The Mo-Ni (Co)-Si metallizing coatings on the SiC ceramic substrate were prepared by vacuum cladding process. The wetting and spreading of molten Al on coated SiC ceramic substrates at 900 oC were investigated by the sessile drop technique, and the interfacial behavior of the Al/coated SiC wetting couples was analyzed. The experimental results showed that the final contact angle of Al/M20NiSi coated SiC was close to 0o. With the increase of Mo content in the Mo-Ni-Si coating, the shape of the sessile drop became very irregular due to the strong interactions between the Al drop and the coating, so it was unable to precisely characterize the contact angles of Al/Mo30NiSi and Al/Mo40NiSi systems. The final contact angle of Al/Mo10CoSi coated SiC system was also close to 0o, however, the final contact angle of Al/Mo20CoSi coated SiC system climbed to ~42o with the Mo content increasing from 10 at.% to 20 at.%. The significant increase of contact angle may be caused by the accumulation of Mo near the triple line which can impede the spreading of Al drop.

A series of nanocomposites, SiCN/A3S2 ceramics, were prepared by hot-pressing method. The nanometer SiCN powder is characterized of high dielectric dissipation. The dielectric properties of the SiCN/A3S2 nanocomposites were investigated. XRD and SEM were conducted to study the phases and microstructure of the nanocomposites. Compared with the pure A3S2 ceramic, the grain size in the nanocomposites is reduced due to the addition of nanometer SiCN powder. The relative densities of the nanocomposites are also lower than that of the pure A3S2 ceramic. Both the real and imaginary parts of the complex permittivity of nanocomposites in X band increase as the content of SCN powder in the samples rises obviously. When the contents of SiCN powder in samples are same, the real and imaginary parts of the samples vary with the sintering temperature. The tanδ of the nanocomposites reduces from 1.9 to 1.4 when sintering temperature increases from 1450OC to 1650 OC. SAED pattern reveals that structure of the SiCN in SiCN/ A3S2 sintered at higher temperatures tend to crystallize. The real, imaginary parts and dissipation factor of the nanocomposites sintered at higher temperature is lower than those sintered at 1450 °C.

The Fe-C composites were fabricated by a combination of high-energy ball milling of Fe-C powder mixtures and plasma activated sintering process. An orthogonal experiment in four factors (including original powder composition, sintering temperature, applied pressure and holding time) and three levels was employed to investigate the effects of preparation technology on mechanical properties (bending strength and hardness) of the Fe-C composite. The experimental results show that the crystalline Fe3C phase can be produced by the rapid sintering process, though it is cannot form theoretically due to the high Gibbs free energy, and more or less holes and composition segregation phenomenon coexist in the composite. The original powder composition plays the leading role in both the mechanical properties of the Fe-C composites. However, the effects of the other parameters on the bending strength and hardness of the composite are somewhat different. The optimal technology combinations for the bending strength and hardness are obtained as follows: 50Fe+50Fe3C/1373 K/400 s/20 MPa and 50Fe+50Fe3C/50 MPa/1273 K/400 s, respectively.

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