Sol-gel processes in glass science and technology

Mukherjee, S. P.

doi:10.1016/0022-3093(80)90046-0

Cited by 194 publications

(35 citation statements)

References 15 publications

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“…Munoz-Aguard and Gregorkiewitz (1997) and Knoblich et al (2001) researched the mechanism of silica sol-gel transition by using 29 Si NMR spectra and small angle X-ray scattering, respectively. Mukherjee (1980) used infrared spectroscopy to probe silica gels with different production methods. Beganskiene et al (2004), Shokri et al (2013), andWang et al (2010) measured the surface properties of silica compounds by Fourier transfer infrared spectroscopy (FTIR).…”

Section: Figmentioning

confidence: 99%

Rheology of Silica Sols/Gels Obtained by a Y-Shaped Reactor with a Dilute Method

Kaide

Saeki

2014

J. Chem. Eng. Japan

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Silica sols can be continuously produced by the neutralization of sodium silicate with sulfuric acid using a Y-shaped reactor. The viscosity of the produced silica sols gradually increases, and gels are finally formed through the sol-gel transition. The gelation properties are significantly affected by the preparation conditions. Here we examined the effect of the dilution of silica sols by water in terms of the gelation properties of the silica sols and gels, using both dynamic viscoelasticity measurement and the creep test. Information that is needed to control the gelation properties of silica sols and gels for making silica materials into a product is also presented.

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Section: Figmentioning

confidence: 99%

Rheology of Silica Sols/Gels Obtained by a Y-Shaped Reactor with a Dilute Method

Kaide

Saeki

2014

J. Chem. Eng. Japan

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“…Diversos autores han preparado vidrios de borosilicato mediante el método sol-gel usando trialquilboratos (7,10,13,17) o ácido bórico (18)(19) como fuente de boro obteniéndose vidrios homogéneos (20) en los que se ha confirmado la presencia de enlaces borosiloxano mediante espectroscopía infrarroja (7). Si embargo, aparte de algunos estudios de Resonancia Magnética Nuclear (12), no existen datos espectroscópicos o químicos relativos a los soles del sistema SiO 2 -B 2 O 3 que verifiquen la formación de enlaces borosiloxano en dichos soles.…”

Section: Introductionunclassified

“…Si embargo, aparte de algunos estudios de Resonancia Magnética Nuclear (12), no existen datos espectroscópicos o químicos relativos a los soles del sistema SiO 2 -B 2 O 3 que verifiquen la formación de enlaces borosiloxano en dichos soles. En general, se asume que la homogeneidad de los materiales obtenidos a partir de estos geles resulta de la incorporación del boro en la red de siloxano a nivel molecular durante los estadios iniciales del proceso (17)(18)(19)(20)(21) Si confirmando la formación y posterior hidrólisis de los enlaces borosiloxano en sistemas que contienen agua. De hecho, es sabido que los enlaces borosiloxano se rompen fácilmente mediante hidrólisis (11,22) y, es por ello que se han preparado algunos compuestos con enlaces B-O-Si en condiciones anhidras (7,13 Debido a la escasez de estudios por espectroscopía infrarroja de la reacción de formación de geles de borosilicato, este trabajo hace uso dicha técnica y pone de manifiesto que el boro juega un papel importante, no sólo a través de la formación de los enlaces borosiloxano, sino en la estructura de los enlaces de la red de silicato.…”

Section: Introductionunclassified

Estudio por espectroscopía infrarroja de la reacción de obtención de geles de borosilicato con diferentes relaciones Si/B

Peña-Alonso¹,

Rubio²,

Rubio³

et al. 2005

Bol. Soc. Esp. Ceram. Vidr.

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Se ha llevado a cabo el estudio de la formación de diferentes geles de borosilicato preparados mediante la reacción sol-gel de hidrólisis y condensación de los alcóxidos TEOS (tetraetilortosilicato) y TEB (trietilborato) en diferentes proporciones Si/B y en medio acuoso acidulado. La formación de los enlaces Si-O-Si que tiene lugar durante la condensación la reacción sol-gel depende de la cantidad de boro añadido a los diferentes soles. Así, la espectroscopia infrarroja ha puesto de manifiesto que el boro juega un papel determinante en la formación de los enlaces siloxano a partir del TEOS hidrolizado, observándose que el entrecruzamiento de los enlaces Si-O-Si disminuye con el empleo de cantidades de TEB superiores al 10% en peso a la vez que aumenta la condensación en forma de estructuras lineales de los mismos. Además, se pone de manifiesto que este comportamiento está relacionado con el aumento de los tiempos de gelificación observados para altas adiciones de boro. Palabras clave: sol-gel, borosilicato, FT-IR, autocondensación.Infrared spectroscopy study of the sol-gel reaction for obtaining borosilicate gels with different Si/B ratios Borosilicate gels with different Si/B ratio have been prepared by the sol-gel method. Such gels were obtained by hydrolysis and further condensation of TEOS (tetraethylorthosilicate) and TEB (triethylborate) alkoxides in acidic aqueous media. The evolution of the Si-O-Si bonds during the sol-gel condensation was dependent on the concentration of boron. Infrared spectroscopy suggested that boron plays an important role on the formation of the siloxane bonds from the hydrolysed TEOS. Thus, the cross-linking of Si-O-Si bonds decreased and the condensation of linear structures increased when the amount of TEB was higher than 10 wt.%. Moreover, it has been observed that this behaviour is directly related with the increase of gelling time in the sols containing significant amount of boron. Keywords: sol-gel, borosilicate, FT-IR, condensation INTRODUCCIÓNLa preparación de vidrios mediante el método sol-gel está cobrando importancia en estas últimas décadas debido a las ventajas que ofrece este método respecto a los tradicionales. Entre ellas destacan la obtención de una gran variedad de composiciones, alta pureza, buena homogeneidad y menor gasto energético (1-4). A partir del método sol-gel se pueden preparar no sólo vidrios de sílice pura, sino también de sistemas con boro, titanio, aluminio, zirconio… (5-6). Por ejemplo, dentro del sistema de vidrios de borosilicato se han obtenido capas vítreas de B 2 O 3 -SiO 2 , de importantes aplicaciones como capas de pasivación, catalizadores, guías de onda o fibra óptica (7-10).La síntesis de materiales del sistema de borosilicato tiene algunos problemas relacionados sobre todo con la alta volatilización de diversos compuestos de boro al emplear altas temperaturas que, sin embargo, son necesarias para que el boro se incorpore a la estructura del material. En este sentido, los enlaces borosiloxano (B-O-Si) se hidrolizan fácilmente en medio a...

