| 치밀층으로 코팅된 다공성 엔지니어링 세라믹스에서의 접촉응력에 의한 균열 거동 |
| 김상겸, 김태우, 김도경1, 이기성 |
국민대학교 기계자동차공학부
1한국과학기술원 신소재공학과 |
| Cracking Behavior Under Contact Stress in Densely Coated Porous Engineering Ceramics |
| Sang-Kyum Kim, Tae-Woo Kim, Do-Kyung Kim1, Kee-Sung Lee |
School of Mechanical and Automotive Engineering, Kookmin University
1Department of Materials Science and Engineering, KAIST |
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| ABSTRACT |
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The engineering ceramic needs the properties of high strength, hardness, corrosion-resistance and heat-resistance in order to withstand thermal shock or applied nonuniform stresses without failure. The densely coated porous ceramics can be used for machine component, electromagnetic component, bio-system component and energy-system component by their high-performances from superior coating properties and light-weight characteristics due to the structure including pore by itself. In this study we controlled the porosity of silica and alumina, $8.2~25.4%$ and $23.4~36.0%$, respectively, by the control of sintering temperature and starting powder size. We made bilayer structures, consisting of a transparent glass coating layer bonded to a thick substrate of different porous ceramics by a thin layer of epoxy adhesive, facilitated observations of crack initiation and propagation. The elastic modulus mismatch could be controlled using different porous ceramics as the substrate layer. Then we applied 150 N force using WC sphere with a radius of 3.18 mm by Hertzian indentation. As a result, the crack initiation in the coating layer was delayed at lower porosity in the substrate layer, and the damage in the coating layer was relatively smaller at the bilayer structure coated on higher elastic substrate. |
| Key words:
Spherical indentation, Contact damage, Ceramic layer structure |
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