1,721,018 research outputs found
Production and investigation of biodegradable implant by powder metallurgy method
No full textAnadolu Üniversitesi ve Bilecik Şeyh Edebali Üniversitesi tarafından ortak yürütülen program.Bu çalışmada doku mühendisliği uygulamaları için doku iskelesi amaçlı gözenekli biyobozunur Mg, Zn, Fe alaşımları ve TCP numunesi toz metalurjisi esaslı boşluk yapıcı yöntemiyle üretilmiştir. Ayrıca, biyobozunur ortopedik implant uygulamalarında kullanılmak üzere (vida, plaka vb.) yoğun Mg, Zn ve Fe, östenit yapılı Fe alaşımları ve TCP numuneleri geleneksel toz metalurjisi yöntemiyle, yoğun Fe numunesi ise toz enjeksiyon kalıplama (TEK) yöntemi ile üretilmiştir. Silindir şekilli ham numunelerin ve sinterlenmiş numunelerin yoğunluk değerleri geometrik (gravimetrik) yöntem ile kütle/hacim ilişkisi kullanılarak belirlenmiştir. Karakterizasyon çalışmaları kapsamında, numunelerin mekanik özellikleri ve mikroyapıları analiz edilmiştir. Numunelerin mekanik özellikleri basma testi ve tahribatsız ultrasonik muayene yöntemi ile belirlenmiştir. Elektrokimyasal korozyon özellikleri yapay vücut sıvısında incelenmiştir. Ayrıca metal iyon salınımı miktarı ve biyobozunurluk hızı yapay vücut sıvısı içerisinde statik daldırma testi ile incelenmiştir. Numunelerin faz yapısını belirlemek amacıyla X-ışını kırınım (XRD) analizi gerçekleştirilmiştir. Gözenekli numunelerin toplam gözenek (açık ve kapalı) miktarları kütle/hacim ilişkisinden (geometrik yöntem) belirlenmiştir. Çalışmanın sonunda, % 68 - % 83 arasında değişen farklı oranlarda gözenek içeren numuneler doku mühendisliği uygulamaları için üretilmiştir. Numunelerin mekanik özellikleri karşılaştırıldığında yüksek östenit yapılı Fe alaşımlarının en yüksek elastisite modülüne sahip olduğu görülmüştür. Biyobozunurluk incelemesinde Fe, Mg ve Zn alaşımlarının ağırlık değişimi beklenen değerlerde değişmektedir. Salınan Fe, Zn ve Mg iyon miktarları, insan vücudu için toksik eşik değerinden düşüktür. XRD sonuçları incelendiğinde alaşımlarda bulunan elementlerin faz yapısının korunduğu görülmektedir. Elektrokimyasal korozyon sonuçlarına bakıldığında, üretilen Mg alaşımlarından Mg-Zr alaşımının, Fe alaşımlarından Fe-Co alaşımının ve Zn alaşımlarından ise Zn-Fe alaşımının korozyon hızlarının düşük olduğu görülmüştür.In this study, porous biodegradable Mg, Zn, Fe alloys and TCP specimens for use as tissue scaffold material in tissue engineering applications were produced by the powder metallurgy based space holder method. Also, for use (as screw, plate, etc.) in biodegradable orthopedic implant applications, dense Mg, Zn and Fe, austenite Fe alloys and TCP specimens were produced by the traditional powder metallurgy method, and dense Fe-based specimen was produced by the powder injection molding (PIM) method. Density values of cylindrical green specimens and sintered specimens were determined using the mass/volume relationship by the geometric (gravimetric) method. Within the scope of characterization studies, the mechanical properties and microstructures of the specimens were analyzed. The mechanical properties of the specimens were determined by compression test and non-destructive ultrasonic testing method. Electrochemical corrosion properties were investigated in simulated body fluid. In addition, the amount of released metallic ions and the rate of biodegradation were investigated in simulated body fluid by the static immersion test. X-ray diffraction (XRD) analysis was performed to determine the phase structure of the specimens. The total pore (open and closed) amounts of the porous specimens were determined using the mass/volume relationship (geometric method). At the end of the study, specimens with different percentages of pores ranging from 68% to 83% were produced for tissue engineering applications. It was seen from the comparison of mechanical properties that Fe alloys with dense austenitic structures have the highest modulus of elasticity. In the biodegradability investigations, the weight change of Fe, Mg and Zn alloys was within the expected values. The amounts of released Fe, Zn and Mg ions were lower than the toxic threshold value for the human body. It was seen from the results of the XRD analyses that the phase structure of the elements in the alloys was preserved. Also, it was observed from the results of the electrochemical corrosion characteristics that the corrosion rates of Mg-Zr alloy from among Mg alloy, Fe-Co alloy from among Fe alloys, and Zn-Fe alloy from among Zn alloys were low.YÖK 100/2000 DOKTORA BURS
