Volume 2, Number 4 (Jul 2005)                   IJMSE 2005, 2(4): 9-15 | Back to browse issues page


XML Print


Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:

SALAHI E., EBADZADEH T., MOZTAR ZADEH F., SOLATI HASHJIN M.. EFFECT OF COMPOSITION ON PHASE EVOLUTION AND MICROSTRUCTURE OF REACTION BONDED MULLITE (RBM). IJMSE. 2005; 2 (4) :9-15
URL: http://ijmse.iust.ac.ir/article-1-62-en.html

Abstract:   (7225 Views)
Compositions of Al2O3+Si, SiO2+Al and Al+Si systems were prepared to study the effect of reaction bonding process on the mullite formation. The composition of each system was adopted according to mullite stoichiometery and sintered in 700-1600°C range. Results showed that the formation of reaction bonded mullite starting from Al2O3+Si mixtures, proceeded in two partially overlapping steps, the oxidation of Si to SiO2, and the reaction of SiO2 and Al2O3 to form mullite. In this system, up to 1400°C, conversion of Si to SiO2 was taken place and cristobalite formed, but mullite formation was not observed. Mullite phase started to form at 1450°C. Results indicated that complete reaction was not occurred up to 1600°C and 2 hours soaking time. XRD patterns of samples in Al+ SiO2 system showed that the reaction through sequences: (a) reduction of SiO2 by Al, (b) formation of a- Al2O3 and SiO2-rderived Si oxidation, and (c) mullite formation. X-ray diffraction patterns of heat-treated Al+Si system showed that reaction between Al and oxygen at 900°C was occurred with the reaction product being a- Al2O3 Oxidation of Si and formation of mullite were not detected in this system. SEM micrographs showed that both Al2O3+Si and SiO2+Al systems have similar microstructures, which consisted of a- Al2O3, mullite and free Si. The microstructures of the samples in Al+Si system consisted of a- Al2O3 free Al and Si with intermetallic Al-Si compound.
     
Type of Study: Research paper | Subject: Ceramics

Add your comments about this article : Your username or email:
Write the security code in the box

© 2016 All Rights Reserved | Iranian Journal of Materials Science and Engineering

Designed & Developed by : Yektaweb