Thematische Bibliographien / Ceramidy

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Auswahl der wissenschaftlichen Literatur zum Thema „Ceramidy“

Autor: Grafiati

Veröffentlicht am 28. Juni 2021

Zuletzt aktualisiert am 30. Mai 2022

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Zeitschriftenartikel zum Thema "Ceramidy"

MATKOVSKA, Ivanna. „Zenoviy Flinta’s artistic ceramics of 1960-80s: Stages of development of the author’s creative manner and influence of artist’s painting on his artistic ceramicsand Ukrainization“. Contemporary Art, Nr. 17 (30.11.2021): 69–84. http://dx.doi.org/10.31500/2309-8813.17.2021.248429.

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The works of Zenovia Flint, an outstanding artist, teacher and nonconformist ceramist, who embodied in his ceramic works of the 1960s and 1980s his own picturesque informal searches and philosophical images-allegories in the author’s manner, are analyzed. For the first time, the systematization of directions and stages of formation of Z. Flint’s authorial style in the field of artistic ceramics was performed, as well as an art analysis of the influence of the artist’s painting on his ceramics.

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Cheng, Zhao Gang, Xin Hua Ni und Xie Quan Liu. „The Mechanical-Stress-Field of Matrix in Eutectic Ceramic Composite“. Applied Mechanics and Materials 121-126 (Oktober 2011): 3607–11. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.3607.

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Based on the interaction between nano-fiber and eutectic interphase, forth-phase mode is used to get the mechanical stress field of matrix in eutectic composite ceramics. The effective flexibility increment tensor of eutectic ceramic composite is obtained by the volumetric average strain. The remote stress boundary condition of the eutectic composite ceramis is accounted for getting the mechanical stress field in matrix. The results show the mechanical stress field of the matrix is associated with the stiffness and the volume fractions of each component in eutectic composite ceramic , the shape of interphase and nano-fiber. The stresses in matrix will decrease due to the strong constraining effects of the eutectic interphase. The eutectic interphase make the eutectic composite ceramics strengthen.

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Uchasova, E. G., O. V. Gruzdeva und Yu A. Dyleva. „CERAMIDS AND THEIR ROLE IN THE DEVELOPMENT OF CARDIOVASCULAR DISEASES (REVIEW OF LITERATURE)“. Russian Clinical Laboratory Diagnostics 65, Nr. 6 (15.05.2020): 341–46. http://dx.doi.org/10.18821/0869-2084-2020-65-6-341-346.

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Almost all known stress stimuli, including inflammatory agonists, chemotherapeutic agents and saturated fatty acids, cause the synthesis of ceramide and its metabolites. In recent studies, it has been shown that excessive synthesis of ceramides causes the development of various metabolic diseases, such as obesity, diabetes and cardiovascular diseases. Currently, the role of ceramids in the development of obesity and diabetes has been studied quite well. At the same time, studies devoted to the study of lipid data in the development of cardiovascular disease are not large. In this review, we generalize the data on this new class of bioactive lipids for understanding their role in the development of cardiovascular diseases.

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Kawana, Momoko, Masatoshi Miyamoto, Yusuke Ohno und Akio Kihara. „Comparative profiling and comprehensive quantification of stratum corneum ceramides in humans and mice by LC/MS/MS“. Journal of Lipid Research 61, Nr. 6 (07.04.2020): 884–95. http://dx.doi.org/10.1194/jlr.ra120000671.

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Ceramides are the predominant lipids in the stratum corneum (SC) and are crucial components for normal skin barrier function. Although the composition of various ceramide classes in the human SC has been reported, that in mice is still unknown, despite mice being widely used as animal models of skin barrier function. Here, we performed LC/MS/MS analyses using recently available ceramide class standards to measure 25 classes of free ceramides and 5 classes of protein-bound ceramides from human and mouse SC. Phytosphingosine- and 6-hydroxy sphingosine-type ceramides, which both contain an additional hydroxyl group, were abundant in the human SC (35% and 45% of total ceramides, respectively). In contrast, in mice, phytosphingosine- and 6-hydroxy sphingosine-type ceramides were present at ∼1% and undetectable levels, respectively, and sphingosine-type ceramides accounted for ∼90%. In humans, ceramides containing α-hydroxy FA were abundant, whereas ceramides containing β-hydroxy or ω-hydroxy FA were abundant in mice. The hydroxylated β-carbon in β-hydroxy ceramides was in the (R) configuration. Genetic knockout of β-hydroxy acyl-CoA dehydratases in HAP1 cells increased β-hydroxy ceramide levels, suggesting that β-hydroxy acyl-CoA, an FA-elongation cycle intermediate in the ER, is a substrate for β-hydroxy ceramide synthesis. We anticipate that our methods and findings will help to elucidate the role of each ceramide class in skin barrier formation and in the pathogenesis of skin disorders.

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Liu, Li-Ka, Vineet Choudhary, Alexandre Toulmay und William A. Prinz. „An inducible ER–Golgi tether facilitates ceramide transport to alleviate lipotoxicity“. Journal of Cell Biology 216, Nr. 1 (23.12.2016): 131–47. http://dx.doi.org/10.1083/jcb.201606059.

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Ceramides are key intermediates in sphingolipid biosynthesis and potent signaling molecules. However, excess ceramide is toxic, causing growth arrest and apoptosis. In this study, we identify a novel mechanism by which cells prevent the toxic accumulation of ceramides; they facilitate nonvesicular ceramide transfer from the endoplasmic reticulum (ER) to the Golgi complex, where ceramides are converted to complex sphingolipids. We find that the yeast protein Nvj2p promotes the nonvesicular transfer of ceramides from the ER to the Golgi complex. The protein is a tether that generates close contacts between these compartments and may directly transport ceramide. Nvj2p normally resides at contacts between the ER and other organelles, but during ER stress, it relocalizes to and increases ER–Golgi contacts. ER–Golgi contacts fail to form during ER stress in cells lacking Nvj2p. Our findings demonstrate that cells regulate ER–Golgi contacts in response to stress and reveal that nonvesicular ceramide transfer out of the ER prevents the buildup of toxic amounts of ceramides.

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Suchard, Suzanne J., Vania Hinkovska-Galcheva, Pamela J. Mansfield, Laurence A. Boxer und James A. Shayman. „Ceramide Inhibits IgG-Dependent Phagocytosis in Human Polymorphonuclear Leukocytes“. Blood 89, Nr. 6 (15.03.1997): 2139–47. http://dx.doi.org/10.1182/blood.v89.6.2139.

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Abstract Ceramide is a product of agonist-induced sphingolipid metabolism in several cell types, including polymorphonuclear leukocytes (PMNs). In adherent PMNs, the kinetics of ceramide production correspond with the termination of fMLP-stimulated H2O2 release. Furthermore, short chain ceramides inhibit fMLP-mediated H2O2 release in adherent PMNs. In the present study, we investigated the effects of short chain ceramides and sphingoid bases on phagocytosis of IgG-opsonized erythrocytes (EIgG) by suspended PMNs activated with fMLP. N-Acetylsphingosine, N-acetylphytosphingosine, phytosphingosine, sphingosine, and dihydrosphingosine, but not N-acetyldihydrosphingosine, inhibited phagocytosis of EIgG. In contrast, these same lipids did not inhibit fMLP-mediated chemotaxis. Endogenous ceramide levels increased within the first few minutes of phagocytosis, with a significant (P < .05) accumulation by 30 minutes, the time by which phagocytosis was terminated. Neutral sphingomyelinase activity paralleled the increase in ceramide, consistent with the generation of ceramide by the hydrolysis of sphingomyelin. The N-acetyl-conjugated sphingols (C2 ceramides) blocked phosphatidylethanol formation indicating that phospholipase D (PLD) is an intracellular target of ceramide action. These data suggest that ceramides, generated through activation of the sphingomyelin cycle, act as negative regulators of FcγR-mediated phagocytosis.

