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:
Ceramics with zero thermal expansion coefficients at room temperature (293K) wereinvestigated. We found the thermal expansion coefficient was controlled by a compounding ratio oflithium aluminum silicate (LAS) and silicon carbide (SiC), which have negative and positive thermalexpansion coefficients respectively. Although it was difficult to densify the composite of the LAS andSiC (LAS/SiC) in the sintering process, an addition of nitride improved the sinterability of theLAS/SiC. In order to examine the effect of the nitride additive, at first, the melting point of the LASwith silicon nitride (Si3N4) or aluminum nitride was measured by TG-DTA. The melting point of theLAS decreased with existence of nitride. It is believed that the densification of the LAS/SiC waspromoted by the nitride, because the nitride causes the LAS/SiC to form a liquid phase, therebydecreasing the melting point. Next, the lattice constant of the LAS with Si3N4 was measured by XRDand it was verified that the a-axis was longer and the c-axis was shorter than those of the LAS withoutadditive. It is supposed that this phenomenon is due to the substitution of nitrogen for oxygen in theLAS lattice, and the decrease of the melting point of the LAS with nitride seems to be influenced bythis substitution of nitrogen
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/51/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.317-318.177.pdf
Permalink