Mullite-alumina composite fabrication using χ-Al2O3 powders

Abstract

For synthesizing mullite-alumina composite ceramics with high hardness χ-Al2O3、?-Al2O3 and cristobalite were used as raw materials and the difference of alumina sources in mullite-alumina between transforming from χ-Al2O3 and using merchant alumina powders(AKP-30) were examined Group A samples were prepared by mixing χ-Al2O3 and cristobalite with different weight ratio; Group B samples were prepared by mixing stoichiometric mullite (71 8wt% χ-Al2O3 and 28 2wt% cristobalite) and ?-Al2O3 with different weight ratio Green bodies were firstly heated up to 1400℃ for mullite reaction then sintered at 1550℃ for varying time By the characterization of χ-Al2O3 high specific area and small diameter lead to the advance of mullite formation temperature to 1250℃ The result show that group A is able to reach higher shrinkage rate and relative density in the same sintering time comparing with group B Average grain size of both group A and B are approximately 1 μm The hardness of group A tended to increase as the χ-Al2O3 content increase while the hardness of group B has opposite trend It is indicated that using χ-Al2O3 as the alumina sources of mullite-alumina has higher hardness than using ?-Al2O3 Comparing with reference mullite-alumina with high hardness and small grain size can be synthesizing by using χ-Al2O3 as raw materials leading to lower sintering temperature and shorter sintering time

Date of Award	2020
Original language	English
Supervisor	Hsing-I Hsiang (Supervisor)