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Kalhorn, Thomas, und Richard A. Zager. „Renal cortical ceramide patterns during ischemic and toxic injury: assessments by HPLC-mass spectrometry“. American Journal of Physiology-Renal Physiology 277, Nr. 5 (01.11.1999): F723—F733. http://dx.doi.org/10.1152/ajprenal.1999.277.5.f723.

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Ceramides are a class of signaling molecules that can acutely accumulate in tissues as part of a “stress response.” They are classically measured by the diacylglycerol kinase assay, which, in general, measures total ceramide rather than individual moieties within the diverse ceramide family. The present study was undertaken to 1) adapt current HPLC-mass spectrometry technology for measuring individual renal ceramides, and 2) use this technique to more fully characterize the nature of the renal ceramide “stress” reaction. Renal cortical tissues were obtained from CD-1 mice under control conditions and 2 or 18 h after renal injury (ischemia-reperfusion and glycerol-mediated myohemoglobinuria). C24, C22, and C16 ceramides were identified in normal renal cortex, constituting 70, 10, and 20% of the total ceramide pool, respectively. Within each of these families, heterogeneity was apparent because of differing degrees of unsaturation (0–3 double bonds) in the constituent fatty acid of ceramide. Renal injury dramatically changed ceramide profiles: 1) total ceramide increased by ∼300%; 2) although all ceramides participated in this reaction, they did so to differing degrees; 3) this caused pronounced changes in ceramide distribution patterns; 4) injury induced a striking shift toward unsaturated (vs. saturated) fatty acids within the C22 and C24 (but not the C16) ceramide pools; and 5) the extent of these qualitative changes differed according to the etiology of the initiating renal damage. Thus we conclude that ceramide stress response involves major qualitative (and not simply quantitative) changes in ceramide expression that are partially disease dependent. These findings underscore the fact that simply measuring total renal ceramide content (e.g., by diacylglycerol kinase assay) substantially oversimplifies the nature and, hence, the potential implications of the ceramide stress reaction.

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Drazba, Margaret A., Ida Holásková, Nadine R. Sahyoun und Melissa Ventura Marra. „Associations of Adiposity and Diet Quality with Serum Ceramides in Middle-Aged Adults with Cardiovascular Risk Factors“. Journal of Clinical Medicine 8, Nr. 4 (17.04.2019): 527. http://dx.doi.org/10.3390/jcm8040527.

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Rates of adverse cardiovascular events have increased among middle-aged adults. Elevated ceramides have been proposed as a risk factor for cardiovascular events. Diet quality and weight status are inversely associated with several traditional risk factors; however, the relationship to ceramides is less clear. This study aimed to determine associations of adiposity and diet quality with circulating ceramides in middle-aged adults (n = 96). Diet quality was estimated using the Healthy Eating Index 2015 (HEI-2015). Serum ceramide concentrations were determined by liquid chromatography–mass spectrometry. A ceramide risk score was determined based on ceramides C16:0, C18:0, and C24:1 and their ratios to C24:0. Participants who were classified as at ‘moderate risk’ compared to ‘lower-risk’ based on a ceramide risk score had significantly higher body mass index (BMI) values, as well as higher rates of elevated fibrinogen levels, metabolic syndrome, and former smoking status. BMI was positively associated with the ceramide C18:0 (R2 = 0.31, p < 0.0001), the ratio between C18:0/C24:0 ceramides (R2 = 0.30, p < 0.0001), and the ceramide risk score (R2 = 0.11, p < 0.009). Total HEI-2015 scores (R2 = 0.42, p = 0.02), higher intakes of vegetables (R2 = 0.44, p = 0.02) and whole grains (R2 = 0.43, p = 0.03), and lower intakes of saturated fats (R2 = 0.43, p = 0.04) and added sugar (R2 = 0.44, p = 0.01) were associated with lower C22:0 values. These findings suggest that circulating ceramides are more strongly related to adiposity than overall diet quality. Studies are needed to determine if improvements in weight status result in lower ceramides and ceramide risk scores.

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Spassieva, Stefka D., Thomas D. Mullen, Danyelle M. Townsend und Lina M. Obeid. „Disruption of ceramide synthesis by CerS2 down-regulation leads to autophagy and the unfolded protein response“. Biochemical Journal 424, Nr. 2 (11.11.2009): 273–83. http://dx.doi.org/10.1042/bj20090699.

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Ceramide metabolism has come under recent scrutiny because of its role in cellular stress responses. CerS2 (ceramide synthase 2) is one of the six mammalian isoforms of ceramide synthase and is responsible for the synthesis of VLC (very-long-chain) ceramides, e.g. C24, C24:1. To study the role of CerS2 in ceramide metabolism and cellular homoeostasis, we down-regulated CerS2 using siRNA (small interfering RNA) and examined several aspects of sphingolipid metabolism and cell stress responses. CerS2 down-regulation had a broad effect on ceramide homoeostasis, not just on VLC ceramides. Surprisingly, CerS2 down-regulation resulted in significantly increased LC (long-chain) ceramides, e.g. C14, C16, and our results suggested that the increase was due to a ceramide synthase-independent mechanism. CerS2-down-regulation-induced LC ceramide accumulation resulted in growth arrest which was not accompanied by apoptotic cell death. Instead, cells remained viable, showing induction of autophagy and activation of PERK [PKR (double-stranded-RNA-dependent protein kinase)-like endoplasmic reticulum kinase] and IRE1 (inositol-requiring 1) pathways [the latter indicating activation of the UPR (unfolded protein response)].

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Unanyan, K. G., I. P. Balmasova, V. N. Tsarev, A. M. Mkrtumyan, K. S. Elbekyan, K. G. Karakov und S. D. Arutyunov. „Ceramids as biomarkers of chronic periodontitis associated with type 2 diabetes“. RUDN Journal of Medicine 24, Nr. 4 (15.12.2020): 325–37. http://dx.doi.org/10.22363/2313-0245-2020-24-4-325-337.

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Relevance . The association of chronic periodontitis with type 2 diabetes mellitus is one of the most frequent manifestations of systemic effects that are etiologically associated with periodontopathogenic bacteria in the biofilm of the gingival sulcus. In this regard, the study of the metabolic mechanisms leading to such systemic effects and serving their markers is an urgent problem. Aim . Study of the features of sphingolipid/ceramide metabolism, both produced by etiologically significant microflora, and present in periodontal tissues of patients on the example of the association of chronic periodontitis with type 2 diabetes. Materials and methods . The observation groups included 58 patients with chronic periodontitis in association with type 2 diabetes, 39 patients with chronic periodontitis without concomitant systemic pathology, and 27 conditionally healthy people. All the examined patients underwent molecular genetic studies of the taxonomic and metabolic profiles of the dental sulcus/ periodontal pockets microbiota using 16S sequencing and evaluation of phosphorylated ceramides in saliva by the activity of the ceramid kinase enzyme. Results . It was found that in the Association of chronic periodontitis with type 2 diabetes mellitus, there are features of the taxonomic composition of the dental sulcus/periodontal pockets microbiota, which are combined with a decrease in sphingolipid metabolism. In addition, in these patients, depending on the duration of diabetes mellitus, there was an increasing drop in the saliva of ceramide kinase, which determines the phosphorylation of sphingolipids/ceramides. Conclusion . In the Association of chronic periodontitis with type 2 diabetes mellitus, the systemic effects of the dental sulcus/ periodontal pockets microbiota are manifested by a decrease in sphingolipid metabolism, including a decrease in ceramide kinase in periodontal tissues, which can serve as a marker of the combined pathological process.

