Investigation of Junction Between Alumina Parts Using Aluminum Borates Nano-needles Synthesized via Electrospinning Method

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Investigation of Junction Between Alumina Parts Using Aluminum Borates Nano-needles Synthesized via Electrospinning Method

ارائه دهنده: Provider: Amir Hosein Sarraf

اساتید راهنما: Supervisors: Dr. Hamid Esfahani

اساتید مشاور: Advisory Professors: Dr. Mohsen Sheikhi

اساتید ممتحن یا داور: Examining professors or referees: Dr. Hasan elmkhah- Dr. Mino Karbasi

زمان و تاریخ ارائه: Time and date of presentation: 2024

مکان ارائه: Place of presentation: calss 71 of engineering faculty

چکیده: Abstract: Junction of ceramic parts of the same or different materials has been a serious challenge for a long time. Various solutions have been proposed, but the use of nanostructured materials has not been extensively studied. In this research, the ability to connect alumina base parts using aluminum borate nano-needle during the electrospinning sintering process was investigated. The effect of the composition and morphology of aluminum borate nano-needle on the bond strength between two pieces was examined at three levels of low, medium, and high boron content in the electrospinning solution and its product. The investigation of field emission scanning electron microscope (FESEM) images of electrospinning nano-fibers showed a random arrangement of smooth and defect-free fibers. Thermal behavior of fibers with high boron content was evaluated from ambient temperature to 1000 degrees Celsius using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicated several heat peaks related to oxidation, polymer removal, and formation of new phases, suggesting 1000 degrees Celsius as the suitable temperature for sintering and ceramic phase formation. The microstructure analysis of low boron content electrospinning sintered nano-needle revealed nanostructures with diameters less than 50 nanometers and lengths greater than 1 micrometer. Additionally, an increase in boron content led to an increase in the length-to-diameter ratio of the nano-needle. X-ray diffraction (XRD) was used to identify the synthesized phases in the nano-needle, showing that all three compositions consisted of two primary phases, B2O3 and Al18B4O33, with no additional phase. It was found that with an increase in boron content, the ratio of B2O3 to Al18B4O33 phase increased. The additional boron did not react with aluminum atoms and created a readily melting B2O3 phase, playing a crucial role in the bonding process of alumina base parts. In this study, an alumina-zirconia nanocomposite (15 mol% zirconia) was used as the base material for bonding. The bonding process involved placing 0.065 grams of electrospinning sinter between two ceramic discs, applying a pressure of 13 kilopascals at 1000 degrees Celsius for one hour. The bonded parts were subjected to ASTM-D905 shear testing to evaluate the bond strength, showing that applying pressure during the bonding process improved the bond strength up to five times. Furthermore, an increase in boron content in the bonding agent increased the force required to break the bond from 77 Newtons to 892 Newtons. Microstructural analysis of the fracture surface indicated that Al18B4O33 nano-needle, acting as a reinforcement in the ceramic phase B2O3 responsible for bonding, were distributed throughout. The results of this research confirmed that with the appropriate composition selection, electrospinning sintering can enable the bonding of ceramic parts

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