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Reaction Between Titanium and Zirconia Powders During Sintering at 1500°C
Author(s) -
Lin KunLin,
Lin ChienCheng
Publication year - 2007
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.1551-2916.2007.01708.x
Subject(s) - materials science , cubic zirconia , yttria stabilized zirconia , titanium , sintering , microstructure , precipitation , dissolution , oxygen , nuclear chemistry , metallurgy , ceramic , chemical engineering , chemistry , physics , organic chemistry , meteorology , engineering
Zirconia–titanium (ZrO 2 –Ti) composites have been considered potential thermal barrier graded materials for applications in the aerospace industry. Powder mixtures of Ti and 3 mol% Y 2 O 3 partially stabilized ZrO 2 in various ratios were sintered at 1500°C for 1 h in argon. The microstructures of the as‐sintered composites were characterized by X‐ray diffraction and transmission electron microscopy/energy‐dispersive spectroscopy. Ti reacted with and was mutually soluble in ZrO 2 , resulting in the formation of α‐Ti(O, Zr), Ti 2 ZrO, and/or TiO. These oxygen‐containing phases extracted oxygen ions from ZrO 2 , whereby oxygen‐deficient ZrO 2 was generated. For relatively small Ti/ZrO 2 ratios, specimens with ≤30 mol% Ti, TiO were formed as oxygen could be sufficiently supplied by excess ZrO 2 . For the specimens with ≥50 mol% Ti, lamellar Ti 2 ZrO was precipitated in α‐Ti(Zr, O), with no TiO being found. Both m ‐ZrO 2− x and t ‐ZrO 2− x were found in specimens with ≤50 mol% Ti; however, only c ‐ZrO 2− x was formed in the specimen with 70 mol% Ti. As ZrO 2 was gradually dissolved into Ti, yttria was retained in ZrO 2 because of the very limited solubility of yttria in α‐Ti(O, Zr) or TiO. The concentration of retained yttria and the degree of oxygen deficiency in ZrO 2 increased with the Ti content. The complete dissolution of ZrO 2 into Ti was followed by the precipitation of Y 2 Ti 2 O 7 in the specimen with 90 mol% Ti.