ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Two α-Al2O3/YAG composite powders have been prepared by reverse-strikeprecipitation, starting from chlorides aqueous solutions, the former containing 50 vol% of the twophases (labelled as AY50) and the latter made of 90 vol% of alumina and 10 vol% of YAG (AY90).The as-prepared powders were characterised by DTA/TG simultaneous analysis as well as by XRDanalysis performed after calcination at different temperatures. A systematic TEM analysis wasperformed on AY50 powders pre-treated at different temperatures, in order to investigate thecrystallites size evolution as a function of the temperature. After that, samples were compacted byuniaxial pressing and sintered at 1600°C for 3h. SEM observations revealed a homogeneousmicrostructure made of micronic alpha-alumina and YAG grains. For limiting grain growth throughthe decreasing of the maximum sintering temperature, an innovative activation procedure bycoupling suitable thermal and mechanical treatments of the powders was performed. After that, highdensification (〉95% of the theoretical density) was easily achieved by performing a free sintering inthe temperature range between 1320° and 1420°C, with different soaking times at the maximumtemperature. The resulting sintered bodies showed an effective retention of the nano-size of theprimary particles. By SEM, highly-homogeneous nanostructures, with an average grains size ofabout 200 and 300 nm for AY50 and AY90, respectively, were observed
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/51/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.317-318.267.pdf
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