| Summary: | 碩士 === 國立高雄應用科技大學 === 模具工程系碩士班 === 102 === This study investigated the surface modification of Ti50Ni50, Ti50Ni49.5Mo0.5 and Ti-30Nb-1Fe-1Hf alloys using electrical discharge machining (EDM) in water and kerosene. Pure titanium rod was used as tool electrode. Several machining parameters including the electrode material, electrode polarity, discharge current (Ip) and pulse duration (P) can significantly affect EDM characteristics, e.g. the material removal rate (MRR), electrode wear rate (EWR), the thickness of the recast layer and surface roughness. The experimental results show that the MRR, EWR, thickness of the recast layer and surface roughness value, Ra, increase with increasing discharge current Ip and pulse duration P in these alloys. The material removal rates (MRRs) of these alloys in the EDM process exhibit a reverse relationship to the product of the alloy’s melting temperature and thermal conductivity (θ x Kα). The MRR and Ra value will have the sequence of Ti50Ni50 > Ti50Ni49.5Mo0.5 > Ti-30Nb-1Fe-1Hf. In addition, the MRRs of these alloys are larger when EDM in water than in kerosene. The recast layer of Ti50Ni50 and Ti50Ni49.5Mo0.5 alloys comprises titanium oxide and nickel oxide, but titanium oxide and niobium oxide in Ti-30Nb-1Fe-1Hf alloy. After EDM, all of the alloys still exhibit better shape recovery.
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