Effect of the La2O3 Addition on Thermal, Microstructure and Mechanical Properties of Mullite–Zirconia Composites

Aydın, H.

doi:10.22068/ijmse.16.4.10

Volume 16, Issue 4 (December 2019) IJMSE 2019, 16(4): 10-19 | Back to browse issues page

‎ 10.22068/ijmse.16.4.10

Effect of the La2O3 Addition on Thermal, Microstructure and Mechanical Properties of Mullite–Zirconia Composites

H. Aydın

Abstract: (13559 Views)

Mullite–zirconia composites were prepared using lanthanum oxide (La₂O₃) additive which three different mole ratio by the reaction sintering (RS) route of alumina, kaolinite and zircon. Starting materials were planetary milled, shaped into pellets and bars and sintered in the temperature range of 1450–1550 ⁰C with 5 h soaking at peak temperature. In this work, the mullite-zirconia composites were characterized by thermal expansion coefficient, physical, microstructures and mechanical properties. The XRD method were employed for determining the crystalline phase composition of these composites. Microstructure of the composites was examined by SEM. ZrO₂ takes part in both the intergranular as well as intragranular positions. However, intragranular zirconias are much smaller compared to intergranular zirconias.

Keywords: Mullite-zirconia composites, thermal expansion coefficient, reaction sintering, mechanical properties

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 Particularly mullite zirconia composites are materials with important technological applications due to their good properties such as toughness, chemical stability, and high-creep resistance. In practice they are employed in the glass industry and where high chemical and corrosion resistance are required.
 
The purpose of the current research was to investigate the effect of La₂O₃additive in the reaction sintering process of conventional raw materials on thermal, microstructure and mechanical properties of mullite–zirconia composites.
 
Usually, mullite zirconia composites can be obtained by various methods such as direct powder compact of mullite and zirconia, reaction sintering of alumina, silica and zirconia; reaction sintering of alumina and zircon. Similarly, various researchers have studied the effect of different additives on the formation and sintered characteristics of the mullite-zirconia composite. It was found that the addition of lanthanum oxide decreased the densification temperature and significantly improved the thermal shock resistance of the mullite–zirconia composites. In addition to the mullite zirconia composites studies containing La₂O₃ originality of our work is to observe the effect of La₂O₃ addition to kaolinite, alumina and zircon mixture synthesized from conventional raw materials and so to form a new reference and field of interest.

Type of Study: Research Paper | Subject: Ceramics

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