EZ43 magnezyum alaşimlarinin mekanik ve biyouyumluluk davranişlarina neodinyum ve seryum alaşim elementleri ile çok yönlü dövme işleminin etkilerinin incelenmesi
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Tarih
2024
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Yayıncı
Karabük Üniversitesi, Lisansüstü Eğitim Enstitüsü
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info:eu-repo/semantics/openAccess
Özet
Bu çalışmada, EZ43A ve EZ43B Mg esaslı malzemelerin ilk defa üretimi ve Ekstrüzyon işlemi ile çok yönlü dövme yöntemleri sonrası mekanik ve korozyon özelliklerinin incelenmesini kapsamaktadır.
Magnezyum elementine Çinko (Zn), Gadolinyum (Gd), Kalsiyum (Ca), Zirkonyum (Zr) ve farklı oranlarda Neodinyum (Nd) ile Seryum (Ce) alaşım elementleri ilave edilerek düşük basınçlı döküm yöntemi ile EZ43A ve EZ43B alaşımlarının üretimleri sağlanmıştır.
EZ43A; %3 Zn, %2 Nd, %1 Ce, %1 Gd, %0.5 Zr, %0.5 Ca kimyasal bileşime sahip EZ43B ise; %3 Zn, %1 Nd, %2 Ce, %1 Gd, %0.5 Zr, %0.5 Ca kimyasal bileşime sahip olan bir alaşımdır.
EZ43A ve EZ43B alaşımlarının üretilmesinde uygulanan yöntem; ergiyik bazlı indüksiyon karıştırma ile alaşımlama ve döküm işlemi olup, döküm sonrası elde edilen EZ43A ve EZ43B alaşımlarına ilk olarak Homojenizasyon ısıl işlemi yapılmış, ardından numunelere Ekstrüzyon işlemi uygulanmıştır. Ekstrüzyon işleminden sonra alaşımdan belli oranda parça alınarak çok yönlü dövme işlemine tabi tutulmuştur. Ardından ekstrüde edilen alaşımlar ile çok yönlü dövmeye tutulan alaşımların Mikroyapı, sertlik, çekme, korozyon, aşınma ve biyouyumlulukları incelenmiştir.
Alaşımların ergitimi kapalı sistem indüksiyon ocağında koruyucu gaz (Ar) kullanılarak ve dökümleri ise yine koruyucu gaz (CO2+%1SF6) altında yapılmıştır.
Ergitme ve karıştırma tamamlandıktan sonra, kalıbın boyutlarına uygun olarak tasarlanmış olan ısıtma plakaları ile döküm kriterlerine uygun olarak tasarlanmış çelik kalıp 270 C' ye ısıtılmış ve iç kısmı döküm öncesi CO2+SF6 gazı ile doldurulduktan sonra gravite yöntemiyle döküm işlemi gerçekleştirilmiş ve döküm işleminden sonra iki kademeli silindirik ingot parça elde dilmiştir. EZ43A alaşımı ve EZ43B alaşımı ile ilgili olarak ayrı ayrı birer adet ingot parça elde edilmiştir.
Döküm işleminin ardından Alaşımların döküm işlemi sırasında üretimi gerçekleştirilen döküm parçaların mikro yapılarında muhtemelen oluşabilecek küçük oranlarda ki mikrosegregasyonlar ile homojen olmayan tane dağılımı ve boyutu gibi kusurları ortadan kaldırmak ve yine ekstrüzyon işlemi sırasında deformasyonu zorlaştıran düşük termal kararlılığa sahip ikincil fazların ana matris fazı içinde çözünmesini temin etmek amacıyla yapılan ekstrüzyon işlemi öncesi iki alaşıma da 400 c de 24 saat süren homojenleştirme ısıl işlemi uygulanmıştır.
Homojenleştirme işlemi tamamlanan alaşımlar hidrolik pres ile 350 c sıcaklıkta 7:1 oranında 0.3 mm/sn basma hızında ekstrüzyon işlemine tabi tutuldu.
Ekstrüzyon işleminden sonra çok yönlü dövme işlemi uygulanacak olan EZ43A ve EZ43B alaşımları çok yönlü dövme işlemine başlamadan önce Ekstrüde edilmiş numuneler uygun boyutlarda kesildi ve elde edilen bu numuneler sonra Biyet boyunca homojen sıcaklık dağılımının olması adına ısıl işlem fırınında 350 c sıcaklıkta iki saat bekletildi. Ardından dövme işlemi için gereken sıcaklığa gelen alaşımların ilk olarak birinci dövme işlemine geçildi. Birinci dövme işlemine tabi tutulan numuneler ikinci dövme işlemi öncesi tekrar tavlama fırınına alındı ve 350 c sıcaklıkta 30 dakika bekletildi. Alaşımların dövme işlem 30 ton kapasiteli hidrolik pres yardımı ile yapıldı. Dövme işlemine başlamadan önce dövme işleminde kullanılan kalıplar sıcaklık kontrollü prese bağlantılı kuşak kelepçe rezistanslar ile ısıtılıp 350 c olması sağlanmıştır.
