Effects of Mechanically Alloying Al₂O₃ and Y₂O₃ Additives on the Liquid Phase Sintering Behavior and Properties of SiC


In order to improve the sintering of SiC, mixtures of Al2O3 and Y2O3 powders are commonly included as sintering additives. The aim of this work was to use mechanically alloyed Al2O3-Y2O3 mixtures as sintering additives to promote liquid phase sintering of SiC using spark plasma sintering. The results showed that milling reduced the particle size of the powders and led to the formation of complex oxide phases (YAP, YAM, and YAG) at low temperatures. As the ball milling time increased, the mass loss of specimens sintered with mechanically alloyed Al2O3-Y2O3 mixtures decreased, and accordingly the relative density increased. However, the hardness and flexural strength of sintered SiC specimens first increased and then decreased. Because the specimens prepared with oxides milled for a long time contained too much YAG/YAP and accordingly too much liquid at sintering temperature. This negatively affected the mechanical properties of the SiC specimens because of the increased volume of the complex oxide phases, which have inferior mechanical properties to SiC, in the sintered specimens. When the ball milling time was 6 h, the hardness (24.02 GPa) and flexural strength (655.61 MPa) of the SiC specimens reached maximum values.


Materials Science and Engineering


R. Chen thanks the funding for Outstanding Doctoral Dissertation from Nanjing University of Aeronautics and Astronautics (award number BCXJ19-09). J. Rittenhouse thanks the Office of Nuclear Energy of U.S. Department of Energy for an Integrated University Program graduate fellowship. H.M. Wen also acknowledges the U.S. Nuclear Regulatory Commission Faculty Development Program (award number NRC 31310018M0044).

Keywords and Phrases

Al O -Y O 2 3 2 3; Mechanical Alloying; Mechanical Properties; SiC; Sintering Additives

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Article - Journal

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Publication Date

01 Jan 2022