| 摘要 |
In a fibre-reinforced composite material, consisting of ceramic or carbon fibres and a fully ceramic glass-ceramic matrix of MAS-Y type (i.e. contg. Mg, Al, Si and Y), the novelty is that the matrix consists of cordierite (Mg2Al4Si5O18) contg. embedded yttrium silicate. Prodn. of the above composite material involves (i) preparing a matrix precursor by contacting a sol of one or more of MgO, Al2O3, SiO2 and Y2O3 with a salt of each of the elements forming the other oxides, drying the resulting suspension and calcining; (ii) impregnating the reinforcing fibres with a slurry of the opt. pre-ground precursor; (iii) producing a preform from the impregnated fibres; (iv) sintering the preform at 1000-1250 deg.C and 5-20 MPa for 45 mins. to 2 hrs.; and opt. (v) heat treating at 1050-1150 deg.C for 1-2 hrs. without pressure. USE/ADVANTAGE - In the aerospace industry, esp. in engines, for mfg. telescope mirror supports and as heat protection, and in general industry, as heat protection and for mfg. heat exchangers (claimed). The material is produced by a simplified pressing cycle and has improved structural and physical characteristics. Compared with conventional glassmaking processes, the sol-salt process provides compsn. control and purity, does not use addns. of secondary elements such as nucleating agents, fluxes and/or refiners and need not employ grinding. Compared with the conventional sol-gel process, the process employs less expensive starting products and a simpler pressing cycle.
|
