Borlanmış Donatının Mikroyapısal Karakterizasyonu ve Korozyon Direnci

Öz

Çelik çubukların korozyona uğraması nedeniyle betonarme yapılarda hizmet verilebilirliği ve nihai dayanımı olumsuz etkilenmektedir. Bu çalışmada borlanmış düşük karbonlu inşaat çeliğinin mikroyapı ve korozyon davranışları incelenmiştir. Çalışmada Ø12 ve Ø14 ebatlarında nervürlü çelik çubuklar kullanılmıştır. Çelik donatıların borlama işlemi sırasıyla 800, 900 ve 1000 oC’de 2 ve 4 saat süresince gerçekleştirilmiştir. Borlama parametresine bağlı olarak, borlanmış donatıların yüzeyindeki borür tabakası kalınlığı 32.58 μm ile 213.74 μm arasında değişmektedir. Borlama işleminden sonra, donatılar betona gömülüp hızlı korozyon testine tabi tutulmuştur. Borlanmış çelik çubukların kesit kayıplarının ve korozyon hızlarının borlanmamış çeliğe göre oldukça düşük çıkmıştır. Borlanmış inşaat demirinin korozyon başlama zamanı, borlanmamış inşaat demiri ile karşılaştırıldığında yaklaşık 2 kat gecikmiştir. Borür tabakaları, borlama sıcaklığına ve süresine bağlı olarak donatıların korozyon oranını 2,39 ila 10,65 kat, donatıların kesit kayıplarını ise 2,54 ila 4,72 kat azaltmıştır.

Anahtar Kelimeler

• İnşaat demiri
• Borlama
• Korozyon
• Korunma

Microstructural Characterization and Corrosion-Resistance of Borided Rebar

Öz

he serviceability and ultimate strength of concrete elements within reinforced structures are affected negatively due to corrosion of steel bars. In the present paper, investigations were carried out to study the corrosion behavior of protected low carbon ribbed reinforcing steel with boron in concrete. The ribbed steel bars were in size of Ø12 and Ø14, and they were coated with boron. The coating process was carried out at 800, 900 and 1000 oC for 2 h and 4 h, respectively. Depending on the boriding parameter the boride layer thickness on the surface of borided rebars ranged from 32.58 μm and 213.74 μm. After boriding, the rebars were embedded into the concrete and exposed to rapid corrosion test. The results show that the corrosion rate and cross section loss of protected steel bars decreases when compared to unprotected rebars. Corrosion beginning time of borided rebars delayed about 2 times when compared to plain rebar. Boride layers reduced the corrosion rate of the reinforcements by 2.39 to 10.65 times and the section losses of the reinforcements by 2.54 to 4.72 times depending on the boriding temperature and duration.

Anahtar Kelimeler

• Rebar
• Boriding
• Corosion
• Protection

Kaynakça

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