Değişik oranlarda alümina katkılı kübik zirkonyadaki (8YSCZ) statik tane büyümesi ve bu malzemenin oda sıcaklığı mekanik özellikleri

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Thesis Type: Postgraduate

Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, METAL EĞİTİMİ ANABİLİM DALI, Turkey

Approval Date: 2004

Thesis Language: Turkish

Student: ÜMİT DEMİR

Supervisor: SÜLEYMAN TEKELİ

Abstract:

In this study, In order to determine the influence of Al203 content on sintering, static grain growth and room temperature mechanical properties of cubic zirconia, high purity commercial powder of 8 mol % yttria-stabilized cubic zirconia (8YSCZ) doped with 0, 1, 5, 10 wt % Al203 were used. Slip casting was used for the mixing of powders in order to achieve a uniform distribution and homogeneous microstructure. The specimens were sintered at different temperatures between 1250 and 1400 °C for 1 hour. The density increased with Al203 content up to 0,5 wt% and further increase in Al203 content led to a decrease in density. The enhanced density with increasing Al203 content up to 0.5 wt% could be due to the rearrangement of Al203 particles during the early stages of sintering. The decreased density and grain growth in higher amount of Al203 doped specimens were due to the lower grain boundary diffusivity and mobility. X-ray diffraction results showed that Al203 had very limited solubility of 0.3 wt% in 8YSCZ. The grain growth in the 0 to 10 wt % Al203 doped 8YSCZ was studied. The experimental results showed that the grain growth in Al203 doped 8YSCZ occurred slowly and more sluggish than that in undoped 8YSCZ. Also, the grain growth rate decreased with increasing Al203 content. The static grain growth exponent value (n) and the activation energy for undoped 8YSCZ was found to be 2 and 289 kJ/mol, respectively. The addition of Al203 raised the grain growth exponent value to 3 and activation energy for the grain growth process was increased from 289 to 410. Also, the introduction of Al203 significantly enhanced the hardness and fracture toughness of 8YSCZ. The hardness and fracture toughness increased with increasing AI2O3 content. The maximum hardness and fracture toughness values reached 1459 kg/mm2 and 2.41 MPa m1'2, respectively with the addition of 10 wt % Al203 while these values were 1314 kg/mm2 and 1.5 MPa m1/2 for undoped 8YSCZ. Science codeKey words : Cubic Zirconia, Grain Growth, Slip casting Sinterebility, Hardness, Fracture Toughness.