Abstract: The field of the present invention is that of novel organosilicon compounds comprising a multifunctional polyorganosiloxane (abbreviated as POS) comprising, per molecule, and attached to silicon atoms, firstly at least one hydroxyl radical and/or at least one alkoxy radical, and secondly at least one group containing an activated ethylenic double bond consisting of a maleimide group. The present invention also relates to functionalization processes leading to the POSs targeted above, which consist in particular in reacting an organosilane bearing a maleamic acid function and at least two alkoxy functions with a polysilazane.

Abstract: Essentially infusible/insoluble crosslinked polysilazanes, well adapted for pyrolysis and conversion into silicon carbide and/or silicon nitride ceramic materials, are produced by intimately contacting a fusible and organic solvent soluble polysilazane starting material with an effective crosslinking amount of gaseous triflic acid, CF.sub.3 SO.sub.3 H, and in which starting polysilazane the organic radicals directly bonded to silicon atoms are saturated and/or aromatic hydrocarbon radicals and such starting polysilazane being devoid of hydrogen atoms directly bonded to a silicon atom.

Abstract: Crosslinked random boron/nitrogen preceramic polymers are prepared by reacting (a) admixture of a trihalogenoborane A and a cyclic boron/nitrogen compound B containing recurring structural units of the following general formula (1): ##STR1## in which A is a halogen atom and R is a hydrogen atom, or a hydrocarbyl, organosilyl or hydrogenoorganosilyl radical, with (b) an amino compound C containing at least one --NH.sub.2 group; the resulting polymers are facilely pyrolyzed into boron nitride ceramic materials.

Abstract: Novel composite ceramic materials include a boron nitride matrix and an amount of silicon components compatible therewith; such ceramic materials comprise a core volume having an external sheath layer on an outer face surface thereof, with the majority of said silicon values being distributed throughout the external layer.

Abstract: Crosslinked boron/nitrogen preceramic polymers are prepared by reacting (a) admixture of a trihalogenoborane A and a compound B containing at least one dihalogenated boron atom, with (b) an amino compound C containing at least one --NH.sub.2 group; the resulting polymers are facilely pyrolyzed into boron nitride ceramic materials.

Abstract: Novel ceramic materials include a boron nitride matrix and an amount of silicon values, such ceramic materials comprising a core volume having an external sheath layer on an outer face surface thereof, with the majority of said silicon values being distributed throughout the external layer.

Abstract: Organopolysilazanes or organopoly(disilyl)-silazanes having controlled physicochemical properties, well adapted for shaping and pyrolysis into useful ceramic articles, are prepared by catalytically polymerizing a silazane monomer to a desired degree of polymerization, and then, either during or upon completion of polymerization, contacting the polymerization reaction medium with at least one ion exchange material.

Abstract: Organopolysilazanes or organopoly(disilyl)silazanes having controlled physicochemical properties, well adapted for shaping and pyrolysis into useful ceramic articles, are prepared by catalytically polymerizing a silazane monomer to a desired degree of polymerization, and then, either during or upon completion of polymerization, contacting the polymerization reaction medium with at least one adsorbent material.

Abstract: Boron/nitrogen preceramic polymers are prepared by reacting (a) the product of mass thermolysis of a compound of Formula (1): ##STR1## in which A is a halogen atom and R is a hydrogen atom, a hydrocarbon radical, or an organosilyl or hydrogenoorganosilyl radical, with (b) an amino compound containing at least one --NH.sub.2 group; the resulting polymers are facilely pyrolyzed into boron nitride ceramic materials.

Abstract: Polydiorganosiloxanes having silanol end groups, well suited for the production of vulcanizable silicone compositions, are conveniently prepared by bulk polycondensing a polydiorganosiloxane oligomer having silanol end groups in a closed reaction zone in the presence of a catalytically effective amount of trifluoromethylsulfonic acid, at a temperature of from 20.degree. to 160.degree. C., while continuously removing water of polycondensation, and terminating the polycondensation reaction by adding a catalyst neutralizing amount of a cyclopolydiorganosilazane or a polydiorganosilazane having diorganoaminosilyl end groups to the medium of reaction.

Abstract: Crosslinked boron/nitrogen preceramic polymers are prepared by reacting (a) admixture of a trihalogenoborane A and a compound B containing at least one dihalogenated boron atom, with (b) an amino compound C containing at least one --NH.sub.2 group; the resulting polymers are facilely pyrolyzed into boron nitride ceramic materials.

