摘要:
A process for producing oxygen-free or low-oxygen shaped bodies of silicon carbide, particularly SiC fibers, by using chemically reactive polysilanes and/or polycarbosilanes as precursors. In accordance with the invention green fibers are stabilized preferably in the presence of reactive gases.
摘要:
A process for preparing polycarbosilanes by co-condensation of dihalosilanes R.sup.1 R.sup.2 SiX.sub.2 and saturated dihalohydrocarbons Y-A-Y in the presence of an alkali metal, wherein the groups R.sup.1, R.sup.2, X, Y and A have the meanings given in the claims, and also new polycarbosilanes are described.
摘要翻译:一种通过二烷基硅烷R 1 R 2 SiX 2和饱和二卤代烃YAY在碱金属存在下共缩合制备聚碳硅烷的方法,其中基团R 1,R 2,X,Y和A具有权利要求中给出的含义,并且还描述了新的聚碳硅烷 。
摘要:
Polycarbosilanes having Si units which are linked by phenyl-substituted methylene bridges or by partially or completely fluorinated hydrocarbon bridges. These polycarbosilanes are obtained by a Grignard polycondensation reaction. If phenyl substituents are present on the silicon atoms of the polycarbosilanes, they may also optionally be exchanged for halogen atoms in additional halogenating reactions, so that polycarbosilanes can be prepared which are both fluorinated on the hydrocarbon bridges and halogenated (particularly fluorinated) on the silicon atoms.
摘要:
Halogenated polycarbosilanes with uniform or mixed halogenation prepared from aryl-substituted, particularly phenyl-substituted polycarbosilanes by reaction with halogenating reagents under polar or ionic reaction conditions, optionally in the presence of a Lewis acid catalyst. The halogen atom introduced can optionally subsequently be replaced by another halogen atom through a transhalogenation reaction.
摘要:
Polycarbosilanes in which some of the silicon atoms have been replaced by a hetero element selected from boron, titanium, zirconium, hafnium, etc. The hetero elements are incorporated into the polycarbosilane skeleton in such a way that, like the silicon atoms, they are bonded to the other parts of the polycarbosilanes via hydrocarbon bridges, and the polycarbosilanes are free of hetero element-oxygen-silicon bonds.
摘要:
A reinforcement element, comprises at least one sensor fiber adapted for strain measurements based on stimulated Brillouin scattering within said sensor fiber. Furthermore, a system for monitoring strain within a structure comprises a reinforcement element comprising at least one sensor fiber adapted for strain measurements based on stimulated Brillouin scattering within said sensor fiber, a pump laser for coupling in laser radiation of a pump frequency into said at least one sensor fiber, a Stokes laser for coupling in laser radiation of a Stokes laser radiation into said at least one sensor fiber, wherein the pump frequency and the Stokes frequency are different from one another and wherein the frequency difference between the pump and Stokes frequencies is within the range of acoustical phonons within said sensor fiber, a sensor adapted to obtain a stimulated Brillouin backscattering signal, and a network analyzer adapted for determining the complex transfer function of the sensor fiber to determine a spatially resolved strain measurement.
摘要:
A binder-containing granulated silicon carbide products for the manufacture of highly dense silicon carbide ceramic products and the SiC ceramic products which can be made from the novel granulated silicon carbide products, especially highly dense SiC high-performance pressurelessly sintered ceramics.
摘要:
A reinforcement element, comprises at least one sensor fiber adapted for strain measurements based on stimulated Brillouin scattering within said sensor fiber. Furthermore, a system for monitoring strain within a structure comprises a reinforcement element comprising at least one sensor fiber adapted for strain measurements based on stimulated Brillouin scattering within said sensor fiber, a pump laser for coupling in laser radiation of a pump frequency into said at least one sensor fiber, a Stokes laser for coupling in laser radiation of a Stokes laser radiation into said at least one sensor fiber, wherein the pump frequency and the Stokes frequency are different from one another and wherein the frequency difference between the pump and Stokes frequencies is within the range of acoustical phonons within said sensor fiber, a sensor adapted to obtain a stimulated Brillouin backscattering signal, and a network analyzer adapted for determining the complex transfer function of the sensor fiber to determine a spatially resolved strain measurement.
摘要:
Halogenated polycarbosilanes with uniform or mixed halogenation prepared from aryl-substituted, particularly phenyl-substituted polycarbosilanes by reaction with halogenating reagents under polar or ionic reaction conditions, optionally in the presence of a Lewis acid catalyst. The halogen atom introduced can optionally subsequently be replaced by another halogen atom through a transhalogenation reaction.