Author :
Abstract
Bu çalışmada, kobalt esaslı Haynes 25 süperalaşımına 900℃’de 2 saat, 900℃’de 4 saat ve 1000℃’de 4 saat süre ile %90 B4C+%10 NaBF4 tozları ortamında kutu borlama işlemi uygulanmıştır. Borlama sonrası numunelerin yüzeyinde oluşturulan borür tabakalarının karakterizasyonu taramalı elektron mikroskobu (SEM), X-ışını difraktometresi (XRD) ve mikrosertlik testleri ile gerçekleştirilmiştir. XRD analizleri sonucunda yüzeyde oluşan borür tabakalarının alaşımın içeriği ve difüze olan bor elementine bağlı olarak baskın fazın CoB olmakla birlikte yapıda düşük miktarda (CoFe)B2, CrB ve W3CoB3 fazlarından oluştuğu tespit edilmiştir. Borlama sıcaklığı ve borlama süresindeki artış kaplama kalınlığı ve sertlik değerlerinde artış ile sonuçlanmıştır. Kullanılan yüksek konsantrasyonlu borlama tozu sayesinde literatüre göre daha kalın borür tabakaları elde edilmiştir. Borlama işlemi sonucu Haynes 25 süperalaşımının sertlik değerinde 5 kat’a varan bir artış meydana gelmiştir.
Keywords
Abstract
In this study, cobalt-based Haynes 25 superalloy was borided in the environment of 90% B4C+10% NaBF4 powders for 2 hours at 900°C, 4 hours at 900°C and 4 hours at 1000°C. The characterization of the boride layers formed on the surface of the samples after borided was carried out by scanning electron microscope (SEM), X-ray diffractometry (XRD) and microhardness tests. In XRD analysis, it was determined that the dominant phase of the boride layers formed on the surface, depending on the alloy content and the diffused boron element, consisted of CoB as well as low amounts of (CoFe)B2, CrB and W3CoB3 phases in the structure. The increase in boriding temperature and boriding time resulted in an increase in coating thickness and hardness values. Thanks to the high concentration boronizing powder used, thicker boride layers were obtained compared to the literature. As a result of the boriding process, the hardness value of Haynes 25 superalloy increased up to 5 times.
Keywords
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