ISSN:
1662-8985
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:
Non-oxide ceramic nanostructured powders are synthesized through metastable transformationprocessing based on the Self-propagating High-temperature Synthesis (SHS) process followed byquenching. Binary systems like the investigated TiC–TiB2, when quenched from the liquid stategive rise to metastable structures capable of being converted into a stable, fine-grained(nanocomposite) microstructure upon recrystallization by medium temperature treatments. Anecessary condition is that the combustion temperature of the SHS reaction is higher than theeutectic temperature.A previous optimisation of the reaction stoichiometry was carried out to obtain SHS productswith composition approximately equal to the eutectic (i.e. 67%mol TiC0,7 – 33%mol TiB2),according to the reaction: 6Ti + B4C + 1.8C → 4TiC0.7 + 2TiB2.In this work, different amounts of sodium borate (borax) were used in order to determine theoptimum amount of additive to produce nanostructured TiC0.7–TiB2 composites. The morphologicalevolution of the powders after thermal treatment yielding re–crystallized structures demonstratesthe metastability of the SHS–quench products. Therefore, the metastability process based on SHS–quench represents an extremely attractive route suitable for the achievement of nanocomposites
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.15-17.225.pdf
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