Formation of Micro and Mesoporous Amorphous Silica-Based Materials from Single Source Precursors

Sokri, Mohd Nazri Mohd; Daiko, Yusuke; Mouline, Zineb; Honda, Sawao; Iwamoto, Yuji

doi:10.3390/inorganics4010005

Cited by 12 publications

(5 citation statements)

References 46 publications

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“…After pyrolysis at 800 °C in Ar, the coating system as well as plain PHPS does not contain Si–H bands anymore, otherwise Si–O absorption peaks are detected for both samples: at ≈1092 cm −1 (stretching mode region), at ≈457 cm −1 (rocking mode region), and at ≈812 cm −1 (bending mode) . This is a hint to a high degree of polymer's oxidation and conversion into SiO 2 ; the incorporation of nitrogen into the glassy network can neither be excluded nor confirmed.…”

Section: Resultsmentioning

confidence: 90%

New‐Type Oxidation Barrier Coatings for Titanium Alloys

Smokovych

Scheffler

et al. 2020

Adv Eng Mater

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Herein, a new type of oxidation protection coating for Ti alloys is developed based on a perhydridopolysilazane preceramic polymer and particulate AlB 2 , Si, B, and Ti 3 AlC 2 (so-called MAX phase) fillers; MAX phases are used due to their high temperature and corrosion resistance, thermal shock resistance, and self-healing capability. For coating consolidation, the as-coated samples are pyrolyzed in argon or nitrogen and exposed to air at 800 C for up to 100 h. Although coatings containing AlB 2 or elemental Si and B show a small mass gain in the initial state of exposure to air and after no mass gain up to 100 h, MAX phase-loaded samples show a significant mass gain up to 7 h of exposure and a sudden mass decrease, which corresponds to coating layer spallation. The mechanisms leading to oxidation protection in AlB 2-filled systems are explained with an alumina layer formation and a glass formation from the preceramic polymer. In Si-and B-filled systems, a borosilicate glass phase may be able to reduce the oxygen diffusion capability and the MAX phases as fillers need further investigations; they may cause thermally induced mechanical stresses in the protective coatings.

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Section: Resultsmentioning

confidence: 90%

New‐Type Oxidation Barrier Coatings for Titanium Alloys

Smokovych

Scheffler

et al. 2020

Adv Eng Mater

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“…In the FT-IR spectra, the crosslinked absorption bands were detected corresponding to Si–H stretching vibration at 2120 cm −1 , Si–N vibrations at 840–1020 cm −1 and Si–O vibrations at 1063 cm −1 (stretching mode region) and at 456 cm −1 (rocking mode region) [26,27,28], (Figure 6b). This demonstrates that at the stage of crosslinking, oxygen atoms particularly replaced nitrogen atoms resulting in silicon oxynitride and silicon oxide amorphous ceramic.…”

Section: Resultsmentioning

confidence: 99%

Tailored Oxidation Barrier Coatings for Mo-Hf-B and Mo-Zr-B Alloys

et al. 2019

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The cyclic oxidation response of Mo-14Hf-23B and Mo-14.8Zr-26B (compositions in at. %) was investigated in air at 800 °C, which is a critical temperature for Mo-based alloys because of the pesting phenomenon. Rapid oxidation was observed for the unprotected samples, and an oxidation protection coating was developed based on a preceramic polymer with silicon and boron as particulate fillers. Cyclic oxidation tests of the coated samples showed excellent oxidation protection: no Mo, Hf or Zr oxides were found after testing and a small mass gain in the initial stage of oxidation indicated the formation of a glassy protection layer on the alloys surfaces after exposure to air at 800 °C.

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“…Under inert atmosphere up to 800 °C, this polymer exhibited a unique thermal decomposition behavior: a cleavage of the oxygen–carbon bond of the EtO group to evolve ethylene as a main gaseous species formed in-situ, which led to the formation of amorphous Si–O–C–N with an extremely low carbon content (1.1 wt %) compared to the theoretical EtOSZ (25.1 wt %). Thus, the EtO group can be expected to act as a “sacrificial template” to afford a micro and mesoporous material as previously reported for the organo-substituted polysilazanes [22,23,25]. …”

Section: Introductionmentioning

confidence: 87%

“…During the crosslinking and subsequent high-temperature pyrolysis of polymer precursors, by-product gases such as CO 2 , CH 4 , NH 3 and H 2 were detected, and the microporosity in the amorphous PDCs could be assigned to the release of the small gaseous species formed in-situ [14,15,16,20,21,22,23]. …”

Section: Introductionmentioning

confidence: 99%

Microporosity and CO2 Capture Properties of Amorphous Silicon Oxynitride Derived from Novel Polyalkoxysilsesquiazanes

et al. 2018

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Polyalkoxysilsesquiazanes ([ROSi(NH)1.5]n, ROSZ, R = Et, nPr, iPr, nBu, sBu, nHex, sHex, cHex, decahydronaphthyl (DHNp)) were synthesized by ammonolysis at −78 °C of alkoxytrichlorosilane (ROSiCl3), which was isolated by distillation as a reaction product of SiCl4 and ROH. The simultaneous thermogravimetric and mass spectrometry analyses of the ROSZs under helium revealed a common decomposition reaction, the cleavage of the oxygen–carbon bond of the RO group to evolve alkene as a main gaseous species formed in-situ, leading to the formation of microporous amorphous Si–O–N at 550 °C to 800 °C. The microporosity in terms of the peak of the pore size distribution curve located within the micropore size range (<2 nm) and the total micropore volume, as well as the specific surface area (SSA) of the Si–O–N, increased consistently with the molecular size estimated for the alkene formed in-situ during the pyrolysis. The CO2 capture capacity at 0 °C of the Si–O–N material increased consistently with its SSA, and an excellent CO2 capture capacity of 3.9 mmol·g−1 at 0 °C and CO2 1 atm was achieved for the Si–O–N derived from DHNpOSZ having an SSA of 750 m2·g−1. The CO2 capture properties were further discussed based on their temperature dependency, and a surface functional group of the Si–O–N formed in-situ during the polymer/ceramics thermal conversion.

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Formation of Micro and Mesoporous Amorphous Silica-Based Materials from Single Source Precursors

Cited by 12 publications

References 46 publications

New‐Type Oxidation Barrier Coatings for Titanium Alloys

New‐Type Oxidation Barrier Coatings for Titanium Alloys

Tailored Oxidation Barrier Coatings for Mo-Hf-B and Mo-Zr-B Alloys

Microporosity and CO2 Capture Properties of Amorphous Silicon Oxynitride Derived from Novel Polyalkoxysilsesquiazanes

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