Preparation of silicon carbide ceramics from the modification of an Si-H containing polysilane

A modified preceramic polymer material prepared by a method comprising:

• (a) mixing one or more organosilicon polymers each having a plurality of Si--H functional groups with
• (b) a catalytically effective amount of a metallocene compound sufficient to cause a dehydrogenative crosslinking reaction;
• and
• (c) allowing the mixture to undergo the dehydrogenative reaction to form the modified polymer material,
• wherein the metallocene compound is selected from the group consisting of the following formulas (I), (II) and (III):
• (R.sup.3.sub.n C.sub.5 H.sub.5-n).sub.2 M'R.sup.4 (I)
• (R.sup.3.sub.n C.sub.5 H.sub.5-n).sub.2 M"R.sup.5 R.sup.6 (II)
• (R.sup.3.sub.n C.sub.5 H.sub.5-n).sub.2 V (III)
• wherein each R.sup.3 on a C.sub.5 H.sub.5-n ring is independently selected from the group consisting of hydrogen, substituted or unsubstituted lower alkyl having from 1 to about 8 carbon atoms, substituted or unsubstituted cycloalkyl having from 3 to about 10 carbon atoms, substituted or unsubstituted lower alkenyl having from 2 to about 8 carbon atoms, substituted or unsubstituted aryl of from 6 to about 10 carbon atoms, and a group of formula R'.sub.3 Si where each R' group is independently selected from the group of hydrogen, substituted or unsubstituted lower alkyl having from 1 to about 8 carbon atoms, substituted or unsubstituted cycloalkyl having from 3 to about 10 carbon atoms, substituted or unsubstituted lower alkenyl having from 2 to about 8 carbon atoms, or substituted or unsubstituted aryl having from 6 to 10 carbon atoms, or two R.sup.3 groups taken together form an aromatic ring fused to said C.sub.5 H.sub.5-n ring;
• R.sup.4, R.sup.5 and R.sup.6 are each independently selected from the group consisting of hydrogen, halogen, substituted or unsubstituted lower alkyl having from 1 to about 8 carbon atoms, substituted or unsubstituted cycloalkyl having from 3 to about 10 carbon atoms, substituted or unsubstituted lower alkenyl having from 2 to about 8 carbon atoms, substituted or unsubstituted aryl having from about 6 to about 10 carbon atoms, and a group of formula R'.sub.3 Si where each R' group is independently selected from the group of hydrogen, substituted or unsubstituted lower alkyl having from 1 to about 8 carbon atoms, substituted or unsubstituted cycloalkyl having from 3 to about 10 carbon atoms, substituted or unsubstituted lower alkenyl having from 2 to about 8 carbon atoms, or substituted or unsubstituted aryl having from about 6 to about 10 carbon atoms;
• M' is selected from the group consisting of Ti, Zr, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu;
• M" is selected from the group consisting of Ti, Zr and Hf;
• and n is an integer of from 0 to 5.