کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8028157 1517638 2014 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Thermally activated transformations in metastable alumina coatings prepared by magnetron sputtering
ترجمه فارسی عنوان
تغییرات حرارتی فعال در پوشش آلومینا متاستاز آماده شده توسط اسپری شدن مگنترون
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد فناوری نانو (نانو تکنولوژی)
چکیده انگلیسی
An as-deposited metastable structure of alumina coatings can be of essential importance for the transformation processes occurring in the coatings during their annealing. The present study focuses on thermal stability and phase transformations in magnetron sputtered alumina coatings with different as-deposited structures characterized by different ratios of an amorphous a-Al2O3 to crystalline γ-Al2O3 phase. Purely amorphous, purely γ-phase and γ-phase/amorphous coatings were investigated by a combination of differential scanning calorimetry (40 °C/min in air) and ex-situ X-ray diffraction analyses. Indentation testing and optical characterization were also carried out. In the coatings with a purely or partially amorphous as-deposited structure two exothermic transformations occurred. An a-to-γ transformation proceeded at ~ 900 °C while a γ-to-α transformation proceeded at ~ 1200 °C. In the crystalline γ-phase as-deposited coating the γ-to-α transformation was the only exothermic transformation observed at the same temperature of ~ 1200 °C. Independently of the as-deposited structure, the γ-to-α transformation was accompanied by the formation of the intermediate metastable θ phase without any detectable heat released. Measured changes in transformation enthalpies for the a-to-γ and γ-to-α transformations were close to each other while the activation energy was higher for the γ-to-α transformation. Hardness, effective Young's modulus and refractive index showed a tendency to increase with a decreasing amount of an amorphous phase in the coating.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Surface and Coatings Technology - Volume 240, 15 February 2014, Pages 7-13
نویسندگان
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