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Mehr Quellen

Dissertationen zum Thema "Ceramidy"

Бутко, Я. О., Л. В. Деримедвідь, О. В. Ткачева und В. А. Уланова. „Поліпшення стану шкіри за допомогою біологічних компонентів“. Thesis, Сумський державний університет, 2017. http://essuir.sumdu.edu.ua/handle/123456789/63262.

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The histological study of the effects of ceramides on skin healing has been carried out. The results of the experiment showed that ceramides increase the degree of maturity of the newly formed connective tissue and their addition to the cream with mometasone allowed to reduce the negative effect of glucocorticosteroid on wound healing. A promising is the further study of drugs that based on the biological components of the skin.
Przeprowadzono badanie histologiczne wpływu ceramidów na leczenie skóry. Wyniki eksperymentu wykazały, że ceramidy zwiększają stopień dojrzałości nowo powstałej tkanki łącznej i ich dodania do kremu z mometazonem pozwala zredukować negatywny wpływ glikokortykosteroidów na gojenie ran. Perspektywa jest dalszym badaniem leków opartych na biologicznych składnikach skóry.
У спортивній медицині порушення цілісності шкіри під дією різних ушкоджуючих чинників (тертя, травми, запалення та ін.) є найпоширенішою проблемою і розробка нових методів для відновлення нормального стану шкіри є актуальним. Завдяки сучасним біологічним дослідженням структури шкіри стало відомо, що порушення бар’єрних функцій шкіри пов’язано з дефіцитом міжклітинних ліпідів, зокрема, керамідів [1]. Встановлено, що кераміди насичують жировими компонентами епідерміс і зволожують його, заповнюють простір між клітинами рогового шару епідермісу, скріплюють їх, відновлюють водно-ліпідний шар, підвищують еластичність і пружність шкіри, в результаті чого знижується проникність шкіри для токсинів, алергенів та ін. Також, до складу керамідів входять поліненасичені жирні кислоти, які є енергетичним резервом для біохімічних процесів і нормалізації регенеративних процесів у клітинах шкіри [2].

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Dobedoe, Richard Simon. „Glass-ceramics for ceramic/ceramic and ceramic/metal joining applications“. Thesis, University of Warwick, 1997. http://wrap.warwick.ac.uk/4217/.

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The use of sintered cordierite/enstatite glass-ceramics as interlayers for joining silicon nitride to itself and to metals has been investigated. The role of the additives B203 and P205, which control the dynamics of sintering and crystallisation, has been studied using SEM, XRD and non-isothermal DTA-based measurements of activation energy. The measured activation energies for the crystallisation of μ-cordierite, for compositions with no additives, with B203 only, and with P205 only, did not differ significantly and were in the range 415-460 kJ mol-1. When both B203 and P205 were present this was increased to 503-524 kJ mol-1. The activation energy for α-cordierite formation when no additives were present was 952 ± 57 kJ mol-1. This was substantially reduced by the presence of B203 (540 ± 27 kJ mol-1), P205 (668 ± 41 kJ mol-1) and when both were present (352 ± 26 kJ mol-1). Cordierite/enstatite glass-ceramics have been successfully used to join silicon nitride to itself. Joining at 1050-1100'C in N2 with an applied load of ~ 2.5 MPa, resulted in joint strengths, measured in 4-pt bending, of 110-170 MPa. This is comparable to the intrinsic strength of the glass-ceramic and sufficient for practical applications. These strengths were obtained using an interlayer with a TCE (5.7 MK-1) greater than that of the silicon nitride (3.0 MK-1). Suggestions for further improvements to the joint strength are discussed. The use of a glass-ceramic joint with graded thermal expansion to bridge a TCE mismatch is discussed, and the geometrical restrictions on the joint, which limit possible practical applications, are outlined. The concept of a ceramic/metal compression joint with a glass-ceramic interlayer has been demonstrated for joining silicon nitride to both Nimonic alloy 80A and Ti. The requirements for continuity of electronic structure at the Nimonic 80A/glass-ceramic and the Ti/glass-ceramic interfaces are satisfied by reaction between the glass/glass-ceramic and, the pre-oxidised surface of the Nimonic alloy to form a MgTi205-Al2TiO5 solid solution phase, and the Ti to form Ti5Si3. For the lower WE mismatch (Ti-silicon nitride) the residual joining stresses generated on cooling were marginally too high and need to be further reduced, either by a slight alteration to the joint geometry and/or a smaller WE mismatch.

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Wade, James. „Contact damage of ceramics and ceramic nanocomposites“. Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/24932.

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Herein, we study the contact damage performance of two armour ceramics, alumina and silicon carbide, with varying microstructures and one particle-reinforced ceramic nanocomposite, alumina/silicon carbide, in an attempt to understand the microstructural mechanisms that affect plasticity and cracking under quasi-static and dynamic conditions. Quasi-static contact damage was imitated using Vickers indentation over a varying load regime. Numerical analysis of the indentation size effect, performed using the proportional specimen resistance model, allowed the contributions of plastic deformation and cracking to be separated into two individual values. In all three samples, higher levels of surface energy were found to correlate with increased amounts of cracking per unit area of indentation impression. Analytical modelling of crack initiation during Vickers indentation together with quantitative measurements of surface flaw populations revealed that such an increase in cracking damage was the result of higher densities of larger flaws. The hardness of the monolithic ceramics was found vary based on grain size and porosity levels, a smaller average grain size and lower porosity levels resulting in higher hardness values. In the nanocomposite materials, hardening was found to occur with further additions of silicon carbide nanoparticles. Such an effect has been attributed to the increased dislocation densities, as measured using Cr3+/Al2O3 fluorescence spectroscopy, and the impedance of dislocation movement within the lattice due to the presence of silicon carbide nanoparticles. In order to simulate dynamic contact damage, a low velocity, scaled-down drop-weight test was designed and developed. The dynamic contact damage resistance was determined based on the depth of penetration of a blunt indenter. In the monolithic ceramics, the indenter penetration was found to be shallower in materials of higher hardness. However, the nanocomposite materials displayed an opposing trend, the indenter penetration becoming deeper in the samples of higher hardness. The macro-scale fracture patterns produced during drop-weight impacts were seen to vary based on flaw populations and indenter penetration. In certain microstructures, extensive micro-cracking was also observed.

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Minatti, José Luiz [UNESP]. „Desenvolvimento de cerâmicas de mulita a partir de alumina, ácido silícico e aerosil“. Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/103747.