Üretimi tamamlanan EZ43A ve EZ43B alaşımların; ekstrüzyon işlemi sonrası mikroyapı görüntüleme işlemleri, XRD analizi, SEM, EDX ve MAP görüntüleme işlemleri, sertlik ve çekme testi, daldırma korozyon testi, potansiyodinamik polarizasyon (Pd) testi, empedans testi, adhezif ve korozif aşınma testi, hidrojen evolution testi ile biyouyumluluk genotoksisite ve sitotoksisite testleri yapılmıştır. Biyouyumluluk testlerinde Genetik yapıyı bozup bozmadıklarına ve Bakterileri öldürüp öldürmediklerine bakılmıştır. Geno Toksitite testleri sonrasında her iki alaşımında Genetik yapıyı bozmadıkları izlenmiştir. Sito toksitite testlerinde ise EZ43A alaşımının Bakteri sayısında %142 den fazla artış sağladığı ve EZ43B alaşımının ise Bakteri sayısında %116 artış sağladığı izlenmiştir. Standartlara göre %70 den fazla olursa malzeme Biyouyumlu olduğundan her iki alaşımda biyouyumlu alaşım olduğu görülmüştür.
Birinci ve ikinci dövme işlemleri sonrası ise mikroyapı görüntüleme işlemleri, SEM, EDX ve MAP görüntüleme analiz işlemleri, sertlik testi, daldırma korozyon testi, potansiyodinamik polarizasyon (Pd) testi, empedans testi, adhezif ve korozif aşınma testi ve hidrojen evolution testleri yapılmıştır.
Korozyon testleri; 7.4 pH’a ve NaCl 8.0 g/l, KCl 0.4 g/l, CaCl2 0.14 g/l, NaHCO3 0.35 g/l, C6H6O6 (glucose) 1.0 g/l, MgCl2·6H2O 0.1 g/l, MgSO4·7H2O 0.06 g/l, KH2PO4 0.06 g/l, Na2HPO4·12H2O 0.06 g/l. bileşime sahip Hank sıvısı içinde 37 °C’de yapılmıştır.
Ekstrüzyon sonrası adezif aşınma uygulanmış EZ43A numunesi ile Çok yönlü dövme işlemi uygulanmış EZ43A numunelerinin kıyaslandığında ise Bir kere Dövme işlemi Uygulanmış EZ43A numunesinin mesafeye bağlı ağırlık kaybının Ekstrüzyon işleminden sonra korozif aşınma testi uygulanmış numuneye göre mesafeye bağlı ağırlık kaybının çok daha yüksek olduğu görülmektedir. İki kere dövme işlemi uygulanmış EZ43A numunesinin Mesafeye bağlı ağırlık kaybının Ekstrüzyon sonrası adezif aşınma uygulanmış EZ43A numunesine göre daha düşük olduğu gözlenmiştir.
Ekstrüzyon sonrası adezif aşınma uygulanmış EZ43B numunesi ile bir kere dövme işlemi uygulanmış EZ43B numunesinin kıyaslandığında ise Bir kere Dövme işlemi Uygulanmış EZ43B numunesinin mesafeye bağlı ağırlık kaybının Ekstrüzyon işleminden sonra korozif aşınma testi uygulanmış numuneye göre mesafeye bağlı ağırlık kaybının çok daha düşük olduğu görülmektedir.
Bir kere dövme işlemi uygulanmış EZ43B numunesinin mesafeye bağlı ağırlık kaybının diğer numunelerle kıyaslandığında en düşük düzeyde olduğu gözlenmiştir.
