SiAlOC glasses derived from sol-gel synthesized ladder-like silsesquioxanes

Bik, Maciej; Jeleń, Piotr; Długoń, E.; Bik, Ewelina; Mroczka, K.; Barańska, Małgorzata; Sitarz, Maciej

doi:10.1016/j.ceramint.2018.10.047

Cited by 24 publications

(22 citation statements)

References 65 publications

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“…In addition, the bands at about 3600 cm −1 corresponding to stretching vibrations of the hydrolyzed Si‐OH groups at the end of the chain, indicated that the structure of ladder‐like prepared are not closed cages [28] . Moreover, the bands at about 690 cm −1 and 740 cm −1 are related to the stretching vibrations of Si−C bonds [29] …”

Section: Resultsmentioning

confidence: 99%

New PEG‐Modified Ladder‐Like Silsesquioxane as an Antifoaming Agent

Goodarzi

Karimi

2020

ChemistrySelect

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New ladder‐like silsesquioxane modified with polyethylene glycol as an antifoaming agent based on silicone was synthesized. Silsesquioxane containing polyethylene glycol fragments was successfully fabricated through the reaction of silsesquioxane bearing cyanuric chloride as a linker molecule with polyethylene glycol groups. The structure of the modified silsesquioxane was characterized by middle infrared spectroscopy (MIR), proton nuclear magnetic resonance (1H‐NMR), field emission scanning electron microscopy (FE/SEM), energy‐dispersive X‐ray spectroscopy (EDX), and transmission electron microscopy (TEM). In addition, thermogravimetric analysis (TGA) showed that the new silsesquioxane had excellent thermal stability. This modified structure was used as antifoaming agent for prevention of carryover in boiler systems. Furthermore, the results indicate that the combination of silsesquioxane and polyethylene glycol groups tends to increase the antifoaming properties of the new silicone‐based agent.

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Section: Resultsmentioning

confidence: 99%

New PEG‐Modified Ladder‐Like Silsesquioxane as an Antifoaming Agent

Goodarzi

Karimi

2020

ChemistrySelect

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“…For Si-O species, the stretching and bending vibrations are expected and seen in the 1060-1080 cm −1 range and at 470 cm −1 , respectively [24,30], whereas potential Si-N stretching and bending modes may be overlapped between 950 and 1000 cm −1 . In addition to these bonding modes, Si-C stretching vibrations are expected between 800-900 cm −1 [31][32][33][34][35] to further complicate the deconvolution of the broad band seen in the 800-1100 cm −1 range. The vertical lines in Figure 4 illustrate the overlap of the discussed peaks and the qualitative nature of their assignments given the broadness/irregularity of the resulting bands.…”

Section: Resultsmentioning

confidence: 99%

Amorphous Silicon Oxynitride-Based Powders Produced by Spray Pyrolysis from Liquid Organosilicon Compounds

et al. 2021

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Silicon oxynitrides (SiOxNy) have many advantageous properties for modern ceramic applications that justify a development of their new and efficient preparation methods. In the paper, we show the possibility of preparing amorphous SiOxNy-based materials from selected liquid organosilicon compounds, methyltrimethoxysilane CH3Si(OCH3)3 and methyltriethoxysilane CH3Si(OC2H5)3, by a convenient spray pyrolysis method. The precursor mist is transported with an inert gas or a mixture of reactive gases through a preheated tube reactor to undergo complex decomposition changes, and the resulting powders are collected in the exhaust filter. The powders are produced in the tube at temperatures of 1200, 1400, and 1600 °C under various gas atmosphere conditions. In the first option, argon Ar gas is used for mist transportation and ammonia NH3 gas serves as a reactive medium, while in the second option nitrogen N2 is exclusively applied. Powder X-Ray Diffraction (XRD) results confirm the highly amorphous nature of all products except those made at 1600 °C in nitrogen. SEM examination shows the spheroidal particle morphology of powders, which is typical for this method. Fourier Transform Infrared (FT-IR) spectroscopy reveals the presence of Si–N and Si–O bonds in the powders prepared under Ar/NH3, whereas those produced under N2 additionally contain Si–C bonds. Raman spectroscopy measurements also support some turbostratic free carbon C in the products prepared under nitrogen. The directly determined O- and N-contents provide additional data linking the process conditions with specific powder composition, especially from the point of view of oxygen replacement in the Si–O moieties formed upon initial precursor decomposition reactions by nitrogen (from NH3 or N2) or carbon (from the carbonization of the organic groups).

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“…It is known that during pyrolysis, Al is able to form the AlO x C y at a relatively low temperature through the reaction of the Al(OH) 3 particles, which are dispersed within the ceramer network with the free carbon, thus decreasing the amount of free carbon and the observed decrease in the O/C ratio at temperatures beyond 800 • C [2]. Moreover, the condensation mechanism of the Al-containing samples occurs via dehydrogenation reactions [46,47] with the formation of the C=C bonds at 700 • C (Figure 2d) [48]. At this temperature, the relative intensity of the TO T /TO LC band is the highest as well.…”

Section: Discussionmentioning

confidence: 99%

“…The differential thermal analysis data (Figure 5) show that the decomposition of the carbon phase occurs in just one single step, indicating that there are no secondary carbon phases evolving from this material and, as expected, the temperature at which this decomposition takes place gradually increases as the treatment temperature does. The decrease in the free-carbon phase content because of the cationic substitution of Si by Al atoms might be also responsible for the minimum oxidation enthalpy [48]. The presence of one type of carbon and the substitution of Si by Al atoms might cause the space charges and thus the polarization of the structure upon determined pressure and, ultimately, its piezoelectric behavior.…”

Section: Discussionmentioning

confidence: 99%

Insights into the Microstructural Evolution Occurring during Pyrolysis of Metal-Modified Ceramers Studied through Selective SiO2 Removal

Tamayo

Rubio

et al. 2021

Materials

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Silicon oxycarbide ceramers containing 5% aluminum, zirconium, and cobalt with respect to the total Si amount are prepared from a commercial polysiloxane and molecular precursors and pyrolyzed at temperatures ranging from 500 to 1000 °C. HF etching is carried out to partially digest the silica phase, thus revealing structural characteristics of the materials, which depend upon the incorporated heteroatom. From the structural and textural characterization, it was deduced that when Al enters into the ceramer structure, the crosslinking degree is increased, leading to lower carbon domain size and carbon incorporation as well. On the contrary, the substitution by Zr induced a phase-separated SiO2-ZrO2 network with some degree of mesoporosity even at high pyrolysis temperatures. Co, however, forms small carbidic crystallites, which strongly modifies the carbonaceous phase in such a way that even when it is added in a small amount and in combination with other heteroatoms, this transient metal dominates the structural characteristics of the ceramer material. This systematic study of the ceramer compounds allows the identification of the ultimate properties of the polymer-derived ceramic composites.

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SiAlOC glasses derived from sol-gel synthesized ladder-like silsesquioxanes

Cited by 24 publications

References 65 publications

New PEG‐Modified Ladder‐Like Silsesquioxane as an Antifoaming Agent

New PEG‐Modified Ladder‐Like Silsesquioxane as an Antifoaming Agent

Amorphous Silicon Oxynitride-Based Powders Produced by Spray Pyrolysis from Liquid Organosilicon Compounds

Insights into the Microstructural Evolution Occurring during Pyrolysis of Metal-Modified Ceramers Studied through Selective SiO2 Removal

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