Kobalt Esaslı Metalik Cam Kaplamaların Pnömatik Sıkıştırma Yöntemi ile Sentezlenmesi

Metalik camlar yüksek dayanım, sertlik ve korozyon direnci gibi üstün özelliklere sahiptirler. Fakat metalik camların üretiminin zor olması ve yüksek saflıktaki bileşenlerin kullanımı nedeniyle maliyetleri yüksektir. Bu sınırlamaya alternatif olarak metalik cam alaşımları kompozit bir malzeme bünyesine yüzey kaplama elemanı olarak dahil edilirse, maliyet problemlerine çözüm sağlayabilecektir. Amorf yapıya sahip bir kaplamanın üretimi düşünüldüğünde, hem hızlı soğutma koşullarını karşılayan hem de kaplama malzemesini altlık yüzeyine yayabilen bir kaplama sistemine ihtiyaç duyulur. Bu çalışmada küçük parçaların kaplanmasında kullanılabilen pnönatik destekli bir sıkıştırma aparatı tasarlanmıştır. Bu yolla, sıvı haldeki bir alaşımın çarpma etkisi ile altlık yüzeyine sıkıştırılması ve hızlı bir şekilde soğutulması Co43Cu1Fe20Ta5,5B26,5Si5 kompozisyonuna sahip amorf kaplamalar farklı metal altlık yüzeylerinde üretilmiştir. Altlık yüzeyleri üzerindeki kaplama tabakalarının yapısal ve termal karakteristikleri XRD, SEM ve DSC analizleri ile değerlendirilmiştir. Mikroyapısal analizler, nispeten daha kalın altlık malzemesi kullanımının tamamen amorf kaplama tabakası elde etmede faydalı olduğunu, ince altlık malzemeleri kullanıldığında ise kaplamanın arayüzey civarındaki belirli bir kısmının kristallenmesine neden olduğunu göstermiştir. Altlık malzemelerine göre çok daha sert özellikteki yeni yüzeylerin sertlikleri yaklaşık 1000 Vickers sertlik değerlerinde ölçülmüştür.

Synthesis of Co-based Metallic Glass Coatings by Pneumatic Squeezing Method

Metallic glasses have superior properties such as high strength, hardness and corrosion resistance. However, the production cost of the metallic glasses is very high due to the difficulties in manufacturing and constituents used in high purity. As an alternative to this limitation, if the metallic glass alloys will be considered in the composite material as a surface coating element, it may be provide solutions to the cost problems. When the production of a coating having amorphous structure was considered, a coating system which satisfies rapid cooling capability and also transmits the coating material to the surface of the substrate, is needed. In this study, pneumatic-assisted squeezing apparatus which could be used for coating the small parts was designed. By this way, it was simultaneously provided that the liquid form of an alloy could be cooled rapidly and squeeze to the substrate surface with an impact effect. In this context, amorphous coatings having a composition of Co43Cu1Fe20Ta5,5B26,5Si5 with thicknesses of 20-80 ?m, was produced on the surface of different metal substrates. Structural and thermal characteristics of the coating layers were evaluated by XRD, SEM and DSC analysis. Microstructural analysis showed that relatively thicker substrates used were beneficial to obtain fully amorphous coating layer, while thinner substrates have led to crystallize in a certain amount of coating near the interface. Consequently, metal substrates having relatively low hardness and wear resistance were coated with a Co-based metallic glass by using an alternative method. The hardness of the amorphous coating were measured about 1000 Hv.

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