics to a zirconia ceramic

    NARCIS (Netherlands)

    Comlekoglu, M. Erhan; Dundar, Mine; Ozcan, Mutlu; Gungor, M. Ali; Gokce, Bulent; Artunc, Celal

    2008-01-01

    Objective: This study evaluated the bond strengths of four different margin ceramics based on fluoroapatite and feldspath to a zirconia ceramic. Methods: Zirconia cores (Zirconzahn) (N = 28, n = 7/margin ceramic group) were fabricated according to the manufacturers' instructions (diameter: 4 mm;

  18. Ceramic Technology Project database: March 1990 summary report. DOE/ORNL Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    Keyes, B.L.P.

    1992-07-01

    This report is the fifth in a series of semiannual data summary reports on information being stored in the Ceramic Technology Project (CTP) database. The overall system status as of March 31, 1990, is summarized, and the latest additions of ceramic mechanical properties data are given for zirconia, silicon carbide, and silicon nitride ceramic mechanical properties data, including some properties on brazed specimens.

  19. Simultaneous removal of mercury, PCDD/F, and fine particles from flue gas.

    Science.gov (United States)

    Korell, Jens; Paur, Hanns-R; Seifert, Helmut; Andersson, Sven

    2009-11-01

    A multifunctional scrubber (MFS) has been developed to reduce the complexity of flue gas cleaning plants. The MFS integrates an oxidizing scrubber equipped with a dioxin-absorbing tower packing material and a space charge electrostatic precipitator. All these processes have been previously developed at Forschungszentrum Karlsruhe. In the described multifunctional scrubber, mercury, sulfur dioxide, hydrogen chloride, polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), and submicrometer particles are removed simultaneously. A MFS pilot plant with a flue gas volume flow of 250 m(3)/h has been installed in a slipstream of a waste incineration pilot plant. Pilot scale testing was performed to measure mercury, particles, and PCDD/F in the raw and clean gas. After optimization of the process these three flue gas components were separated from the flue gas in the range 87-97%.

  20. Fabrication and Properties of 5% Ce-Doped BaTiO3 Nanofibers-Based Ceramic

    Science.gov (United States)

    Liu, Xin; Zhuang, Yongyong; Xu, Zhuo; Li, Fei; Li, Jinglei; Tian, Ye; Dong, Guoxiang

    2017-10-01

    In order to meet the demand for miniaturized devices, ferroelectric ceramics with micro- or nano-crystal particle size are among the primary needs. In this work, we fabricated 5 mol.% cerium-doped BaTiO3 (CBTO) nanofibers by using sol-gel combined with electrospinning. The mechanism of doping has been investigated in detail by multiple methods. In addition, the dielectric and ferroelectric properties of the obtained CBTO ceramics fabricated by these nanofibers were investigated. Their phase transition temperature shifted to a lower temperature due to the cerium dopant and size effects. An obvious decrease of ferroelectricity of the ceramics was observed, possibly due to the existence of polar nano-regions and cerium ions. The lower curie temperature of CBTO ceramics makes it possible for over-temperature protection applications.

  1. [Comparative study of 4 types of luting cements on shear bond strength of Zirconia ceramics to dentin].

    Science.gov (United States)

    Yin, Bao-di; Zhang, Xian-fang; Zheng, Hu; Han, Dong-wei

    2010-04-01

    To investigate the adequate luting cements for zirconia ceramics to dentin. Blocks of sintered zirconia ceramics were randomly divided into 4 groups with 8 slices in each. After saliva immersion,airborne-particle abraded ceramic specimens were cleaned with phosphoric acid gel(containing 35% phosphoric acid) and then bonded to dentin with these four kinds of luting cements. After preserved in 37 degrees centigrade distilled water for 24 hours, the shear bonding strength of these specimens was tested and the data was analyzed with SPSS12.0 software package. The Multilink Automix could attain the highest shear bonding strength and the 3M RelyXTM Unicem AplicapTM could attain higher shear bonding strength, which were both significantly higher than in the Tokuso Ionomer and Shofu Polycarboxylate Cement groups(P<0.05). Total etching resin luting cement is an ideal option to the bonding of zirconia ceramics and can provide a strong bonding.

  2. The Electrospun Ceramic Hollow Nanofibers

    Directory of Open Access Journals (Sweden)

    Shahin Homaeigohar

    2017-11-01

    Full Text Available Hollow nanofibers are largely gaining interest from the scientific community for diverse applications in the fields of sensing, energy, health, and environment. The main reasons are: their extensive surface area that increases the possibilities of engineering, their larger accessible active area, their porosity, and their sensitivity. In particular, semiconductor ceramic hollow nanofibers show greater space charge modulation depth, higher electronic transport properties, and shorter ion or electron diffusion length (e.g., for an enhanced charging–discharging rate. In this review, we discuss and introduce the latest developments of ceramic hollow nanofiber materials in terms of synthesis approaches. Particularly, electrospinning derivatives will be highlighted. The electrospun ceramic hollow nanofibers will be reviewed with respect to their most widely studied components, i.e., metal oxides. These nanostructures have been mainly suggested for energy and environmental remediation. Despite the various advantages of such one dimensional (1D nanostructures, their fabrication strategies need to be improved to increase their practical use. The domain of nanofabrication is still advancing, and its predictable shortcomings and bottlenecks must be identified and addressed. Inconsistency of the hollow nanostructure with regard to their composition and dimensions could be one of such challenges. Moreover, their poor scalability hinders their wide applicability for commercialization and industrial use.

  3. Ceramic technology for Advanced Heat Engines Project

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.R.

    1991-07-01

    Significant accomplishments in fabricating ceramic components for advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and database and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. An assessment of needs was completed, and a five year project plan was developed with extensive input from private industry. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities. This project is managed by ORNL for the Office of Transportation Technologies, Office of Transportation Materials, and is closely coordinated with complementary ceramics tasks funded by other DOE offices, NASA, DOD, and industry.

  4. Emerging ceramic-based materials for dentistry.

    Science.gov (United States)

    Denry, I; Kelly, J R

    2014-12-01

    Our goal is to give an overview of a selection of emerging ceramics and issues for dental or biomedical applications, with emphasis on specific challenges associated with full-contour zirconia ceramics, and a brief synopsis on new machinable glass-ceramics and ceramic-based interpenetrating phase composites. Selected fabrication techniques relevant to dental or biomedical applications such as microwave sintering, spark plasma sintering, and additive manufacturing are also reviewed. Where appropriate, the authors have added their opinions and guidance. © International & American Associations for Dental Research.

  5. Ceramic-Metal Interfaces in Multilayer Actuators

    DEFF Research Database (Denmark)

    Engell, John; Pedersen, Henrik Guldberg; Andersen, Bjørn

    1996-01-01

    on the quality and strength of this interface. In the case of a weak ceramic-metal interface, delaminations will occur under severe working conditions.Work has been carried out on a commercial PZT type ceramic and various types of Pt electrode paste. The present study involves characterization of the interface......Multilayer actuators consist of a number of piezoelectric or electrostrictive ceramic layers, separated by thin metal electrodes. Thus, the ceramic-metal interface plays an even more important role than for bulk piezoceramics. The performance and durability of the actuator depends closely...

  6. Ceramic Technology For Advanced Heat Engines Project

    Energy Technology Data Exchange (ETDEWEB)

    1990-12-01

    Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DoD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. This advanced materials technology is being developed in parallel and close coordination with the ongoing DOE and industry proof of concept engine development programs. To facilitate the rapid transfer of this technology to U.S. industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities. Abstracts prepared for appropriate papers.

  7. Portland blended cements: demolition ceramic waste management

    Directory of Open Access Journals (Sweden)

    M. A. Trezza

    2017-01-01

    Full Text Available Demolition ceramic wastes (DCWs were investigated in order to determine their potential use as supplementary cementitious materials in Portland Blended Cements (PBCs. For this purpose, three ceramic wastes were investigated. After characterization of the materials used, the effect of ceramic waste replacement (8, 24 and 40% by mass was analyzed. Pozzolanic activity, hydration progress, workability and compressive strength were determined at 2, 7 and 28 days. The results showed that the ground wastes behave as filler at an early age, but as hydration progresses, the pozzolanic activity of ceramic waste contributes to the strength requirement.

  8. Manufacturing of superconductive silver/ceramic composites

    DEFF Research Database (Denmark)

    Seifi, Behrouz; Bech, Jakob Ilsted; Eriksen, Morten

    2000-01-01

    Manufacturing of superconducting metal/ceramic composites is a rather new discipline within materials forming processes. High Temperature SuperConductors, HTSC, are manufactured applying the Oxide-Powder-In-Tube process, OPIT. A ceramic powder containing lead, calcium, bismuth, strontium, and cop......Manufacturing of superconducting metal/ceramic composites is a rather new discipline within materials forming processes. High Temperature SuperConductors, HTSC, are manufactured applying the Oxide-Powder-In-Tube process, OPIT. A ceramic powder containing lead, calcium, bismuth, strontium...

  9. Improved Slip Casting Of Ceramic Models

    Science.gov (United States)

    Buck, Gregory M.; Vasquez, Peter; Hicks, Lana P.

    1994-01-01

    Improved technique of investment slip casting developed for making precise ceramic wind-tunnel models. Needed in wind-tunnel experiments to verify predictions of aerothermodynamical computer codes. Ceramic materials used because of their low heat conductivities and ability to survive high temperatures. Present improved slip-casting technique enables casting of highly detailed models from aqueous or nonaqueous solutions. Wet shell molds peeled off models to ensure precise and undamaged details. Used at NASA Langley Research Center to form superconducting ceramic components from nonaqueous slip solutions. Technique has many more applications when ceramic materials developed further for such high-strength/ temperature components as engine parts.

  10. Ballistic Performance of Porous-Ceramic, Thermal Protection Systems to 9 km/s

    Science.gov (United States)

    Miller, Joshua E.; Bohl, William E.; Foreman, Cory D.; Christiansen, Eric C.; Davis, Bruce A.

    2010-01-01

    Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of US manned spacecraft, Orion. These materials insulate the structural components and sensitive components of a spacecraft against the intense thermal environments of atmospheric reentry. These materials are also highly exposed to solid particle space environment hazards. This paper discusses recent impact testing up to 9.65 km/s on ceramic tiles similar to those used on the Orbiter. These tiles are a porous-ceramic insulator of nominally 8 lb/ft(exp 3) alumina-fiber-enhanced-thermal-barrier (AETB8) coated with a damage-resistant, toughened-unipiece-fibrous-insulation/reaction-cured-glass layer (TUFI/RCG).

  11. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-11-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the current research, the electrical conductivity and Seebeck coefficient were measured as a function of temperature in air. Based on these measurements, the charge carrier concentration, net acceptor dopant concentration, activation energy of conduction and mobility were estimated. The studies on the fracture toughness of the LSFT and dual phase membranes at room temperature have been completed and reported previously. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affects the mechanical properties. To study the effect of temperature on the membranes when exposed to an inert environment, the membranes (LAFT and Dual phase) were heat treated at 1000 C in air and N{sub 2} atmosphere and hardness and fracture toughness of the membranes were studied after the treatment. The indentation method was used to find the fracture toughness and the effect of the heat treatment on the mechanical properties of the membranes. Further results on the investigation of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appears to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model will serve to study ''frozen'' profiles in patterned or composite membranes.

  12. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-02-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. The in situ electrical conductivity and Seebeck coefficient measurements were made on LSFT at 1000 and 1200 C over the oxygen activity range from air to 10{sup -15} atm. The electrical conductivity measurements exhibited a p to n type transition at an oxygen activity of 1 x 10{sup -10} at 1000 C and 1 x 10{sup -6} at 1200 C. Thermogravimetric studies were also carried out over the same oxygen activities and temperatures. Based on the results of these measurements, the chemical and mechanical stability range of LSFT were determined and defect structure was established. The studies on the fracture toughness of the LSFT and dual phase membranes exposed to air and N{sub 2} at 1000 C was done and the XRD and SEM analysis of the specimens were carried out to understand the structural and microstructural changes. The membranes that are exposed to high temperatures at an inert and a reactive atmosphere undergo many structural and chemical changes which affect the mechanical properties. A complete transformation of fracture behavior was observed in the N{sub 2} treated LSFT samples. Further results to investigate the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Recent results on transient kinetic data are presented. The 2-D modeling of oxygen movement has been undertaken in order to fit isotope data. The model is used to study ''frozen'' profiles in patterned or composite membranes.

  13. On the possibility of producing alumina ceramic with a slight electrical conductivity

    CERN Document Server

    Caspers, Fritz

    1989-01-01

    Antistatic alumina ceramic is desirable for certain particle accelerator applications. In general, highly insulating surface close to a charged particle beam must be avoided in order to prevent the formation of ion pockets and other unwanted electrical effects. For the AA vacuum chamber (UHV), an antistatic ferrite has been produced and successfully installed. The fabrication of antistatic alumina might be possible in a similar way. By using certain metal oxides in the cement, which holds the alumina particles together, a slight conductivity could be obtained after the firing and sintering process, without deteriorating the mechanical and outgassing properties of the alumina compound.

