Alumina ceramics have great application potential in various wear environments, but their intrinsic properties usually negatively affect mechanical properties. A significant attention has been therefore attracted to alumina-silicon carbide composites with high flexural strength and increased fracture toughness.
The mechanical properties of these composites are superior to those of the monolithic polycrystalline alumina. The most promising method appears to be the preparation of composites with higher silicon carbide content by the utilizing organosilicon polymers, which transforms to silicon carbide with high yield and without the formation of free carbon.
The volume fraction and the size of derived silicon carbide particles can be adjusted by the size and volume of open porosity in the pre-sintered alumina matrix, and by the concentration of the polymer solution. The most important seems to be the possibility of preparation of ceramics with microstructure of percolating phases of alumina and silicon carbide, but this in fact was not studied or published previously.
The major goal of the proposed project is the preparation of alumina-silicon carbide nanocomposites with a high content of silicon carbide and with homogeneously distribution of percolated phases. To achieve the goal these composites will be prepared by multiple infiltration of presintered alumina matrix with organosilicon polymer precursor and its consecutive in-situ pyrolytical decomposition. Both the hardness and fracture toughness are likely to increase, when fine-grained microstructure of percolating phases of alumina and silicon carbide will be formed.
The size, morphology and position of the carbide particles within the alumina matrix will be controlled by proper adjustment of the processing conditions. A significant improvement of reliability and reproducibility of the mechanical properties of alumina-silicon carbide composites is expected to result from the project.
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