The carbon brake discs were manufactured by densification the carbon fiber preform using PG-CVI technology with Propene as a carbon precursor gas and Nitrogen as a carrier gas. The densities of carbon brake discs were tested at different densification time. The results indicate that the densification rate is more rapid before 100 hrs than after 200 hrs. The CTscanning image and the SEM technology were used to observe the inner subtle structure. CT-images show the density distribution in the carbon brake disc clearly. The carbon brake disk made by PG-CVI is not very uniform. There is a density gradient in the bulk. The high-density part in the carbon brake is really located in the friction surface, especially in the part of inner circle. This density distribution is most suitable for the stator disc.

Sintered Ti(C,N)-based cermets were treated with hot isostatic pressing (HIP) at different nitrogen pressures. The tribological properties of the treated cermets have been evaluated. The results show that a hard near-surface area rich in TiN formed after HIP treatment. The cermets treated at higher pressure had a relatively lower friction coefficient and specific wear rate. In all cases the microhardness of treated cermets is higher than that without HIP natridation. The wear mechanisms of cermets were hard particle flaking-off and ploughing. It was also found that the HIP natridation is well-suited for improving the tribological properties of cermets.

The particulate strengthened composites were prepared by a PM process to develop novel copper based composites with reasonable strength, high thermal conductivity and low thermal expansion coefficient. Microstructure of the composites was investigated by SEM; the tensile strength, elongation, thermal conductivity and thermal expansion coefficient (CTE) of the composites were examined. A comparative analysis of mechanical and thermal properties of various Cu-matrix composites currently in use was given and the strengthening mechanisms for the composites were discussed.

Three different male-sterile cytoplasmic lines and their common maintainer 'Zhenshan 97B' and two elite restorer lines were used to study cytoplasmic effects on agronomic trait manifestation per se under different nitrogen supply levels. The result showed that cytoplasmic effects could be modified by nitrogen environments. The cytoplasmic effect on grain yield under 150 kg N/ha varied depending on crosses, while it was significantly negative in most crosses under both 60 and 330 kg N/ha. The correlation and path-coefficient analyses suggested that it was expected to improve cytoplasmic effects through reducing maximum tillers and increasing the percentage of productive tillers, leading to increased productive tillers and higher yield in hybrid rice by the aid of cultural practice and genetic transformation. This study also revealed that the same cytoplasm in different combinations had differential effect under the same nitrogen environment, indicating that cytoplasmic effect was produced by interaction of nuclear genes with cytoplasm rather than cytoplasm per se. These results indicated the usefulness of evaluating diverse cytoplasmic sources in various nuclear genotypes bred for hybrid rice breeding program. The finding also suggested that negative cytoplasmic effect could be effectively overcome by elite restorer lines through the interaction of nuclear genes with female cytoplasm.