  14. Liquid Film Capillary Mechanism for Densification of Ceramic Powders during Flash Sintering

    Directory of Open Access Journals (Sweden)

    Rachman Chaim

    2016-04-01

    Full Text Available Recently, local melting of the particle surfaces confirmed the formation of spark and plasma during spark plasma sintering, which explains the rapid densification mechanism via liquid. A model for rapid densification of flash sintered ceramics by liquid film capillary was presented, where liquid film forms by local melting at the particle contacts, due to Joule heating followed by thermal runaway. Local densification is by particle rearrangement led by spreading of the liquid, due to local attractive capillary forces. Electrowetting may assist this process. The asymmetric nature of the powder compact represents an invasive percolating system.

  15. Porous ceramics achievement by soybean and corn agricultural waste insertion; Obtencao de ceramicas porosas pela insercao de residuos agricolas de soja e milho

    Energy Technology Data Exchange (ETDEWEB)

    Valdameri, C.Z.; Ank, A., E-mail: cledison@unipar.br [Universidade Paranaense (UNIPAR), Francisco Beltrao, PR (Brazil). Departamento de Engenharia Civil; Zatta, L. [Universidade Tecnologica Federal do Parana (UTFPR), Pato Branco, PR (Brazil). Departamento de Quimica; Anaissi, F.J. [Universidade Estadual do Centro-Oeste (UNICENTRO), Guarapuava, PR (Brazil). Departamento de Quimica

    2014-07-01

    Porous ceramic materials are produced by incorporating organic particles and stable foams. Generally it improves low thermal conductivity, which gives thermal comfort for buildings. The southwest region of Parana state is one of the largest producers of grains in Brazil, this causes the disposal of a large amount of waste in the agricultural processing. This paper presents the characterization of porous ceramics produced from clay minerals and agricultural waste (soybeans and corn). The precursor was characterized by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) techniques. For the ceramic materials produced, characterizations about density, water absorption, tensile strength by diametrical compression strength and flexural strength curves was performed. The results showed high possibility of industrial/commercial application because the ceramic materials were produced from low costs precursors leading to ceramic products with properties of interest in construction. (author)

  16. Are PEEK-on-Ceramic Bearings an Option for Total Disc Arthroplasty? An In Vitro Tribology Study.

    Science.gov (United States)

    Siskey, Ryan; Ciccarelli, Lauren; Lui, Melissa K C; Kurtz, Steven M

    2016-11-01

    Most contemporary total disc replacements (TDRs) use conventional orthopaedic bearing couples such as ultrahigh-molecular-weight polyethylene (polyethylene) and cobalt-chromium (CoCr). Cervical total disc replacements incorporating polyetheretherketone (PEEK) bearings (specifically PEEK-on-PEEK bearings) have been previously investigated, but little is known about PEEK-on-ceramic bearings for TDR. (1) What is the tribologic behavior of a PEEK-on-ceramic bearing for cervical TDR under idealized, clean wear test conditions? (2) How does the PEEK-on-ceramic design perform under impingement conditions? (3) How is the PEEK-on-ceramic bearing affected by abrasive wear? (4) Is the particle morphology from PEEK-on-ceramic bearings for TDRs affected by adverse wear scenarios? PEEK-on-ceramic cervical TDR bearings were subjected to a 10 million cycle ideal wear test based on ASTM F2423 and ISO 181912-1 using a six-station spine wear simulator (MTS, Eden Prairie, MN, USA) with 5 g/L bovine serum concentration at 23° ± 2° C (ambient temperature). Validated 1 million cycle impingement and 5 million cycle abrasive tests were conducted on the PEEK-on-ceramic bearings based, in part, on retrieval analysis of a comparable bearing design as well as finite element analyses. The ceramic-on-PEEK couple was characterized for damage modes, mass and volume loss, and penetration and the lubricant was subjected to particle analysis. The resulting mass wear rate, volumetric wear rate, based on material density, and particle analysis were compared with clinically available cervical disc bearing couples. The three modes of wear (idealized, impingement, and abrasive) resulted in mean mass wear rates of 0.9 ± 0.2 mg/MC, 1.9 ± 0.5 mg/MC, and 2.8 ± 0.6 mg/MC, respectively. The mass wear rates were converted to volumetric wear rates using density and found to be 0.7 ± 0.1 mm3/MC, 1.5 ± 0.4 mm3/MC, and 2.1 ± 0.5 mm3/MC, respectively. During each test, the PEEK endplates were

  17. Particle number, particle mass and NOx emission factors at a highway and an urban street in Copenhagen

    Directory of Open Access Journals (Sweden)

    D. Fang

    2010-03-01

    Full Text Available This paper presents measurements of traffic-generated gas and particle pollution at two sites, one near a major highway and one near a busy urban street in Copenhagen, Denmark. Both sites were equipped for a 4-week period with a set of two measurement stations, one close to the kerbside and one background station. Measurements were carried out from March to April~2008, investigating NOx concentrations, submicrometer particle number size distribution (size range 10–700 nm, particle mass (PM2.5, PM10, and meteorological parameters. In this study we also estimate the emission factors for NOx, particle number and particle mass using measured traffic volume and dilution rate calculated by the Operational Street Pollution Model (WinOSPM. The mean concentrations of most of the measured pollutants are similar for the highway and the urban kerbside stations due to similar traffic density. The average concentrations of NOx are 142 μg m−3 and 136 μg m−3 for the highway and the urban kerbside stations, respectively. These values are about 5 times higher compared to the corresponding background values. The average particle number concentration is 24 900 particles cm−3 and 27 100 particles cm−3 for the highway and the urban kerbside stations, respectively, and these values exceed those measured at the background stations by a factor of 3 to 5. The temporal variation of the traffic contribution (difference of kerbside and background concentrations is analysed for NOx, particle number and mass, and it follows the traffic pattern at the urban and the highway sites. Emission factors for particle number are found to be quite similar at both sites, (215±5 1012 particles veh−1 km−1 for the highway and (187±3 1012 particles veh−1 km−1 for the urban site. Heavy duty vehicles (HDVs are found to emit about 20 times more particles than light duty vehicles (LDVs, which is in good agreement with other published studies. Emission factors are also

  18. Effect of particle size of starting materials on the structure and properties of biogenic hydroxyapatite/glass composites

    National Research Council Canada - National Science Library

    Oleksandr Parkhomey; Nataliia Pinchuk; Olena Sych; Tamara Tomila; Oleksiy Kuda; Hanna Tovstonoh; Viktor Gorban; Valeriy Kolesnichenko; Yan Evych

    2016-01-01

    The work is devoted to investigation of porous glass-ceramic composite materials on the basis of biogenic hydroxyapatite and sodium borosilicate glass prepared from starting powders with different particle sizes (<50 µm and <160 µm...

  19. Effect of particle size of starting materials on the structure and properties of biogenic hydroxyapatite/glass composites

    OpenAIRE

    Oleksandr Parkhomey; Nataliia Pinchuk; Olena Sych; Tamara Tomila; Oleksiy Kuda; Hanna Tovstonoh; Viktor Gorban’; Valeriy Kolesnichenko; Yan Evych

    2016-01-01

    The work is devoted to investigation of porous glass-ceramic composite materials on the basis of biogenic hydroxyapatite and sodium borosilicate glass prepared from starting powders with different particle sizes (

  20. Polygamous particles.

    Science.gov (United States)

    Wu, Kun-Ta; Feng, Lang; Sha, Ruojie; Dreyfus, Rémi; Grosberg, Alexander Y; Seeman, Nadrian C; Chaikin, Paul M

    2012-11-13

    DNA is increasingly used as an important tool in programming the self-assembly of micrometer- and nanometer-scale particles. This is largely due to the highly specific thermoreversible interaction of cDNA strands, which, when placed on different particles, have been used to bind precise pairs in aggregates and crystals. However, DNA functionalized particles will only reach their true potential for particle assembly when each particle can address and bind to many different kinds of particles. Indeed, specifying all bonds can force a particular designed structure. In this paper, we present the design rules for multiflavored particles and show that a single particle, DNA functionalized with many different "flavors," can recognize and bind specifically to many different partners. We investigate the cost of increasing the number of flavors in terms of the reduction in binding energy and melting temperature. We find that a single 2-μm colloidal particle can bind to 40 different types of particles in an easily accessible time and temperature regime. The practical limit of ∼100 is set by entropic costs for particles to align complementary pairs and, surprisingly, by the limited number of distinct "useful" DNA sequences that prohibit subunits with nonspecific binding. For our 11 base "sticky ends," the limit is 73 distinct sequences with no unwanted overlaps of 5 bp or more. As an example of phenomena enabled by polygamous particles, we demonstrate a three-particle system that forms a fluid of isolated clusters when cooled slowly and an elastic gel network when quenched.

  1. Fracture Strength of Monolithic All-Ceramic Crowns on Titanium Implant Abutments.

    Science.gov (United States)

    Weyhrauch, Michael; Igiel, Christopher; Scheller, Herbert; Weibrich, Gernot; Lehmann, Karl Martin

    2016-01-01

    The fracture strengths of all-ceramic crowns cemented on titanium implant abutments may vary depending on crown materials and luting agents. The purpose of this study was to examine differences in fracture strength among crowns cemented on implant abutments using crowns made of seven different monolithic ceramic materials and five different luting agents. In total, 525 crowns (75 each of Vita Mark II, feldspathic ceramic [FSC]; Ivoclar Empress CAD, leucite-reinforced glass ceramic [LrGC]; Ivoclar e.max CAD, lithium disilicate [LiDS]; Vita Suprinity, presintered zirconia-reinforced lithium silicate ceramic [PSZirLS]; Vita Enamic, polymer-reinforced fine-structure feldspathic ceramic [PolyFSP], Lava Ultimate; resin nanoceramic [ResNC], Celtra Duo; fully crystallized zirconia-reinforced lithium silicate [FcZirLS]) were milled using a CAD/CAM system. The inner surfaces of the crowns were etched and silanized. Titanium implant abutments were fixed on implant analogs, and airborne-particle abrasion was used on their exterior specific adhesion surfaces (Al2O3, 50 μm). Then, the abutments were degreased and silanized. The crowns were cemented on the implant abutments using five luting agents (Multilink Implant, Variolink II, RelyX Unicem, GC FujiCEM, Panavia 2.0). After thermocycling for 5,000 cycles (5 to 55°C, 30 seconds dwell time), the crowns were subjected to fracture strength testing under static load using a universal testing machine. Statistical analyses were performed using analysis of variance (α = .0002) and the Bonferroni correction. No significant difference among the luting agents was found using the different all-ceramic materials. Ceramic materials LiDS, PSZirLS, PolyFSP, and ResNC showed significantly higher fracture strength values compared with FSC, FcZirLS, and LrGC. The PSZirLS especially showed significantly better results. Within the limitations of this study, fracture strength was not differentially affected by the various luting agents. However

  2. A novel bioactive glass-ceramic for treating dentin hypersensitivity

    Directory of Open Access Journals (Sweden)

    Camila Tirapelli

    2010-12-01

    Full Text Available Dentin hypersensitivity (DH is a painful response to stimulus applied to the open dentinal tubules of a vital tooth. It's a common oral condition, however, without an ideal treatment available yet. This work evaluated in vitro the effect of micron-sized particles from a novel bioactive glass-ceramic (Biosilicate in occluding open dentinal tubules. A dentin disc model was employed to observe comparatively, using scanning electron microscopy (SEM, dentinal tubule occlusion by different products and deposition of hydroxyl carbonate apatite (HCA on dentin surface by Biosilicate, after a single application: G1 - Dentifrice with potassium nitrate and fluoride; G2 - Two-step calcium phosphate precipitation treatment; G3 - Water-free gel containing Biosilicate particles (1%; G4 - Biosilicate particles mixed with distilled water in a 1:10 ratio; all of them after 1, 12 and 24 hours of immersion in artificial saliva. Fourier transform infrared spectroscopy (FTIR was performed to detect HCA formation on dentin discs filled with Biosilicate after 2 minutes, 30 minutes and 12 hours of immersion in artificial saliva. SEM showed a layer of HCA formed on dentin surface after 24 hours by G4. G1, G2 and G3 promoted not total occlusion of open dentinal tubules after 24 hours. FTIR showed HCA precipitation on the dentin surface induced by Biosilicate after 30 minutes. The micron-sized particles from the bioactive glass-ceramic thus were able to induce HCA deposition in open dentinal tubules in vitro. This finding suggests that Biosilicate may provide a new option for treating DH.

  3. Study of Wettability of Clayey Ceramic and Fluorescent Lamp Glass Waste Powders

    Science.gov (United States)

    Morais, Alline Sardinha Cordeiro; Monteiro, Sergio Neves; Ribeiro, Sebastião; Sardinha, Leonardo Carneiro; Vieira, Carlos Maurício Fontes

    The glass tube of spent fluorescent lamps is contaminated with mercury, which might be a serious hazard in the case of conventional recycling by melting with other glasses. A possible solution could be its incorporation into a clay body to fabricate common fired ceramics such as bricks and tiles. The objective of this work is to characterize a type of fluorescent lamp glass waste to be incorporated into a clayey ceramic. The characterization was performed in terms of wettability tests to evaluate the interaction between the surface of the clayey ceramic and glass waste as a function of the firing temperature. The results showed that the contact angle decreased with increasing temperature, reaching a value of 79°, at a temperature of 1100°C, but not sufficient to completely wet the ceramic. However, compatible chemical composition and reduction of porosity by the flow of soft glass waste between the clay particles favor the consolidation of the ceramics structure above 900°C.

  4. Solid state reduction of chromium (VI) pollution for Al2O3-Cr metal ceramics application

    Science.gov (United States)

    Zhu, Hekai; Fang, Minghao; Huang, Zhaohui; Liu, Yangai; Tang, Hao; Min, Xin; Wu, Xiaowen

    2016-04-01

    Reduction of chromium (VI) from Na2CrO4 through aluminothermic reaction and fabrication of metal-ceramic materials from the reduction products have been investigated in this study. Na2CrO4 could be successfully reduced into micrometer-sized Cr particles in a flowing Ar atmosphere in presence of Al powder. The conversion ratio of Na2CrO4 to metallic Cr attained 96.16% efficiency. Al2O3-Cr metal-ceramic with different Cr content (5 wt%, 10 wt%, 15 wt%, 20 wt%) were further prepared from the reduction product Al2O3-Cr composite powder, and aluminum oxide nanopowder via pressure-less sintering. The phase composition, microstructure and mechanical properties of metal-ceramic composites were characterized to ensure the potential of the Al2O3-Cr composite powder to form ceramic materials. The highest relative density and bending strength can reach 93.4% and 205 MP, respectively. The results indicated that aluminothermic reduction of chromium (VI) for metal-ceramics application is a potential approach to remove chromium (VI) pollutant from the environment.

  5. Porosity and biocompatibility study of ceramic implants based on ZrO{sub 2} and Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Litvinova, Larisa, E-mail: larisalitvinova@yandex.ru, E-mail: vshupletsova@mail.ru, E-mail: leitsin@mail.ru; Shupletsova, Valeria, E-mail: larisalitvinova@yandex.ru, E-mail: vshupletsova@mail.ru, E-mail: leitsin@mail.ru; Leitsin, Vladimir, E-mail: larisalitvinova@yandex.ru, E-mail: vshupletsova@mail.ru, E-mail: leitsin@mail.ru [Immanuel Kant Baltic Federal University, Kaliningrad (Russian Federation); Vasyliev, Roman, E-mail: rvasiliev@ukr.net, E-mail: zoubov77@yahoo.com; Zubov, Dmitry, E-mail: rvasiliev@ukr.net, E-mail: zoubov77@yahoo.com [State Institute of Genetic and Regenerative Medicine, National Academy of Medical Sciences of Ukraine, Kiev (Ukraine); Buyakov, Ales, E-mail: kulkov@ms.tsc.ru, E-mail: kulkov@ms.tsc.ru; Kulkov, Sergey, E-mail: kulkov@ms.tsc.ru, E-mail: kulkov@ms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2014-11-14

    The work studies ZrO{sub 2}(Me{sub x}O{sub y})-based porous ceramics produced from the powders consisting of hollow spherical particles. It was shown that the structure is represented by a cellular framework with bimodal porosity consisting of sphere-like large pores and pores that were not filled with the powder particles during the compaction. For such ceramics, the increase of pore volume is accompanied by the increased strain in an elastic area. It was also shown that the porous ZrO{sub 2} ceramics had no acute or chronic cytotoxicity. At the same time, ceramics possess the following osteoconductive properties: adhesion support, spreading, proliferation and osteogenic differentiation of MSCs.

  6. Coated particle waste form development

    Energy Technology Data Exchange (ETDEWEB)

    Oma, K.H.; Buckwalter, C.Q.; Chick, L.A.

    1981-12-01

    Coated particle waste forms have been developed as part of the multibarrier concept at Pacific Northwest Laboratory under the Alternative Waste Forms Program for the Department of Energy. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low-temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed (FB) coaters, screw agitated coaters (SAC), and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated at PNL as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders-of-magnitude increase in chemical durability. Because the aluminum coatings were porous, the superior leach resistance must be due to either a chemical interaction or to a pH buffer effect. Because they are complex, coated waste form processes rank low in process feasibility. Of all the possible coated particle processes, plasma sprayed marbles have the best rating. Carbon coating of pellets by CVD ranked ninth when compared with ten other processes. The plasma-spray-coated marble process ranked sixth out of eleven processes.

  7. Steric stabilization of nonaqueous silicon slips. I - Control of particle agglomeration and packing. II - Pressure casting of powder compacts

    Science.gov (United States)

    Kerkar, Awdhoot V.; Henderson, Robert J. M.; Feke, Donald L.

    1990-01-01

    The application of steric stabilization to control particle agglomeration and packing of silicon powder in benzene and trichloroethylene is reported. The results provide useful guidelines for controlling unfavorable particle-particle interactions during nonaqueous processing of silicon-based ceramic materials. The application of steric stabilization to the control and improvement of green processing of nonaqueous silicon slips in pressure consolidation is also demonstrated.

  8. Particle cosmology

    CERN Multimedia

    CERN. Geneva

    2007-01-01

    The understanding of the Universe at the largest and smallest scales traditionally has been the subject of cosmology and particle physics, respectively. Studying the evolution of the Universe connects today's large scales with the tiny scales in the very early Universe and provides the link between the physics of particles and of the cosmos. This series of five lectures aims at a modern and critical presentation of the basic ideas, methods, models and observations in today's particle cosmology.

  9. Preliminary analysis in a clayey mass aimed at ceramic blocks production: physical and mineralogical characteristics; Analise preliminar em uma massa argilosa visando a producao de blocos ceramicos: caracteristicas fisicas e mineralogicas

    Energy Technology Data Exchange (ETDEWEB)

    Silva, L.J.M.D. da; Apolonio, T.G.; Salviano, A.F.; Taveira, S.K.A.; Garcia, T.G.C.; Silva, J; Luna, P.A.; Macedo, R.S., E-mail: reginaldo.severo@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2016-07-01

    The physical, chemical and mineralogical characterization of the clayey mass are important in determining its properties, allowing a better knowledge of the raw material used in the manufacture of ceramic products. This work aims to characterize the raw material used in the manufacture of ceramic sealing blocks in a ceramic industry. Thus, it was evaluated by laboratory tests the raw material used in the production of ceramic blocks in a ceramics industry in the region of Carnauba dos Dantas, RN. The methodology used in the tests is the same as the IPT, which consists in carrying out the plasticity testing, particle size, chemical analysis and X-ray diffraction. Results indicate that the sample studied by the physical and mineralogical characteristics, has the potential to be applied in the manufacture of red ceramic products for use in construction. (author)

  10. Particle Physics

    CERN Document Server

    Martin, B R

    2008-01-01

    An essential introduction to particle physics, with coverage ranging from the basics through to the very latest developments, in an accessible and carefully structured text. Particle Physics: Third Edition is a revision of a highly regarded introduction to particle physics. In its two previous editions this book has proved to be an accessible and balanced introduction to modern particle physics, suitable for those students needed a more comprehensive introduction to the subject than provided by the 'compendium' style physics books. In the Third Edition the standard mod

  11. Influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage restorations.

    Science.gov (United States)

    Bakeman, E M; Rego, N; Chaiyabutr, Y; Kois, J C

    2015-01-01

    This study evaluated the influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage ceramic restorations. Forty extracted molars were allocated into four groups (n=10) to test for two variables: 1) the thickness of ceramic (1 mm or 2 mm) and 2) the ceramic materials (a lithium disilicate glass-ceramic [IPS e.max] or leucite-reinforced glass ceramic [IPS Empress]). All ceramic restorations were luted with resin cement (Variolink II) on the prepared teeth. These luted specimens were loaded to failure in a universal testing machine, in the compression mode, with a crosshead speed of 1.0 mm/min. The data were analyzed using two-way analysis of variance and the Tukey Honestly Significantly Different multiple comparison test (α =0.05). The fracture resistance revealed a significant effect for materials (pmaterials was not significant (p=0.406). Mean (standard deviation) fracture resistance values were as follows: a 2-mm thickness of a lithium disilicate bonded to tooth structure (2505 [401] N) revealed a significantly higher fracture resistance than did a 1-mm thickness of leucite-reinforced (1569 [452] N) and a 2-mm thickness of leucite-reinforced ceramic bonded to tooth structure (1716 [436] N) (presistance values between a lithium disilicate ceramic at 1-mm thickness (2105 [567] N) and at 2-mm thickness. Using a lithium disilicate glass ceramic for partial coverage restoration significantly improved fracture resistance compared to using a leucite-reinforced glass ceramic. The thickness of ceramic had no significant effect on fracture resistance when the ceramics were bonded to the underlying tooth structure.

  12. Science and Technology of Ceramics -16 ...

    Indian Academy of Sciences (India)

    Science and Technology of Ceramics. 1. Traditional Ceramics. Sheela K Ramasesha is at present in the. Materials Science. Division of the National Aerospace. Laboratories, Bangalore as a senior UGC Re- search. Scientist. She got her. PhD from Indian Institutt of Science in 1980 and was a post doctoral. Fellow at ...

  13. Dense ceramic membranes for methane conversion

    NARCIS (Netherlands)

    Bouwmeester, Henricus J.M.

    2003-01-01

    Dense ceramic membranes made from mixed oxygen-ionic and electronic conducting perovskite-related oxides allow separation of oxygen from an air supply at elevated temperatures (>700 °C). By combining air separation and catalytic partial oxidation of methane to syngas into a ceramic membrane reactor,

  14. Experiences with Voice to Design Ceramics

    DEFF Research Database (Denmark)

    Hansen, Flemming Tvede; Jensen, Kristoffer

    2013-01-01

    This article presents SoundShaping, a system to create ceramics from the human voice and thus how digital technology makes new possibilities in ceramic craft. The article is about how experiential knowledge that the craftsmen gains in a direct physical and tactile interaction with a responding...

  15. Fabrication of hybrid ceramic matrix composites

    Science.gov (United States)

    Haug, S. B.; Dharani, L. R.; Carroll, D. R.

    1994-03-01

    The desire to improve the transverse properties and microcracking stress of unidirectional continuous fiber reinforced ceramic matrix composites has led to development of the hybrid ceramic matrix composite (HCMC). This paper discusses the techniques we used in the fabrication of HCMC specimens used for mechanical characterization.

  16. New ceramic materials; Nuevos materiales ceramicos

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, R.; Dominguez-Rodriguez, A.

    2010-07-01

    This article is to provide a new ceramic materials in which, with a control of their processing and thus their microstructural properties, you can get ceramic approaching ever closer to a metal, both in its structural behavior at low as at high temperatures. (Author) 30 refs.

  17. Shock wave fabricated ceramic-metal nozzles

    NARCIS (Netherlands)

    Carton, E.P.; Stuivinga, M.E.C.; Keizers, H.L.J.; Verbeek, H.J.; Put, P.J. van der

    1999-01-01

    Shock compaction was used in the fabrication of high temperature ceramic-based materials. The materials' development was geared towards the fabrication of nozzles for rocket engines using solid propellants, for which the following metal-ceramic (cermet) materials were fabricated and tested: B4C-Ti

  18. Prestresses in bilayered all-ceramic restorations

    NARCIS (Netherlands)

    Aboushelib, M.N.; Feilzer, A.J.; de Jager, N.; Kleverlaan, C.J.

    2008-01-01

    Introduction: A general trend in all ceramic systems is to use veneering ceramics of slightly lower thermal expansion coefficients compared with that of the framework resulting in a positive mismatch in thermal expansion coefficient (+ΔTEC). The concept behind this TEC mismatch is to generate

  19. Synthesis of lead-free piezoelectric powders by ultrasonic-assisted hydrothermal method and properties of sintered (K0.48Na0.52)NBO3 ceramics.

    Science.gov (United States)

    Isobe, Gaku; Maeda, Takafumi; Bornmann, Peter; Hemsel, Tobias; Morita, Takeshi

    2014-02-01

    (K,Na)NbO3 ceramics have attracted much attention as lead-free piezoelectric materials with high piezoelectric properties. High-quality (K,Na)NbO3 ceramics can be sintered using KNbO3 and NaNbO3 powders synthesized by a hydrothermal method. In this study, to enhance the quality factor of the ceramics, high-power ultrasonic irradiation was employed during the hydrothermal method, which led to a reduction in the particle size of the resultant powders.

  20. Cracking cone fracture after cold compaction of argillaceous particles

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Cold uniaxial pressing of powder into a green body is a common forming process used in ceramic and pharmaceutical industries. Argillaceous particles are used as a model system to investigate granule failure during compaction. Indeed, the volume enclosed between the die and punches is reduced and the ...

  1. Modelling of Tape Casting for Ceramic Applications

    DEFF Research Database (Denmark)

    Jabbari, Masoud

    of functional ceramics research. Advances in ceramic forming have enabled low cost shaping techniques such as tape casting and extrusion to be used in some of the most challenging technologies. These advances allow the design of complex components adapted to desired specific properties and applications. However...... of ceramic processing are generally focused on the control of the microstructure while the importance of shaping is often underestimated. Improved performance requires the design and shaping of both controlled architectures and microstructures. Novel functionally graded ceramic materials may be formed...... process of functionally graded ceramic materials for fuel cell applications as well as magnetic refrigeration. Models to simulate the shaping of monolayer/multilayer and graded materials by tape casting are developed. The emphasis is on analyzing the entry flow of multiple slurries from the reservoir...

  2. FY2015 ceramic fuels development annual highlights

    Energy Technology Data Exchange (ETDEWEB)

    Mcclellan, Kenneth James [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

    2015-09-22

    Key challenges for the Advanced Fuels Campaign are the development of fuel technologies to enable major increases in fuel performance (safety, reliability, power and burnup) beyond current technologies, and development of characterization methods and predictive fuel performance models to enable more efficient development and licensing of advanced fuels. Ceramic fuel development activities for fiscal year 2015 fell within the areas of 1) National and International Technical Integration, 2) Advanced Accident Tolerant Ceramic Fuel Development, 3) Advanced Techniques and Reference Materials Development, and 4) Fabrication of Enriched Ceramic Fuels. High uranium density fuels were the focus of the ceramic fuels efforts. Accomplishments for FY15 primarily reflect the prioritization of identification and assessment of new ceramic fuels for light water reactors which have enhanced accident tolerance while also maintaining or improving normal operation performance, and exploration of advanced post irradiation examination techniques which will support more efficient testing and qualification of new fuel systems.

  3. FY2016 Ceramic Fuels Development Annual Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Mcclellan, Kenneth James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-24

    Key challenges for the Advanced Fuels Campaign are the development of fuel technologies to enable major increases in fuel performance (safety, reliability, power and burnup) beyond current technologies, and development of characterization methods and predictive fuel performance models to enable more efficient development and licensing of advanced fuels. Ceramic fuel development activities for fiscal year 2016 fell within the areas of 1) National and International Technical Integration, 2) Advanced Accident Tolerant Ceramic Fuel Development, 3) Advanced Techniques and Reference Materials Development, and 4) Fabrication of Enriched Ceramic Fuels. High uranium density fuels were the focus of the ceramic fuels efforts. Accomplishments for FY16 primarily reflect the prioritization of identification and assessment of new ceramic fuels for light water reactors which have enhanced accident tolerance while also maintaining or improving normal operation performance, and exploration of advanced post irradiation examination techniques which will support more efficient testing and qualification of new fuel systems.

  4. Polymer and ceramic nanocomposites for aerospace applications

    Science.gov (United States)

    Rathod, Vivek T.; Kumar, Jayanth S.; Jain, Anjana

    2017-09-01

    This paper reviews the potential of polymer and ceramic matrix composites for aerospace/space vehicle applications. Special, unique and multifunctional properties arising due to the dispersion of nanoparticles in ceramic and metal matrix are briefly discussed followed by a classification of resulting aerospace applications. The paper presents polymer matrix composites comprising majority of aerospace applications in structures, coating, tribology, structural health monitoring, electromagnetic shielding and shape memory applications. The capabilities of the ceramic matrix nanocomposites to providing the electromagnetic shielding for aircrafts and better tribological properties to suit space environments are discussed. Structural health monitoring capability of ceramic matrix nanocomposite is also discussed. The properties of resulting nanocomposite material with its disadvantages like cost and processing difficulties are discussed. The paper concludes after the discussion of the possible future perspectives and challenges in implementation and further development of polymer and ceramic nanocomposite materials.

  5. Polymer and ceramic nanocomposites for aerospace applications

    Science.gov (United States)

    Rathod, Vivek T.; Kumar, Jayanth S.; Jain, Anjana

    2017-11-01

    This paper reviews the potential of polymer and ceramic matrix composites for aerospace/space vehicle applications. Special, unique and multifunctional properties arising due to the dispersion of nanoparticles in ceramic and metal matrix are briefly discussed followed by a classification of resulting aerospace applications. The paper presents polymer matrix composites comprising majority of aerospace applications in structures, coating, tribology, structural health monitoring, electromagnetic shielding and shape memory applications. The capabilities of the ceramic matrix nanocomposites to providing the electromagnetic shielding for aircrafts and better tribological properties to suit space environments are discussed. Structural health monitoring capability of ceramic matrix nanocomposite is also discussed. The properties of resulting nanocomposite material with its disadvantages like cost and processing difficulties are discussed. The paper concludes after the discussion of the possible future perspectives and challenges in implementation and further development of polymer and ceramic nanocomposite materials.

  6. Ceramic Technology for Advanced Heat Engines Project

    Energy Technology Data Exchange (ETDEWEB)

    1989-08-01

    The Ceramic Technology for Advanced Heat Engines Project was developed by the Department of Energy's Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Advanced Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DoD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially.

  7. Moisture expansion of ceramic tiles produced using kaolin and granite wastes; Expansao por umidade de revestimentos ceramicos incorporados com residuos de granito e caulim

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, A.M.G.D.; Cartaxo, J.M.; Santana, L.N.L; Neves, G.A.; Ferreira, H.C., E-mail: ana.duartemendonca@gmail.com, E-mail: gelmires@dema.ufcg.edu.br, E-mail: lisiane@dema.ufcg.edu.br [Unidade Academica de Engenharia de Materiais, Universidade Federal de Campina Grande,Campina Grande, PB (Brazil); Menezes, R.R. [Departamento de Engenharia de Materiais, Universidade Federal da Paraiba, Joao Pessoa, PB (Brazil)

    2012-04-15

    Moisture expansion (ME) is the term used to describe the expansion of ceramic materials due to the adsorption of water. ME usually occurs slowly and is relatively small, but, it can damage the ceramic tiles adhesion to the underlayment, craze the glaze and lead to the development of cracks on ceramics bricks. In this work kaolin and granite wastes were incorporated in ceramic compositions aiming study their influence on the ME of ceramic tiles. Raw materials were processed and submitted to characterization: physical and mineralogical by laser diffraction particle size analysis, chemical analysis, thermo differential and thermogravimetric analysis and X-ray diffraction. Results showed that kaolin and granite wastes can be incorporated in ceramic composition because display characteristics similar to conventional not plastic ceramic materials, providing satisfactory ME results when compared to the ME limit value of 0.6 mm/m (0.06%) indicated by the ABNT for ceramic tiles. Compositions containing up to 20% of waste can be produced when firing above 1000 deg C. (author)

  8. Fracture of ceramic/ceramic/polymer trilayers for biomechanical applications.

    Science.gov (United States)

    Deng, Yan; Miranda, Pedro; Pajares, Antonia; Guiberteau, Fernando; Lawn, Brian R

    2003-12-01

    Fracture damage in trilayers consisting of outer and inner brittle layers bonded to a compliant (polycarbonate) substrate and subjected to concentrated surface loading is analyzed. The principal mode of fracture is radial cracking at the undersurface of the inner (core) layer, even in the strongest of core ceramics--other damage modes, including radial cracking in the outer (veneer) layer, are less invasive in these all-brittle coating systems. Tests on simple trilayer structures fabricated from glasses, sapphire, and dental ceramics are used to examine the dependence of the critical load for radial fracture in terms of relative outer/inner layer thickness and modulus, and inner layer strength. An explicit relation for the critical load, based on a flexing plate model in which the outer/inner bilayer is reduced to an "equivalent" monolithic coating with "effective" composite modulus, is used to examine these dependencies. The theoretical relation describes all the major trends in the critical load data over a broad range of variables, thus providing a sound basis for trilayer design. Relevance of the analysis to dental crowns and other biomechanical applications is a central theme of the study. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 828-833, 2003

  9. The effects of particle size, shape, density and flow characteristics on particle margination to vascular walls in cardiovascular diseases.

    Science.gov (United States)

    Ta, Hang T; Truong, Nghia P; Whittaker, Andrew K; Davis, Thomas P; Peter, Karlheinz

    2018-01-01

    Vascular-targeted drug delivery is a promising approach for the treatment of atherosclerosis, due to the vast involvement of endothelium in the initiation and growth of plaque, a characteristic of atherosclerosis. One of the major challenges in carrier design for targeting cardiovascular diseases (CVD) is that carriers must be able to navigate the circulation system and efficiently marginate to the endothelium in order to interact with the target receptors. Areas covered: This review draws on studies that have focused on the role of particle size, shape, and density (along with flow hemodynamics and hemorheology) on the localization of the particles to activated endothelial cell surfaces and vascular walls under different flow conditions, especially those relevant to atherosclerosis. Expert opinion: Generally, the size, shape, and density of a particle affect its adhesion to vascular walls synergistically, and these three factors should be considered simultaneously when designing an optimal carrier for targeting CVD. Available preliminary data should encourage more studies to be conducted to investigate the use of nano-constructs, characterized by a sub-micrometer size, a non-spherical shape, and a high material density to maximize vascular wall margination and minimize capillary entrapment, as carriers for targeting CVD.

  10. Geopolymers for Structural Ceramic Applications

    Science.gov (United States)

    2006-08-31

    Barbosa and MacKenzie, who observed the crystallization of leucite, kalsilite, quartz and cristobalite when heating potassium geopolymers to 1 000,C.4...Lobo, "A pair distribution function analyvsis of zeolite beta ," Microporous and Mesoporous Materials, 77[1] 55-66 (2005). "V. Petkov, V. Parvanov, P...of the American Ceramic Society, 85[5] 1235-1242 (2002). 20N. J. Hess, F. J. Espinosa, S. D. Conradson and W. J. Weber, " Beta radiation effects in

  11. NDE for heat engine ceramics

    Science.gov (United States)

    Klima, S. J.

    1984-01-01

    Radiographic, ultrasonic, and scanning laser acoustic microscopy (SLAM) techniques were used to characterize silicon nitride and silicon carbide MOR bars in various stages of fabrication. Conventional and microfocus x-ray techniques were found capable of detecting minute high density inclusions in as-received powders, green compacts, and fully densified specimens. Significant density gradients in sintered bars were observed by radiography, ultrasonic velocity, and SLAM. Ultrasonic attenuation was found sensitive to microstructural variations due to grain and void morphology and distribution. SLAM was also capable of detecting voids, inclusions, and cracks in finished test bars. It was determined that thermoacoustic microscopy techniques have promise for application to green and densified ceramics.

  12. Properties of ceramic candle filters

    Energy Technology Data Exchange (ETDEWEB)

    Pontius, D.H.

    1995-06-01

    The mechanical integrity of ceramic filter elements is a key issue for hot gas cleanup systems. To meet the demands of the advanced power systems, the filter components must sustain the thermal stresses of normal operations (pulse cleaning), of start-up and shut-down conditions, and of unanticipated process upsets such as excessive ash accumulation without catastrophic failure. They must also survive the various mechanical loads associated with handling and assembly, normal operation, and process upsets. For near-term filter systems, these elements must survive at operating temperatures of 1650{degrees}F for three years.

  13. Review - Fabrication of crystal-oriented barium-bismuth titanate ceramics in high magnetic field and subsequent reaction sintering

    Directory of Open Access Journals (Sweden)

    Satoshi Tanaka, Yusuke Tomita, Ryoichi Furushima, Hiroyuki Shimizu, Yutaka Doshida and Keizo Uematsu

    2009-01-01

    Full Text Available High magnetic field was applied to fabricate novel lead-free piezoelectric ceramics with a textured structure. A compact of crystallographically oriented grains was prepared by dry forming in a high magnetic field from a mixed slurry of bismuth titanate and barium titanate powders. Bismuth titanate particles with a size of about 1 μ m were used as the host material. In the forming process, the slurry was poured into a mold and set in a magnetic field of 10 T until completely dried. Bismuth titanate particles were highly oriented in the slurry under the magnetic field. The dried powder compact consisted of highly oriented bismuth titanate particles and randomly oriented barium titanate particles. Barium bismuth titanate ceramics with a- and b-axis orientations were successfully produced from the dried compact by sintering at temperatures above 1100 ° C.