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“…To introduce SiO in the solution, we used tetraethyl orthosilicate (TEOS) Si(OC 2 H 5 ) 4 . The matrix elements were introduced via salts soluble in water and ethanol (nitrates, chlorides, acetates).…”

mentioning

confidence: 99%

“…-primary structurization of the solution, which is defined in [5] as complex formation; sol formation occurs at this stage [4,6]; -gel formation, i.e., the formation of a 3D lattice as a result of hydrolysis and polycondensation reactions; a gel is formed from the solution and its structure determines subsequent processes; the processes of complex formation, hydrolysis, and polycondensation are simultaneous; with mutual overlapping, their duration depends on several factors and may vary within wide limits [5,7]; -gel aging: the polycondensation reactions continue in the gel-like state, which is accompanied by a change in the gel structure, its decreasing porosity, and increasing strength; -gel drying: the removal of the residual liquid phase consisting of mixed water, alcohol, and ethers from the gel pores; the structure of the gel changes with dehydration: from a soft jelly-like mixture it gradually transforms into a solid substance; dry gel is called xerogel.…”

mentioning

confidence: 99%

Formation of glass synthesized by sol-gel technology

2006

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The process of glass synthesis by the sol-gel method is studied using analysis of EPR spectra. The gelation process and formation of xerogels are considered depending on the temperature-time parameters and the type of initial components. It is established that the glass phase starts to be formed at 800°C.The expanded use of glass in developing a new generation of instruments requires high-quality homogeneous glass materials. The improvement of all stages of glass production, including the melting process, is of great importance.A promising method for producing homogeneous glasses is the sol-gel method.Analysis of published sources suggests two directions in the technology of sol-gel synthesis of glasses.Production of amorphous batches from gels and their subsequent melting according to the traditional technology. This direction is mainly focused on the synthesis of extra pure multicomponent glasses, primarily optical glasses, including glass for fiber optics. This technology includes preparation of solutions based on extra pure soluble materials (salts, metal hydroxides, organometallic compounds, SiO 2 sol), transition from the solution to a sol, then to a gel, its drying, and formation of an amorphous powder batch achieving a perfect (at the molecular level) mixing of the components [1].Apart from the high purity and homogeneity of the glass, the use of such batch decreased (by 150 -200°C) the vitrification temperature due to the high dispersion of the batch particles, its amorphous nature, and the emergence of chemical bonds typical of glass. At the same time, the high gas-saturation of the batch complicates the clarification process and in the case of high-viscosity melts sometimes prevents lowering the general melting temperature.Production of glass by polycondensation (polymerization) of gel and its subsequent consolidation under heat treatment (without melting), i.e., the method implementing a gradual sol ® gel ® glass transition.The purpose of our study is the investigation of sol-gel synthesis of alkali-free aluminocalcium silicate glass and stage-by-stage analysis of the structure of resulting materials depending on their temperature-time parameters and the type of initial material.In the traditional technology such glass is melted in tank furnaces at 1560°C, the clarification temperature is 1520°C, and the working temperature 1450°C. The annealed samples contain bubbles and plenty of "fly-like" defects.One can single out the following stages in sol-gel technology [2 -4]:-preparing solutions by mixing alkoxides or salts of the elements comprising glass with water and alcohol at a certain pH level and temperature;-primary structurization of the solution, which is defined in [5] as complex formation; sol formation occurs at this stage [4,6]; -gel formation, i.e., the formation of a 3D lattice as a result of hydrolysis and polycondensation reactions; a gel is formed from the solution and its structure determines subsequent processes; the processes of complex formation, hydrolysis, and polycondensation are s...

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Sol-gel processes in glass science and technology

Cited by 194 publications

References 15 publications

Rheology of Silica Sols/Gels Obtained by a Y-Shaped Reactor with a Dilute Method

Rheology of Silica Sols/Gels Obtained by a Y-Shaped Reactor with a Dilute Method

Estudio por espectroscopía infrarroja de la reacción de obtención de geles de borosilicato con diferentes relaciones Si/B

Formation of glass synthesized by sol-gel technology

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