Ordered Mesoporous Silicoboron Carbonitride Materials via Preceramic Polymer Nanocasting

Abstract

Highly ordered two-dimensional (2D) mesoporous silicoboron carbonitride (SiBCN) materials were prepared by a double nanocasting approach using mesoporous SBA-15 silica as starting template. The latter was converted into its negative replica CMK-3 carbon template, which was subsequently impregnated with a boron-modified polysilazanes of the type [B(C2H4SiCH3NCH3)3] n ([C14.4H31.4N4.1B1.0Si3.0] n ) using a liquid-phase impregnation (LPI) process. The derived [B(C2H4SiCH3NCH3)3] n -carbon composite was cross-linked under ammonia at 200 °C and then thermolyzed under nitrogen at 1000 °C to generate a SiBCN-carbon composite. The carbon template was subsequently removed through thermal treatment at 1000 °C in an ammonia atmosphere to generate ordered mesoporous structures. XRD and TEM analyses revealed that as a negative replica of the CMK-3 template, the obtained amorphous mesoporous material exhibited open, continuous, and ordered 2D hexagonal frameworks, whereas elemental analyses indicated the formation of materials with an empirical formula of Si3.0B1.0C4.2N3.5. The ordered mesoporous Si3.0B1.0C4.2N3.5 material displayed high surface area (600 m2 g−1), high pore volume (0.61 cm3 g−1), and narrow pore size distribution (around 3.4 nm) and exhibited a relatively good thermal stability in air through heat-treatment to 1400 °C.

Electromagnetic wave absorbing properties of SiC/SiO2 composites with ordered inter-filled structure

“…1aec). The morphologies of these monoliths were similar to that of the SBA-15, which confirmed that the SiC grains were restricted into channels of the SBA-15 [25,27]. When the calcination temperature was 1500 C, the as-prepared composite was constructed from unconnected particles (shown in Fig.…”

Progress of a novel non-oxide Si-B-C-N ceramic and its matrix composites

“…Additionally, the preparation process is complex and the ceramic structure and ceramic property are greatly affected by complicated factors. Generally, the organic polymer pyrolyzing route is applicable to the preparation of ceramic fiber [50], ceramic coating [51], porous ceramic [18], or fiber reinforced ceramic matrix composite [19]. However, by this method, it is difficult to prepare a dense bulk ceramic particularly with large dimensions [12].…”

“…Pyrolysis of this precursor at 1000 ℃ in the argon atmosphere produces a kind of Si-B-C-N ceramic, whose structure is amorphous at temperatures lower than 1700 ℃ in air and does not lose weight even at 2000 ℃ in an inert atmosphere. At present, using the polymer pyrolyzing route, various kinds of Si-B-C-N ceramics can be prepared, such as bulk ceramic, ceramic fiber, ceramic coating, porous ceramic, ceramic matrix composite or ceramic microdevice [16][17][18][19]. These products have found potential applications in aerospace craft, traffic transport system, and micromachine or microcircuit used at elevated temperatures, etc [20].…”

Synthesis of Polyyttriocarbosilane and its Conversion to Yttrium-Containing Ceramic

“…According to previously published data, the silicon-containing polymers, such as polysilanes [6], polycarbosilanes (PCS) [7], and polyorganosilazanes [1], have proved to be promising precursors for the production of technologically important non-oxide ceramics in various forms, including fibers [9,10], coatings [11][12][13], infiltrated porous ceramics [14][15][16], and other complex-shaped bulk parts [17][18][19]. PCS with a linear -Si-C-Si-C-backbone and organic side chains are considered to be very useful precursors for synthesizing metal-containing ceramics due to their high ceramic yield and insensitivity to oxygen and moisture.…”