Magnezyum matrisli nanopartikül takviyeli kompozit malzemelerin toz metalurjisi yöntemiyle üretilmesi ve karakterizasyonu
Küçük Resim Yok
Tarih
2018
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Karabük Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu çalışmada, farklı matrisli magnezyum ve magnezyum alaşımlarına farklı oranlarda (ağırlıkça 0.1, 0.25 ve 0.5) karbon nanotüp, grafen ve fulleren başarılı bir şekilde katılarak toz metalurjisi yöntemiyle metal matrisli kompozitler üretilmiştir. Karbon nanopartiküller ile mikron boyuttaki matris malzemelerinin homojen karışması, mekanik alaşımlama gibi geleneksel yöntemlerle zor olduğu için sıvı bazlı özel bir yöntem geliştirmiştir. Bu yöntemle vakum destilasyon sistemi içerisinde manyetik karıştırıcı vasıtasıyla solüsyon içerisinde matris ve takviye malzemeleri uniform bir şekilde karıştırılmıştır. X ışını kırınımı yöntemiyle (XRD) faz analizleri yapılmış, Taramalı Elektron Mikroskopu (SEM) ile mikroyapı analizleri gerçekleştirilmiştir. Sertlik, basma ve aşınma testleri ile mekanik özellikler incelenmiştir. Elektrokimyasal korozyon testleriyle karbon nanopartiküllerin takviyesiz matris malzemesinin korozyon direncine olan etkisi araştırılmıştır. Mikroyapı analizleri neticesinde özellikle düşük oranlarda karbon nanopartikül ilavesi magnezyum matrisi içerisinde homojen bir şekilde dağılmıştır. Takviye oranının ağırlıkça %0.5'e ulaşması durumunda yapıda topaklanmalar görülmeye başlamıştır. Karbon nanotüp takviyesinde karbon atomları arasında güçlü van der waals bağlarının bulunması homojen bir şekilde karışımı zor hale getirmiştir. Bu da mekanik özellikler hususunda yeterince olumlu bir değişikliğe olanak sağlamamıştır. Diğer yandan grafen ve fullerenin matris içerisinde daha uniform dağıldığı gözlemlenmiştir. Karbon ilavesi matrislerde genellikle sertlik, basma dayanımlarını ve aşınma direncini arttırmış ve en iyi sonuçlar genellikle fulleren takviyeli kompozitlerde elde edilmiştir. Karbon nanotüp, grafen ve fullerenin mikroyapı ve mekanik özelliklerdeki olumlu etkilerine ragmen korozyon dirençlerini olumsuz etkilediği gözlemlenmiştir. Bunun sebebi olarak magnezyum ve karbon nanopartiküllerinin arasında galvanik etkileşimin önem arz ettiği tespit edilmiştir.
In this study, different matrix of magnesium and its alloys were reinforced with different weight fractions (0.1 wt.%, 0.25 wt.% and 0.5 wt.%) of carbon nanotubes, graphene and fullerene were fabricated succesfully via powder metallurgy. Solution based technique was established for homogeously mixture of powders because it can be serious problem such as agglomeration when the powders were mixed mechanical alloying. In this method, matrix and reinforcement were mixed uniformly using magnetic stirrer in the vacuum distillation system. Phase analysis was completed by X-ray diffraction method (XRD) and microstructures of samples were investigated using Scanning Electron Microscobe (SEM). Mechanical performances were examined by hardness, compression and wear tests. However, effect of carbonaceous reinforcement on corrosion performances of magnesium matrix composites was evaluated with electrochemical corrosion tests. According to the microstructure analysis, especially at low rates, the carbon nanoparticle addition was homogeneously dispersed in the magnesium matrix. If the reinforcement ratio reaches 0.5% by weight, agglomeration in the microstructure began to occur. The presence of strong van der waals bonds between the carbon atoms in the carbon nanotube reinforcement makes the mixture homogeneously difficult. This situation didn't allow enough positive change in mechanical properties. On the other hand, it was observed that graphene and fullerenes were more uniformly distributed in the matrix. In carbon additive matrices, generally hardness, wear resistance and compressive strength were increased, and best results were generally obtained in fullerene reinforced composites. It was observed that carbon nanotubes, graphenes and fullerenes adversely affect the corrosion resistance despite the positive effects on the microstructure and mechanical properties. This could be attributed that galvanic interaction between magnesium and carbon nanoparticles has important effect to determine the corrosion performances.
In this study, different matrix of magnesium and its alloys were reinforced with different weight fractions (0.1 wt.%, 0.25 wt.% and 0.5 wt.%) of carbon nanotubes, graphene and fullerene were fabricated succesfully via powder metallurgy. Solution based technique was established for homogeously mixture of powders because it can be serious problem such as agglomeration when the powders were mixed mechanical alloying. In this method, matrix and reinforcement were mixed uniformly using magnetic stirrer in the vacuum distillation system. Phase analysis was completed by X-ray diffraction method (XRD) and microstructures of samples were investigated using Scanning Electron Microscobe (SEM). Mechanical performances were examined by hardness, compression and wear tests. However, effect of carbonaceous reinforcement on corrosion performances of magnesium matrix composites was evaluated with electrochemical corrosion tests. According to the microstructure analysis, especially at low rates, the carbon nanoparticle addition was homogeneously dispersed in the magnesium matrix. If the reinforcement ratio reaches 0.5% by weight, agglomeration in the microstructure began to occur. The presence of strong van der waals bonds between the carbon atoms in the carbon nanotube reinforcement makes the mixture homogeneously difficult. This situation didn't allow enough positive change in mechanical properties. On the other hand, it was observed that graphene and fullerenes were more uniformly distributed in the matrix. In carbon additive matrices, generally hardness, wear resistance and compressive strength were increased, and best results were generally obtained in fullerene reinforced composites. It was observed that carbon nanotubes, graphenes and fullerenes adversely affect the corrosion resistance despite the positive effects on the microstructure and mechanical properties. This could be attributed that galvanic interaction between magnesium and carbon nanoparticles has important effect to determine the corrosion performances.
Açıklama
Fen Bilimleri Enstitüsü, Metalurji ve Malzeme Mühendisliği Ana Bilim Dalı, Malzeme Bilim Dalı
Anahtar Kelimeler
Metalurji Mühendisliği, Metallurgical Engineering
