Investigation of Surface Properties of Ti-6Al-4V Alloy Machined by Micronized Hydroxyapatite Powder Mixed Electrical Discharge Machining and Evaluation of the Powder Penetration to the Surface

Abstract

Electrical Discharge Machining (EDM) is a nontraditional manufacturing processes that is particularly preferred in the machining of very hard and complex shaped materials. It is aimed to increase the process performance with powder additive added to the dielectric liquid in the Powder Mixed Electrical Discharge Machining (PMEDM). For this purpose, many powder additives such as silicon carbide (SiC), copper (Cu), aluminum (Al), iron (Fe) and carbon (C) have been used. Hydroxyapatite (HA) is a biocompatible ceramic that is usually used as a filler in bones or to support implants. Besides this, Titanium (Ti) and titanium alloys are frequently preferred in medical applications due to their mechanical properties and corrosion resistance. In this study, surface properties of Ti-6Al-4V alloy machined by micronized HA mixed EDM and powder penetration on the surface during machining were investigated. Samples were processed at 4 different current levels with 10 different pulse duration for each current level. Machined samples were examined by Scanning Electron Microscope (SEM), Energy Distribution Spectrometer (EDS), X-Ray Diffractometer (XRD) and Optical Microscope. HA-rich occurrences were observed on the surface and parameters in which the occurrences are observed were determined. Accordingly, the best penetration was observed in the pulse current of 22 A and the pulse durations of 100 µs and 800 µs. HA-rich functional surfaces are demanded for medical applications. In addition, it is an innovative approach to obtain these surfaces by PMEDM method.points of the article will be included in this section. Not to exceed two hundred words, abstract stating the main points of the article will be included in this section.

Keywords

• Powder Mixed Electrical Discharge Machining,Hydroxyapatite,Surface Properties,Bioceramics

MİKRONİZE HİDROKSİAPATİT TOZ KATKILI ELEKTRİKSEL KIVILCIMLA İŞLENMİŞ Tİ-6AL-4V ALAŞIMININ YÜZEY ÖZELLİKLERİNİN İNCELENMESİ VE YÜZEYE TOZ KATKISI NÜFUZİYETİNİN DEĞERLENDİRİLMESİ

Abstract

Elektriksel Kıvılcımla İşleme (EKİ), özellikle çok sert ve karmaşık şekilli malzemelerin işlenmesinde tercih edilen alışılmamış imalat yöntemidir. Toz Katkılı Elektriksel Kıvılcımla İşleme (TKEKİ) yönteminde ise dielektrik sıvıya katılan toz partikülleri ile işlem performansının artırılması amaçlanmıştır. Bu amaçla, silisyum karbür (SiC), bakır (Cu), alüminyum (Al), demir (Fe) ve karbon (C) gibi birçok toz katkısı kullanılmaktadır. Hidroksiapatit (HA) genellikle kemiklerde dolgu malzemesi olarak ya da implantları desteklemek amacıyla kullanılan biouyumlu seramiktir. Bunun yanında, Titanyum (Ti) ve titanyum alaşımları da sahip olduğu mekanik özellikleri ve korozyon direnci nedeniyle medikal uygulamalarda sıkça tercih edilmektedir. Bu çalışmada, mikronize HA toz katkılı EKİ yöntemiyle işlenmiş Ti-6Al-4V alaşımının yüzey özellikleri ve işleme sırasında yüzeye toz katkısı nüfuziyeti incelenmiştir. Numuneler, 4 farklı akım seviyesinde ve her bir akım seviyesi için 10 farklı darbe süresi uygulanarak işlenmiştir. İşlenen numuneler, Taramalı Elektron Mikroskopu (SEM), Enerji Dağılım Spektrometresi (EDS), X-Işını Kırınım Difraktometresi (XRD) ve Optik Mikroskop ile incelenmiştir. Yüzeyde HA yönünden zengin oluşumlar gözlemlenmiş ve bu oluşumların gözlemlendiği parametreler tespit edilmiştir. Buna göre en iyi nüfuziyetin 22 A darbe akımı ve 100 µs ve 800 µs darbe sürelerinde gerçekleştiği gözlemlenmiştir. Tıbbi uygulamalar için HA bakımından zengin fonksiyonel yüzeyler talep edilmektedir. Ayrıca bu yüzeylerin TKEKİ yöntemiyle elde edilmesi yenilikçi bir yaklaşımdır.

Keywords

• Toz Katkılı Elektriksel Kıvılcımla İşleme,Hidroksiapatit,Yüzey Özellikleri,Biyoseramikler

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