A Study of the Sintering Using Nanometer Sized α-Alumina Powders
| Autor: | Chen-yu Yang, 楊宸宇 |
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| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 This research was study the sinterting behavior of two kinds nanometer-sized α-alumina powders.One is the nanometric sized α-alumina powders manufactured from hydroxide gel precursor mixing with oleic.Another kinds of nanometer-sized α-alumina powders was bought from ALFA company and was named n44652(Alfa) powders. Green body was prepared by mixing aluminum hydroxide gel into α-alumina and pelleted with 100 mesh screen.The drying green body were formed with 200 MPa automatic uniaxial hydraulic press. These green bodies were sintered at 1250℃ to 1450℃for 2 hours duration and furnace-cooling to room temperature.The sintered ceramic bodies were identified by relative apparent density,volume shrinkage rate, micro-structure obsvervation and grain size distribution measurement. The results indicated the α-alumina powders manufactured from aluminum hydroxide gel mixed with oleic acid and heated until 1200℃ for 20 mins,the average size of this α-alumina powders was 40nm from XRD peak broaden measurement.The BET surface srea was 40.4m2/g,and the average grain size from SEM photo was 55nm.The ALFA company n44652(Alfa) powder was indicated that the average size of this α-alumina powders of individual crystal diameters was 60nm,the BET surface area was 35.7m2/g,and the average grain size for SEM photo was 110nm. In the process of sintering,we found that all green bodies adding aluminum hydroxide gel had more dance green body. Less of the agglomerates in our alumina powders had the more dance sintered bodies than that of ALFA company powders.The best sample sintering of α-alumina green body,the relative density sintered at 1450℃ for 2hours were calculated 96% and the grain size of that was indentified 1μm. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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