Delia Gutierrez - Academia.edu (original) (raw)

Papers by Delia Gutierrez

Cerâmica, Jun 1, 1999

Refractories containing magnesium aluminate spinel (MgAl2O4) are materials for emerging technolog... more Refractories containing magnesium aluminate spinel (MgAl2O4) are materials for emerging technology in several applications like cement and steelmaking processes. In order to deep the understanding of these castables, this work presents the microstructural characteristics of an alumina-magnesia/self-forming spinel castable. Several variables such as MgO content, firing temperature and spinel formation are analyzed through XRD and SEM analysis. The results showed that the processes of spinel formation and nucleation are not strongly affected by the MgO content, but that the crystal growth is enhanced for samples with 6.0 wt% MgO. Hibonite (CA6) bonding in the castable matrix showed a needlelike structure that could increase hot properties of the material. MgO content in the castable seems to affect the hibonite development. The development of a self-forming spinel castable without any synthetic spinel grains appears to be promissory for optimum refractory linings.

HAL (Le Centre pour la Communication Scientifique Directe), 2002

Cerâmica, May 1, 1999

This study was carried out in conjunction with the investigation, reported in Part I, on the micr... more This study was carried out in conjunction with the investigation, reported in Part I, on the microstructural characteristics of an alumina-spinel castable with several percentages of MgO content. Bulk density and cold crushing strength of samples were evaluated dried and at three fired states (1000, 1200, 1400 °C). Results indicate little influence of MgO additions on physico-chemical properties of the alumina-magnesia/self-forming spinel castable. Characteristics compared with those reported for conventional alumina-spinel castables did not show large difference in values. Therefore, the alumina-magnesia/self-forming spinel castable could be a possible material for substitution of the conventional alumina-spinel castable.

Revista Latinoamericana De Metalurgia Y Materiales, 2008

… de Metalurgia y …, 2010

... ONDA D. Gutiérrez-Campos 1* , Rosa María Rodríguez 2 , Luis Arellano 1 , Isabela García 2 , A... more ... ONDA D. Gutiérrez-Campos 1* , Rosa María Rodríguez 2 , Luis Arellano 1 , Isabela García 2 , Alexis Mijares 1 , ... Otra porción de estos polvos se sometió a tratamiento térmico a 800 ya 1200 °C durante 1h, con una rampa de calentamiento d 5 °C/min. ...

Revista Internacional de Contaminación Internacional, 2020

The aim of this study was to develop an alternative methodology for the synthesis of transition a... more The aim of this study was to develop an alternative methodology for the synthesis of transition aluminas, in order to reduce ecological costs by using recycled metal scrap as raw material (cans of soft drinks) and generate a product with high added value. The synthesis technique employed yielded a precursor comprised of 55.4 % of bayerite, 41.2 % of boehmite, and ammonium salt, according the characterization performed with X-ray diffraction and quantification by the Rietveld method. The ammonium chloride salt present is not relevant for the process, since given its solubility in water, it could be eliminated by successive washing. Scanning electron microscopy evaluations showed the presence of agglomerates of particles between 50 and 300 μm. A bimodal grain sizes distribution was detected during the laser granulometric test. Thermogravimetric analysis of the precursor indicated a 40.6 % total weight loss at 1000 ºC. The heat treatments at 350 and 750 ºC of precipitates for 1, 2 and 4 h, produced various transition aluminas (γ, η, θ), which are products where value has been added and might have a potential use as binders in monolithic products, catalyst support, or additives for puzzolanic materials, among others.

This study was initiated in order to develop an alternative methodology for the synthesis of tran... more This study was initiated in order to develop an alternative methodology for the synthesis of transition aluminas that could potentially be used as binder of monolithic refractories. The objective was established with the purpose to reduce ecological costs by using recycled metal scrap as raw material. The synthesis technique employed yield a precursor comprised 55.4% of bayerite, 41.2% of boehmite and ammonium salt, according the characterization performed with X-ray diffraction and quantification by the Rietveld method. SEM evaluations showed the presence of agglomerates of particles between 50 and 300 μm. Bimodal grain sizes distribution was detected during laser granulometric test. Thermogravimetric analysis of the precursor indicated 40.6% total weight loss at 1000°C. The heat treatments at 350°C and 750°C of precipitates for 1, 2 and 4 hours, produced various transition aluminas (γ, η, θ), which might have potential use as binder in monolithic products, catalyst support or addi...

Anales De La Universidad Metropolitana, 2002

Resumen En este trabajo se busca desarrollar una metodología que permita mejorar las ya existente... more Resumen En este trabajo se busca desarrollar una metodología que permita mejorar las ya existentes, en cuanto a la purificación de la alúmina Bayer. El proceso está basado en la solubilidad del sistema Al 2 O 3. H 2 O (1) , y en la utilización de un agente acomplejante, ácido etilen-diamino-tretracético, (EDTA). La solubilidad de dicho sistema, está relacionada, a su vez, con la temperatura y el pH, siendo estos parámetros los que determinan la naturaleza de las especies en solución. Por otra parte, se conoce de la bibliografía, que en el intervalo de pH ,utilizado en el presente trabajo, se forma un complejo Al-EDTA (quelato) altamente estable. Es así, como se escogen cuatro diferentes valores de pH para promover la formación del complejo Al-EDTA, seguido de una modificación del pH, para inducir la formación de un precipitado, de características coloidales. Posteriormente, a través de un proceso de evaporación a sequedad, se recupera el sólido. Este sólido (intermediario) es caracterizado por Espectroscopía de Emisión Atómica y por Difracción de Rayos X. Por último, se realiza el tratamiento térmico de dicho sólido, a temperaturas que oscilan entre 800 y 1.000°C, este producto calcinado es nuevamente caracterizado por Difracción de Rayos X. Como resultado, se logra una disminución del 98% del contenido de sodio y se observa la aparición de Alfa y Theta-Alúmina.