Abstract: A process for treating a polysilazane, characterized in that a polysilazane possessing on average at least two, and preferably at least three, hydrocarbon groups having aliphatic unsaturation per molecule is treated catalytically in the presence of a catalytically efficient amount of a co-ordination catalyst. The polysilazanes treated in this manner possess high thermal resistance and can be used, in particular, as precursors of ceramic products, with a high yield of inorganic product.

Abstract: A process for the catalytic treatment of a polysilazane containing an average of at least two, preferably at least three, .tbd.SiH groups per molecule with a catalytically effective quantity of a strong inorganic or organic acid catalyst. The other organic radicals in the polysilazane that are bonded to the silicon or nitrogen atoms are hydrocarbon radicals free from alkene or alkyne unsaturations. The polysilazanes treated in this manner can be characterized by good thermal behavior and can be used, in particular, as precursors of ceramic products with a high yield of inorganic products.

Abstract: Method of spinning fibers and coating from an organopolysilazane composition that can be crosslinked by an energy input. The organopolysilazane composition comprises an organopolysilazane and a free radical generator in an amount effective to crosslink the organopolysilazane. The energy input capable of generated the radical may be provided in the form of heat, ultraviolet radiation, an electron beam, and the like.The crosslinked organopolysilazane compositions exhibit good thermal behavior and, in particular, can be used, after pyrolysis, as precursors of ceramic products.

Abstract: An organopolysilazane composition that can be crosslinked by an energy input. The organopolysilazane composition comprises an organopolysilazane and a free radical generator in an amount effective to crosslink the organopolysilazane. The energy input capable of generating the radical may be provided in the form of heat, ultraviolet radiation, an electron beam, and the like.The crosslinked organopolysilazane compositions exhibit good thermal behavior and, in particular, can be used, after pyrolysis, as precursors of ceramic products.

Abstract: A process for the treatment of polyorganosilazanes and/or polyorgano(disilyl)silazanes with an effective quantity of a catalyst system comprising (i) an ionic inorganic salt of the formula M.sup.30 A.sup.-, and (II) a compound capable of complexing with the cation M.sup.+ of the salt. The M.sup.+ cation is a metal ion or a quaternary ammonium ion, and A.sup.- is a compatible anion.The polysilazanes are selected from organopolysilazanes and organopoly(disilyl)silazanes. When treated in this manner, the polysilazanes are characterized by good thermal behavior and can, in particular, be used, after pyrolysis, as precursors of ceramic products.

Abstract: A crosslinkable composition comprising at least one polysilazane containing at least 2, preferably at least 3, .tbd.SiH groups per molecule and at least 2 SiR.sub.2 groups per molecule, R.sub.2 being an unsaturated hydrocarbon radical and a catalytically effective quantity of a metal element or of a metal compound to catalyze the hydrosilylation reaction SiH/SiR.sub.2.The compositions according to the invention can crosslink under the effect of heat and can be used for coating or impregnating substrates with ceramic material after pyrolysis. The mechanical properties of the crosslinked compositions are assessed by evaluating the relative rigidity RR measured by the fiber torsion pendulum method (FIG. 1).

Abstract: The present invention relates to a process for the treatment of polysilazane in a homogeneous phase with a catalytically effective quantity of an acid catalyst selected from HClO.sub.4 and CF.sub.3 SO.sub.3 H. The polysilazane is preferably selected from the group consisting of organopolysilazane, organopoly(disilyl)silazane and mixtures thereof. The organic radicals bonded to the silicon atoms are preferably saturated or aromatic hydrocarbon radicals and the silicon atoms of the polysilazane are substantially free from any hydrogen atom bonded directly to the silicon atoms.The polysilazanes treated in this manner have good thermal behavior and, are particularly useful as precursors of ceramic products.

Abstract: A process for the thermal treatment of a polysilazane at a temperature from about 40.degree. C. to 220.degree. C. The polysilazane contains on average at least two, preferably at least three, .tbd.SiH groups per molecule and at least two ##STR1## groups and, if appropriate, unsaturated aliphatic hydrocarbon groups bonded to the silicon atoms. The polysilazanes treated in this manner have good thermal behavior and can be used in particular as precursors of ceramic products with a high yield of inorganic products.