Hardness and EDM Processing of MoSi$_2$Intermetallics for High Temperature Ship Engine |
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고온선박엔진용 MoSi$_2$금속간화합물의 경도와 방전가공특성 |
윤한기,이상필 |
동의대학교 기계·정보산업공학부,동의대학교 기계·정보산업공학부 |
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© 2002 The Korean Society of Ocean Engineers
Open access / Under a Creative Commons License
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Keywords:
MoSi_2Intermetallics MoSi_2, Nb/MoSi$_2$_2aminate Composite Nb/MoSi_2, Electrical Discharge Machine (EDM), ED-Drilling, Workability, Fabricating Temperature, Micro Vickers Hardness |
핵심용어:
금속간화합물, 적층복합재료, 방전가공, 방전에 의한 드릴링, 가공성, 성형온도, 마이크로 비커스 경도 |
Abstract |
This paper describes the machining characteristics of the MoSi$_2$--based composites through the process of electric discharge drilling with various tubular electrodes. In addition to hardness characteristics, microstructures of Nb/MoSi$_2$laminate composites were evaluated from the variation of fabricating conditions, such as preparation temperature, applied pressure, and pressure holding time. MoSi$_2$-based composites have been developed in new materials for jet engines of supersonic-speed airplanes and gas turbines for high-temperature generators. These high performance engines may require new hard materials with high strength and high temperature-resistance. Also, with the exception of grinding, traditional machining methods are not applicable to these new materials. Electric discharge machining (EDM) is a thermal process that utilizes a spark discharge to melt a conductive material. The tool electrode is almost -unloaded, because there is n direct contact between the tool electrode and the work piece. By combining a non-conducting ceramic with more conducting ceramic, it was possible to raise the electrical conductivity. From experimental results, it was found that the lamination from Nb sheet and MoSi$_2$ powder was an excellent strategy to improve hardness characteristics of monolithic MoSi$_2$. However, interfacial reaction products, like (Nb, Mo)SiO$_2$and Nb$_2$Si$_3$formed at the interface of Nb/MoSi$_2$, and increased with fabricating temperature. MoSi$_2$composites, with which a hole drilling was not possible through the conventional machining process, enhanced the capacity of ED-drilling by adding MbSi$_2$, relative to that of SiC or ZrO$_2$reinforcements. |
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