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Zirconium Aluminum Carbides: New Precursors for Synthesizing ZrO 2 –Al 2 O 3 Composites
Author(s) -
He LingFeng,
Bao YiWang,
Zhou YanChun
Publication year - 2009
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2009.03281.x
Subject(s) - materials science , nanocrystalline material , crystallite , sintering , microstructure , hot pressing , raman spectroscopy , amorphous solid , zirconium , phase (matter) , carbide , tetragonal crystal system , composite number , ternary operation , solid solution , composite material , chemical engineering , metallurgy , crystallography , nanotechnology , chemistry , programming language , physics , organic chemistry , engineering , computer science , optics
ZrO 2 –Al 2 O 3 nanocrystalline powders have been synthesized by oxidizing ternary Zr 2 Al 3 C 4 powders. The simultaneous oxidation of Al and Zr in Zr 2 Al 3 C 4 results in homogeneous mixture of ZrO 2 and Al 2 O 3 at nanoscale. Bulk nano‐ and submicro‐composites were prepared by hot‐pressing as‐oxidized powders at 1100°–1500°C. The composition and microstructure evolution during sintering was investigated by XRD, Raman spectroscopy, SEM, and TEM. The crystallite size of ZrO 2 in the composites increased from 7.5 nm for as‐oxidized powders to about 0.5 μm at 1500°C, while the tetragonal polymorph gradually converted to monolithic one with increasing crystallite size. The Al 2 O 3 in the composites transformed from an amorphous phase in as oxidized powders to θ phase at 1100°C and α phase at higher temperatures. The hardness of the composite increased from 2.0 GPa at 1100°C to 13.5 GPa at 1400°C due to the increase of density.