GALLARDO LÓPEZ , Ángela María

La Ciencia de los Materiales ayuda a completar el ciclo que comienza con la necesidad de encontrar materiales que cumplan unos determinados requisitos, y mediante la caracterización e investigación de los ya existentes logra diseñar otros "hechos a medida" para funcionar en distintas situaciones. Esta ciencia está desarrollándose enormemente en...

Zirconia composites with few-layer graphene (FLG) were prepared by two powder processing routines -ultrasonic agitation or planetary ball milling- and spark plasma sintered at 1250 and 1300 °C. An in-depth study of the crystallinity of FLG, in terms of presence and nature of defects, was performed by Raman spectroscopy, revealing enhanced FLG...

3 mol% yttria tetragonal zirconia polycrystalline (3YTZP) ceramic composites with 2.5, 5 and 10 vol% graphene nanoplatelets (GNP) were pressureless sintered in argon atmosphere between 1350 and 1450 °C. The effects of the GNP content and the sintering temperature on the densification, microstructure and electrical properties of the composites...

Graphene oxide (GO) was mixed with 3 mol% yttria tetragonal zirconia polycrystal (3YTZP) using two powder processing routines: a colloidal method in an aqueous solution and a combination of ultrasonication with high-energy planetary ball milling in wet conditions. Highly densified 3YTZP composites with reduced GO (rGO) were consolidated by...

Muestras de YTZP (policristales de oxido de circonio dopado con itria) con tamaño medio de grano de 50 nm, puras y con un 10% en peso de diferentes fases vítreas han sido deformadas a carga constante en un rango de temperatura comprendido entre 1150-1200 ºC. Con dicho estudio se pretende caracterizar el comportamiento mecánico del material y...

In this work, the synthesis of graphene-like nanosheets (GNS) by an electrochemical exfoliation method, their microstructural characterization and their performance as fillers in a ceramic matrix composite have been assessed. To fabricate the composites, 3 mol % yttria tetragonal zirconia (3YTZP) powders with 1 vol % GNS were processed by...

Yttria tetragonal zirconia polycrystalline (3YTZP) ceramic composites with 5, 10 and 20 vol% graphene nanoplatelets (GNPs) were prepared by spark plasma sintering (SPS) and their electrical conductivity as a function of temperature was characterized. The composites exhibit anisotropic microstructures so the electrical conductivity studies were...

Las cerámicas monocristalinas han sido objeto de un considerable interés a lo largo de estos años, debido a la posibilidad de obtener información esencial sobre propiedades fundamentales que puedan ayudar a la comprensión de sistemas policristalinos complejos. La circona dopada con itria ha merecido un estudio...

The tribological behavior of graphene nanoplatelet (GNP) reinforced 3 mol% yttria tetragonal zirconia polycrystals (3YTZP) composites with different GNP content (2.5, 5 and 10 vol%) was analyzed and discussed. Their dry sliding behavior was studied using a ball-on-disk geometry with zirconia balls as counterparts, using loads between 2 and 20 N...

En este trabajo se presenta un modelo para explicar las inestabilidades dinámicas observadas durante la deformación plástica a alta temperatura de monocristales de circona estabilizada con itria, (YCSZ, yttria cubic stabilized zirconia) con alto contenido en itria. El modelo se basa en el fenómeno Portevin-Le Chatelier (PLC), que consiste en...

In this work, novel 3mol% yttria tetragonal zirconia polycristalline (3YTZP) ceramic composites with boron nitride nanosheets (BNNS) are investigated for the first time. Highly densified composites with 1 and 4vol% BNNS were obtained by spark plasma sintering (SPS) after BNNS synthesis using a solution exfoliation method and BNNS dispersion...

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En este trabajo se pretende analizar la microestructura de monocristales de TeO2 (paratelurita) deformados plásticamente en compresión uniaxial a alta temperatura (∼870 K) en distintas condiciones. Para ello, se han ensayado muestras con orientación cristalográfica [110], y se han cortado láminas correspondientes a los planos de deslizamiento...

3 mol% yttria tetragonal zirconia polycrystal (3YTZP) composites with orthotropic or isotropic microstructures were obtained incorporating few layer graphene (FLG) or exfoliated graphene nanoplatelets (e-GNP) as fillers. Electrical conductivity was studied in a wide range of contents in two configurations: perpendicular (σꓕ) and parallel (σ//)...

Yttria tetragonal zirconia ceramic composites with 1, 2.5, 5 and 10 vol% nominal contents of graphene nanoplatelets (GNPs) were fabricated and characterized. First, the GNP dispersion in isopropanol was optimized to de-agglomerate the GNPs without damaging their structure. Then, submicrometric fully dense composites were obtained via spark...

Different colloidal powder processing routines have been used to prepare composites of 3 mol% Y2O3 -ZrO2 (tetragonal zirconia polycrystals, 3YTZP) with 2.5 vol% multiwall carbon nanotubes (MWNT) with the aim of achieving a homogeneous distribution of the MWNTs in the ceramic, eliminating agglomerates but also minimizing carbon nanotube (CNT)...

The addition of graphene-based nanostructures (GBNs) can improve the inherent fragility of ceramics and provide them with improved electrical and thermal conductivities. However, both the starting material (ceramic matrix and GBNs) and the processing/sintering approach are crucial for the final composite microstructure and properties. This work...

Electrical-discharge machining (EDM) of advanced ceramics allows the miniaturization of parts with complex shapes. Since electrical conductivity is required, non-conductive ceramics need a conductive second phase. This work assesses the feasibility of industrial EDM in advanced yttria-stabilized tetragonal zirconia (3YTZP) composites with 20...