| abstract |
An alkali aluminosilicate geopolymeric matrix for the production of composite materials with a fiber reinforcement has a composition, after dehydration, expressed as oxides, as follows: n n yM.sub.2 O:Al.sub.2 O.sub.3 :xSiO.sub.2 n n where "x" is 6.5-70, "y" is 0.95-9.50 and M is Na, K or Na+K. The geopolymeric matrix comprises a nanocomposite material with at least two phases, with (a) a first nodular silicious phase composed of nanospheres with diameters of less than 1 micron, preferably less than 500 nm, and (b) a second polymeric phase essentially composed of alkali poly(aluminosilicate) having one or more sialate bridge (--Si--O--Al--O) cross-linking sites of total formula M 4 Si 2 AlO 10 to M 2 Si 4 AlO 16 , such that, in the alkali poly(aluminosilicate), the ratio of Si(O 4 ) to Al(O 4 ) is >3.5, preferably >5. The geopolymeric matrix has a spectrum of 29 Si MASNMR with three resonance regions: -87±5 ppm, -98 ±5 ppm, -107 ±5 ppm, and prevents the oxidation at high temperatures of the carbon fibre. The resulting composite materials can be used at temperatures of up to 1000° C. |