P.W.M. Peters et al. / Journal of the European Ceramic Society 20(2000)531-535 In the present work the mechanical behaviour of a the polymer, which is also cross-linked and pyrolyzed mullite-based CMC with oxide fibres(Nextel 610)and a One to three reinfiltration cycles show the best results fugitive interface is characterized. The material is pro- As a final process, the composite is annealed in air to duced by Dornier Forschung by the polymer route and reduce internal stresses and to remove the carbon coat tested at DLR ing on the fibres. The microstructure of the composite is shown in Fig. 2. The matrix is characterized by a homogeneous distribution of the mullite and the Si-O- 2. Materials and experiments C phase and a small grain size of the particles compared to the fibre dimensions The material investigated(designated Nextel 610/ A crossply laminate(0/90/0/90/0/ 90)s with, in total, 12 Umox)is produced by Dornier Forschung. The manu- layers was produced. The average thickness of the plate facturing technique is based on the polymer infiltration was 2.00 mm(ply thickness 0.167 mm), the fibre volume nd pyrolysis process. 7. It comprises three steps. First, fraction and the porosity measured Ve=0.456 and the fibre bundles are coated with a carbon layer of about 0. 1 um thickness. The fibres are pulled through a vessel containing a solution of a carbon precursor polymer Thus, a polymer film on each single fibre is produced and subsequently converted into a carbon layer by pyrolysis in a furnace The infiltration technique is similar to the production of fibre reinforced plastics. The fibres can be infiltrated by filament winding(as shown in Fig. 1), resin transfer molding or wet lamination with the slurry out of diluted silicon polymer and mullite powder. After infil tration, the polymer is cross-linked and densified in an autoclave to form a solid green body Subsequently the polymer is pyrolyzed in an oven with an inert atmosphere. Thus, a ceramic matrix is roduced that consists of mullite and a Si-O-C phase Fig. 2 structural details on polished surface of a Nextel 610/ To minimize porosity, the composite is reinfiltrated with Mox crossply laminate CMC Production by Infiltration and Pyrolysis of Polymers precursor ● solvent of prepregs filament winding ceramic powder filament winding by Resin Transfer Moulding (RTM under autoclave conditions out forming tools 200-300C.10-20bar 1100·1600C protecton integral structure from CMC Fig. I. Production of mullite/mullite CMCs by poylmer impregnation and pyrolysis.In the present work the mechanical behaviour of a mullite-based CMC with oxide ®bres (Nextel 610) and a fugitive interface is characterized. The material is pro￾duced by Dornier Forschung by the polymer route and tested at DLR. 2. Materials and experiments The material investigated (designated Nextel 610/ Umox) is produced by Dornier Forschung. The manu￾facturing technique is based on the polymer in®ltration and pyrolysis process.7,8 It comprises three steps. First, the ®bre bundles are coated with a carbon layer of about 0.1 mm thickness. The ®bres are pulled through a vessel containing a solution of a carbon precursor polymer. Thus, a polymer ®lm on each single ®bre is produced and subsequently converted into a carbon layer by pyrolysis in a furnace. The in®ltration technique is similar to the production of ®bre reinforced plastics. The ®bres can be in®ltrated by ®lament winding (as shown in Fig. 1), resin transfer molding or wet lamination with the slurry out of a diluted silicon polymer and mullite powder. After in®l￾tration, the polymer is cross-linked and densi®ed in an autoclave to form a solid green body. Subsequently the polymer is pyrolyzed in an oven with an inert atmosphere. Thus, a ceramic matrix is produced that consists of mullite and a Si±O±C phase. To minimize porosity, the composite is rein®ltrated with the polymer, which is also cross-linked and pyrolyzed. One to three rein®ltration cycles show the best results. As a ®nal process, the composite is annealed in air to reduce internal stresses and to remove the carbon coat￾ing on the ®bres. The microstructure of the composite is shown in Fig. 2. The matrix is characterized by a homogeneous distribution of the mullite and the Si±O± C phase and a small grain size of the particles compared to the ®bre dimensions. A crossply laminate (0/90/0/90/0/90)s with, in total, 12 layers was produced. The average thickness of the plate was 2.00 mm (ply thickness 0.167 mm), the ®bre volume fraction and the porosity measured Vf=0.456 and Fig. 1. Production of mullite/mullite CMCs by poylmer impregnation and pyrolysis.7 Fig. 2. Macrostructural details on polished surface of a Nextel 610/ Umox crossply laminate. 532 P.W.M. Peters et al. / Journal of the European Ceramic Society 20 (2000) 531±535