A method to synthesize SiO2–TiO2 glasses based on the synergy between VAD and ALD techniques: study of TiO2doping profile along radial direction

Manfrim, Tarcio P.; Ono, Eduardo Akifumi; Fujiwara, Eric; Santos, Murilo Ferreira Marques dos; Boery, Mirella N.O.; Santos, Juliana S.; Pizani, P. S.; Suzuki, Carlos Kenichi

doi:10.1016/j.optmat.2011.03.036

Cited by 4 publications

(2 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When using the methodology for the special case where M = 1, the expression which must be valid if Equation 17 is correct is the Equation 19. This expression gives a linear plot when its left side is graphically correlated with reaction time.…”

Section: Mechanistic Hypothesis and Integral Analysismentioning

confidence: 99%

See 1 more Smart Citation

Kinetic and Thermodynamic Study in Pozzolanic Chemical Systems as an Alternative for Chapelle Test

et al. 2018

Self Cite

View full text Add to dashboard Cite

Important properties in cementitious materials, such as concrete, are related to the presence of additives that influence the rigidity and the physical and chemical resistances. For the evaluation of the additive effectiveness, known as pozzolanic activity, a simple procedure, the Chapelle test, is commonly used, and it essentially consists in a reaction between the additive with calcium oxide in aqueous medium. However, such procedure presents limitations in terms of processing time and lack of information regarding the reactions kinetics. In this sense, a simple method based on the kinetic and thermodynamic principles of chemical reactions is proposed, which can be performed using conventional electronic pH sensors. The study provides an alternative methodology with many advantages over the traditional procedure, such as energy and time-savings, more robustness and more confidence. In this paper, three types of silica nanoparticles that can be used as low-cost additives were characterized in relation to their morphology and crystallinity by XRD and SEM, the particles average diameters were obtained and the particles were used for studying the chemical process that takes place during the Chapelle test. Results and the semi-empirical analysis provided strong evidence that the process is an acid-base 1:1 reaction and it was verified that the mean reaction times varied from 64 to 195 min. It is a remarkable result, since the proposed analysis can be performed with simple, fast and low-cost instrumentation and needs only a worksheet software, whereas the Chapelle test takes 16 hours and provides no dynamic information. Besides the limitation that the methodology is not able to quantify and to elucidate the effects of the specific surface area of the particles, which needs a complete BET study, the research provides a significant contribution for the understanding of the pozzolanic process, of great importance in both concrete and ceramic research.

show abstract

Section: Mechanistic Hypothesis and Integral Analysismentioning

confidence: 99%

“…The particles morphologies can be precisely controlled by adjusting the gases flow rates, such as H 2 , O 2 , N 2 , and SiCl 4 flow rates, and by controlling the burner-target distance D, the burnertarget inclination angle θ, and the target vertical translation speed v 18,19 , as shown in Figure 1.…”

mentioning

confidence: 99%