Phase reaction and sintering behavior in the pseudoternary system AlN-Y{sub 2}O{sub 3}-Al{sub 2}O{sub 3}

Journal Article · Tue Oct 01 04:00:00 EDT 1996 · Journal of the American Ceramic Society

OSTI ID:413316

Kim, N H; Fun, Q D; Komeya, Katsutoshi; Meguro, Takeshi ^[1]

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1. Yokohama National Univ., Hodogayaku, Yokohama (Japan). Dept. of Materials Chemistry

Phase reaction and sintering behavior in the ternary system AlN-Y{sub 2}O{sub 3}(0--10 wt%)-Al{sub 2}O{sub 3} (0--40 wt%) at temperatures ranging from 1,600 to 2,000 C were studied. The density of the sintered 100 Wt% AlN specimens increased monotonically with firing temperature, but the maximum value was limited to 95%, even at 2,000 C firing. All the specimens containing Y{sub 2}O{sub 3}, regardless of their Al{sub 2}O{sub 3} content, achieved full density by sintering at 1,800 C. However, at and above 1,900 C, the densities decreased with increased Al{sub 2}O{sub 3} content. This densification behavior appeared to be based on the grain morphology and decomposability of the existing compounds in the products. The phases present in the sintered AlN-Al{sub 2}O{sub 3} were composed of AlN, Al{sub 2}O{sub 3}, and {gamma}-AlON below 1,900C, and 27R, 20H, and 16H at and above 1,950 C. In the AlN-Y{sub 2}O{sub 3}-Al{sub 2}O{sub 3} specimen, yttrium aluminum garnet (YAG) phase formed in the first stage at a temperature <1,600 C, after which aluminum oxynitrides appeared. In the specimens sintered at 1,950 C or higher, {gamma}-AlON phase, with a higher Al{sub 2}O{sub 3}:AlN ratio, and 27R phase, with a lower Al{sub 2}O{sub 3}:AlN ratio, coexisted, and the contents were quantitatively low in comparison with the Y{sub 2}O{sub 3}-free specimens, although Y{sub 2}O{sub 3} trapped Al{sub 2}O{sub 3} to produce YAG. This differed from the AlN-Al{sub 2}O{sub 3} phase diagram proposed by McCauley et al. The grain morphologies depended on the presence of the above phases. The grains based on AlN and {gamma}-AlON were granular, and those based on 27R, 20H, and 16H polytypoids were platelike.

• OSTI ID: 413316
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 10 Vol. 79; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM NITRIDES
ALUMINIUM OXIDES
BULK DENSITY
CHEMICAL COMPOSITION
MORPHOLOGY
PARTICLE SIZE
PHASE STUDIES
POWDERS
SINTERING
TEMPERATURE DEPENDENCE
X-RAY DIFFRACTION
YTTRIUM OXIDES