Polymer-Derived Ceramics with engineered mesoporosity: From design to application in catalysis

Lale, Abhijeet; Schmidt, M.; Mallmann, Maira Debarba; Bezerra, André Vinícius Andrade; Acosta, Emanoelle Diz; Machado, Ricardo Antônio Francisco; Demirci, Umit B.; Bernard, Samuel

doi:10.1016/j.surfcoat.2018.07.061

Cited by 55 publications

(35 citation statements)

References 130 publications

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“…The latter offers the advantages for the in-situ synthesis of the ceramic nano-precipitates in a ceramic (possibility of different nature) matrix during the pyrolysis and annealing experiments. In addition, it allows processing materials in particular shapes and morphologies (dense or porous) that are difficult, or even impossible to obtain from conventional routes [ 20 , 21 , 22 , 23 , 24 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

In-Situ Synthesis and Characterization of Nanocomposites in the Si-Ti-N and Si-Ti-C Systems

et al. 2020

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The pyrolysis (1000 °C) of a liquid poly(vinylmethyl-co-methyl)silazane modified by tetrakis(dimethylamido)titanium in flowing ammonia, nitrogen and argon followed by the annealing (1000–1800 °C) of as-pyrolyzed ceramic powders have been investigated in detail. We first provide a comprehensive mechanistic study of the polymer-to-ceramic conversion based on TG experiments coupled with in-situ mass spectrometry and ex-situ solid-state NMR and FTIR spectroscopies of both the chemically modified polymer and the pyrolysis intermediates. The pyrolysis leads to X-ray amorphous materials with chemical bonding and ceramic yields controlled by the nature of the atmosphere. Then, the structural evolution of the amorphous network of ammonia-, nitrogen- and argon-treated ceramics has been studied above 1000 °C under nitrogen and argon by X-ray diffraction and electron microscopy. HRTEM images coupled with XRD confirm the formation of nanocomposites after annealing at 1400 °C. Their unique nanostructural feature appears to be the result of both the molecular origin of the materials and the nature of the atmosphere used during pyrolysis. Samples are composed of an amorphous Si-based ceramic matrix in which TiNxCy nanocrystals (x + y = 1) are homogeneously formed “in situ” in the matrix during the process and evolve toward fully crystallized compounds as TiN/Si3N4, TiNxCy (x + y = 1)/SiC and TiC/SiC nanocomposites after annealing to 1800 °C as a function of the atmosphere.

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Section: Introductionmentioning

confidence: 99%

In-Situ Synthesis and Characterization of Nanocomposites in the Si-Ti-N and Si-Ti-C Systems

et al. 2020

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“…The shape of isotherms for samples pyrolyzed at 1000°C, especially those with 4.5 μm SiC particles, was associated with type IV isotherm, corresponding to mesoporosity (2‐50 nm), where capillary condensation takes place . Recent advances in the design of mesoporous PDCs hold much promise for the development of novel catalysts or catalyst supports …”

Section: Characterization Of Tape Cast Pdcsmentioning

confidence: 99%

“…Indeed, due to the high degree of control on the physical and rheological properties of PCPs, the PDC route allows polymer shaping before, after, or even during the cross‐linking or curing step to produce a large variation of shapes and sizes. This includes thin ceramic parts or multilayered laminates, such as those obtained from tape casting, as well as fibers, coatings, or dense monoliths …”

Section: Conventional and Pdc‐based Tape Casting Comparedmentioning

confidence: 99%

“…This includes thin ceramic parts or multilayered laminates, such as those obtained from tape casting, as well as fibers, coatings, or dense monoliths. 107 Another even harder challenge is adjusting the rheology of a polymer with a large amount of nanosized powders, 116 which are typically required to produce a near net shape PDC within a desired composition. Because of the decrease in flow ability of the polymer containing the nanoparticles, suitable precursors and processing conditions need to be carefully selected, depending on the forming technology employed.…”

Section: Based Tape Casting Comparedmentioning

confidence: 99%

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Tape casting of preceramic polymers toward advanced ceramics: A review

Hotza

Nishihora

Machado

et al. 2019

Int J Ceramic Engine & Sci

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In the last 20 years, tape casting, a standard wet‐shaping process to produce thin ceramics, has been applied to manufacture polymer‐derived ceramics (PDCs). Si‐based polymers, such as polysiloxanes and polysilazanes, also known as preceramic polymers (PCPs), have been used as precursors/binders replacing conventional raw materials and additives for tape casting process. Thermal processing of PCPs is carried out at lower temperatures in comparison with classical ceramic sintering, particularly of carbides and nitrides. Furthermore, polymeric precursors can be converted into hybrid or composite ceramics, when parts of the polymers remain unreacted. Inert or reactive fillers might be used to reduce both shrinkage and porosity inherently caused by the weight loss occurring during polymer pyrolysis while forming new ceramic phases in the final materials. Alternatively, pore formers might also be added to tailor pore shape, connectivity, and volume (macroporosity). Nevertheless, current equipment and process parameters for tape casting‐based products must be eventually adjusted to fit the characteristics of ceramic precursors. Therefore, the aim of this review is focused on listing and discussing the efforts to produce PDCs using tape casting as a shaping technique. Interactions of system components and effects of treatment, particularly thermal stages, on final microstructure and properties are stressed out. Gaps in the literature concerning processing optimization are pointed out, and suggestions are given for further development of PDCs produced by tape casting.

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“…Typically, the PDCs were synthesized through thermal decomposition of certain high molecular weight polymeric polymers. It has been shown that the direct polymer‐to‐ceramic processing route of PDCs could make the materials very suitable for the fabrication of ceramics materials with varied morphologies and meets the requirements of high thermal stability, excellent oxidation resistance and favorable mechanical property …”

Section: Introductionmentioning

confidence: 99%

Amorphous SiCNO hollow nanofibers with mesoporous walls

2018

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In this work, for the first time, we reported the fabrication of polymer‐derived amorphous SiCNO ceramics via electrospinning of tetraethoxysilane (TBOS), polyvinylpyrrolidone (PVP), cetrimonium bromide (CTAB), and urea combined with subsequent air calcination. The resultant products exhibited a well‐defined one‐dimensional (1D) hollow fiber nanostructure with mesoporous walls. The BET surface area of SiCNO hollow nanofibers is ~95.6 m2/g, and the average pore diameter is sized in ~9 nm. The movement of urea within the core of the as‐spun polymeric fibers accounted for the formation of hollow nanofibers, and the thermal decomposition of polymers such as PVP, TEOS, and urea responded for the formation of mesopores within the walls. In addition, it was found that the contents of urea within the raw materials played a critically important role in the formation of SiCNO mesoporous hollow nanofibers, making their growth in a controlled manner.

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Polymer-Derived Ceramics with engineered mesoporosity: From design to application in catalysis

Cited by 55 publications

References 130 publications

In-Situ Synthesis and Characterization of Nanocomposites in the Si-Ti-N and Si-Ti-C Systems

In-Situ Synthesis and Characterization of Nanocomposites in the Si-Ti-N and Si-Ti-C Systems

Tape casting of preceramic polymers toward advanced ceramics: A review

Amorphous SiCNO hollow nanofibers with mesoporous walls

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