Synthesis and characterization of Ti-Co alloy foam for biomedical applications
No full textHighly porous Ti-Co alloy specimens for biomedical applications were synthesized by powder metallurgy based space holder technique. Ti alloys have high melting temperature and affinity for oxygen, which makes Ti alloys difficult to be processed. The Co addition reduces the melting temperature and Ti-Co alloy was sintered at lower temperatures. The electrochemical corrosion behaviour of the specimens was examined in the artificial saliva solution. The effects of Co content of the alloy, the pH value and fluoride concentration of the artificial saliva solution on the electrochemical corrosion properties of the specimens were investigated. The microstructure and mechanical properties of the specimens were examined. The electrochemical impedance spectroscopy results indicate that the corrosion resistance of the specimens decreases at high fluoride concentrations and low pH value. The defect density increases with increasing the fluoride concentration and decreasing the pH value of artificial saliva according to Mott-Schottky analysis
Production and Precipitation Hardening of Mg-Ca-Zn-Co Alloy for Tissue Engineering
No full textIn this study, Mg-Ca-Zn-Co alloy specimens for biomedical applications were produced by the powder metallurgy method. The Mg-Ca-Zn-Co alloy could be used as a scaffold material in tissue engineering applications. Electrochemical corrosion behavior of the specimens was investigated in simulated body fluid environment. Electrochemical corrosion resistance of the specimens was increased with increasing Zn and Ca contents of the alloy up to an optimum composition and then decreased. Optimum values for Ca and Zn additions were about 0.7 wt.% and 3.0 wt.% respectively. Young's modulus values of the specimens were determined by nondestructive ultrasonic measurement. Alloying element addition increased the Young's modulus of the specimens. Precipitation hardening of the Mg-Ca-Zn-Co alloy increased the Young's modulus and the corrosion rate of the specimens
Localised Corrosion Behaviour of Ti-Mo Alloy by Cyclic Polarization and Electrochemical Potentiokinetic Reactivation Method
No full textSingle-step sinter-aging heat treatment of metastable-beta type Ti-Nb-Cu alloy
No full textPrecipitation hardenable metastable-beta type Ti-Nb-Cu alloy was produced by powder metallurgy for implant applications. Specimens were sintered, quenched and aged in a single-step process to enhance the mechanical properties. Sinter-aging combines the sintering, quenching and aging in a single step. This process reduces the cost of operation. Although, there are studies about the aging or sinter-hardening of titanium, there is no study on the sinter-aging of the titanium or any other metals. The effects of process parameters (sintering temperature, cooling rate and aging) on the mechanical properties were investigated. Young's modulus and strength values were enhanced with increasing sintering temperature and cooling rate. Strength and elastic modulus values were increased with increasing aging temperature. Increasing Cu content lowered the corrosion potential and increased the current density. Metal release values are not higher than the reference levels in the body
Characterisation of localised corrosion behaviour of Ti-Ta-Mo alloy for the nuclear industry
No full textthis study, Ti-Ta-Mo alloy specimens were produced by powder metallurgy for the nuclear industry. For evaluating application of Ti alloys as components for nuclear fuel reprocessing plants, corrosion behaviour of Ti-Ta-Mo alloy was investigated. Localised corrosion (crevice and pitting) behaviour of the Ti-Ta-Mo alloys containing 5-15 wt.% Mo was investigated in 10 wt.% NaCl solution. The effect of composition of the alloys on the corrosion behaviour of specimens was studied. Resistance against localised attack was found to depend on the Mo content of the alloys. Mechanical properties (Young's modulus) of the specimens were investigated by nondestructive ultrasonic tests
Pitting Corrosion Behaviour of Powder Metallurgy Ti-Mo Alloy by Critical Pitting Potential Method
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