High temperature oxidation-sulfidation behavior of Cr-Al2O3 and Nb-Al2O3 composites densified by spark plasma sintering

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2007-12, Vol.471 (1-2), p.69-74
• Main Authors: SAUCEDO-ACUNA, R. A, MONREAL-ROMERO, H, MARTINEZ-VILLAFANE, A, CHACON-NAVA, J. G, ARCE-COLUNGA, U, GAONA-TIBURCIO, C, DE LA TORRE, S. D
• Format: Article
• Language: English
• Subjects: Applied sciences; Corrosion; Corrosion mechanisms; Exact sciences and technology; Metals. Metallurgy
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2007.02.115

The high temperature oxidation-sulfidation behavior of Cr-Al2O3 and Nb-Al2O3 composites prepared by mechanical alloying (MA) and spark plasma sintering (SPS) has been studied. These composite powders have a particular metal-ceramic interpenetrating network and excellent mechanical properties. Oxidation-sulfidation tests were carried out at 900 deg C, in a 2.5%SO2+3.6%O2+N2(balance) atmosphere for 48h. The results revealed the influence of the sintering conditions on the specimens corrosion resistance, i.e. the Cr-Al2O3 and Nb-Al2O3 composite sintered at 1310 deg C/4min showed better corrosion resistance (lower weight gains) compared with those found for the 1440 deg C/5min conditions. For the former composite, a protective Cr2O3 layer immediately forms upon heating, whereas for the later pest disintegration was noted. Thus, under the same sintering conditions the Nb-Al2O3 composites showed the highest weight gains. The oxidation products were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy.