Contrary to traditional notions, recent studies in several engineering ceramics have provided persuasive evidence of degradation and premature failure under cyclic loading. In the present study, such cyclic fatigue-crack propagation behavior is investigated in a range of advanced ceramic materials, including monolithic alumina, partially-stabilized zirconia (PSZ), zirconia-toughened alumina (ZTA), graphite, and silicon nitride. Cyclic crack-growth is unequivocally demonstrated for tension-tension loading; growth rates over the range 10−10-10−6 m/cycle are found to be power-law dependent on the stress intensity range, and to exhibit mean-stress, crack-closure, frequency, and environmental effects, analogous to behavior in metals. In addition, transient growth rate behavior following block loading sequences, anomalous growth rate behavior of small fatigue cracks, and comparisons of stress-corrosion crack growth under monotonic loads with cyclic crack velocities are reported. Mechanisms for such cyclic fatigue behavior are described.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEnantioselective addition of diethylzinc to aldehydes catalyzed by polymer-supported chiral amino alcohols. Evidence for a two zinc species mechanismShinichi Itsuno and Jean M. J. FrechetCite this: J. Org. Chem. 1987, 52, 18, 4140–4142Publication Date (Print):September 1, 1987Publication History Published online1 May 2002Published inissue 1 September 1987https://pubs.acs.org/doi/10.1021/jo00227a043https://doi.org/10.1021/jo00227a043research-articleACS PublicationsRequest reuse permissionsArticle Views656Altmetric-Citations131LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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Experimentally determined growth laws of bilayer tantalum oxide films formed by anodizing sputter-deposited tantalum anodes in a 0.1 M phosphoric acid electrolyte are reported. Transmission electron microscopy, Fourier transform IR reflectance spectroscopy, and wet capacitance measurements are used to measure the growth rates of the inner layer, the outer layer, and the total bilayer oxide thickness in the time domain of . The anodization constants for 250 mV/s potentiodynamic growth in 0.1 M followed by a 50 min hold at the formation voltage are , , and for the total oxide, the inner layer, and the outer layer, respectively. After several days of anodization, the oxide continues to grow, thus confirming the lack of significant tantalum oxide dissolution in nonfluorinated electrolytes. Parametrization of the growth laws allows the ionic currents that are due to the generation of oxygen vacancies and tantalum interstitials to be separately calculated.
Abstract The year 2009 saw a series of events celebrating the first decade of Europe's monetary union. Within a year, however, the eurozone descended into the most serious crisis in its short history. The question posed in this article is whether scholarly analysis of European monetary integration was deficient in ways that led observers to miss impending problems. The answer given here is that the standard analysis was broadly on the mark, although it missed the need for effective oversight of banking and financial systems at the level of the monetary union and underemphasized political economy considerations.
Abstract The conditions under which it is possible to neglect the change of the saturation of the liquid in SG crevices were obtained. It has been shown that in the entry region of the SG crevices the liquid velocity can be described by a linear function. The calculations show that the species concentrations and the potential reach quasi - asymptotic limits throughout the cavity; the limits are determined by the available superheat. After the attainment of these limits, a constant crevice corrosion rate is predicted. The condition was determined whereby the transport processes in the external environment determine the corrosion current density in the crevice. Due to the low value of conductivity and a relatively large crevice width assumed in the calculations, this condition can actually be fulfilled, if the cathodic processes in the crevice do not essentially reduce the current, which flows out of the crevice.
Redox potential measurements on platinum and Type 304 stainless steel in equilibrium ( or ) and nonequilibrium boric acid/lithium hydroxide solutions at 275°C are reported. For equilibrium systems containing hydrogen, good agreement was obtained between the measured potentials on platinum and calculated equilibrium potentials for pH . For highly basic systems , however, the observed potentials tended to be more positive than the calculated values; the difference was probably due to trace amounts of oxygen remaining in the system. In oxygenated equilibrium systems, good agreement was found between the observed and calculated potentials for the solution for , but the observed potentials tended to be less positive than the calculated values for more acidic solutions and for lower oxygen concentrations. Steady‐state measurement on nonequilibrium boric acid solutions at 275°C showed that the redox potential on platinum becomes more negative as the ratio increases. Transient studies on nonequilibrium boric acid solution revealed that the redox potential can vary over a wide range on cycling the relative concentrations of oxygen and hydrogen. The experimental findings are interpreted in terms of mixed potential model from which numerical simulations have reproduced the essential features of the data.
ADVERTISEMENT RETURN TO ISSUECommunicationNEXTPt−Ag Catalyst System for Hydroarylations with Unactivated Arenes and OlefinsDmitry Karshtedt, Alexis T. Bell, and T. Don TilleyView Author Information Department of Chemistry and Department of Chemical Engineering, University of California, Berkeley, Berkeley, California 94720, and Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 Cite this: Organometallics 2004, 23, 18, 4169–4171Publication Date (Web):July 29, 2004Publication History Received26 June 2004Published online29 July 2004Published inissue 1 August 2004https://pubs.acs.org/doi/10.1021/om0495325https://doi.org/10.1021/om0495325rapid-communicationACS PublicationsCopyright © 2004 American Chemical SocietyRequest reuse permissionsArticle Views1555Altmetric-Citations101LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Aromatic compounds,Arylation,Catalysts,Hydrocarbons,Platinum Get e-Alerts
