Investigation of the oxidation mechanism of an Al–Si–Al2O3 composite at 1100 °C and 1550 °C. Issue 9 (15th June 2020)

• Record Type: Journal Article
• Authors: Ma, Chenhong; Li, Yong; Xue, Wendong; Jiang, Peng; Shen, Yinan
• Is Part Of: Ceramics international. Volume 46:Issue 9(2020)
• Page Start: 13813
• Page End: 13820
• Publication Date: 2020-06-15
• Subjects: Al-Si-Al2O3 composite -- Anti-oxidation mechanism -- Mullite -- Al2O; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2020.02.172
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: An Al–Si–Al2 O3 composite was prepared and sintered in air at 1100 °C and 1550 °C for 3 h to investigate the oxidation mechanism. The results show that the anti-oxidation performance of the Al–Si–Al2 O3 composite is excellent, with anti-oxidation protection layers formed at both 1100 °C and 1550 °C, whereas the underlying oxidation mechanisms differ completely. At 1550 °C, Al(l), Si(l), and Al2 O3 (s) react with O2 directly to form a dense mullite solid solution at the surface of the sample, which seals all the diffusion channels of O2 into the sample, resulting in a rapid decrease in P O2 in the sample. At low P O2, Al(l), Si(l), and C(s) from the resin react with N2 (g), and an AlN–SiC solid solution reinforcement is formed in the interior of the sample. At 1100 °C, the oxidation behaviour of Al(l), Si(s), and α-Al2 O3 (s) is different: Al(l) is oxidized to active α-Al2 O3, and Si(s) particles are incompletely oxidized to Si@SiO2, accompanied by a volume expansion and a slow layer by layer decrease in P O2 in the sample. Then, the active oxidation of Al(l) occurs and a substantial amount of Al2 O(g) is formed in the sample, which acts as a gas barrier to prevent O2 from penetrating into the sample, further lowering P O2 . Then, the Al2 O(g) and C(s) from the resin and the Al(l) in the interior react with N2 (g) to form a whisker-like (Al2 OC) 1-x (AlN) x reinforcement in the sample. The Al–Si–Al2 O3 composite shows the ability of self-healing at high temperatures in air atmosphere. The reaction model is established.