This study covers the production of EZ43A and EZ43B Mg based materials for the first time and the investigation of their mechanical and corrosion properties after extrusion process and multidirectional forging methods. Zinc (Zn), Gadolinium (Gd), Calcium (Ca), Zirconium (Zr), Neodymium (Nd) and Cerium (Ce) alloying elements were added to the Magnesium element and EZ43A and EZ43B alloys were produced by low pressure casting method. EZ43A has a chemical composition of 3% Zn, 2% Nd, 1% Ce, 1% Gd, 0.5% Zr, 0.5% Ca and EZ43B has a chemical composition of 3% Zn, 1% Nd, 2% Ce, 1% Gd, 0.5% Zr, 0.5% Ca. The method applied in the production of EZ43A and EZ43B alloys; alloying and casting process with melt-based induction stirring. Homogenisation heat treatment was first applied to the EZ43A and EZ43B alloys obtained after casting, and then extrusion process was applied to the samples. After the extrusion process, a certain amount of parts were taken from the alloy and subjected to multidirectional forging process. Then, the microstructure, hardness, tensile, corrosion, wear and biocompatibility of the extruded alloys and the alloys subjected to multidirectional forging were investigated. The alloys were melted in a closed system induction furnace using protective gas (Ar) and cast under protective gas (CO2+1%SF6). After the melting and mixing was completed, the steel mould, which was designed in accordance with the casting criteria with the heating plates designed in accordance with the dimensions of the mould, was heated to 270 C and the interior was filled with CO2 + SF6 gas before casting and the casting process was carried out by gravity method and after the casting process, two graded cylindrical ingot parts, one from each alloy, were obtained. After the casting process, both alloys were subjected to homogenisation heat treatment at 400°C for 24 hours before the extrusion process in order to eliminate defects such as microsegregations and inhomogeneous grain distribution and size in small ratios that may possibly occur in the microstructure of the cast parts produced during the casting process of the alloys and to ensure that the secondary phases with low thermal stability, which make deformation difficult during the extrusion process, are dissolved in the main matrix phase. After homogenisation, the alloys were extruded with a hydraulic press at 350 c at a ratio of 7:1 at a compression speed of 0.3 mm/sec. After the extrusion process, the EZ43A and EZ43B alloys, which will be subjected to multidirectional forging process after the extrusion process, were cut to the appropriate dimensions before starting the multidirectional forging process, and these samples were then kept in the heat treatment furnace at 350 c for two hours in order to ensure homogeneous temperature distribution along the billet. Then, the alloys that reached the temperature required for the forging process were first subjected to the first forging process. The samples subjected to the first forging process were taken into the annealing furnace again before the second forging process and kept at 350 c for 30 minutes. The forging process of the alloys was carried out with the help of a hydraulic press with a capacity of 30 tonnes. Before starting the forging process, the moulds used in the forging process were heated with belt clamp resistances connected to the temperature-controlled press and 350 c was ensured. After the extrusion process, microstructure imaging, XRD analysis, SEM, EDX and MAP imaging processes, hardness and tensile test, immersion corrosion test, potentiodynamic polarisation (Pd) test, impedance test, adhesive and corrosive wear test, hydrogen evolution test, biocompatibility genotoxicity and cytotoxicity tests were performed on EZ43A and EZ43B alloys. In biocompatibility tests, it was checked whether they disrupt the genetic structure and kill bacteria. After the genotoxicity tests, it was observed that both alloys did not disrupt the genetic structure. In cyto toxicity tests, it was observed that EZ43A alloy increased the number of bacteria by more than 142% and EZ43B alloy increased the number of bacteria by 116%. According to the standards, if more than 70% of the material is biocompatible, both alloys are biocompatible alloys. After the first and second forging processes, microstructure imaging processes, SEM, EDX and MAP imaging analysis processes, hardness test, immersion corrosion test, potentiodynamic polarisation (Pd) test, impedance test, adhesive and corrosive wear test and hydrogen evolution tests were performed. Corrosion tests were performed at pH 7.4 and NaCl 8.0 g/l, KCl 0.4 g/l, CaCl2 0.14 g/l, NaHCO3 0.35 g/l, C6H6O6 (glucose) 1.0 g/l, MgCl2-6H2O 0. 1 g/l, MgSO4-7H2O 0.06 g/l, KH2PO4 0.06 g/l, Na2HPO4-12H2O 0.06 g/l in Hank's fluid at 37 °C. When the EZ43A specimen with adhesive wear after extrusion is compared with the EZ43A specimens with multiple forging processes, it is seen that the distance dependent weight loss of the EZ43A specimen with one forging process is much higher than the corrosive wear test after extrusion process. It was observed that the distance dependent weight loss of the EZ43A sample which was forged twice was lower than the EZ43A sample which was subjected to adhesive wear after extrusion. When the EZ43B sample with adhesive wear after extrusion is compared with the EZ43B sample with forging process once, it is seen that the weight loss due to distance of the EZ43B sample with forging process once is much lower than the sample with corrosive wear test after extrusion process. It was observed that the distance dependent weight loss of the EZ43B sample, which was forged once, was at the lowest level compared to the other samples.
