Polycrystalline Ceramics
Mostrando 13-21 de 21 artigos, teses e dissertações.
-
13. Influence of the type of framework system in the adaptation and microleakage of all-ceramic crowns / Influência do tipo de sistema de infra-estrutura na adaptação e microinfiltração de coroas totais cerâmicas
The objectives of this study were to quantify the microleakage and the loss of marginal adaptation before and after cementation of all-ceramic crowns, with four types of infrastructure systems, and to compare these parameters. After approval by the Committee on Ethics in Research of Dental School of University of São Paulo, 40 human third molars received al
Publicado em: 2008
-
14. ESTUDO DA CINÉTICA DE SINTERIZAÇÃO DO SISTEMA SnO2.ZnO
The polycrystalline ceramics study the base of SnO2 presents great interest due to the inherent properties of emiconductor, which allows the application in some types of components, such as, protective gas sensors, varistors, protects films for different refractory uses and for glasses fusion of heavy metals. The addition of ZnO to the SnO2, makes with that
Publicado em: 2007
-
15. Electronic ceramics based on polycrystalline SnO2, TiO2 and (Sn xTi1-x)O2 solid solution
In the present text we discuss on electronic properties arising from polycrystalline semiconductor ceramics of SnO2, TiO2 and (Sn xTi1-x)O2 solid solution rutile-type structure. This is intended to be a short overview of the most recent papers in this area. One of the most important content discussed in this text is based on sinterability of these polycrysta
Materials Research. Publicado em: 2006-09
-
16. Normal-state properties of uniaxially pressed Bi1.65Pb0.35Sr2Ca2Cu3O10+delta ceramics
We have studied the effects of the uniaxial compacting pressure on the physical properties of polycrystalline Bi1.65Pb0.35Sr2Ca2Cu3O10+delta (Bi-2223) superconductors. Powders of this material were pressed at different uniaxial compacting pressures ranging from ~ 90 to ~ 600 MPa and heat-treated at the same temperature. A characterization of samples by using
Brazilian Journal of Physics. Publicado em: 2005-09
-
17. High speed machining of aero-engine alloys
Materials used in the manufacture of aero-engine components generally comprise of nickel and titanium base alloys. Advanced materials such as aero-engine alloys, structural ceramic and hardened steels provide serious challenges for cutting tool materials during machining due to their unique combinations of properties such as high temperature strength, hardne
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2004-03
-
18. Diffusion of the 65Zn radiotracer in ZnO polycrystalline ceramics
Zinc self-diffusion coefficients were measured in polycrystalline ZnO of high density (>99% of the theoretical density) and of high purity (> 99.999%). The diffusion experiments were performed from 1006 to 1377 °C, in oxygen atmosphere, for times between 16 and 574 h. The diffusion profiles were established by means of Residual Activity Method using the 65Z
Materials Research. Publicado em: 2003-06
-
19. OBTAINMENT, MACHINING AND WEAR OF METAL MATRIX COMPOSITES PROCESSED BY POWDER METALLURGY. / OBTENÇÃO, USINAGEM E DESGASTE DE MATERIAIS COMPÓSITOS DE MATRIZ METÁLICA PROCESSADOS VIA METALURGIA DO PÓ.
The aim of this investigation was the obtainment of metal matrix composites (MMC) by the route of powder metallurgy, and the valuation of these materials with relation to their machining and wear characteristics. Firstly, were obtained pure comercial aluminium matrix composites materials, with 5, 10 and 15% volumectric fraction of silicon carbide particles.
Publicado em: 1998
-
20. Caracterização de vidros e vitro-cerâmicas com composição 2Na2O1CaO3SiO2 / Characterization of glasses and glass-ceramics with composition 2Na2O1CaO3SiO2
Glass with composition 2Na2O1CaO3SiO2, undergoes homogeneous crystal nucleation between 450 and 56OoC. The nuclei are essentially spherical and presumable have the same composition as the glass matrix. Measuriments of density, X-ray diffraction, thermal analysis by differential scanning calorimetry (DSC), ultrasonics by pulse-echo method, optical absorption,
Publicado em: 1990
-
21. Attenuation of Seismic Waves by Grain Boundary Relaxation
Experimental observations of the attenuation of elastic waves in polycrystalline ceramics and rocks reveal an attenuation mechanism, called grain boundary relaxation, which is likely to be predominant cause of seismic attenuation in the earth's mantle. For this mechanism, the internal friction (the reciprocal of the “intrinsic Q” of the material) depends