Three different types of SiC preforms, with open porosities between 60 and 70%, were prepared by pyrolysis of polysilanes and polycarbosilanes at 1670 K. Some samples of each type of SiC structure were oxidized in air at 1070 K to promote wetting by the glass melt. Preforms were then applied for gas pressure infiltration with an alumosilicate glass melt at 1670 K in 3 MPa argon, and the influence of pore-size distribution and surface composition on infiltration ti me was investigated. The composition of the precursors was determined by chemical analysis, and pyrolysed SiC was analysed by thermal decomposition. The porosity and pore-size distribution of the SiC-preforms were measured on photographs of sample cross-sections. The SiC-glass composites were examined by light microscopy, scanning electron microscopy and electron scanning microanalysis.