This study covers the production of EZ43A and EZ43B Mg based materials for the first time and the investigation of their mechanical and corrosion properties after extrusion process and multidirectional forging methods. Zinc (Zn), Gadolinium (Gd), Calcium (Ca), Zirconium (Zr), Neodymium (Nd) and Cerium (Ce) alloying elements were added to the Magnesium element and EZ43A and EZ43B alloys were produced by low pressure casting method. EZ43A has a chemical composition of 3% Zn, 2% Nd, 1% Ce, 1% Gd, 0.5% Zr, 0.5% Ca and EZ43B has a chemical composition of 3% Zn, 1% Nd, 2% Ce, 1% Gd, 0.5% Zr, 0.5% Ca. The method applied in the production of EZ43A and EZ43B alloys; alloying and casting process with melt-based induction stirring. Homogenisation heat treatment was first applied to the EZ43A and EZ43B alloys obtained after casting, and then extrusion process was applied to the samples. After the extrusion process, a certain amount of parts were taken from the alloy and subjected to multidirectional forging process. Then, the microstructure, hardness, tensile, corrosion, wear and biocompatibility of the extruded alloys and the alloys subjected to multidirectional forging were investigated. The alloys were melted in a closed system induction furnace using protective gas (Ar) and cast under protective gas (CO2+1%SF6). After the melting and mixing was completed, the steel mould, which was designed in accordance with the casting criteria with the heating plates designed in accordance with the dimensions of the mould, was heated to 270 C and the interior was filled with CO2 + SF6 gas before casting and the casting process was carried out by gravity method and after the casting process, two graded cylindrical ingot parts, one from each alloy, were obtained. After the casting process, both alloys were subjected to homogenisation heat treatment at 400°C for 24 hours before the extrusion process in order to eliminate defects such as microsegregations and inhomogeneous grain distribution and size in small ratios that may possibly occur in the microstructure of the cast parts produced during the casting process of the alloys and to ensure that the secondary phases with low thermal stability, which make deformation difficult during the extrusion process, are dissolved in the main matrix phase. After homogenisation, the alloys were extruded with a hydraulic press at 350 c at a ratio of 7:1 at a compression speed of 0.3 mm/sec. After the extrusion process, the EZ43A and EZ43B alloys, which will be subjected to multidirectional forging process after the extrusion process, were cut to the appropriate dimensions before starting the multidirectional forging process, and these samples were then kept in the heat treatment furnace at 350 c for two hours in order to ensure homogeneous temperature distribution along the billet. Then, the alloys that reached the temperature required for the forging process were first subjected to the first forging process. The samples subjected to the first forging process were taken into the annealing furnace again before the second forging process and kept at 350 c for 30 minutes. The forging process of the alloys was carried out with the help of a hydraulic press with a capacity of 30 tonnes. Before starting the forging process, the moulds used in the forging process were heated with belt clamp resistances connected to the temperature-controlled press and 350 c was ensured. After the extrusion process, microstructure imaging, XRD analysis, SEM, EDX and MAP imaging processes, hardness and tensile test, immersion corrosion test, potentiodynamic polarisation (Pd) test, impedance test, adhesive and corrosive wear test, hydrogen evolution test, biocompatibility genotoxicity and cytotoxicity tests were performed on EZ43A and EZ43B alloys. In biocompatibility tests, it was checked whether they disrupt the genetic structure and kill bacteria. After the genotoxicity tests, it was observed that both alloys did not disrupt the genetic structure. In cyto toxicity tests, it was observed that EZ43A alloy increased the number of bacteria by more than 142% and EZ43B alloy increased the number of bacteria by 116%. According to the standards, if more than 70% of the material is biocompatible, both alloys are biocompatible alloys. After the first and second forging processes, microstructure imaging processes, SEM, EDX and MAP imaging analysis processes, hardness test, immersion corrosion test, potentiodynamic polarisation (Pd) test, impedance test, adhesive and corrosive wear test and hydrogen evolution tests were performed. Corrosion tests were performed at pH 7.4 and NaCl 8.0 g/l, KCl 0.4 g/l, CaCl2 0.14 g/l, NaHCO3 0.35 g/l, C6H6O6 (glucose) 1.0 g/l, MgCl2-6H2O 0. 1 g/l, MgSO4-7H2O 0.06 g/l, KH2PO4 0.06 g/l, Na2HPO4-12H2O 0.06 g/l in Hank's fluid at 37 °C. When the EZ43A specimen with adhesive wear after extrusion is compared with the EZ43A specimens with multiple forging processes, it is seen that the distance dependent weight loss of the EZ43A specimen with one forging process is much higher than the corrosive wear test after extrusion process. It was observed that the distance dependent weight loss of the EZ43A sample which was forged twice was lower than the EZ43A sample which was subjected to adhesive wear after extrusion. When the EZ43B sample with adhesive wear after extrusion is compared with the EZ43B sample with forging process once, it is seen that the weight loss due to distance of the EZ43B sample with forging process once is much lower than the sample with corrosive wear test after extrusion process. It was observed that the distance dependent weight loss of the EZ43B sample, which was forged once, was at the lowest level compared to the other samples.
Açıklama
Anahtar Kelimeler
Magnezyum alaşımları, Ekstrüzyon, Korozyon, Mikroyapı ve mekanik özellikler, EZ43, Nadir toprak elementleri., Magnesium alloys, Extrusion, Corrosion, Microstructure and mechanical properties, Rare earth elements
