Preparation and characterization of a silicon oxycarbide coating with crack-healing capability for silicon carbide ceramics

Preparation and characterization of a silicon oxycarbide coating with crack-healing capability for silicon carbide ceramics

Silicon carbide ceramics have good mechanical and thermal properties, but they have a failure problem by brittle fracture due to fast crack growth. Attempts were made to self-heal cracks in ceramics. The SiC ceramics were coated with silicon oxycarbide glass films which were prepared by dip-coating and pyrolysis of polymer precursors. The crack-healing capability was evaluated by mechanical testing and microstructural analysis. Cracks were artificially generated in the sample by either micro indentation or notch making. Healing treatments at 1100, 1300, 1400, or 1500 oC were made. Bending strengths were measured before and after crack growth and a healing treatment. It was found that the strength dropped low by the generation of cracks but was fully recovered after the healing treatment. The cracks were found filled and healed by the coating material.

Silicon carbide ceramics have good mechanical and thermal properties, but they have a failure problem by brittle fracture due to fast crack growth. Attempts were made to self-heal cracks in ceramics. The SiC ceramics were coated with silicon oxycarbide glass films which were prepared by dip-coating and pyrolysis of polymer precursors. The crack-healing capability was evaluated by mechanical testing and microstructural analysis. Cracks were artificially generated in the sample by either micro indentation or notch making. Healing treatments at 1100, 1300, 1400, or 1500 oC were made. Bending strengths were measured before and after crack growth and a healing treatment. It was found that the strength dropped low by the generation of cracks but was fully recovered after the healing treatment. The cracks were found filled and healed by the coating material.