  14. SUPPORTED DENSE CERAMIC MEMBRANES FOR OXYGEN SEPARATION

    Energy Technology Data Exchange (ETDEWEB)

    Timothy L. Ward

    2002-07-01

    Mixed-conducting ceramics have the ability to conduct oxygen with perfect selectivity at elevated temperatures, making them extremely attractive as membrane materials for oxygen separation and membrane reactor applications. While the conductivity of these materials can be quite high at elevated temperatures (typically 800-1000 C), much higher oxygen fluxes, or, alternatively, equivalent fluxes at lower temperatures, could be provided by supported thin or thick film membrane layers. Based on that motivation, the objective of this project was to explore the use of ultrafine aerosol-derived powder of a mixed-conducting ceramic material for fabrication of supported thick-film dense membranes. The project focused on the mixed-conducting ceramic composition SrCo{sub 0.5}FeO{sub x} (SCFO) because of the desirable permeability and stability of that material, as reported in the literature. Appropriate conditions to produce the submicron SrCo{sub 0.5}FeO{sub x} powder using aerosol pyrolysis were determined. Porous supports of the same composition were produced by partial sintering of a commercially obtained powder that possessed significantly larger particle size than the aerosol-derived powder. The effects of sintering conditions (temperature, atmosphere) on the porosity and microstructure of the porous discs were studied, and a standard support fabrication procedure was adopted. Subsequently, a variety of paste and slurry formulations were explored utilizing the aerosol-derived SCFO powder. These formulations were applied to the porous SCFO support by a doctor blade or spin coating procedure. Sintering of the supported membrane layer was then conducted, and additional layers were deposited and sintered in some cases. The primary characterization methods were X-ray diffraction and scanning electron microscopy, and room-temperature nitrogen permeation was used to assess defect status of the membranes.We found that non-aqueous paste/slurry formulations incorporating

  15. Particle physics

    CERN Document Server

    Carlsmith, Duncan

    2012-01-01

    Particle Physics is the first book to connect theory and experiment in particle physics. Duncan Carlsmith provides the first accessible exposition of the standard model with sufficient mathematical depth to demystify the language of gauge theory and Feynman diagrams used by researchers in the field. Carlsmith also connects theories to past, present, and future experiments.

  16. Ceramic Technology for Advanced Heat Engines Project

    Energy Technology Data Exchange (ETDEWEB)

    1990-08-01

    The Ceramic Technology For Advanced Heat Engines Project was developed by the Department of Energy's Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Advanced Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DOD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. An assessment of needs was completed, and a five year project plan was developed with extensive input from private industry. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic hearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines.

  17. Fibrous-Ceramic/Aerogel Composite Insulating Tiles

    Science.gov (United States)

    White, Susan M.; Rasky, Daniel J.

    2004-01-01

    Fibrous-ceramic/aerogel composite tiles have been invented to afford combinations of thermal-insulation and mechanical properties superior to those attainable by making tiles of fibrous ceramics alone or aerogels alone. These lightweight tiles can be tailored to a variety of applications that range from insulating cryogenic tanks to protecting spacecraft against re-entry heating. The advantages and disadvantages of fibrous ceramics and aerogels can be summarized as follows: Tiles made of ceramic fibers are known for mechanical strength, toughness, and machinability. Fibrous ceramic tiles are highly effective as thermal insulators in a vacuum. However, undesirably, the porosity of these materials makes them permeable by gases, so that in the presence of air or other gases, convection and gas-phase conduction contribute to the effective thermal conductivity of the tiles. Other disadvantages of the porosity and permeability of fibrous ceramic tiles arise because gases (e.g., water vapor or cryogenic gases) can condense in pores. This condensation contributes to weight, and in the case of cryogenic systems, the heat of condensation undesirably adds to the heat flowing to the objects that one seeks to keep cold. Moreover, there is a risk of explosion associated with vaporization of previously condensed gas upon reheating. Aerogels offer low permeability, low density, and low thermal conductivity, but are mechanically fragile. The basic idea of the present invention is to exploit the best features of fibrous ceramic tiles and aerogels. In a composite tile according to the invention, the fibrous ceramic serves as a matrix that mechanically supports the aerogel, while the aerogel serves as a low-conductivity, low-permeability filling that closes what would otherwise be the open pores of the fibrous ceramic. Because the aerogel eliminates or at least suppresses permeation by gas, gas-phase conduction, and convection, the thermal conductivity of such a composite even at

  18. Waste-to-resource preparation of a porous ceramic membrane support featuring elongated mullite whiskers with enhanced porosity and permeance

    NARCIS (Netherlands)

    Zhu, Li; Dong, Yingchao; Hampshire, Stuart; Cerneaux, Sophie; Winnubst, Aloysius J.A.

    2015-01-01

    Different from traditional particle packing structure, a porous structure of ceramic membrane support was fabricated, featuring elongated mullitewhiskers with enhanced porosity, permeance and sufficient mechanical strength. The effect of additives (MoO3and AlF3) and sintering procedureon open

  19. Ceramic Electrolyte Membrane Technology: Enabling Revolutionary Electrochemical Energy Storage

    Science.gov (United States)

    2015-10-05

    Sep-2014 Approved for Public Release; Distribution Unlimited Final Report: Ceramic Electrolyte Membrane Technology : Enabling Revolutionary...2601 30-Sep-2014 ABSTRACT Number of Papers published in peer-reviewed journals: Final Report: Ceramic Electrolyte Membrane Technology : Enabling... technology to fabricate larger LLZO ceramic membranes . The goal of this work is to develop ceramic processing technology to fabricate LLZO membranes that

  20. A fractographic study of clinically retrieved zirconia-ceramic and metal-ceramic fixed dental prostheses.

    Science.gov (United States)

    Pang, Zhen; Chughtai, Asima; Sailer, Irena; Zhang, Yu

    2015-10-01

    A recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia-ceramic and metal-ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia-ceramic systems occurred more frequently than those in metal-ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis. Vinyl-polysiloxane impressions of 12 zirconia-ceramic and 6 metal-ceramic FDPs with veneer fractures were taken from the patients at the end of a mean observation of 40.3±2.8 months. Epoxy replicas were produced from these impressions [1]. All replicas were gold coated, and inspected under the optical microscope and scanning electron microscope (SEM) for descriptive fractography. Among the 12 zirconia-ceramic FDPs, 2 had small chippings, 9 had large chippings, and 1 exhibited delamination. Out of 6 metal-ceramic FDPs, 5 had small chippings and 1 had large chipping. Descriptive fractographic analysis based on SEM observations revealed that fracture initiated from the wear facet at the occlusal surface in all cases, irrespective of the type of restoration. Zirconia-ceramic and metal-ceramic FDPs all fractured from microcracks that emanated from occlusal wear facets. The relatively low fracture toughness and high residual tensile stress in porcelain veneer of zirconia restorations may contribute to the higher chipping rate and larger chip size in zirconia-ceramic FDPs relative to their metal-ceramic counterparts. The low veneer/core interfacial fracture energy of porcelain-veneered zirconia may result in the occurrence of delamination in zirconia-ceramic FDPs. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. A fractographic study of clinically retrieved zirconia–ceramic and metal–ceramic fixed dental prostheses

    Science.gov (United States)

    Pang, Zhen; Chughtai, Asima; Sailer, Irena; Zhang, Yu

    2015-01-01

    Objectives A recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia–ceramic and metal–ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia–ceramic systems occurred more frequently than those in metal–ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis. Methods Vinyl-polysiloxane impressions of 12 zirconia–ceramic and 6 metal–ceramic FDPs with veneer fractures were taken from the patients at the end of a mean observation of 40.3 ± 2.8 months. Epoxy replicas were produced from these impressions [1]. All replicas were gold coated, and inspected under the optical microscope and scanning electron microscope (SEM) for descriptive fractography. Results Among the 12 zirconia–ceramic FDPs, 2 had small chippings, 9 had large chippings, and 1 exhibited delamination. Out of 6 metal–ceramic FDPs, 5 had small chippings and 1 had large chipping. Descriptive fractographic analysis based on SEM observations revealed that fracture initiated from the wear facet at the occlusal surface in all cases, irrespective of the type of restoration. Significance Zirconia–ceramic and metal–ceramic FDPs all fractured from microcracks that emanated from occlusal wear facets. The relatively low fracture toughness and high residual tensile stress in porcelain veneer of zirconia restorations may contribute to the higher chipping rate and larger chip size in zirconia–ceramic FDPs relative to their metal–ceramic counterparts. The low veneer/core interfacial fracture energy of porcelain-veneered zirconia may result in the occurrence of delamination in zirconia–ceramic FDPs. PMID:26233469

  2. Third-body Wear Damage Produced in CoCr Surfaces by Hydroxyapatite and Alumina Ceramic Debris: A 10-cycle Metal-on-Metal Simulator Study

    Directory of Open Access Journals (Sweden)

    Thomas Halim

    2015-12-01

    Full Text Available Ceramic particles are believed to be particularly abrasive due to their extreme hardness. Ceramic debris has been reported in retrieved total hip arthroplasty (THA due to chipping and fracture of alumina components or by flaking of hydroxyapatite from implant coatings. However there appears to be no abrasion ranking of such particle behavior. The hypotheses in this study were, i alumina particles would create large scratches in CoCr surfaces and ii hydroxyapatite would produce very mild scratching comparable to bone-cement particles. Hydroxyapatite beads came in two types of commercial powders while the flakes were scraped from retrieved femoral stems. Alumina beads came in two commercial powders and flakes were retrieved from a fractured ceramic head. Particle morphologies were determined by SEM and CoCr surface damage by interferometry and SEM. Six 38-mm MOM were mounted inverted in a hip simulator and run with ceramic particles inserted for a 10-second test. Surface-roughness ranking after 10-second abrasion test revealed that bone cement and hydroxyapatite produced least damage to CoCr surfaces while alumina produced the most. Alumina increased surface roughness 19-fold greater than either hydroxyapatite or bone-cement particles. The alumina debris produced numerous scratches typically 20-80 µm wide with some up to 140µm wide. Surprisingly the alumina beads and flakes were pulverized within the 10-second test interval and remained adherent to the CoCr surfaces. Additionally, the hydroxyapatite although also a ceramic had no more effect on CoCr than the bone-cement debris. Use of well-characterized and commercially available alumina and hydroxyapatite powders appeared advantageous for abrasion tests. These new data indicated that such ceramic powders have merit.

  3. Radiopaque strontium fluoroapatite glass-ceramics

    Directory of Open Access Journals (Sweden)

    Wolfram eHöland

    2015-10-01

    Full Text Available The controlled precipitation of strontium fluoroapatite crystals, was studied in four base glass compositions derived from the SiO2 – Al2O3 – Y2O3 – SrO – Na2O – K2O/Rb2O/Cs2O – P2O5 – F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: a Sr5(PO43F – leucite, KAlSi2O6 , b Sr5(PO43F – leucite, KAlSi2O6, and nano-sized NaSrPO4 c Sr5(PO43F – pollucite, CsAlSiO4 , and nano-sized NaSrPO4, d Sr5(PO43F – Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4.The proof of crystal phase formation was possible by X-ray diffraction (XRD. The microstructures, which were studied using scanning electron microscopy (SEM demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needlelike morphology. The study of the crystal growth of needlelike Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism.The formation of leucite, pollucite and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite – pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal

  4. Olivine, dolomite and ceramic filters in one vessel to produce clean gas from biomass.

    Science.gov (United States)

    Rapagnà, Sergio; Gallucci, Katia; Foscolo, Pier Ugo

    2018-01-01

    Heavy organic compounds produced during almond shells gasification in a steam and/or air atmosphere, usually called tar, are drastically reduced in the product gas by using simultaneously in one vessel a ceramic filter placed in the freeboard and a mixture of olivine and dolomite particles in the fluidized bed of the gasifier. The content of tar in the product gas during a reference gasification test with air, in presence of fresh olivine particles only, was 8600mg/Nm3 of dry gas. By gasifying biomass with steam at the same temperature level of 820°C in a bed of olivine and dolomite (20% by weight), and in the presence of a catalytic ceramic filter inserted in the freeboard of the fluidized bed gasifier, the level of tar was brought down to 57mg/Nm3 of dry producct gas, with a decrease of more than two orders of magnitude. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    CERN Document Server

    Blanc, Wilfried; Nguyen, Luan; Bhaktha, S N B; Sebbah, Patrick; Pal, Bishnu P; Dussardier, Bernard

    2011-01-01

    Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporati...

  6. Glass ceramic seals to inconel

    Science.gov (United States)

    McCollister, Howard L.; Reed, Scott T.

    1983-11-08

    A glass ceramic composition prepared by subjecting a glass composition comprising, by weight, 65-80% SiO.sub.2, 8-16%, Li.sub.2 O, 2-8% , Al.sub.2 O.sub.3, 1-8% K.sub.2 O, 1-5% P.sub.2 O.sub.5 and 1.5-7% B.sub.2 O.sub.3, to the following processing steps of heating the glass composition to a temperature sufficient to crystallize lithium metasilicate therein, holding the glass composition at a temperature and for a time period sufficient to dissolve the lithium metasilicate therein thereby creating cristobalite nucleii, cooling the glass composition and maintaining the composition at a temperature and for a time period sufficient to recrystallize lithium metasilicate therein, and thermally treating the glass composition at a temperature and for a time period sufficient to cause growth of cristobalite and further crystallization of lithium metasilicate producing a glass ceramic composition having a specific thermal expansion coefficient and products containing said composition.

