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AssigneeFraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V.
InventorJörg Adler
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The invention relates to the field of ceramics and open-celled silicon carbide foam ceramics, which can find application, for example, as high temperature- and thermal shock-resistant silicon carbide foam. The aim of the invention is to disclose an open-celled silicon carbide foam ceramic with improved thermal shock resistance, which may be produced by a simple method. Said aim is achieved with an open-celled silicon carbide foam ceramic, the structure of which is made up of sintered silicon carbide with a 5 to 30% pore volume of closed pores with an average diameter of <20 μm. The invention further relates to a method for the production of an open-celled silicon carbide foam ceramic, whereby coarse and fine silicon carbide powder in the ratio 20:80 to 80:20 parts are mixed and a suspension produced therefrom. An open-celled foam or open-celled network is then coated with said suspension, the foam or network material removed and sintering carried out at a temperature of >1800° C. under a protective atmosphere or in vacuo.
Open-celled silicon carbide foam ceramic comprising a three-dimensionally cross-linked ceramic structure of many webs connected to one another and open cells lying between the webs, said webs comprise substantially sintered silicon carbide with 5 to 30% pore volume of completely closed or substantially completely closed pores with an average diameter of <20 μm.
Process for producing an open-celled silicon carbide foam ceramic with 5 to 30% pore volume of completely closed or substantially completely closed pores with an average diameter of <20 μm in the webs comprising mixing coarse silicon carbide powder and fine silicon carbide powder in a ratio of 20:80 to 80:20 with sintering additives to obtain a mixture, the coarse silicon carbide powder having an average grain size of 5-100 μm and the fine silicon carbide powder having an average grain size of <2 μm, forming a suspension from the mixture, and subsequently coating an open-celled foam or an open-celled network with the suspension at least once, drying the foam or the network, removing the foam or network material and sintering the remaining green body at temperatures >1800° C. in protective gas or in a vacuum.
Dependencies are inferred from the claim text.