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Made available in DSpace on 2014-06-11T19:32:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-08-10Bitstream added on 2014-06-13T19:22:33Z : No. of bitstreams: 1 minatti_jl_dr_guara.pdf: 4184715 bytes, checksum: be99db6c3fdb82f4af8b5cf4d8f633d9 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Neste trabalho, apresenta-se uma rota alternativa para produção de cerâmicas de mulita (3Al2O3.2SiO2), a partir da mistura de pós de alumina (Al2O3) e sílica (SiO2), para uma possível aplicação em um dispositivo de perfuração de rochas por jato supersônico quente (thermal spallation). Os pós precursores foram utilizados de dois modos diferentes: no primeiro com tamanho micrométrico, tal como fornecido pelos fabricantes; no segundo, a alumina foi moída e misturada separadamente com ácido silícico e aerosil nanométricos, ambos usados como fontes de sílica. O processo consistiu basicamente na mistura a úmido dos pós, secagem, prensagem e sinterização. Além do tamanho das partículas dos pós, foi avaliada a influência da pressão de prensagem (40 a 300 MPa), dos aditivos de sinterização (MgO, CaO e Y2O3), do meio de dispersão (água e álcool), da calcinação dos pós, da temperatura (1600 e 1650 ºC) e do tempo (1 e 3h) de sinterização. As cerâmicas obtidas foram caracterizadas de acordo com a contração, perda de massa, porosidade e densidade aparente e resistência à flexão. A microestrutura foi caracterizada por meio da microscopia óptica e microscopia eletrônica de varredura (MEV), e complementada com difração de raios X. Os resultados obtidos mostram que cerâmicas de mulita para aplicações comerciais, que requerem resistência mecânica até aproximadamente 207 MPa, podem ser obtidas utilizando pós de alumina moída e aerosil 380, com 1 % de CaO, homogeneizadas com álcool, calcinadas a 600 ºC, prensadas com 160 MPa (ou mais), pré-sinterizadas a 1000 ºC por 1h e sinterizadas a 1650 ºC por 1h. Estas cerâmicas demonstram também, grande potencial para uso em queimadores para fornos e tubeiras para thermal spallation.
The present study was made in order to obtain an alternative process to produce mullite ceramic (3Al2O3.2SiO2), from powder mixture of alumina (Al2O3) and silica (SiO2), for a possible use in a device for rock drilling hot supersonic jet (thermal spallation). The precursors powders were employed in two different ways: the first powder, in micrometric size, was used as supplied by the manufacturer; the second, milled alumina was alternated with silicic acid and nanometric aerosil®, both used as silica sources. The ceramic processing consisted basically of four steps: mixture of humid powders, drying, pressing and sintering. Besides the powder particle size, it was also evaluated the influence of the pressing (40 to 300 MPa), the sintering additives (MgO, CaO and Y2O3), the middle of dispersion (water and alcohol), the powder calcination and the time (1 and 3h) and sintering temperature (1600 and 1650 ºC). The obtained ceramics were characterized according to the contraction, mass loss, porosity, densification and resistance to flexing. The microstructure was analyzed by light microscopy, scanning electron microscopy (SEM) besides X-ray diffraction. The obtained results show that mullite ceramic for commercial applications requiring mechanical resistance up to about approximately 207 MPa, it can be obtained using milled alumina powder and aerosil 380® with 1 % CaO, homogenized with alcohol, calcined in 600 ºC, pressed with 160 MPa (or more), pre-sintered to 1000 ºC for 1h and sintered to 1650 ºC for 1h. These ceramic also show, great potential to be used in burners for ovens and nozzles for thermal spallation.

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Mussi, Toschi Vitoria. „Lead-free ferroelectric ceramics for multilayer ceramic capacitors“. Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC089.

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De nos jours, la consommation des condensateurs céramiques multicouches (MLCCs) augmente en raison de leur efficacité et leur fiabilité. La miniaturisation résultant dans une plus grande dissipation volumique de chaleur et les nouvelles applications demandent des MLCCs qui peuvent travailler de 300 à 350°C, au-delà des limites actuelles de 200 – 250°C. De plus, les exigences environnementales augmentent également avec les réglementations REACH et RoHS qui interdisent l'utilisation du plomb en Europe. Il est donc impératif de créer des nouveaux matériaux sans plomb capables de répondre aux nouvelles attentes des MLCC.Cependant, la compatibilité avec les méthodes de production industrielle, ainsi que les prix du marché sont des limites importantes. Trois familles de matériaux sans plomb ont été examinées : celle du BaTiO3 (BT), du K0.5Na0.5NbO3 et du Na0.5Bi0.5TiO3 (NBT). Le NBT-BT à la MPB (6 % BT) a été choisi comme matériau diélectrique de base. Plusieurs méthodes et paramètres de synthèse ont ensuite été étudiés pour déterminer les meilleures conditions de synthèse. La synthèse à l'état solide et le frittage traditionnel ont été choisis pour les échantillons en massif et le coulage en bande a été choisi pour les couches. Pour éviter l'évaporation des espèces volatiles, le frittage a été effectué en couvrant le NBT-BT par une poudre de ZrO2. Tous les échantillons présentaient des phases secondaires contenant du Ba (Ba2TiO4 et Ba2Ti9O20) en raison de l'évaporation du Na pendant le frittage. Un effet de peau créé par la coexistence des phases tétragonale, rhomboédrique et cubique a également été observé, lié à la concentration locale de Ba dans le réseau cristallin du NBT. Les effets des paramètres de synthèse et la stœchiométrie des réactifs sur les propriétés diélectriques, la résistance d'isolement et la séparation des phases ont été analysés. La stœchiométrie nominale Na0.44Bi0.48Ba0.06TiO3 était la plus appropriée pour les MLCC en raison de sa résistance d'isolement élevée, de ses faibles pertes diélectriques et de sa stabilité de la permittivité en température. La présence de phases secondaires est initialement bénéfique en raison de l'élimination des lacunes d'oxygène. Au-delà d'une fraction volumique critique (2.5 à 3.0 %) et d'une taille de grain moyenne critique (0.9 à 3.0 m2), la tendance s'inverse en raison de la nature conductrice des phases secondaires.Pour atteindre la fraction volumique et la taille de grain critiques, un agent dispersant a été utilisé lors du broyage dans la jarre de YSZ, avec du MEK et de l'éthanol comme solvants, et sans sécher les réactifs avant la pesée. Enfin, la relaxation des contraintes a été réalisée à 400°C pendant 3 heures. Trois modèles ont été utilisés pour expliquer la dispersion des propriétés diélectriques en fréquence : le modèle de Maxwell-Wagner, le modèle de Nyquist et la loi de Curie-Weiss modifiée. Les incompatibilités entre les propriétés diélectriques du NBT-BT rapportées dans la littérature ont ensuite été analysées soulignant l'importance d'avoir des méthodes de synthèse et de mesure strictes. Les trois principaux facteurs affectant les propriétés diélectriques induisant ces incompatibilités étaient la stœchiométrie, la méthode de métallisation et la fixation des fils électriques à l'aide de la laque d'argent. Des pertes diélectriques croissantes à haute température a aussi été observée après chaque cycle thermique dépassant les 300°C, indiquant une dégradation thermique des échantillons.Enfin, les monocouches céramiques ont montré une faible densité (62%) après frittage, limitant la plage de température correspondant aux spécifications d'Exxelia. Cependant, en utilisant un pressage des couches avant frittage, l'échantillon multicouche fritté présentait une densité élevée (89%). Une mesure des propriétés diélectriques doit être effectuée sur cet échantillon multicouche synthétisé, afin de déterminer sa compatibilité avec les spécifications d’Exxelia
MLCC consumption is today increasing due to their high efficiency, reliability and frequency characteristics. MLCCs that can work from 300 to 350°C are required both for miniaturization, resulting in greater volume heat dissipation and for new applications. Moreover, environmental requirements are also increasing, the REACH and RoHS regulations prohibiting the use of lead in Europe. It is imperative to create new lead-free materials that are able to meet those requirements.However, the compatibility with the production methods, price, and market are important industrial limitations that need to be considered.Three families of lead-free materials were examined: BaTiO3-based, K0.5Na0.5NbO3-based and Na0.5Bi0.5TiO3-based materials. NBT-BT at the morphotropic phase boundary (6% BT) was chosen as the base dielectric material.Several synthesis methods and parameters were studied to determine the best synthesis conditions. Solid-state synthesis and traditional sintering were chosen for the bulk samples and tape casting was chosen for the layer samples preparation. Sintering was done under ZrO2 powder to prevent the evaporation of volatile species.All samples had secondary Ba-containing phases (Ba2TiO4 and Ba2Ti9O20) formed because of the evaporation of Na during sintering. A skin-effect was observed due to a phase coexistence (tetragonal, rhombohedral, and cubic) due to the local concentration of Ba in the NBT lattice.The effects of the synthesis parameters and the stoichiometry of the reactants on dielectric properties, insulation resistance, and phase separation were analysed.The Na0.44Bi0.48Ba0.06TiO3 nominal stoichiometry was the most suitable for the MLCCs due to its high insulation resistance, low dielectric losses, and stability of permittivity in temperature.The phase separation was initially beneficial, due to the resulting elimination of oxygen vacancies. Above a critical volume fraction (2.5 to 3.0%) and a critical mean surface area (0.9 to 3.0 m2), the trend was reversed due to the conductive nature of the secondary phases.To achieve the critical volume fraction and surface area of the secondary phases, a dispersing agent was used during ball-milling in YSZ jar, with MEK and ethanol as solvents, and without drying the reactants prior to weighing. Finally, a strain relaxation was done at 400°C for 3 hours.Three models explained the frequency dispersion of the dielectric properties: the Maxwell-Wagner model, the Nyquist plot and the modified Curie-Weiss law.Incompatibilities between the dielectric properties of NBT-BT reported in the literature were then analysed, showing the importance of maintaining strict synthesis and measurement methods. The three main factors affected the dielectric properties, creating these incompatibilities in the bulk samples. There were the stoichiometry, the metallization method, and the fixing of the electrical leads using silver paste.An increase of the high-temperature dielectric losses after each thermal cycle reaching more than 300°C was observed, indicating a thermal degradation of the material.Finally, the sintered ceramic monolayers showed a low density (62%), limiting the temperature range corresponding to Exxelia’s specifications. However, after pressing the layers together before sintering, the sintered multilayer sample showed a high density (89%). Dielectric property measurement should be carried out for these synthesized multilayers

