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:
Current high temperature ceramics, such as ZrO2, Si3N4 and SiC, cannot be used attemperatures over 1600°C due to their low melting temperature or dissociation temperature. For ultrahightemperature applications over 1800°C, materials with high melting points, high phase compositionstability, high thermal conductivity, good thermal shock and oxidation resistance are needed. Thetransition metal diborides, mainly include ZrB2 and HfB2, have melting temperatures of above 3000°C,and can basically meet the above demands. However, the oxidation resistance of diboride monolithicceramics at ultra-high temperatures need to be improved for the applications in thermal protectionsystems for future aerospace vehicles and jet engines. On the other hand, processing science for makinghigh performance UHTCs is another hot topic in the UHTC field. Densification of UHTCs at mildtemperatures through reactive sintering is an attracting way due to the chemically stable phasecomposition and microstructure as well as clean grain boundaries in the obtained materials. Moreover, thestability studies of the materials in phase composition and microstructures at ultra high applicationtemperatures is also critical for materials manufactured at relatively low temperature. Furthermore, theoxidation resistance in simulated reentry environments instead of in static or flowing air of ambientpressure should be evaluated. Here we will report the concept, advantages and some recent progress onthe reactive sintering of diboride–based composites at mild temperatures
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.336-338.1159.pdf
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