Special toughening process for zirconia ceramic matrix composites

The brittleness of zirconia ceramics In recent years, some researchers have been working hard to solve this problem, and various methods of toughening ceramic matrix composites have emerged. The following two methods will be introduced by Kezhong Ceramics Factory, synergistic toughening and particle Toughened.

Synergistic toughening compound synergistic toughening is the coexistence of two or more toughening reinforcing agents to produce synergistic toughening mechanism, and its effect is far greater than the sum of their individual effects. Zhou Yang and others studied the partially stabilized ZrO2 toughened Al2O3 (ZTA), ZTA-SiC and ZTA-SiC composite materials. It is believed that among the three toughening and strengthening methods, phase change whisker composite toughening effect is the best, phase change particle composite toughening effect is second, and pure phase change toughening effect is small.

Zirconia ceramic ring

Among these methods, the research on the preparation of TiC/Al2O) composite materials conducted by Zuhair A Munius of California University has achieved certain results. By adopting pressureless sintering and thermal processing methods, high wear resistance, high strength, high fracture toughness and good electrical conductivity can be obtained. The main use is cutting tools, which occupy the mainstream of ceramic cutting tools, and ceramic cutting tools account for about 5% of the entire cutting tools.

Particle toughening Use particles as a toughening agent to make particle toughened ceramic matrix composites. The uniform dispersion of raw materials and sintering densification are simpler and easier than short fiber and whisker composite materials. Therefore, although the toughening effect of particles is not as good as whiskers and fibers, if the particle type, particle size, content and matrix material are properly selected, there is still a certain toughening effect, and at the same time it will bring about improvements in high-temperature strength and high-temperature denaturation.

Therefore, particle toughened ceramic matrix composites have also been paid attention to, and effective research work has been carried out. The toughening mechanism of particle toughened ceramic matrix composites mainly includes matrix grain refinement, crack diversion and separation, etc. In recent years, nanoparticle toughened ceramic matrix composites have become a research hotspot. In 1987, Germany's Karch et al. reported that the developed nano-ceramics had high toughness and low-temperature superplastic behavior.

High temperature resistant ceramic parts insulation

Hiroichi Niihara of Osaka University in Japan and others introduced nano-SiC dispersed phases into the micron-sized Al2O2 matrix, which greatly improved the mechanical properties of the material. Compared with single-component All2O3 ceramics, its strength was increased by nearly 300%, and its fracture toughness was also increased by 40%. %In addition, nano-nano composites can also affect the hardness, elastic modulus, thermal expansion coefficient, thermal conductivity, and thermal shock resistance of materials.

In the particle toughening process of Al2O3 ceramics, the metal strengthening method, that is, adding certain metal (such as Ni, Al, Cr, Ag, etc.) particles can obtain more obvious effects. Zhou Zheng of Chongqing University pointed out in a new method of preparing Al/Al2O3 composite materials that Al/Al2O3 composite materials have the characteristics of low density, high temperature resistance, wear resistance and thermal shock resistance. They studied the microstructure and performance of the AI/Al2O3 composite material through three processes of sintering, melt infiltration, and high-temperature oxidation of aluminum alloy, and obtained good results.

The enhanced toughness of metal-toughened A2O2 composite ceramics is mainly attributed to the plastic deformation of metal particles. However, due to the generally low melting point of metals and poor wettability with Al2O) ceramics, the addition of metal particles will reduce the density and high-temperature mechanical properties of the sintered body, so the amount of metal that can be added will be limited; in addition, due to The oxidation resistance and corrosion resistance of metals are poor, and the chemical stability of Al2O3 ceramics will be reduced due to the addition of metals.

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