Composite article comprising aerogel particles, ceramic and/or glass fibers and opacifiers

A composite article comprising aerogel particles, graphite and ceramic and/or glass fibers, wherein one or more of the following requirements (i) to (vii) are fulfilled:

• (i) the composite article contains less than 15% by weight organic compounds;
• (ii) at least 50% of the fibers in the composite article have a length of 5 mm or more;
• (iii) the composite article contains less than 10% by weight binder;
• (iv) the composite article exhibits a total weight loss in thermogravimetric analysis (TGA) when being heated in a nitrogen atmosphere from 30° C. to 1100° C. with a temperature increase of 10° C./min of less than 35% by weight;
• (v) the weight ratio of the one or more aerogels to the one or more fibers (aerogel/fiber) in the composite article is 1:8 or higher;
• (vi) the composite article has a burn-through time of 60 minutes or more, wherein the burn-through resistance is determined using the composite article in the form of a 30 cm×30 cm sheet with a thickness of 13 mm and treating the composite article at the centre of its first major surface with a flame having a temperature of 1400° C., using a soldering torch, wherein the burn-through time is the duration from start of the flame treatment until the centre of the second major surface reaches a temperature of 1000° C.;
• (vii) when using the composite article in the form of a 20 cm×50 cm sheet with a thickness of 13 mm and treating the composite article at the full surface of its first major surface in accordance with the ISO 834 temperature-time curve for 180 minutes, the centre of the second major surface has a temperature of less than 1000° C.