Self-healing evolution of oxidized surface of AL4SIC4 and its effect on mechanical properties

SELF-HEALING EVOLUTION OF OXIDIZED SURFACE OF AL

SIC

AND ITS EFFECT ON MECHANICAL PROPERTIES

X. Huang1, X. Geng1, G. Wen1,2, G. Song3, Y. Zhou1

1_{School of Materials Science and Technology, Harbin Institute of Technology, Harbin 150001,}

P. R. China-e-mail: swliza@hit.edu.cn; Xingeng@hit.edu.cn; g.wen@hit.edu.cn; yzhou@hit.edu.cn

2_{School of Materials Science and Technology, Harbin Institute of Technology at WeiHai,}

WeiHai 264209, P. R. China-e-mail: g.wen@hit.edu.cn

3_{Department of Materials Science and Engineering, Delft University of Technology, Mekelweg}

2, 2628 CD Delft, The Netherlands-e-mail: songguim@yahoo.com

Keywords: Al4SiC4, microstructure, self-healing, mechanical testing

ABSTRACT

The recently developed ternary carbide Al4SiC4 has attracted extensive attention

owing to its lower density (3.03 g/cm3), higher melt point (2000 C), excellent self-healing and high temperature mechanical properties. It is a very promising material for high-temperature applications. The self-healing evolution of the surface of Al4SiC4 ceramics oxidized at 900-1400 C for 2-10 hours in air was investigated with

X-ray diffraction (XRD) and scanning electron microscopy (SEM). After a heat treatment at 1000C, nanosized newborn phase, Al2SiO5, with 100 nm in length

appeared which kept its existence until to 1200 C for 6 hours. The surface of the specimen heat treated at 1200C for longer time (>8 h) or at higher temperatures (>1200 °C) was covered with oxidation products consisting primarily of Al2O3 as well

as some mullite (3Al2O32SiO2). The flexural strength at room temperature increased

of 70% (491.713.2 MPa) for the specimen heat treated at 1000C for 6 h compared with the polished specimen (29713 MPa).