Method of forming a low-density insulating thermostructural composite material

Method for producing an insulating, low density thermostructural composite material comprising:

• placing a premade first composite, comprising SiC fibers and glass, on a rigid support,
• placing, on said first composite, an expanded foam layer, comprising glass, whose shape corresponds to the shape of said low density thermostructural composite material and whose thickness together with the thickness of said first composite corresponds to the thickness of said low density thermostructural composite material, to form a first unit;
• placing a rigid counterform on said first unit opposite to said rigid support to form a second unit;
• applying a uniformly distributed mechanical pressure to said second unit through said rigid support and said rigid counterform;
• placing said second unit under said mechanical pressure in an oven and heating it under air at atmospheric pressure to a temperature, and for a time sufficient to bond said first composite to said foam layer and cause migration of chemical elements from each of said foam layer and said first composite into the other across an interface therebetween to form a fusion bonded second composite of said first composite and said foam layer, but insufficient to substantially damage said glass/SiC fibers first composite or said expanded foam layer;
• removing the second unit, held under said mechanical pressure, from said oven;
• cooling said second unit under said mechanical pressure until said second composite becomes substantially rigid;
• and
• separating said second composite article, consisting essentially of said bonded first composite and foam layer, from said second unit as said insulating, low density thermostructural composite material.