617 Alaşımının Kuru Hava Atmosferindeki Yüksek Sıcaklıklarda Oksidasyon Davranışları

Öz

Çok yüksek sıcaklık reaktörleri (VHTR), elektrik ve hidrojen üretimi konusunda en önemli IV. nesil reaktörlerinden biridir. IV. Nesil reaktörleri, özellikle çok yüksek sıcaklık reaktörlerinin (VHTR) yapısında birçok farklı malzeme düşünülmektedir. Nükleer reaktör aday malzemesi 617 alaşımının yüksek sıcaklıktaki oksidasyonu farklı sıcaklıklarda incelenmiştir. Kontrollü hava ortamlarında 24 saat boyunca 800 ° C ile 1000 ° C arasındaki sıcaklıklarda (100 ° C 'lik adımlarla) izotermal olarak oksidasyon hızı üzerindeki oksidasyon/korozyon etkisinin analizini Termogravimetrik analiz (TGA) ile incelendi. Oksidasyon öncesi ve sonrası (900 ° C) sıcaklıklardaki, malzemenin yüzeyleri hakkında elementel ve kimyasal bilgisi edinmek için yüzey analiz tekniği olan X-ray Fotoelektron Spektroskopisi (XPS) kullanıldı ve yüzey morfolojisini incelemek için Atomik Kuvvet Mikroskobu (AFM) kullanılmıştır. Oksidasyon davranışı, Wagner'in parabolik oksidasyon kinetik hızı yasasını ile ve Arrhenius denkleminin çözümünü yaparak ilgili verilerle bağlantılı olarak, aktivasyon enerjisi 800 ° C ile 1000 ° C için 203.91 kJ/mol bulunmuştur. TGA sonuçlarına bakıldığında, 800°C ile 1000°C arasında kütle artışı görülmüştür. XPS tablosundaki verilere göre 617 alaşımı numunesinin üzerindeki Cr2O3 tabakasında sıcaklıkla birlikte artış görülmüştür. AFM analizi göz önüne alındığında, sıcaklık arttıkça açıklıklar, ara boşluklar ve tanecikli yapılar sıcaklığa bağlı olarak artış göstermiştir. Şekiller, dış oksit ölçeklerinin ve sıcaklıklarla tane sınırlarının sürekli büyümesini sırayla göstermektedir. 617 alaşımının oksit morfolojisi ve yapısı, ortamlardan güçlü bir şekilde etkilenmiştir. Sıcaklık arttıkça oksidasyon derinliği artar. Gözenek, boşluk ve tane sınırlarının oluşumuna atfedilen artan oksidasyon sıcaklıkları, yüksek sıcaklıklara maruz kalmanın etkisiyle oluşmuştur.

Anahtar Kelimeler

• 617 Alaşımı
• VHTR
• TGA
• XPS
• AFM
• Oksidasyon

Oxidation Behaviors of Alloy 617 at High Temperatures in Dry Air Atmosphere

Öz

A very high temperature reactors (VHTR), the most important of the generation IV reactors for producing electricity and hydrogen production. Variety materials reviewed for Generation IV reactor concept, especially very high temperature reactors (VHTR). The high temperature oxidation of the nuclear reactor candidate material 617 alloy was investigated at different temperatures. The analysis of the oxidation/corrosion effect on the oxidation rate isothermally at temperatures between 800 °C and 1000 °C (in 100 °C steps) for 24 hours in controlled air environments was investigated by Thermogravimetric analysis (TGA). X-ray Photoelectron Spectroscopy (XPS), a surface analysis technique, was used to obtain elemental and chemical information about the surfaces of the material at pre- and post-oxidation (900 °C) temperatures and Atomic Force Microscopy (AFM) was used to examine the surface morphology. The oxidation behavior, in conjunction with Wagner's law of parabolic oxidation kinetic rate and by solving the Arrhenius equation, , the activation energy was found to be 203.91 kJ/mol for 800 °C to 1000 °C. Looking at the TGA results, mass increase was observed between 800°C and 1000°C. According to the data in the XPS table, the Cr2O3 layer on the 617-alloy sample increased with temperature. Considering the AFM analysis, as the temperature increased, the apertures, interspaces and granular structures increased depending on the temperature. The figures show, in sequence, the continuous growth of outer oxide scales and grain boundaries with temperatures. The oxide morphology and structure of the 617 alloy were strongly influenced by the environments. As the temperature increases, the oxidation depth increases. The increased oxidation temperatures attributed to the formation of pores, voids, and grain boundaries were generated by exposure to high temperatures.

Anahtar Kelimeler

• VHTR
• TGA
• XPS
• AFM
• Oxidation
• Alloy 617

Kaynakça

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