Elektrik Akım Destekli Sinterleme ile Üretilen Ötektik Yapılı NiAl-34Cr ve NiAl28Cr-6Mo Alaşımlarının Yüksek Sıcaklık Korozyon Davranışı

Bu çalışmada, NiAl-34Cr ve NiAl-28Cr-6Mo ötektik alaşımları elektrik akım destekli sinterleme (ECAS) yöntemiyle 3500- 4200 A akım aralığında 47 dakika bekleme süresiyle üretilmiştir. Elde edilen numunelerin faz incelemeleri, X-ışınları difraksiyon analizi (XRD) yardımıyla gerçekleştirilmiştir. XRD paternlerinden, NiAl-34Cr alaşımının NiAl ve Cr fazları belirlenirken; NiAl-28Cr-6Mo alaşımının ise NiAl ve CrMo fazları ile birlikte düşük miktarda reaksiyona girmemiş Mo fazının varlığı tespit edilmiştir. Archimed prensibine göre yapılan yoğunluk ölçümlerinde NiAl-34Cr ve NiAl-28Cr-6Mo alaşımlarının nispi yoğunlukları sırasıyla %96.2, %97.9 ve mikrosertlik cihazında Brinell sertlik ucu kullanılarak tespit edilen sertlik değerleri sırasıyla 275 ± 13 HB ve 255 ± 20 HB olarak belirlenmiştir. Ayrıca numunelerin korozyon özellikleri 25% ağ. K2SO4 + 75% ağ. Na2SO4 tuz ortamında 800, 900 ve 1000°C’de 165 saat (15 Çevrim) sürede sıcak korozyon deneyleriyle incelenmiştir. Korozyon sonrası numunelerin süreye bağlı olarak ağırlık değişimleri, mikroyapı (SEM-EDS) ve faz analizleri gerçekleştirilmiş olup NiAl-34Cr alaşımının korozyon özelliklerinin Mo ilaveli alaşıma kıyasla daha iyi olduğu görülmüştür.

High Temperature Corrosion Behavior of Eutectic Structured NiAl-34Cr and NiAl28Cr-6Mo Alloys Produced by Electric Current Activated Sintering

In this study, NiAl-34Cr and NiAl-28Cr-6Mo eutectic alloys were produced by electric current assisted sintering (ECAS) method in a 3500-4200 A current range with a waiting time of 47 minutes. Phase examinations of the obtained samples were carried out with the help of X-ray diffraction analysis (XRD). While determining NiAl and Cr phases in NiAl-34Cr alloy from XRD patterns; It was determined that NiAl-28Cr-6Mo alloy consists of two phases, together with Mo residues, NiAl and CrMo. According to the Archimed principle, the relative density of NiAl-34Cr and NiAl-28Cr-6Mo alloys was determined as 96.2%, 97.9% respectively. The hardness values of NiAl-34Cr and NiAl-28Cr-6Mo samples were approximately 275 ± 13 HB and 255 ± 20 HB detected. In addition, the corrosion properties of the samples were examined by hot corrosion tests at 800, 900 and 1000°C for 165 hours (15 cycles) in 25% wt. K2SO4 + 75% wt. Na2SO4 salt medium. Weight changes, microstructure (SEM-EDS) and phase analysis of the samples after corrosion were carried out, and the corrosion properties of NiAl-34Cr alloy were found to be better compared to the Mo-added alloy.

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