Our website is currently undergoing maintenance. Article records and full texts remain available. Submissions can be made through the Editorial Manager.

In-Situ Synthesis and Formation Mechanism of Al₂O₃-Spinel(N) Composite in Nitrogen Atmosphere under Low Oxygen Partial Pressure

S. Tong, Y. Li, J. Zhao, M. Yan, Y. Hong, Q. Zheng

Journal of Ceramic Science and Technology, Vol. 8, No. 4 (2018), pp. 513-518

DOI: 10.4416/JCST2017-00030

Download full article (PDF)

Abstract

Al2O3-spinel-containing nitrogen element composite, abbreviated as Al2O3-spinel(N) composite, was prepared using white corundum, sintered magnesia and active α-Al2O3 powder as raw materials, with magnesium aluminate sol as a binder, and fired at 1600 °C for 4 h in a nitrogen atmosphere with low oxygen partial pressure. The prepared Al2O3-spinel(N) composite was characterized and analyzed by means of XRD, SEM, and EDS and the mechanism for the formation of the spinel(N) was further investigated. The results show that in nitrogen atmosphere with low oxygen partial pressure, Al2O3-spinel(N) composite is composed of alumina, spinel-containing nitrogen element and a little aluminum nitride; the spinel-containing nitrogen bonds the aggregates and matrix together, further realizing dense sintering of the Al2O3-spinel(N) composite. The mechanism for formation of the spinel(N) can be described as follows: in nitrogen atmosphere with low oxygen partial pressure, magnesia is unstable and decomposes into Mg(g). Mg(g) diffuses and transfers along the pores or gaps in Al2O3-MgO composites and reacts with corundum or spinel, forming gas aluminum at the same time. The gas metal aluminum then nitrides into aluminum nitride. The formed aluminum nitride further solid-solves into spinel, forming the spinel-containing nitrogen element.

Keywords

Magnesia aggregates, low oxygen partial pressure, Mg(g), spinel

View this issue · Article & DOI index