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).