The present work deals with the formation of Ni-B/Ni-B-W duplex coatings on steel by electroless plating process and evaluation of their microstructure and corrosion resistance. The Ni-B/Ni-B-W duplex coatings were prepared using dual baths (alkaline borohydride- reduced electroless nickel baths) with Ni-B as inner layer. EDS analyses were carried out for chemical composition analyses. Scanning electron microscopy (SEM) of the cross-sectional view of the electroless nickel duplex coatings reveal that the coatings are uniform and the compatibility between the layers is good. Also the surface morphology was analysed to characterize the surface properties. Coatings were characterized using XRD. The study reveals that the Ni-B and Ni-B-W coatings are amorphous in their as-plated condition and upon heat treatment at 450 ºC for 1 h, both Ni-B and Ni-B-W coatings crystallize and produce nickel and nickel borides (Ni2B ve Ni3B) in the respective coatings. Polarization tests (in 3,5% NaCl aqueous solution) and immersion tests (in 5% H2SO4 solutions) were carried out to analyse the corrosion properties. The tests were applied on substrate steel, as-plated and heat treated Ni-B and Ni-B/Ni-B-W coatings and were compared with each other. According to the results, all coatings performed better corrosion resistance (CR) than the substrate steel. As-plated Ni-B/Ni-B-W coatings demonstrated better CR than Ni-B coatings. By applying heat treatment, corrosion characteristics improved in both Ni-B and Ni-B/Ni-B-W coatings but much more improvement was observed by Ni-B/Ni-B-W coatings. Adding tungsten to the coating improved additionally the CR due to the formation of protective tungsten oxide layer.
|Supporting Institution||İstanbul Teknik Üniversitesi|
|Thanks||Bu çalışma İstanbul Teknik Üniversitesi MYL-36421 no.lu Bilimsel Araştırma Proje (BAP) ile desteklenmiştir.|
: April 7, 2020
|APA||Dil, G , Göksenli, A , Yüksel, B , Muhaffel, F . (2020). Isıl İşlemin Akımsız Ni-B/Ni-B-W Dubleks Kaplamanın Korozyon Direncine Etkisinin Analiz Edilmesi . Bilecik Şeyh Edebali Üniversitesi Fen Bilimleri Dergisi , 7 (2) , 911-922 . DOI: 10.35193/bseufbd.716170|