نوع مقاله : علمی و پژوهشی
نویسنده
مرکز تحقیقات مواد پیشرفته، دانشکده مهندسی مواد، واحد نجف آباد، دانشگاه آزاد اسلامی، نجف آباد، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسنده [English]
In the present research, nanoparticles based on the alumina-yttria system were synthesized using a sol-gel method. Then, the effect of heat treatment on the phase evolution and crystallite size in this composite system was investigated. The produced composite powder was characterized using X-ray diffraction and scanning electron microscopy. Scherrer equation was used to investigate the effect of temperature on crystallite sizes. The composite powder was cold isostatically pressed and subjected to a pressureless sintering process at different temperatures to evaluate its density changes. The X-ray diffraction results showed that the powder sample was initially amorphous. By increasing the temperature, the components of this composite system reacted and Alpha-Al2O3 and Y3Al5O12 phases are formed. The crystallite size of the Theta-alumina phase grew with increasing temperatures up to 1000 C. At higher temperatures, crystallite size decreased due to the decomposition of theta-alumina. The density of the samples increased by increasing the temperature up to 1600 C so that the samples reached a relative density of about 96%. The densification curve of the composite showed three different stages during sintering. Examining the hardness of the samples showed that the hardness increases with the increase of the sintering temperature, and in the sample sintered at 1600 C for 3 hours, the Vickers hardness reached about 14 GPa.
کلیدواژهها [English]
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