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Hill, Arnold Hill. „PRODUCTION OF BULK CERAMIC SHAPES FROM POLYMER DERIVED CERAMICS“. Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4248.

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A method has been developed to produce bulk ceramic components from a class of ceramics known as polymer derived ceramics. In the past polymer derived ceramics have been limited to thin film applications or in the fabrication of MEMS devices. The reason being that when the polymer is into a ceramic, large quantities of gas are generated which produce internal pressure that fractures the ceramic components. The method developed here solves that issue by casting into the polymer a 3 dimensional network of polymer fibers in the form of a foam which, during pyrolysis, burns out and leaves a network of open channels that allows decomposition gases to escape thus preventing pressure from building up. The inclusion of the polymer foam allows for the formation of strong plastic like green bodies which can be machined into any shape. The green bodies are then pyrolized into ceramic components. This process allows for the simple and inexpensive fabrication of complex ceramic components that have the potential to replace current components that are made with traditional methods.
M.S.M.S.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr MSMSE

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Feilden, Ezra. „Additive manufacturing of ceramics and ceramic composites via robocasting“. Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/55940.

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In the last two decades additive manufacturing (AM) has emerged as a highly important and influential technology. A large range of approaches to AM have been developed which give rise to hundreds of distinct techniques. Many of these are specific to one material system, and only a handful have been successful at producing ceramic parts. Robocasting is one such technique, having been used to produce complex ceramic parts with reasonable mechanical properties. In this thesis robocasting is investigated further, firstly by characterising the rheology of the robocasting paste, and then by measuring the strength and reliability of ceramic parts produced by robocasting. The critical defects associated with the process are identified, and efforts have been made to eliminate them. Furthermore, it was possible to produce a new class of ceramic composites consisting of alumina platelets aligned by the shear forces that arise during printing. These platelets themselves and the composites were extensively characterised. A new in-situ double cantilever test was developed in order to study the fracture behaviour of the composites. Lastly, the principle of using the printing process to align platelets was applied to fibres in order to create printed fibre reinforced ceramic matrix composites, and printed carbon fibre reinforced epoxy.

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Sütçü, Mücahit Akkurt Sedat. „Development of Dense Ceramic Tiles From Mixtures of Alumina Powders With Different Psd/“. [s.l.]: [s.n.], 2004. http://library.iyte.edu.tr/tezler/master/malzemebilimivemuh/T000462.pdf.

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Santana, Jerusa Góes Aragão [UNESP]. „Desenvolvimento de cerâmicas multicamadas de carbeto de silício destinadas a aplicações térmicas“. Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/103760.

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Made available in DSpace on 2014-06-11T19:32:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-28Bitstream added on 2014-06-13T19:22:34Z : No. of bitstreams: 1 santana_jga_dr_guara.pdf: 3216476 bytes, checksum: e873d90ab626be457200e6023fa5308c (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Companhia Siderurgica de Tubarao
Cerâmicas multicamadas de carbeto de silício foram obtidas por conformação por consolidação ou prensagem e utilizando diferentes técnicas de adesão das camadas. Produzidas com duas ou três camadas e apresentando gradientes de porosidades, a sistemática para obtenção destas cerâmicas teve início com o estudo individual das amostras. Para atender a níveis de porosidades previamente estabelecidos (15, 30 e 50%), foram conformadas amostras com diferentes composições e percentuais de sólidos. Na prensagem uniaxial utilizou-se um aditivo de sinterização (YAG) para controle do nível de porosidade das amostras. Por meio da realização de ensaios físicos, mecânicos, microscópicos e termomecânicos, foi possível conhecer as particularidades e características inerentes ao método de conformação empregado. As cerâmicas conformadas por prensagem apresentaram melhores acabamentos superficiais, poros pequenos, menores incidências de defeitos, porosidade e resistência mecânica influenciada pelo teor de aditivo empregado. Nas cerâmicas conformadas por consolidação, a existência de uma elevada porosidade associada a defeitos como trincas e fissuras, deterioraram a resistência mecânica das amostras. Baseando-se nos resultados obtidos, partiu-se então, para confecção das cerâmicas multicamadas. Na conformação por consolidação foram produzidas cerâmicas com duas ou três camadas, utilizando-se dois métodos: sobreposição direta e sobreposição por meio de sulcos. Na sobreposição direta a constituição das camadas ocorreu por entorno da dispersão sobre uma camada anteriormente processada. Entretanto, as tensões originadas durante as etapas de secagem conduziram a formação de abaulamento no ponto de adesão das camadas, comprometendo a sua resistência. A utilização de um defloculante polietilenimina...
Multilayer ceramics of silicon carbide were obtained by consolidation or pressing by using different techniques for layers adhesion. Produced with two or three layers and showing porosity gradients, the method for obtaining these ceramics began with the individual study of the samples. In order to achieve the porosity levels previously established (15, 30 and 50%), the samples were conformed with different compositions and percentages of solids. A sintering additive (YAG) was used in the uniaxial pressing in order to control the porosity of the samples. Through physical, mechanical, microscopic and thermomechanical tests, it was possible to know the peculiarities and characteristics related to the conforming method that was used. The obtained ceramics by pressing showed better superficial finish, small pores, lower incidence of defects, porosity and mechanical strength, influenced by the percentage of additive employed in the samples. The ceramic samples by consolidation had their mechanical strength damaged due to the high porosity associated with defects such as cracks and fissures. Multilayer ceramics were produced from the obtained results. Ceramic samples were produced by consolidation with two or three layers, by using two methods: direct overlap and overlap through grooves. In the direct overlap, the layer forming was performed by pouring the dispersion over another layer previously processed. However, the arisen tensions during the drying steps, made the interface between the layers become convex, compromising their strength. The use of the dispersant polyethylenimine (Lupasol SK), with high molecular weight, formed a thick film on the sample surface, allowing the production of grooves between the layers. The reduction of tensions on sample layers enabled the ceramic forming without defects on the interface. Samples produced... (Complete abstract click electronic access below)

