تأثیر ذرات بیوسرامیک در ماشین های برش دی الکتریک پودر الکتریکی بر روی ماشینکاری و ویژگی های سطح آلیاژهای تیتانیوم
|کد مقاله||سال انتشار||تعداد صفحات مقاله انگلیسی||ترجمه فارسی|
|153464||2017||41 صفحه PDF||سفارش دهید|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Journal of Materials Processing Technology, Volume 245, July 2017, Pages 70-79
In powder-mixed electrical discharge machining (PMEDM), a suspension of powder particles is added to the dielectric to achieve a high surface quality and to improve the material removal rate (MRR). However, for biomedical applications, the machined surface must be nontoxic and also contain bioactive species; these constraints limit the choice of powder material. This study focuses on machining orthopedic-implant materials based on titanium and titaniumâtantalum alloys using bioactive hydroxyapatite (HA)-powder suspension as the dielectric. The influence of the powder particles and the work-piece composition on the machining performance was investigated. Employing a suspension dielectric with 5Â g/L HA caused a smoother surface (Ra 2.1Â Î¼m) with a thinner recast layer (â¼9Â Î¼m) as compared to using water to machine titanium which has surface roughness of Ra 2.4Â Î¼m with a recast layer close to 10Â Î¼m. In addition, the MRR of titanium machined in the HA-powder-suspension dielectric (6.4Â ÃÂ 10â4Â gÂ minâ1) was greatly lower than that in water (28.6Â ÃÂ 10â4Â gÂ minâ1). However, increasing the HA concentration led to a gradual increase in the MRR, electrode wear rate (EWR), surface roughness, and recast-layer thickness. The MRR, EWR, and the surface roughness of titanium and titaniumâtantalum alloys under PMEDM exhibited an inverse relation with respect to the melting temperature and thermal conductivity of the alloy. Furthermore, calcium and phosphorus were incorporated into the recast layer, and their amounts decreased when the discharge current was increased.