Macroporous silicon carbide foams for porous burner applications and catalyst supports

• Published in: The Journal of physics and chemistry of solids 2007-05, Vol.68 (5), p.1234-1238
• Main Authors: Vogt, U.F., Györfy, L., Herzog, A., Graule, T., Plesch, G.
• Format: Article
• Language: English
• Subjects: A. Ceramics; A. Inorganic compounds; A. Microporous structures; A. Polymer; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; D. Mechanical properties; Deformation and plasticity (including yield, ductility, and superplasticity); Exact sciences and technology; Materials science; Materials synthesis; materials processing; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Physics; Specific materials
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2006.12.008

Pre-ceramic polymer (MK-polymer)-based nitrogen-bounded silicon carbide (NBSiC) has been developed and the concept utilised to produce macroporous ceramic foam structures by a modified sponge replica technique. In order to increase the strut thickness and to fill up the hollow struts and thus increase the mechanical strength of the microporous structures, repeated re-infiltrations and pre-sintering steps are investigated. The double-ring bending strength could be increased with increasing polymer content and coating, respectively infiltration cycles up to a maximum value of 140 MPa for NBSiC discs, nitrided at 1400 °C. After a re-crystallisation process at 1850 °C, the influence of the polymer is negligible and the bending strength is only in the region of 50 MPa, as re-crystallised SiC (RSiC) is the dominant phase. The oxidation behaviour of NBSiC corresponds with the oxidation behaviour of commercial SiC. EDX analysis of samples nitrided at 1400 °C shows the composition containing grains of SiC, Si 3N 4 and Si 2N 2O.