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Adicks, Michael Kent. „Strength characterization of thin-wall hollow ceramic spheres from slurries“. Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/9318.

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Bücher zum Thema "Ceramidy"

Shi, Feng. Ceramic materials: Progress in modern ceramics. Rijeka, Croatia: InTech, 2012.

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Vary, Alex. NDE of ceramis and ceramic composites. [Washington, DC]: National Aeronautics and Space Administration, 1991.

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Żak, Katarzyna. Bolesławiec, miasto ceramiki =: Bolesławiec, town of ceramics. Jelenia Góra: Moniatowicz Foto Studio, 2004.

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Seminar and Meeting on Ceramics, Cells, and Tissues (4th 1997 Museo di Storia Naturale Malmerendi). Ceramics, Cells and Tissues: Ceramic- polymer composites. Faenza (Ravenna): Istituto di ricerche tecnologiche per la ceramica del CNR, 1998.

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Walgrave, Jan. Ars ceramica: Céramique contemporaine en Belgique = Ars ceramica : contemporary ceramics in Belgium. Liège: P. Mardaga, 1992.

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Canada. Office of Industrial Innovation. Advanced ceramics. [Ottawa]: Office of Industrial Innovation, 1986.

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Ontario, Ministry of Industry Trade and Technology. The Impact of advanced ceramics on Ontario industry: An overview = L'effet des céramiques de pointe sur l'industrie en Ontario : aperçu. [Toronto]: Technology Policy Branch, Ontario Ministry of Industry, Trade and Technology, 1988.

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1949-, Kōmoto Kunihito, Hrsg. Seramikku zairyō. Tōkyō: Tōkyō Daigaku Shuppankai, 1986.

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Barsoum, M. W. Fundamentals of ceramics. New York: McGraw Hill, 1997.

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Pampuch, Roman. ABC of contemporary ceramic materials. Faenza, Italy: Techna Group, 2008.

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Buchteile zum Thema "Ceramidy"

Li, Mao Qiang. „Making Fluorophlogopite Ceramics through Ceramic Processing“. In Key Engineering Materials, 1833–35. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-410-3.1833.

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Sahoo, Prasanta, und J. Paulo Davim. „Tribology of Ceramics and Ceramic Matrix Composites“. In Tribology for Scientists and Engineers, 211–31. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-1945-7_7.

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Schmidt, Helmut, Frank Tabellion, Karl-Peter Schmitt und Peter-William Oliveira. „Ceramic Nanoparticle Technologies for Ceramics and Composites“. In Ceramic Transactions Series, 171–86. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118406083.ch18.

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Godin, Nathalie, Pascal Reynaud und Gilbert Fantozzi. „AE in Ceramics and Ceramic Matrix Composites“. In Springer Tracts in Civil Engineering, 663–710. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-67936-1_22.

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Hannun, Yusuf A., Lina M. Obeid und Ghassan S. Dbaibo. „Ceramide“. In Lipid Second Messengers, 177–204. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4899-1361-6_5.

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Becker, Katrin Anne, und Erich Gulbins. „Ceramide“. In Encyclopedia of Cancer, 1–3. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27841-9_1030-2.

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Bährle-Rapp, Marina. „Ceramide“. In Springer Lexikon Kosmetik und Körperpflege, 96–97. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_1755.

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Becker, Katrin Anne, und Erich Gulbins. „Ceramide“. In Encyclopedia of Cancer, 906–8. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-662-46875-3_1030.

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Niwa, Koichi, Koji Omote, Yasushi Goto und Nobuo Kamehara. „Ceramic-Metal Interfaces in Electronic Ceramics —Interface Between Ain Ceramics and Conductors“. In Ceramic Microstructures, 391–97. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-5393-9_37.

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Nicholson, Patrick S. „Processing Defects and the Fracture of Ceramics and Designed Ceramic/Ceramic Composites“. In Mechanical Behavior of Materials, 133–46. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-1968-6_15.

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Konferenzberichte zum Thema "Ceramidy"

Easley, M. L., und J. R. Smyth. „Ceramic Gas Turbine Technology Development“. In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-367.

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Under the U.S. Department Of Energy/National Aeronautics and Space Administration (DOE/NASA) funded Ceramic Turbine Engine Demonstration Program, AlliedSignal Engines is addressing the remaining critical concerns slowing the commercialization of structural ceramics in gas turbine engines. These issues include demonstration of ceramic component reliability, readiness of ceramic suppliers to support ceramic production needs, and enhancement of ceramic design methodologies. The AlliedSignal/Garrett Model 331-200[CT] Auxiliary Power Unit (APU) is being used as a ceramics test bed engine. For this program, the APU First-stage turbine blades and nozzles were redesigned using ceramic materials, employing the design methods developed during the earlier DOE/NASA funded Advanced Gas Turbine (AGT) and Advanced Turbine Technologies Application Project (ATTAP) programs. The present program includes ceramic component design, fabrication, and testing, including component bench tests and extended engine endurance testing and field testing. These activities will demonstrate commercial viability of the ceramic turbine application. In addition, manufacturing process scaleup for ceramic components to the minimum level for commercial viability will be demonstrated. Significant progress has been made during the past year. Engine testing evaluating performance with ceramic turbine nozzles has accumulated over 910 hours operation. Ceramic blade component tests were performed to evaluate the effectiveness of vibration dampers and high-temperature strain gages, and ceramic blade strength and impact resistance. Component design technologies produced impact-resistance design guidelines for inserted ceramic axial blades, and advanced the application of thin-film thermocouples and strain gages on ceramic components. Ceramic manufacturing scaleup activities were conducted by two ceramics vendors, Norton Advanced Ceramics (East Granby, CT) and AlliedSignal Ceramic Components (Torrance, CA). Following the decision of Norton Advanced Ceramics to leave the program, a subcontract was initiated with the Kyocera Industrial Ceramics Company Advanced Ceramics Technology Center (Vancouver, WA). The manufacturing scaleup program emphasizes improvement of process yields and increased production rates. Work summarized in this paper was funded by the U.S. Dept. Of Energy (DOE) Office of Transportation Technologies, part of the Turbine Engine Technologies Program, and administered by the NASA Lewis Research Center, Cleveland, OH under Contract No. DEN3-335.