ZrO 2 coatings of 2-7 µm thickness were obtained by the aerosol thermal spraying process on 316L ... more ZrO 2 coatings of 2-7 µm thickness were obtained by the aerosol thermal spraying process on 316L stainless steel. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed that these films consisted of nanocrystalline ZrO 2 aggregates with a monoclinic structure. Corrosion tests were performed in aqueous NaCl (0.5 M) and H 2 SO 4 (20 wt%) using potentiodynamic cyclic polarization curves. Surfaces and cross-sections of coated samples were compared with the uncoated substrate. This evaluation indicated decreased pitting of the steel with coating. The protection against corrosion in NaCl solution depended strongly on coating thickness. No protection was found for thicknesses less than 5 µm. Meanwhile, a marked reduction of the current density was produced by thicker coatings that acted as an effective corrosion barrier. Coatings thicker than 5 µm also provided significant protection against corrosion in H 2 SO 4 .

Materials Letters, 2002

A chemical route, using industrial raw materials, was developed for the synthesis of MgAl 2 O 4 s... more A chemical route, using industrial raw materials, was developed for the synthesis of MgAl 2 O 4 spinel precursor. The asobtained powder was then calcined in air, up to 1200 jC for a period of 1 h. It was found that spinel single phase is formed at several hundred degrees lower than temperatures reported for the conventional powder preparation methods. Moreover, at 500 jC the degree of crystallinity is higher than that reported by other chemical processes at this temperature. The calcined powder reaches 83% of relative density at 1200 jC, indicating reactivity and good sintering behaviour. Scanning electron microscopy images revealed that the product consisted of fine spherical particles of magnesium aluminate spinel.

Materials Science and Engineering: A, 2007

... [4] D. Gutiérrez-Campos, JI Díaz and RM Rodríguez. Cerámica, 45 (1999), p. 93. [5] MA Sainz, ... more ... [4] D. Gutiérrez-Campos, JI Díaz and RM Rodríguez. Cerámica, 45 (1999), p. 93. [5] MA Sainz, AD Mazzoni, EF Aglietti and A. Caballero. Mater. Chem. Phys., 86 (2004), pp. 399–408. [6] C. Aksel, B. Rand, FL Riley and PD Warren. J. Eur. Ceram. Soc., 24 (2004), pp. 2839–2845. ...

International Journal of Refractory Metals and Hard Materials, 2001

Sliding friction, abrasion and erosion tests were performed on several materials: cemented carbid... more Sliding friction, abrasion and erosion tests were performed on several materials: cemented carbides, partially stabilized zirconia (Mg±PSZ), electroless Ni±P coatings and SAE 4140 steel as reference material. Sliding friction test was carried out in a pin-on-disk system. A micro-abrasion test was performed using the ball cratering methods. The erosion test consisted an air stream carrying abrasive particles of SiC, impinging¯at samples. Sizes of wear scars were determined by optical microscopy and laser pro®lometry. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) were employed to observe morphological and chemical features of worn surfaces. The sliding pin-on-disk results of Ni±P coating showed smooth variation of the friction coecient (mean values of 0.16±0.21), as well as the lowest wear rate compare with the other evaluate materials. Experimental results of the microabrasion test showed linear behavior between wear volume and sliding distance for all the evaluate materials. Cemented carbides showed the lowest wear rates followed by SAE 4140 steel, Mg±PSZ and Ni±P coating, respectively. Erosion test values ranked evaluated materials from lower to higher eroded volume as follows: SAE 4140 Steel, Ni±P coating, cemented carbides and Mg±PSZ ceramic.

Universidad Ciencia Y Tecnologia, Mar 1, 2012

Las cerámicas porosas han sido utilizadas en diversas aplicaciones como: procesos de refinación, ... more Las cerámicas porosas han sido utilizadas en diversas aplicaciones como: procesos de refinación, filtración, sensores, entre otros; gracias a sus propiedades como absorción, permeabilidad y conductividad térmica. Estas piezas porosas pueden ser elaboradas por diversas vías, sin embargo una de las más innovadoras es el conformado por gelificación térmica de biopolímeros como polisacáridos y proteínas, utilizando agentes surfactantes; debido a que es una tecnología que resulta poco agresiva en términos ambientales. En este trabajo se realizó un estudio preliminar sobre la capacidad de formación y estabilidad de espuma del sulfato de dodecilo sódico, usado como agente surfactante (espumante) en dispersiones de alúmina. Se determinó la concentración óptima de la solución surfactante a utilizar (0.004M), preparándose dispositivos porosos de alúmina utilizando dicha solución. A continuación, se evaluaron algunos parámetros esenciales como: Cantidad del agente espumante y tipo de agitación. Las piezas conformadas fueron analizadas por MEB, BET, análisis estereológico y principio de Arquímedes. Los resultados obtenidos evidencian la formación de una cerámica porosa, con un porcentaje de porosidad (debido al agente espumante) de 52.3% y con un tamaño de poro 47-77 µm (frecuencia 50%). En cuanto al método de incorporación de la espuma en la dispersión de alúmina, se determinó que el más adecuado era el que, simultáneamente aplicaba agitación magnética y agitación por aspas, puesto que fue el único método que permitió la mezcla total entre la espuma y la dispersión de alúmina.