Abstract: The present invention relates to a preparation of modified organic core materials and metallic shell composite microspheres, in which, the surface zeta potential of an organic core materials can attract the opposite zeta potential of the polyelectrolyte and form a polyelectrolyte layer so as to modify the surface of organic core materials. Moreover, the polyelectrolyte layer could attract a first metal ions, particles or complexes added later in suitable condition such that the surface of organic core materials could be metallized and covered with a first metal layer. Furthermore, the organic core materials could be covered with at least one surface metal layer. The first metal layer can be modified by second metal layer with redox-transmetalation® technology to obtain multi-metal layers organic-metallic composite structure.

Abstract: A composite ceramic is produced by forming a mixed powder of Si and a compound oxide as the starting material into a formed material, nitriding and firing the formed material to form a sinter, and subjecting the sinter to oxidation treatment. The composite ceramic, which is:lightweight and reduced in heat conductivity, has a specific gravity of at most 2.6, and comprises a phase composed of all of elements Si, O and N, and at least one element selected from the element group consisting of A1, Zr, Li, P and Mg, in which phase a subphase composed of Si, Al, 0 and N and a subphase composed of Si, O and N are formed. Another composite ceramic has pores and a disperse phase in a matrix phase composed of Si.sub.3 N.sub.4 crystal grains, an oxide and an oxynitride, and further comprises coarse Si.sub.3 N.sub.4 grains dispersed in the matrix phase with O-containing boundary reaction product layers formed in the boundaries between the matrix phase and the coarse Si.sub.3 N.sub.4 grains.

Abstract: A silicon nitride based sintered product produced with Si powder, a Si.sub.3 N.sub.4 powder, and an assistant component effective for sintering silicon nitride as raw materials. A resultant sintered product has fine tissue, exhibits little presence of pores and remaining silicon, and possesses high mechanical strength which can be enhanced by calcinating the product under low pressure after it has been reacted and first sintered.