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Oxidation Behavior of a Ti 3 AlC 2 /TiB 2 Composite at 1000°−1400°C in Air
Author(s) -
Li Meishuan,
Li Chao,
Li Jingjing,
Zhou Yanchun
Publication year - 2010
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.1551-2916.2009.03434.x
Subject(s) - composite number , materials science , eutectic system , diffusion , substrate (aquarium) , oxide , titanium , graphite , oxygen , layer (electronics) , chemical engineering , composite material , metallurgy , microstructure , chemistry , physics , oceanography , organic chemistry , engineering , thermodynamics , geology
The oxidation behaviors of a Ti 3 AlC 2 /20(vol%)TiB 2 composite, synthesized by means of in situ reactions of Ti, Al, graphite, and B 4 C powder mixtures under hot pressing, have been investigated at 1000°–1400°C in air. The Ti 3 AlC 2 /20TiB 2 composite followed the logarithmic oxidation law, and had a lower oxidation rate than the matrix Ti 3 AlC 2 . During the oxidation at 1000°–1400°C, a continuous Al 2 O 3 formed on the composite, meanwhile other different oxides formed on the top surface of the Al 2 O 3 layer, depending on the oxidation temperature: discontinuous α‐TiO 2 at below 1200°C, mixture of Al 2 TiO 5 and TiO 2 at 1300°C, and continuous Al 2 TiO 5 at 1400°C. The selective oxidation of Al occurred at the oxide/substrate interface through inward diffusion of oxygen, and TiO 2 overgrew the Al 2 O 3 layer to form coarse grains through outward diffusion of titanium ions. When the temperature was above 1280°C, Al 2 TiO 5 appeared due to a eutectic reaction between TiO 2 and Al 2 O 3 . The incorporation of TiB 2 promoted the generation of great numbers of voids at the Al 2 O 3 /substrate interface and in the Al 2 O 3 inner layer, which is proposed as being the main reason for the Ti 3 AlC 2 /20TiB 2 composite to follow a logarithmic oxidation law.