Abstract:
Das Verfahren zur Herstellung von NO 2 -freien, NO-haltigen Gasen basiert auf der Verwendung eines schwefelhaltigen Polymers in Gegenwart von Wasser als Filtermaterial. Ein schwefelhaltiges Polymer ist beispielsweise Polyphenylensulfid. Es wird ein Filter zur Entfernung von NO 2 beschrieben, das ein schwefelhaltiges Polymer und Wasser enthält. Der Filter wird zum Beispiel zur Erzeugung von NO2 - freiem NO/N 2 /O 2 -Gasgemischen für medizinische Applikationen verwendet.
Abstract:
The invention relates to novel chlorine-containing silazane polymers, to their preparation, their further processing to ceramic material containing silicon nitride, and this material itself. In order to prepare the chlorine-containing silazane polymers, oligosilazanes of the formula (I) in which a>0, b>/=0 and n is about 2 to about 12, are reacted with at least one of the chlorosilanes Cl2R4Si-CH2-CH2-SiR4Cl2, Cl3Si-CH2-CH2-Sir5Cl2, R6SiCl3 or R7SiHCl2 at 30 DEG C. to 300 DEG C., where, independently of one another, R1 and R2=H, C1-C6-alkyl or C2-C6-alkenyl, R3, R4, R5, R6 and R7=C1-C6-alkyl or C2-C6-alkenyl and where if b=0 the reaction with R7SiHCl2, if R7=C1-C6-alkyl and none of the other chlorosilanes is present, is to be excluded. The chlorine-containing silazane polymers according to the invention can be converted by reaction with ammonia into polysilazanes, which in their turn can be pyrolyzed to form ceramic materials containing silicon nitride.
Abstract:
The invention relates to a high-strength ceramic composite, in particular made from silicon nitride, a process for its preparation and its use. The process comprises impregnating an open-pore matrix with a molten polysilazane in a first step and, in a second step, heating the impregnated matrix to 800 DEG to 2500 DEG C. under a blanketing gas, such as nitrogen or a noble gas, or to 800 DEG to 1500 DEG C. under a gas containing ammonia. The high-strength ceramic composite prepared can be used as a component to be subjected to high thermal, mechanical or corrosive stress.
Abstract:
The invention relates to a fibre-containing composite ceramic and a process for the preparation thereof. The process comprises, in a first step, impregnating fibres with a polysilazane melt, in a second step, converting the polysilazane in the fibres into the infusible state, and, in a third step, heating the impregnated fibres to from 800 to 2000 DEG C in a nitrogen, noble-gas or ammonia atmosphere.
Abstract:
The invention relates to novel polymeric ethylene-bridged chlorosilazanes, their preparation, their further processing to give silicon nitride containing ceramic material, and to this material itself. For the preparation of the polymeric chlorosilazanes, oligosilazanes of the formula (I) … … are reacted with at least one of the chlorosilanes … … R SiCl3 or R SiHCl2, where R to R are C1-C6-alkyl or C2-C6-alkenyl groups which can be identical or different. … The polymeric chlorosilazanes according to the invention can be converted by reaction with ammonia into polysilazanes which, in turn, can be pyrolysed to give silicon nitride-containing ceramic materials.
Abstract:
The polymeric hydridosilazanes are prepared by reacting polymeric hydridothiosilazanes with NH3. The silicon nitride-containing ceramic material is prepared by pyrolysing the polymeric hydridosilazanes.
Abstract:
In the process for making ceramic microstructures from polymer precursors, the precursor materials are first prepared, then introduced into preformed structures in a intrinsically stable mould material, after which the organic constituents are finally decomposed by pyrolysis.