کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1548461 997740 2013 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Vapor phase codeposition of Cr and Si on Nb-base in situ composites by pack cementation process
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد مواد الکترونیکی، نوری و مغناطیسی
پیش نمایش صفحه اول مقاله
Vapor phase codeposition of Cr and Si on Nb-base in situ composites by pack cementation process
چکیده انگلیسی

In order to identify suitable halide activators and pack compositions for codepositing Cr and Si to form diffusion coatings on Nb-base in situ composites by the pack cementation process, thermochemical calculation was taken to analyze the vapor pressure of halide species generated at high temperatures. NH4Cl, NaF and CrCl3·6H2O were selected as the halide salts. The results of thermochemical calculations suggested that the pack powder mixtures, which contained Cr, Si, halide salts and Al2O3, may be activated by NH4Cl and NaF. According to the thermochemical calculations, the pack powder mixture of 12Cr–6Si–5NH4Cl–77Al2O3 (wt%) activated by NH4Cl was formulated and coating deposition experiments were carried out at 1200 and 1300 °C. With adequate control of pack compositions and deposition conditions, it was found that codeposition of Cr and Si could indeed be achieved at these temperatures. The coating has a three-layer structure, of which was mainly composed of Cr2(Nb,X) (X represents Ti and Hf elements), Nb5Si3 and (Nb,Cr)3Si. Then the kinetics of coating growth process affected by temperature was studied. The experimental results of the oxidation showed that the coating can efficiently prevent substrate from oxidizing.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Progress in Natural Science: Materials International - Volume 23, Issue 2, April 2013, Pages 198–204
نویسندگان
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