In Situ Formation of Silicon Carbide Nanofibers on Cordierite Substrates

Abstract

Twenty‐five years of diesel particulate filter (DPF) developments have shown that high‐volume ceramic materials are well suited for the harsh requirements of exhaust after treatment. Nevertheless, problems regarding filter reliability and durability associated with the regeneration of the filter have limited their serious application until only recently. To extend useful filter life, the present study has examined the growth of silicon carbide (SiC) nanofibers by a simple carbothermal reduction process on cordierite support surfaces using cheap raw materials such as kaolin, talc, and carbon black. Transmission electron microscopy confirms the crystalline (β‐SiC) nature of the nanofibers (10–20 nm diameter). The growth of these nanofibers increases the support‐specific surface area restricting the agglomeration of noble metal catalyst particles that otherwise occurs in wash‐coat sintering. As a result, fewer particles are needed to perform the catalyst role (at reduced cost) and the support structure can host the catalyst for prolonged times at higher temperatures. As the future will see increasing economic competition in filter fabrication routes and materials, this new design of catalytic DPF promises to play a significant role.

Growth of One‐Dimensional Nanostructures in Porous Polymer‐Derived Ceramics by Catalyst‐Assisted Pyrolysis. Part II: Cobalt Catalyst

“…7(b) shows the growth direction of the nanowire). This observed growth direction is indeed typical of SiC nanowires grown by a solution–precipitation mechanism 24,62,64 . In some cases, the SiC nanowires contained arrays of planar defects, also resulting in characteristic multiple reflexes in the diffraction pattern (see SAED pattern in Fig.…”

Low‐Density Open Cellular Silicon Carbide Foams from Sucrose and Silicon Powder

“…In most of the cases, the nanostructures produced on the cell wall surfaces had a length in the range of 2–3 μm . The growth of the nanostructures was by a vapor–liquid–solid (VLS) mechanism in which gaseous precursor molecules first dissolve in a liquid droplet formed by the catalysts at high temperature . The crystallization of nanostructures takes place upon the supersaturation of the catalyst droplet with the precursor molecules.…”

Growth of One‐Dimensional Nanostructures in Porous Polymer‐Derived Ceramics by Catalyst‐Assisted Pyrolysis. Part I: Iron Catalyst

“…In particular, the use of preceramic polymers is very promising, due to the great tailorability of their structures on a molecular scale and ease of processing. It has been shown that various types of nanostructures, such as whiskers, 2 nanotubes, 3–5 and nanocables 6 /wires 7–9 /fibers 10–12 of different compositions can be produced directly from preceramic polymers, without the use of any transition metal additives as catalyst. Recently, great progress has been made in the production of nanostructures from preceramic polymers (mostly polysilazanes or polycarbosilanes (PCSs)) by applying catalyst‐assisted pyrolysis (CAP), leading to improved yield and the formation of varied morphologies.…”