  7. Surface scattering from ceramic phosphors

    Science.gov (United States)

    Lenef, Alan; Kelso, John; Peters, Christopher

    2012-02-01

    Scattering from phosphor converters and epitaxial surfaces is critical for solid state lighting device performance. Volume and surface scattering in solid state lighting devices can play a critical role in efficiency/efficacy, color points, and color angular consistency. Surface scattering in particular has not been well characterized in solid state lighting devices and can be complex to model. Because large angle scattering is important in lighting applications, surface scattering models generally require vector electromagnetic theory to avoid ambiguities often associated with scalar theory at these angles. Furthermore, surface features are often on the order of a few wavelengths, bringing ray tracing approaches into question. In this work, experimental angular scattering measurements are made on ceramic phosphor components where surface scattering dominates. The surface ceramic grain structure is responsible for the scattering. The results are compared to approximate statistical vector theory predictions that use the height autocorrelation functions as input. The autocorrelation measurements were derived from atomic-force microscopy topography measurements. Resulting predictions are in fairly good agreement with measurements.

  8. Randomized, controlled clinical trial of bilayer ceramic and metal-ceramic crown performance.

    Science.gov (United States)

    Esquivel-Upshaw, Josephine; Rose, William; Oliveira, Erica; Yang, Mark; Clark, Arthur E; Anusavice, Kenneth

    2013-04-01

    Analyzing the clinical performance of restorative materials is important, as there is an expectation that these materials and procedures will restore teeth and do no harm. The objective of this research study was to characterize the clinical performance of metal-ceramic crowns, core ceramic crowns, and core ceramic/veneer ceramic crowns based on 11 clinical criteria. An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study. The following three types of full crowns were fabricated: (1) metal-ceramic crown (MC) made from a Pd-Au-Ag-Sn-In alloy (Argedent 62) and a glass-ceramic veneer (IPS d.SIGN veneer); (2) non-veneered (glazed) lithium disilicate glass-ceramic crown (LDC) (IPS e.max Press core and e.max Ceram Glaze); and (3) veneered lithia disilicate glass-ceramic crown (LDC/V) with glass-ceramic veneer (IPS Empress 2 core and IPS Eris). Single-unit crowns were randomly assigned. Patients were recalled for each of 3 years and were evaluated by two calibrated clinicians. Thirty-six crowns were placed in 31 patients. A total of 12 crowns of each of the three crown types were studied. Eleven criteria were evaluated: tissue health, marginal integrity, secondary caries, proximal contact, anatomic contour, occlusion, surface texture, cracks/chips (fractures), color match, tooth sensitivity, and wear (of crowns and opposing enamel). Numerical rankings ranged from 1 to 4, with 4 being excellent, and 1 indicating a need for immediate replacement. Statistical analysis of the numerical rankings was performed using a Fisher's exact test. There was no statistically significant difference between performance of the core ceramic crowns and the two veneered crowns at year 1 and year 2 (p > 0.05). All crowns were rated either as excellent or good for each of the clinical criteria; however, between years 2 and 3, gradual roughening of the occlusal surface occurred in some of the ceramic-ceramic crowns, possibly caused by dissolution and

  9. Randomized, Controlled Clinical Trial of Bilayer Ceramic and Metal-Ceramic Crown Performance

    Science.gov (United States)

    Esquivel-Upshaw, Josephine; Rose, William; Oliveira, Erica; Yang, Mark; Clark, Arthur E.; Anusavice, Kenneth

    2013-01-01

    Purpose Analyzing the clinical performance of restorative materials is important, as there is an expectation that these materials and procedures will restore teeth and do no harm. The objective of this research study was to characterize the clinical performance of metal-ceramic crowns, core ceramic crowns, and core ceramic/veneer ceramic crowns based on 11 clinical criteria. Materials and Methods An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study. The following three types of full crowns were fabricated: (1) metal-ceramic crown (MC) made from a Pd-Au-Ag-Sn-In alloy (Argedent 62) and a glass-ceramic veneer (IPS d.SIGN veneer); (2) non-veneered (glazed) lithium disilicate glass-ceramic crown (LDC) (IPS e.max Press core and e.max Ceram Glaze); and (3) veneered lithia disilicate glass-ceramic crown (LDC/V) with glass-ceramic veneer (IPS Empress 2 core and IPS Eris). Single-unit crowns were randomly assigned. Patients were recalled for each of 3 years and were evaluated by two calibrated clinicians. Thirty-six crowns were placed in 31 patients. A total of 12 crowns of each of the three crown types were studied. Eleven criteria were evaluated: tissue health, marginal integrity, secondary caries, proximal contact, anatomic contour, occlusion, surface texture, cracks/chips (fractures), color match, tooth sensitivity, and wear (of crowns and opposing enamel). Numerical rankings ranged from 1 to 4, with 4 being excellent, and 1 indicating a need for immediate replacement. Statistical analysis of the numerical rankings was performed using a Fisher’s exact test. Results There was no statistically significant difference between performance of the core ceramic crowns and the two veneered crowns at year 1 and year 2 (p > 0.05). All crowns were rated either as excellent or good for each of the clinical criteria; however, between years 2 and 3, gradual roughening of the occlusal surface occurred in some of the ceramic-ceramic crowns

  10. Metals and Ceramics Division materials science program. Annual progress report for period ending June 30, 1981

    Energy Technology Data Exchange (ETDEWEB)

    McHargue, C.J. (comp.)

    1981-09-01

    Information is presented concerning the theoretical studies of metals and alloys; x-ray diffraction research; structural ceramics; structure of coal; analytical and high-voltage electron microscopy; deformation and mechanical properties; mechanisms of surface and solid-state reactions; physical properties research; metastable materials; neutron radiation effects; charged particle radiation effects; theory and modeling of radiation effects; facility and advanced technique development; fundamentals of welding and joining; and studies in nondestructive evaluation.

  11. [Release of toxic agents from ceramic utensils].

    Science.gov (United States)

    Herrmann, H J

    1978-01-01

    Under the influence of acidic agents, ceramic glazes and decorations for ceramics may release certain toxicants, especially lead and cadmium. Both elements are essential constituents of ceramic colours and glazes; their release to acidic foods is technologically unavoidable, but it may be minimized by the utilization of appropriate decoration agents and techniques. In most industrial countries, the release of toxicants from utensils is severely limited, the maximum permissible values and the methods of test and analysis being in part very different and not always in agreement with the demands and conditions of practice. The problems related to the release of toxicants from ceramic utensils are treated from the aspects of ceramics, test techniques, analytics, toxicology and food law, with special regard to the necessity for a well-balanced compromise between the justified hygienic demands of health protection and the actual technological possibilities. The endeavours of the ceramic industry of the GDF to produce ceramic utensils releasing as little toxicants as possible are outlined.

  12. Ceramic restoration repair: report of two cases

    Directory of Open Access Journals (Sweden)

    Luís Henrique Araújo Raposo

    2009-04-01

    Full Text Available The esthetic and functional rehabilitation of patients with multiple missing teeth can be performed with several techniques and materials. Ceramic restorations provide reliable masticatory function and good esthetics. However, fracture can occur in some cases due to their brittle behavior. In some cases, the replacement of an extensive prosthesis is a problem due to the high treatment cost. In this paper, two cases are presented, in which fractures occurred in extensive metal-ceramic fixed partial dentures, and their replacement was not possible. Ceramic repair was chosen and the sequences of treatment with and without presence of the ceramic fragment are also discussed. The cases illustrate that, in some situations, fractured metal-ceramic partial dentures can be successfully repaired when prosthetic replacement is not a choice. Prosthodontists must use alternatives that allow a reliable repair to extensive metal-ceramic fixed partial dentures. Surface preparation of the ceramic with hydrofluoric acid in conjunction with a silane coupling agent is essential for a predictable bonding of composite resin. The repair performed with composite resin is an esthetic and functional alternative when extensive fixed partial dentures cannot be replaced.

  13. Tribology of ceramics: Report of the Committee on Tribology of Ceramics

    Science.gov (United States)

    1988-01-01

    The current state of knowledge of ceramic surface structures, composition, and reactivity is reviewed. The tribological requirements of advanced mechanical systems now being deployed (in particular, heat engines) exceed the capabilities of traditional metallic-based materials because of the high temperatures encountered. Advanced ceramic materials for such applications are receiving intense scrutiny, but there is a lack of understanding of the properties and behavior of ceramic surfaces and the influence of processing on the properties of ceramics is described. The adequacy of models, ranging form atomic to macro, to describe and to predict ceramic friction and wear are discussed, as well as what is known about lubrication at elevated temperatures. From this analysis, recommendations are made for coordination, research, and development that will lead to better performance of ceramic materials in tribological systems.

  14. A challenge to develop a continuous centrifuge for precision particle size fractionation

    Science.gov (United States)

    Kawahara, Jun-Ichi; Ito, Yoichiro

    2007-03-01

    In producing particles, including nanoparticles, of narrow particle size distribution, synthetic methods have been widely used, since considerable amounts of products could rather simply be obtained. On the other hand, such sort of processes have a significant drawback, since applicable range of materials is rather limited. Under such circumstances, we have started to develop a continuous centrifuge for precision particle size fractionation, which could be applied, in principle, to any material, in stark contrast to synthetic processes. Besides, continuous systems could realize not only considerable processing capacity but also the exact particle sizes we want, in contrast to batch systems. Furthermore, since such methodology is based upon principles completely different from those of synthetic processes, it could complement them, by further sharpening the size distribution of the products, for example. We chose liquid phase as separation medium, since it enables high processing capacity and also suppresses the possible aggregation of the particles. At present, there are no continuous particle size fractionation systems in liquid phase applicable to the size range below several micrometers. The designs to widen this range down to submicrometers and further, together with realization of high resolution, are to be discussed.

  15. Flight-vehicle materials, structures, and dynamics - Assessment and future directions. Vol. 3 - Ceramics and ceramic-matrix composites

    Science.gov (United States)

    Levine, Stanley R. (Editor)

    1992-01-01

    The present volume discusses ceramics and ceramic-matrix composites in prospective aerospace systems, monolithic ceramics, transformation-toughened and whisker-reinforced ceramic composites, glass-ceramic matrix composites, reaction-bonded Si3N4 and SiC composites, and chemical vapor-infiltrated composites. Also discussed are the sol-gel-processing of ceramic composites, the fabrication and properties of fiber-reinforced ceramic composites with directed metal oxidation, the fracture behavior of ceramic-matrix composites (CMCs), the fatigue of fiber-reinforced CMCs, creep and rupture of CMCs, structural design methodologies for ceramic-based materials systems, the joining of ceramics and CMCs, and carbon-carbon composites.

  16. Elementary particles

    Science.gov (United States)

    Fritzsch, Harald; Heusch, Karin

    Introduction -- Electrons and atomic nuclei -- Quantum properties of atoms and particles -- The knives of Democritus -- Quarks inside atomic nuclei -- Quantum electrodynamics -- Quantum chromodynamics -- Mesons, baryons, and quarks -- Electroweak interactions -- Grand unification -- Conclusion.

  17. Stabilization of Heavy Metal Particles in AL2O3-W Suspensions

    Directory of Open Access Journals (Sweden)

    Kędzierska – Sar A.

    2016-09-01

    Full Text Available Ceramic – metal composites are widely used materials in a whole world. There were invented many fabrication methods for those kind of materials, but still exists some problems which need to be fixed. Stability of high density metal particles (e.g. W, Mo, Nb in ceramic-metal composite suspensions is one of crucial issues to be solved in order to obtain homogenous composite material with desired properties such as high fracture toughness, mechanical strength, hardness, wear resistance.

  18. Surface treatments for repair of feldspathic, leucite - and lithium disilicate-reinforced glass ceramics using composite resin.

    Science.gov (United States)

    Neis, Christian Alencar; Albuquerque, Nadine Luísa Guimarães; Albuquerque, Ivo de Souza; Gomes, Erica Alves; Souza-Filho, Celso Bernardo de; Feitosa, Victor Pinheiro; Spazzin, Aloisio Oro; Bacchi, Atais

    2015-01-01

    The aim of this study was to evaluate the efficacy of different surface conditioning methods on the microtensile bond strength of a restorative composite repair in three types of dental ceramics: lithium disilicate-reinforced, leucite-reinforced and feldspathic. Twelve blocks were sintered for each type of ceramic (n=3) and stored for 3 months in distilled water at 37 °C. The bonding surface of ceramics was abraded with 600-grit SiC paper. Surface treatments for each ceramic were: GC (control) - none; GDB - diamond bur #30 µm; GHF - hydrofluoric acid (10%); GT- tribochemical silica coating (45-μm size particles). Treatments were followed by cleaning with phosphoric acid 37% for 20 s + silane + adhesive. The composite resin was used as restorative material. After repair, samples were subjected to thermocycled ageing (10,000 cycles between 5 °C and 55 °C for 30 s). Thereafter, the samples were sectioned into 1.0 mm2 sticks and tested for microtensile bond strength with 0.5 mm/min crosshead speed. Data were compared by two-way ANOVA and Tukey's test (α=0.05). The superficial wear with diamond bur proved to be suitable for feldspathic porcelain and for leucite-reinforced glass ceramic while hydrofluoric acid-etching is indicated for repairs in lithium disilicate-reinforced ceramic; tribochemical silica coating is applicable to leucite-reinforced ceramic. Predominance of adhesive failures was observed (>85% in all groups). In conclusion, the success of surface treatments depends on the type of ceramic to be repaired.