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Kara-Slimane, A., und D. Treheux. „Prebrazing of Ceramics by Plasma Spraying for Metal-Ceramic Joining“. In ITSC 1998, herausgegeben von Christian Coddet. ASM International, 1998. http://dx.doi.org/10.31399/asm.cp.itsc1998p1513.

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Abstract Traditionnal brazing ailoys does not wet ceramic and therefore are unusable for metal ceramic bonding. To overcome this problem, we have pre-metallized different ceramics (AI2O3, AIN, SiAION) by plasma spraying of copper on ceramics. The good wettability of AgCu or AgCuTi alloy on so-coated ceramics is explained by effect of residual oxygen at interface which favours the thermodynamic adhesion during brazing. The interface analysis showed that silver or titanium segregation occurs at ceramic surface and that, conversely, sprayed copper diffuses in the brazed joint

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LEVINE, STANLEY. „Ceramics and ceramic matrix composites - Aerospace potential and status“. In 33rd Structures, Structural Dynamics and Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1992. http://dx.doi.org/10.2514/6.1992-2445.

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Chavez, T., C. B. DiAntonio, M. Winter, M. Rodriguez, P. Yang, G. Burns und A. Blea. „Ceramic processing of template-induced microstructure textured ceramics PI008“. In 2008 17th IEEE International Symposium on the Applications of Ferroelectrics (ISAF). IEEE, 2008. http://dx.doi.org/10.1109/isaf.2008.4693807.

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Espinosa, H. D. „High strain rate modeling of ceramics and ceramic composites“. In High-pressure science and technology—1993. AIP, 1994. http://dx.doi.org/10.1063/1.46434.

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Song, Xiao-Fei, Jianhui Peng, Ling Yin und Bin Lin. „In Vitro Dental Cutting of Feldspar and Leucite Glass Ceramics Using an Electric Handpiece“. In ASME 2012 International Manufacturing Science and Engineering Conference collocated with the 40th North American Manufacturing Research Conference and in participation with the International Conference on Tribology Materials and Processing. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/msec2012-7290.

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Glass ceramics are important restorative materials in dentistry. They are used as veneer-core bilayer all-ceramic or metal-fused ceramic restorations or monolithic inlays/onlays/crowns to replace missing or damaged tooth structures for aesthetic and functional purposes. However, glass ceramic materials, such as feldspar and leucite glass ceramics, which are subject to this investigation, are brittle and easily induced microfractures in abrasive cutting using dental handpieces and coarse burs. In this paper, we investigated the dental abrasive cutting characteristics of feldspar and leucite glass ceramics using a high-speed electric handpiece and coarse diamond burs. Cutting forces, specific removal energy, surface roughness and morphology were investigated as functions of specific material removal rate and maximum undeformed chip thickness. The results indicate that increasing the specific material removal rate or the maximum undeformed chip thickness resulted in increases in both tangential and normal forces, but a decrease in specific removal energy for both ceramics. Tangential, normal forces and specific removal energy were significantly larger in up cutting than those in down cutting. Surface roughness for the two ceramics was not affected by the specific removal rate or the maximum undeformed chip thickness. Both microfrature and ductile microcutting morphology were observed in the machined surfaces for both ceramics. There existed a brittle to ductile transition trend when decreasing the specific material removal rate or the maximum undeformed chip thickness for the two ceramics. In comparison with feldspar glass ceramic, leucite glass ceramic generated better surfaces due to its more ductile deformation occurring in dental cutting.

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Hentschel, Manfred P., Karl-Wolfram Harbich, Joerg Schors und Axel Lange. „X-Ray Refraction Characterization of the Interface Structure of Ceramics“. In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0061.

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Advanced ceramics require specific methods for their nondestructive characterization. X-ray refraction techniques determine the specific surfaces and interfaces of high performance ceramics, composites and other low density materials down to nano-meter dimensions. X-ray refraction occurs due to the interference of phase shifted X-rays in ultra small angle X-ray scattering (USAXS) at objects above 100 nm size. Applications to monolithic ceramics and ceramic composites are presented. The well localized mean pore size of ceramics and the crack growth of ceramic composites are measured non-destructively.

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Smyth, J. R., R. E. Morey und R. W. Schultze. „Ceramic Gas Turbine Technology Development and Applications“. In ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/93-gt-361.

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Under the ongoing DOE/NASA-funded Advanced Turbine Technology Applications Project (ATTAP), Garrett Auxiliary Power Division (GAPD) is continuing to address the issues of developing and applying structural ceramics to production gas turbine engines. Several critical technologies are being developed to advance this issue, including design methods development, component design, component fabrication, material characterization, and engine testing. The brittle nature of structural ceramics highlights concerns regarding impact damage. Through analysis and experimentation, design methods are being developed to improve the resistance of ceramic components to impact damage. Ceramic component designs now integrate these design methods into practice and proof testing methods are being developed to verify the results for actual engine components. Ceramic component fabrication processes are being optimized by selected subcontractors, resulting in deliveries of high-quality ceramic components which fully meet engine test needs. Verification of the component material properties is being achieved through comparisons of material property data from test bars cut from actual engine components with data generated from ceramic material test specimens. All these efforts are aimed at demonstrating endurance of the AGT101 all-ceramic turbine engine at the maximum operating temperature conditions up to 2500F (1371C). These critical ceramics technologies being developed under ATTAP are also providing a critical launch pad into production-oriented programs. GAPD has three concurrent programs underway, aimed at integrating ceramics into production Auxiliary Power Units (APUs). These include: installing and evaluating ceramic turbine nozzles under actual field conditions in a well-established product line (the 85 Series Ceramic Nozzle Demonstration Program); incorporating ceramic first-stage turbine stators and blades in a three-stage axial turbine APU (the 331-200 Ceramic Demonstration Program); and incorporation of a ceramic first-stage turbine stator in our latest APU design, the G250 Auxiliary Power Generation System (APGS) for the USAF F-22 fighter aircraft.

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Rettler, M. W., M. L. Easley und J. R. Smyth. „Ceramic Gas Turbine Technology Development“. In ASME 1995 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/95-gt-207.

