Macroporous silicon carbide foams for porous burner applications and catalyst supports Original Research Article

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, Si3N4 and Si2N2O.