Toughening method of zirconia ceramic matrix composites---fiber toughening

A phase change toughening method for zirconia ceramic matrix composites was introduced above. Next, Kezhong Ceramics Factory will continue to introduce a ceramic matrix toughening method that can increase the processing performance of zirconia ceramics --- fiber toughening.

Fibers and whiskers have a prominent bridging and pulling-out mechanism due to their shape characteristics that their length is much greater than their diameter, and can greatly improve the fracture toughness of ceramics without sacrificing or slightly sacrificing strength.

Among them, the whisker-reinforced Al2O)-based composite material was first obtained by the Oak Ridge Laboratory in the United States, and the research on this material is still in progress. Since Becher published Al2O2/SiC whisker-reinforced composite materials, people have carried out a lot of research work on fiber (whisker) toughening from three aspects: theory, experiment and technology.

In the preparation, the sintering of Al2O3/SiC whisker composite materials is generally difficult, and the hot pressing method is often used for manufacturing. Such materials are expected to be used in high-temperature fields due to their high hardness, strength, fracture toughness, and good conductivity. But now it is mainly limited by the preparation cost and other aspects, and the main application fields are small and single-shaped cutting tools. Especially in difficult-to-cut materials such as high-temperature alloys, it has demonstrated its superiority and established the status of new cutting tools.

However, the effect of whisker toughened ceramics is still relatively limited. However, continuous fiber ceramic matrix composites (CFCC) are expected to greatly improve the fracture toughness of ceramic materials due to their unique toughening mechanism. Judging from current research reports, the fracture toughness of CFCC is as high as 36MPam2, or even higher, which is an order of magnitude higher than that of a single ceramic. At present, four types of reinforcing fibers for ceramic matrix composites that have been industrialized are: alumina series (including mullite) fibers; silicon carbide series fibers, silicon nitride series fibers; carbon fibers. However, the following issues of fiber and whisker reinforced ceramic matrix composites need to be further explored:

① Optimal bonding interface between fibers, whiskers and matrix;

② Dispersion of fibers and whiskers in the matrix;

③The best whisker length to diameter ratio;

④ High-strength whisker products with complete crystallization

⑤ Simplification of the preparation process. The mechanical properties of several silicon carbide ceramic materials are shown in Table 4-1.

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