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Under the U.S. Dept. of Energy/National Aeronautics and Space Administration (DOE/NASA) funded Ceramic Turbine Engine Demonstration Project, formerly the Advanced Turbine Technology Applications Project (ATTAP), AlliedSignal Engines is addressing the remaining critical concerns slowing the commercialization of structural ceramics in gas turbine engines. These issues include demonstration of ceramic component reliability, readiness of ceramic suppliers to support ceramic production needs, and development of ceramic design technologies. The AlliedSignal/Garrett Model 331-200[CT] Auxiliary Power Unit (APU) is being used as a ceramics test bed engine. The first-stage turbine blades and nozzles were redesigned using ceramic materials, employing the design methods developed during the earlier DOE/NASA-funded Advanced Gas Turbine (AGT) and ATTAP programs. Ceramic engine components have been fabricated and are now being evaluated in laboratory engine testing. The fabrication processes for these components will provide the framework for a demonstration of manufacturing process scale-up to the minimum level for commercial viability. The laboratory engine testing is helping to refine the component designs and focus the development of ceramic component technologies. Extended engine endurance testing and field testing in commercial aircraft is planned to demonstrate ceramic component reliability. Significant progress has been made during 1994. An engine with ceramic turbine nozzles was successfully operated and engine tests in the laboratory are continuing to gather useful data. An engine equipped with ceramic blades was also tested, but blade fractures occurred, interrupting operation. An extensive investigation has identified possible vibration and contact problems. Investigative evaluation efforts are continuing to identify the problem source and determine go-forward plans for ceramic blade development. Component design technologies have progressed in the areas of modeling particle impact pulverization, development of a ceramic hot corrosion environmental life model, and methods for evaluating ceramic contact damage. The planned ceramic manufacturing scale-up was initiated with two ceramics vendors, Norton Advanced Ceramics (East Granby, CT) and AlliedSignal Ceramic Components (Torrance, CA). The scaleup demonstration program is emphasizing improvement of ceramic processing yields and increased production rates. Work summarized in this paper was funded by the U.S. Dept. of Energy (DOE) Office of Transportation Technologies, as part of the Turbine Engine Technologies Program, and administered by the NASA Lewis Research Center, Cleveland, OH under Contract No. DEN3-335.

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Medvedovski, Eugene, und David D. Marchant. „Wear- and Corrosion-Resistant Ceramics for Protection of Pipelines and Rotating Equipment“. In 2000 3rd International Pipeline Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/ipc2000-128.

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Engineering ceramics have a growing application potential for the wear- and corrosion protection of piping systems and for manufacturing of working parts of rotating equipment in mining and -mineral industries, including oil, gas, coal, ores, and others. The alumina, zirconia, alumina-zirconia, and silicon carbide-based engineering ceramics developed and manufactured by Ceramic Protection Corporation used for extraction, processing, conveying, and dust collection equipment are reviewed. These ceramics have high hardness (greater than the majority of processed materials) and mechanical strength, moderate fracture toughness (fracture toughness of zirconia ceramics is close to metal fracture toughness), excellent wear- and corrosion resistance, ability to withstand high temperatures (greater than 1000°C) and thermal shocks. These ceramics successfully withstand various solid and liquid abrasive media transported at high velocity and turbulence, under high pressure and cavitation. In terms of wear- and corrosion resistance ceramics are significantly stronger than hard steels widely used in the piping systems, and may successfully replace hard metals such as tungsten carbide. The features of the compositions, microstructure, and properties of these ceramics are considered. The wear test results are discussed; the factors effected wear resistance are emphasized. In dependence on the working conditions and the product design, a ceramic material may be chosen or developed in each particular case. The manufacturing processes of the considered ceramics and the installation technique are described. These ceramics are produced on the large-scale basis, and the parts may be manufactured in accordance with the customer design and requirements. The ceramic components may be manufactured as monolithic bodies, including bodies with the complicated shapes, or as tiles; in both cases they are easily installed into equipment. The main features of the ceramic product design are discussed. Pipe lining, including elbows, T- and Y-sections, cyclones and reducers, nozzles, pump parts, seals, valves, and others made from these ceramics are successfully used in the most important sections of piping systems and rotating equipment. The use of the ceramics reduces the wear- and corrosion problems, increases the life cycle of equipment without damage and shutdowns.

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Berichte der Organisationen zum Thema "Ceramidy"

Clarke, D. R., und D. Wolf. Grain boundaries in ceramics and ceramic-metal interfaces. Office of Scientific and Technical Information (OSTI), Januar 1986. http://dx.doi.org/10.2172/6923214.

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Tortorelli, P. F. High-temperature corrosion resistance of ceramics and ceramic coatings. Office of Scientific and Technical Information (OSTI), Juni 1996. http://dx.doi.org/10.2172/450771.

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Weiss, Charles, William McGinley, Bradford Songer, Madeline Kuchinski und Frank Kuchinski. Performance of active porcelain enamel coated fibers for fiber-reinforced concrete : the performance of active porcelain enamel coatings for fiber-reinforced concrete and fiber tests at the University of Louisville. Engineer Research and Development Center (U.S.), Mai 2021. http://dx.doi.org/10.21079/11681/40683.

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A patented active porcelain enamel coating improves both the bond between the concrete and steel reinforcement as well as its corrosion resistance. A Small Business Innovation Research (SBIR) program to develop a commercial method for production of porcelain-coated fibers was developed in 2015. Market potential of this technology with its steel/concrete bond improvements and corrosion protection suggests that it can compete with other fiber reinforcing systems, with improvements in performance, durability, and cost, especially as compared to smooth fibers incorporated into concrete slabs and beams. Preliminary testing in a Phase 1 SBIR investigation indicated that active ceramic coatings on small diameter wire significantly improved the bond between the wires and the concrete to the point that the wires achieved yield before pullout without affecting the strength of the wire. As part of an SBIR Phase 2 effort, the University of Louisville under contract for Ceramics, Composites and Coatings Inc., proposed an investigation to evaluate active enamel-coated steel fibers in typical concrete applications and in masonry grouts in both tension and compression. Evaluation of the effect of the incorporation of coated fibers into Ultra-High Performance Concrete (UHPC) was examined using flexural and compressive strength testing as well as through nanoindentation.

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Wayne, S. F., J. H. Selverian und D. O'Neil. Development of adherent ceramic coatings to reduce contact stress damage of ceramics. Office of Scientific and Technical Information (OSTI), November 1992. http://dx.doi.org/10.2172/6623608.

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Wayne, S. F., J. H. Selverian und D. O`Neil. Development of adherent ceramic coatings to reduce contact stress damage of ceramics. Final report: DOE/ORNL Ceramic Technology Project. Office of Scientific and Technical Information (OSTI), November 1992. http://dx.doi.org/10.2172/10145939.

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Lange, Fred F., M. P. Rao, A. J. Sanchez-Herencia, G. E. Beltz und R. M. McMeeking. Reliable Ceramic Structural Composites Designed with a Threshold Strength. Laminar Ceramics That Exhibit a Threshold Strength. Fort Belvoir, VA: Defense Technical Information Center, April 2000. http://dx.doi.org/10.21236/ada389140.

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Lilley, E., G. A. Rossi und P. J. Pelletier. Tribology of improved transformation-toughened ceramics-heat engine test. Final report: DOE/ORNL Ceramic Technology Project. Office of Scientific and Technical Information (OSTI), April 1992. http://dx.doi.org/10.2172/10176289.

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Spoerke, Erik, Jill Wheeler, Jonathon Ihlefeld, Mia Blea, Harlan Brown-Shaklee und Mark Rodriguez. Ion Selective Ceramics for Waste Separations: Performance and Design of Ion Selective Ceramic Membrane for Molten Salt Recycle. Office of Scientific and Technical Information (OSTI), September 2014. http://dx.doi.org/10.2172/1163124.

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Pilania, Ghanshyam. Misfit dislocations at metal-ceramic and ceramic-ceramic interfaces. Office of Scientific and Technical Information (OSTI), Juni 2015. http://dx.doi.org/10.2172/1184608.

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Vedula, Krishna M. Ultra High Temperature Ceramic-Ceramic Composites. Fort Belvoir, VA: Defense Technical Information Center, Oktober 1989. http://dx.doi.org/10.21236/ada230593.

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