  19. Porous ceramic scaffolds with complex architectures

    Energy Technology Data Exchange (ETDEWEB)

    Saiz, Eduardo; Munch, Etienne; Franco, Jaime; Deville, Sylvain; Hunger, Phillip; Saiz, Eduardo; Tomsia, Antoni P.

    2008-03-15

    This work compares two novel techniques for the fabrication of ceramic scaffolds for bone tissue engineering with complex porosity: robocasting and freeze casting. Both techniques are based on the preparation of concentrated ceramic suspensions with suitable properties for the process. In robocasting, the computer-guided deposition of the suspensions is used to build porous materials with designed three dimensional (3-D) geometries and microstructures. Freeze casting uses ice crystals as a template to form porous lamellar ceramic materials. Preliminary results on the compressive strengths of the materials are also reported.

  20. Method of making multilayered titanium ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, George T., II; Hansen; Jeffrey S.; Oden; Laurance L.; Turner; Paul C.; Ochs; Thomas L.

    1998-08-25

    A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body follwed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet.

  1. Strong ultrasonic microwaves in ferroelectric ceramics.

    Science.gov (United States)

    Arlt, G

    1998-01-01

    It is well known that ferroelectric materials have piezoelectric properties which allow the transformation of electrical signals into mechanical signals and vice versa. The transducer action normally is restricted to frequencies up to the mechanical resonance frequency of the sample. There are, however, two mechanisms which allow transducer action in ferroelectric ceramics at much higher frequencies: one is the normal piezoelectric effect in a ferroelectric ceramic in which the crystallites have periodic domain structures, the other is a domain wall effect in which ferroelastic domain walls in a periodic domain structure are powerful shear wave emitters. Both mechanisms give rise to extensive dielectric losses in ceramics at microwave frequencies.

  2. Nanostructure and surface activation of mayenite (12CaO·7Al2O3) ceramics via femtosecond laser irradiation in solvents

    Science.gov (United States)

    Visbal, Heidy; Hirano, Minami; Omura, Takuya; Shimizu, Masahiro; Takaishi, Taigo; Hirao, Kazuyuki

    2017-07-01

    Mayenite (12CaO·7Al2O3) is a highly interesting functional material due to the wide variety of its possible future applications. In this study, we used femtosecond laser irradiation in several solvents with varying polarities to increase the specific surface area of 12CaO·7Al2O3 ceramics and reduce their particle size without any structural degradation or loss of crystallinity. We observed that when femtosecond laser irradiation was applied to solvents bearing hydroxyl groups, a smaller particle size was obtained with the particle size decreasing as the polarity of the solvent increased. Using infrared spectroscopy, we confirmed the presence of hydroxyl and carbonyl surface functional groups at the surface of 12CaO·7Al2O3 ceramics after femtosecond laser irradiation. This is attributed to the direct chemical bonds breaking of the solvent via multiphoton ionization and/or tunneling ionization, followed by the Coulomb explosion and the subsequent production of ions that are adsorbed on the surfaces of 12CaO·7Al2O3 ceramics. Femtosecond laser irradiation in polar solvents with hydroxyl groups can reduce the particle size and increase the specific surface area without degradation or loss of crystallinity of 12CaO·7Al2O3 ceramics. Additionally, this method can be used for the surface modification and introduction of functional groups on the 12CaO·7Al2O3 ceramics surface.

  3. Auroral particles

    Science.gov (United States)

    Evans, David S.

    1987-01-01

    The problems concerning the aurora posed prior to the war are now either solved in principle or were restated in a more fundamental form. The pre-war hypothesis concerning the nature of the auroral particles and their energies was fully confirmed, with the exception that helium and oxygen ions were identified as participating in the auroral particle precipitation in addition to the protons. The nature of the near-Earth energization processes affecting auroral particles was clarified. Charged particle trajectories in various electric field geometries were modeled. The physical problems have now moved from determining the nature and geometry of the electric fields, which accelerate charged particles near the Earth, to accounting for the existence of these electric fields as a natural consequence of the solar wind's interaction with Earth. Ultimately the reward in continuing the work in auroral and magnetospheric particle dynamics will be a deeper understanding of the subtleties of classical electricity and magnetism as applied to situations not blessed with well-defined and invariant geometries.

  4. Bond strength, microhardness, and core/veneer interface quality of an all-ceramic system.

    Science.gov (United States)

    Fahmy, Nadia Z

    2010-02-01

    This study was designed to evaluate three veneering materials for an all-ceramic alumina system in terms of bond strength, microhardness, and core/veneer interface quality. Fifteen In-Ceram cores were constructed for this study, forming three groups of five specimens each divided by the veneering ceramic disc fired on the occlusal surface of the alumina core: Vitadur N, Vitadur Alpha, or VM7. The specimens underwent shear bond and microhardness testing. Gross examination of debonded discs by SEM and EDAX analysis was conducted. Data for shear bond strength (SBS) and microhardness were presented as means and standard deviation (SD) values. One-way ANOVA and Duncan's post hoc test were used for pairwise comparison between the means when ANOVA test was significant. VM7 showed the highest shear bond value and lowest microhardness values of the three tested veneering materials. No statistically significant difference was evident between the SBSs of Vitadur N and Vitadur Alpha to the alumina cores. Vitadur Alpha showed statistically the highest mean VHN, followed by Vitadur N, while VM7 showed statistically the lowest mean values of VHN. In-Ceram core/Vitadur N disc debondings appeared to be interfacial by complete delaminations, leaving a shiny visible and quite distinct area, whereas there appeared to be perfect adhesion between the core and VM7 veneering material. VM7 appeared to possess ultra-fine texture with intimate contact to the core, forming what seemed like a transition zone where the ceramic and core appeared to blend for a distance. VM7's finer particle size has improved the core/veneer bond strength and decreased micohardness values. This new veneering material will probably enhance the performance and esthetics of the In-Ceram system.

  5. Resin bond to indirect composite and new ceramic/polymer materials: a review of the literature.

    Science.gov (United States)

    Spitznagel, Frank A; Horvath, Sebastian D; Guess, Petra C; Blatz, Markus B

    2014-01-01

    Resin bonding is essential for clinical longevity of indirect restorations. Especially in light of the increasing popularity of computer-aided design/computer-aided manufacturing-fabricated indirect restorations, there is a need to assess optimal bonding protocols for new ceramic/polymer materials and indirect composites. The aim of this article was to review and assess the current scientific evidence on the resin bond to indirect composite and new ceramic/polymer materials. An electronic PubMed database search was conducted from 1966 to September 2013 for in vitro studies pertaining the resin bond to indirect composite and new ceramic/polymer materials. The search revealed 198 titles. Full-text screening was carried out for 43 studies, yielding 18 relevant articles that complied with inclusion criteria. No relevant studies could be identified regarding new ceramic/polymer materials. Most common surface treatments are aluminum-oxide air-abrasion, silane treatment, and hydrofluoric acid-etching for indirect composite restoration. Self-adhesive cements achieve lower bond strengths in comparison with etch-and-rinse systems. Thermocycling has a greater impact on bonding behavior than water storage. Air-particle abrasion and additional silane treatment should be applied to enhance the resin bond to laboratory-processed composites. However, there is an urgent need for in vitro studies that evaluate the bond strength to new ceramic/polymer materials. This article reviews the available dental literature on resin bond of laboratory composites and gives scientifically based guidance for their successful placement. Furthermore, this review demonstrated that future research for new ceramic/polymer materials is required. © 2014 Wiley Periodicals, Inc.

  6. Comparison of shear bond strength of two veneering ceramics to zirconia.

    Science.gov (United States)

    Rismanchian, Mansour; Shafiei, Soufia; Askari, Navid; Khodaeian, Niloufar

    2012-09-01

    Chip-off fracture of veneering porcelain has been described as the most frequent reason for the failure of zirconia-based fixed partial dentures. The purpose of this study was to evaluate the shear bond strength (SBS) of two commercial zirconia core ceramics to their corresponding veneering ceramics. Zirconia disks with 7-mm diameter and 3-mm height were prepared (Cercon and Biodenta systems) and veneered with recommended layering ceramics (Cercon ceram and 2 in 1 ceramic, respectively) (n = 10). The disks were polished with diamond paste and airborne-particle abraded before layering. The specimens were mounted in a T-shaped metal holder using autopolymerized acrylic resin and stored in 37°C distilled water for one week, after which they were subjected to thermal cycling. SBS of zirconia core to veneering ceramic was measured using a universal testing machine and failure modes were determined microscopically. Data were analyzed using t test (α < 0.05). Mean (±SD) SBS values were 27.19(±3.43) and 28.22(±4.08) MPa for Cercon and Biodenta systems, respectively, with no significant difference. Biodenta system showed more adhesive failure compared to more combined (adhesive and cohesive) failures in Cercon system. Within the limitations of this study it can be concluded that SBS of Biodenta and Cercon specimens were nearly the same, but the fracture mode of these two systems were different. Since Biodenta fracture pattern was predominantly adhesive, it seems that maybe Biodenta porcelain was stronger than Cercon porcelain where as its adhesive bond was weaker.

  7. Influence of thermal and mechanical cycling on the flexural strength of ceramics with titanium or gold alloy frameworks.

    Science.gov (United States)

    Oyafuso, Denise Kanashiro; Ozcan, Mutlu; Bottino, Marco Antonio; Itinoche, Marcos Koiti

    2008-03-01

    The aim of this study was to evaluate the effect of thermal and mechanical cycling alone or in combination, on the flexural strength of ceramic and metallic frameworks cast in gold alloy or titanium. Metallic frameworks (25 mm x 3 mm x 0.5 mm) (N=96) cast in gold alloy or commercial pure titanium (Ti cp) were obtained using acrylic templates. They were airborne particle-abraded with 150 microm aluminum oxide at the central area of the frameworks (8 mm x 3 mm). Bonding agent and opaque were applied on the particle-abraded surfaces and the corresponding ceramic for each metal was fired onto them. The thickness of the ceramic layer was standardized by positioning the frameworks in a metallic template (height: 1 mm). The specimens from each ceramic-metal combination (N=96, n=12 per group) were randomly assigned into four experimental fatigue conditions, namely water storage at 37 degrees C for 24h (control group), thermal cycling (3000 cycles, between 4 and 55 degrees C, dwell time: 10s), mechanical cycling (20,000 cycles under 10 N load, immersion in distilled water at 37 degrees C) and, thermal and mechanical cycling. A flexural strength test was performed in a universal testing machine (crosshead speed: 1.5 mm/min). Data were statistically analyzed using two-way ANOVA and Tukey's test (alpha=0.05). The mean flexural strength values for the ceramic-gold alloy combination (55+/-7.2MPa) were significantly higher than those of the ceramic-Ti cp combination (32+/-6.7 MPa) regardless of the fatigue conditions performed (pgold alloy (52+/-6.6 and 53+/-5.6 MPa, respectively) and ceramic-Ti cp combinations (29+/-6.8 and 29+/-6.8 MPa, respectively) compared to the control group (58+/-7.8 and 39+/-5.1 MPa, for gold and Ti cp, respectively) (pgold alloy frameworks exhibited a residue of ceramic material on the surface in all experimental groups. Mechanical and thermo-mechanical fatigue conditions decreased the flexural strength values for both ceramic-gold alloy and ceramic

  8. Emission analysis of Sm{sup 3+} and Dy{sup 3+}: Ba{sub 3}Y{sub 2}WO{sub 9} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Raju, K. Vemasevana; Raju, C. Nageswara; Sailaja, S. [Department of Physics (Research Centre), S.V. Degree College, Kadapa 516003,YSR District (India); Dhoble, S.J. [Department of Physics, RTM Nagpur University, Nagpur 440 001 (India); Reddy, B. Sudhakar, E-mail: drbsreddyphd@gmail.com [Department of Physics (Research Centre), S.V. Degree College, Kadapa 516003,YSR District (India)

    2013-02-15

    A series of Sm{sup 3+} and Dy{sup 3+} ions activated Ba{sub 3}Y{sub 2}WO{sub 9} (BaYW) ceramics were synthesized by using a conventional solid state reaction method. Photoluminescence spectra of Sm{sup 3+} and Dy{sup 3+}: BaYW ceramics have shown strong reddish-orange (596 nm) and blue (494 nm) emission. The tetragonal phase structure has been assigned to the prepared ceramics by the measurement of X-ray diffraction (XRD) profiles. Agglomeration and the nanometer particle size (130 nm to 220 nm) were observed from the SEM images of the ceramics. The functional groups like O--H, CO{sub 3}, W--O bonds, Y--O bonds and the elements such as Ba, Y, W, O, Sm and Dy present in the prepared ceramics were identified by measuring the FTIR and EDAX spectra. In this contribution, we have reported the emission properties of Sm{sup 3+} and Dy{sup 3+}: BaYW ceramics to explore them as novel optical materials and also reported the effect of Sm{sup 3+} and Dy{sup 3+} concentration on the luminescence behavior. Decay kinetics of the prominent emission transitions of Sm{sup 3+} and Dy{sup 3+}: BaYW ceramics are also discussed. - Highlights.: Black-Right-Pointing-Pointer Sm{sup 3+} and Dy{sup 3+}: BaYW ceramics were prepared by solid state reaction method. Black-Right-Pointing-Pointer Sm{sup 3+}: BaYW ceramics have shown an intense reddish-orange color emission. Black-Right-Pointing-Pointer Dy{sup 3+}: BaYW ceramics have shown an intense blue color emission. Black-Right-Pointing-Pointer The nature of the transitions observed in the emission spectra is explained. Black-Right-Pointing-Pointer Phenomenon of concentration quenching has been clearly discussed.

