other suitable welding processes to form an inner annular weld seal 46 and an outer annular weld seal 48 as shown in fig7 the sealed assembly is evacuated using a vacuum pump and pipe 50 connected to the grooves or chambers 42 and 44 the sealed assembly is then heated while being continuously evacuated to remove the glue 22 from the annular fibre preforms 20 and to remove the glue 22 from the sealed assembly after all the glue 22 has been removed from the annular fibre preforms 20 and the interior of the sealed assembly is evacuated the pipe 50 is sealed the sealed assembly is then heated and pressure is applied to the sealed assembly to produce axial consolidation of the annular fibre preforms 20 and diffusion bonding of the first metal ring 30 to the second metal ring 36 and diffusion bonding of the metal on the metal coated 18 ceramic fibres 14 to the metal on other metal coated 18 ceramic fibres 14 to the first metal ring 30 and to the second metal ring 36 during the application of heat and pressure the pressure acts equally from all directions on the sealed assembly and this causes the annular projection 38 to move axially into the annular.