کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5352799 | 1503568 | 2017 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Effects of Defects on Hydrogen Diffusion in NbC
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
Exceptional mechanical and physical properties of transition metal carbides and nitrides make them good coating-material candidates for extreme corrosive environments such as oil and natural gas wells. However, existence of small pores, pinholes and columnar structures of these ceramics significantly affect their resistance to corrosion, as pore sites would accelerate the diffusion of corrosive media into the substrate. In this research, molecular dynamics atomistic simulations are employed to investigate the effects of the isolated vacancies and the columnar structure on the diffusion rate of H atoms in NbC single crystal at various temperatures. Diffusion coefficient (D) of H atoms in NbC increased with C vacancy concentration. At elevated temperatures, the trapping effect of Nb vacancies is less effective when C vacancies are also present, as H atoms gain enough energy to jump back and forth between the C vacancies. Atomistic simulations also showed a jump in diffusion coefficient for cylindrical pore size of larger than 3Â Ã
radius. Furthermore, D increased monotonically with temperature up to 1000Â K in the presence of cylindrical pores. Further increase in temperature resulted in a drop in the diffusion coefficient for small pores while the large pores only showed a lower increasing trend in diffusion coefficient with the temperature.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Surface Science - Volume 401, 15 April 2017, Pages 198-205
Journal: Applied Surface Science - Volume 401, 15 April 2017, Pages 198-205
نویسندگان
Iman Salehinia, Ioannis Mastorakos, Hussein M. Zbib,