  9. Manufacturing of planar ceramic interconnects

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, B.L.; Coffey, G.W.; Meinhardt, K.D.; Armstrong, T.R. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-12-31

    The fabrication of ceramic interconnects for solid oxide fuel cells (SOFC) and separator plates for electrochemical separation devices has been a perennial challenge facing developers. Electrochemical vapor deposition (EVD), plasma spraying, pressing, tape casting and tape calendering are processes that are typically utilized to fabricate separator plates or interconnects for the various SOFC designs and electrochemical separation devices. For sake of brevity and the selection of a planar fuel cell or gas separation device design, pressing will be the only fabrication technique discussed here. This paper reports on the effect of the characteristics of two doped lanthanum manganite powders used in the initial studies as a planar porous separator for a fuel cell cathode and as a dense interconnect for an oxygen generator.

  10. Nondestructive evaluation of sintered ceramics

    Science.gov (United States)

    Baaklini, George Y.; Klima, Stanley J.; Sanders, William A.

    1988-01-01

    Radiography and several acoustic and thermoacoustic microscopy techniques are investigated for application to structural ceramics for advanced heat engines. A comparison is made of the results obtained from the use of scanning acoustic microscopy (SAM), scanning laser acoustic microscopy (SLAM), and thermoacoustic microscopy (TAM). These techniques are evaluated on research samples of green and sintered monolithic silicon nitrides and silicon carbides in the form of modulus-of-rupture (MOR) bars containing deliberately introduced flaws. Strengths and limitations of the techniques are described, with the emphasis being on statistics of detectability of flaws that constitute potential fracture origins. Further, it is shown that radiographic evaluation and guidance helped develop uniform high-density Si3N4 MOR bars with improved four-point flexural strength (875, 544, and 462 MPa at room temperature, 1200 C, 1370 C, respectively) and reduced scatter in bend strength.

  11. Mechanical behaviour of structural ceramics

    Directory of Open Access Journals (Sweden)

    Bueno, S.

    2007-06-01

    Full Text Available The use of ceramic materials in structural applications is limited by the lack of reliability associated with brittle fracture behaviour. In order to extend the structural use of ceramics, the design of microstructures which exhibit flaw tolerance due to toughening mechanisms which produce an increase in crack growth resistance during crack propagation has been proposed. This work is a review of the mechanical behaviour of structural ceramic materials and its characterisation. Firstly, the basic brittle fracture parameters and the statistical criteria to determine the probability of exceeding the safety factors demanded for a particular application are analysed. Then, the toughening mechanisms which can be developed in the materials through microstructural design as well as the mechanical characterisation of toughened ceramics are discussed. The experimental values of linear elastic fracture toughness parameters (critical stress intensity factor, KIC, and critical energy release rate, GIC are not intrinsic properties for toughened materials and depend on crack length and the loading system. In this work, the different mechanical parameters proposed to characterise such materials are reviewed. The following fracture parameters are analysed: work of fracture (γWOF, critical J-integral value (JIC and R-curve. For the determination, stable fracture tests are proposed in order to ensure that the energy provided during the test is no more than the necessary one for crack propagation.

    El uso de los materiales cerámicos en aplicaciones estructurales está limitado por la falta de fiabilidad asociada a su comportamiento frágil durante la fractura. Para extender su aplicación se ha propuesto el diseño de microestructuras que presenten tolerancia a los defectos debido a la actuación de mecanismos de refuerzo. Este trabajo es una puesta al día sobre el estudio del comportamiento mecánico de los materiales cerámicos estructurales y su

  12. Hybrid Ti-ceramic bionanomaterials for medical engineering

    Energy Technology Data Exchange (ETDEWEB)

    Niespodziana, K.; Miklaszewski, A.; Jurczyk, M. [Institute of Materials Science and Engineering, Poznan University of Technology, Sklodowska-Curie 5 Sq., 60-965 Poznan (Poland); Jurczyk, K. [Department of Conservative Dentistry and Periodontology, University of Medical Sciences, Bukowska 70 St., 60-812 Poznan (Poland)

    2010-05-15

    In the last decade a great interest has been observed in the field of nanoscale materials. Commercially pure titanium as well as titanium alloys have become predominant in implantology. Low hardness and poor tribiological properties of titanium alloys may become critical factor when wear phenomena are involved. One of the methods that allow the change of properties of Ti alloys is the production of nanocomposites, which will exhibit the favorable mechanical properties of titanium and excellent biocompatibility and bioactivity of ceramics. In this work hybrid Ti-x wt% ceramic (45S5 Bioglass, SiO{sub 2}, Al{sub 2}O{sub 3}) bionanocomposites (x =0, 3 and 10) were prod-uced by the combination of mechanical alloying and powder metallurgical process. Reinforced by 45S5 Bioglass, SiO{sub 2} or Al{sub 2}O{sub 3} particles, Vickers hardness of Ti-based nanocomposite is higher from two to six times in comparison with pure microcrystalline Ti. Additionally, the experimental results show that in Ringer's solution at 37 C, Ti-based nanocomposites have good corrosion resistance. On the other hand, in vitro studies show that these bionanocomposites have excellent biocompatibility and could integrate with bone (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Salt splitting using ceramic membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kurath, D.E. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-10-01

    Many radioactive aqueous wastes in the DOE complex have high concentrations of sodium that can negatively affect waste treatment and disposal operations. Sodium can decrease the durability of waste forms such as glass and is the primary contributor to large disposal volumes. Waste treatment processes such as cesium ion exchange, sludge washing, and calcination are made less efficient and more expensive because of the high sodium concentrations. Pacific Northwest National Laboratory (PNNL) and Ceramatec Inc. (Salt Lake City UT) are developing an electrochemical salt splitting process based on inorganic ceramic sodium (Na), super-ionic conductor (NaSICON) membranes that shows promise for mitigating the impact of sodium. In this process, the waste is added to the anode compartment, and an electrical potential is applied to the cell. This drives sodium ions through the membrane, but the membrane rejects most other cations (e.g., Sr{sup +2}, Cs{sup +}). The charge balance in the anode compartment is maintained by generating H{sup +} from the electrolysis of water. The charge balance in the cathode is maintained by generating OH{sup {minus}}, either from the electrolysis of water or from oxygen and water using an oxygen cathode. The normal gaseous products of the electrolysis of water are oxygen at the anode and hydrogen at the cathode. Potentially flammable gas mixtures can be prevented by providing adequate volumes of a sweep gas, using an alternative reductant or destruction of the hydrogen as it is generated. As H{sup +} is generated in the anode compartment, the pH drops. The process may be operated with either an alkaline (pH>12) or an acidic anolyte (pH <1). The benefits of salt splitting using ceramic membranes are (1) waste volume reduction and reduced chemical procurement costs by recycling of NaOH; and (2) direct reduction of sodium in process streams, which enhances subsequent operations such as cesium ion exchange, calcination, and vitrification.

  14. Compact Ceramic Microchannel Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Lewinsohn, Charles [Ceramatec, Inc., Salt Lake City, UT (United States)

    2016-10-31

    The objective of the proposed work was to demonstrate the feasibility of a step change in power plant efficiency at a commercially viable cost, by obtaining performance data for prototype, compact, ceramic microchannel heat exchangers. By performing the tasks described in the initial proposal, all of the milestones were met. The work performed will advance the technology from Technology Readiness Level 3 (TRL 3) to Technology Readiness Level 4 (TRL 4) and validate the potential of using these heat exchangers for enabling high efficiency solid oxide fuel cell (SOFC) or high-temperature turbine-based power plants. The attached report will describe how this objective was met. In collaboration with The Colorado School of Mines (CSM), specifications were developed for a high temperature heat exchanger for three commercial microturbines. Microturbines were selected because they are a more mature commercial technology than SOFC, they are a low-volume and high-value target for market entry of high-temperature heat exchangers, and they are essentially scaled-down versions of turbines used in utility-scale power plants. Using these specifications, microchannel dimensions were selected to meet the performance requirements. Ceramic plates were fabricated with microchannels of these dimensions. The plates were tested at room temperature and elevated temperature. Plates were joined together to make modular, heat exchanger stacks that were tested at a variety of temperatures and flow rates. Although gas flow rates equivalent to those in microturbines could not be achieved in the laboratory environment, the results showed expected efficiencies, robust operation under significant temperature gradients at high temperature, and the ability to cycle the stacks. Details of the methods and results are presented in this final report.

  15. Nuclear Rocket Ceramic Metal Fuel Fabrication Using Tungsten Powder Coating and Spark Plasma Sintering

    Science.gov (United States)

    Barnes, M. W.; Tucker, D. S.; Hone, L.; Cook, S.

    2017-01-01

    Nuclear thermal propulsion is an enabling technology for crewed Mars missions. An investigation was conducted to evaluate spark plasma sintering (SPS) as a method to produce tungsten-depleted uranium dioxide (W-dUO2) fuel material when employing fuel particles that were tungsten powder coated. Ceramic metal fuel wafers were produced from a blend of W-60vol% dUO2 powder that was sintered via SPS. The maximum sintering temperatures were varied from 1,600 to 1,850 C while applying a 50-MPa axial load. Wafers exhibited high density (>95% of theoretical) and a uniform microstructure (fuel particles uniformly dispersed throughout tungsten matrix).

  16. Modeling the mechanical behavior of ceramic and heterophase structures manufactured using selective laser sintering and spark plasma sintering

    Science.gov (United States)

    Skripnyak, Vladimir A.; Skripnyak, Evgeniya G.; Skripnyak, Vladimir V.; Vaganova, Irina K.

    A model for predicting mechanical properties of ultra-high temperature ceramics and composites manufactured by selective laser sintering (SLS) and spark plasma sintering (SPS) under shock loading is presented. The model takes into account the porous structure, the specific volume and average sizes of phases, and the temperature of sintering. Residual stresses in ceramic composites reinforced with particles of refractory borides, carbides and nitrides after SLS or SPS were calculated. It is shown that the spall strength of diboride-zirconium matrix composites can be increased by the decreasing of porosity and the introduction of inclusions of specially selected refractory strengthening phases.

  17. Thermoluminescence properties of AlN ceramics

    DEFF Research Database (Denmark)

    Trinkler, L.; Christensen, P.; Agersnap Larsen, N.

    1998-01-01

    The paper describes thermoluminescence (TL) properties of AlN:Y2O3 ceramics irradiated with ionising radiation. A high TL sensitivity of AlN:Y2O3 ceramics to radiation encouraged a study of the AlN ceramics for application as a dosimetric material. The paper presents experimental data on: glow...... curve, emission spectrum, dose response, energy dependence, influence of heating rate and fading rate. The measured TL characteristics were compared with those of well-known, widely used TLDs, i.e. LiF:Mg,Ti, LiF:Mg,Cu,P and Al2O3:C. It is concluded that AlN:Y2O3 ceramics showing a radiation sensitivity...

  18. Digital Crafting in the field of Ceramics

    DEFF Research Database (Denmark)

    Hansen, Flemming Tvede; Evers, Henrik Leander; Tamke, Martin

    2015-01-01

    This article aims to discuss and explore how craft knowledge in the field of ceramics can be utilized through digital technologies. Based on a set of experiments, which led to the development of a computational system that negotiates between the movement of the designer’s hands and the 3d clay...... custom digital design tools are developed and the way craftsmen in the field of ceramics are developing their material and tools for the making of ceramics. The communalities are especially centred on the experimental approach, pursued by both fields. Reflecting on these positions through our own work we...... identify different modes of experimenting, which are useful to drive design development and to develop the concept of digital crafting in the fields of ceramics. We explore how novel digital means can be utilized for a parametric setup that directly informs ornamentation through bodily engagement...

  19. Celsian Glass-Ceramic Matrix Composites

    Science.gov (United States)

    Bansal, Narottam P.; Dicarlo, James A.

    1996-01-01

    Glass-ceramic matrix reinforced fiber composite materials developed for use in low dielectric applications, such as radomes. Materials strong and tough, exhibit low dielectric properties, and endure high temperatures.

  20. Testing Consent Order on Refractory Ceramic Fibers

    Science.gov (United States)

    This notice announces that EPA has signed signed an enforceable testing consent order under the Toxic Substances Control Act (TSCA), 15 U.S.C. section 2601 at seq., with three of the primary producers of refractory ceramic fibers (RCF).