Kimyasal buhar çöktürme yöntemi ile bor karbür üretimi
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Date
2001-01
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Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Kimya Mühendisliği
Abstract
Gelişen teknolojide yüksek teknoloji ürünleri önemli bir yer teşkil etmektedir. Dünyanın birçok ileri ülkesinde kompozit maddelerin üretimiyle uzay, havacılık, nükleer çalışmalar, sanayii v.b. alanlarda büyük ilerlemeler sağlanmıştır. Hem dayanıklılık hem de enerji tasarrufu sağlaması; ulaşılması istenen hedeflere daha çabuk varılmasında önemli malzemedir. Bor karbür kompozit madde olarak çok amaçlı kullanıldığı gibi nötron tutucu özelliği nedeniyle nükleer yakıt kaplanmasında ve atıkların muhafazasında da kullanılmaktadır. Bu malzemenin kaynak malzemelerinden olan borun dünya rezervlerinin % 63 'den fazlası Türkiye'de bulunmaktadır. Bu nedenle stratejik malzeme olan kompozitlerden bor karbürün Türkiye'de üretilmesi daha da büyük bir önem arz etmektedir. Bu çalışmada yüksek teknoloji ürünü olan bor karbürün üretiminde bor kaynağı olarak BCb, karbon kaynağı olarak da CCU kullanılırken sabit B/C oranında sıcaklığın ürün çeşidi ve ürün niteliği üzerindeki etkileri incelenmiştir.
1050-1325°C aralığında yürütülen çalışmalarda, ürün niteliği X-ışını kırınım desenleri (XRD), taramalı mikroskop görüntüleri (SEM), atomik kuvvet mikroskobu (AFM), X-ışım floresans (XRF) teknikleri yardımıyla incelenmiştir. XRD sonuçlarında bor karbür pikleri elde edilirken XRF sonuçları tepkimede olası yan ürünlerin oluşmadığını göstermektedir. AFM çalışmasında yüzey morfolojisi incelenmiştir ve sıcaklıkla pürüzlülüğün azaldığı ancak bazı tepe ve çukurların oluştuğu saptanmıştır. SEM resimlerinde AFM çekimlerinde meydana gelen bu değişimin, kaplamanın amorf yapıya dönüşmesinden kaynaklandığı belirlenmiştir.
Sıcaklık artışının ürün kaplama yapısında çekirdeksel bir oluşum yerine amorf bir yapının oluşmasına neden olduğu saptanmıştır. Sıcaklık değişiminin yan tepkimelerin oluşumunda bir etkisi olmadığı tespit edilmiştir.
High technology composite materials products have occupied an important place in advancing technology. In several developed countries a lot of progress has been made in many areas such as space, aeronautics, nuclear studies, industry etc... Because of providing economy on energy and firmness it has become an important tool to reach the desired target more quickly. Boron carbide which is used for different purposes as composite material could also be used to coat nuclear fuel and to store nuclear wastes as boron absorbs neutrons. More than % 63 of the world reservations of boron minerals, which are the source for boron carbide, is found in Turkey. For this reason the production of boron carbide, which is among the strategical metarials, in Turkey gains even more importance. In this study, BCI3 was used as the source of boron and CCU was used as the source of carbon. The B/C ratio was kept constant and the effect of different temperature on the quality and the variety of the product was examined. The product synthesized between 1050 and 1325°C was examined by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray florance (XRF). Boron carbide peaks were dedected by XRD. The results of XRF proves that no side products were produced during the reaction. The AFM study showed that the coated surface got smoother as the reaction temperature increased. However, the disturbances in the coating thickness become apparent. As it was shown by the photographs of SEM, this change happened because the coating was turned into an amorf structure. The increase in the tempaerature change the coating type to change from grain structure to graphite structure. Since no side reaction occured, the desired boron carbide can be obtained without being effected by the change in the temperature.
High technology composite materials products have occupied an important place in advancing technology. In several developed countries a lot of progress has been made in many areas such as space, aeronautics, nuclear studies, industry etc... Because of providing economy on energy and firmness it has become an important tool to reach the desired target more quickly. Boron carbide which is used for different purposes as composite material could also be used to coat nuclear fuel and to store nuclear wastes as boron absorbs neutrons. More than % 63 of the world reservations of boron minerals, which are the source for boron carbide, is found in Turkey. For this reason the production of boron carbide, which is among the strategical metarials, in Turkey gains even more importance. In this study, BCI3 was used as the source of boron and CCU was used as the source of carbon. The B/C ratio was kept constant and the effect of different temperature on the quality and the variety of the product was examined. The product synthesized between 1050 and 1325°C was examined by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray florance (XRF). Boron carbide peaks were dedected by XRD. The results of XRF proves that no side products were produced during the reaction. The AFM study showed that the coated surface got smoother as the reaction temperature increased. However, the disturbances in the coating thickness become apparent. As it was shown by the photographs of SEM, this change happened because the coating was turned into an amorf structure. The increase in the tempaerature change the coating type to change from grain structure to graphite structure. Since no side reaction occured, the desired boron carbide can be obtained without being effected by the change in the temperature.
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Keywords
Bor karbür, Boron carbide, Chemical vapor deposition, Kimyasal buhar çöktürme, Boron, Bor
Citation
İzmir, A.İ. (2001) Kimyasal buhar çöktürme yöntemi ile bor karbür üretimi (Yayımlanmamış yüksek lisans tezi). Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Kimya Mühendisliği.