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Synthesis and Pressureless Sintering of Zirconium Phosphate Ceramics
Author(s) -
Chen Fei,
Shen Qiang,
Schoenung Julie M.,
Zhang Lianmeng
Publication year - 2008
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.1551-2916.2008.02610.x
Subject(s) - sintering , materials science , microstructure , ceramic , decomposition , zirconium , grain growth , relative density , scanning electron microscope , flexural strength , zirconium phosphate , phase (matter) , grain size , phosphate , mineralogy , chemical engineering , composite material , metallurgy , chemistry , organic chemistry , engineering
Zirconium phosphate (ZrP 2 O 7 ) powder is synthesized by direct reaction between ZrO 2 and H 3 PO 4 and is used to prepare ZrP 2 O 7 ceramics with MgO and Al 2 O 3 as the sintering additives by pressureless sintering technique. The mechanism of reaction between ZrO 2 and H 3 PO 4 is analyzed. The results suggest that the reaction between ZrO 2 and H 3 PO 4 is completed at 250°C and ZrP 2 O 7 is stable up to ∼1200°C. At temperatures above ∼1200°C, decomposition starts to occur, resulting in the formation of Zr 2 O(PO 4 ) 2 . After exposure to temperatures as high as 1500°C, decomposition is still not complete. The pure ZrP 2 O 7 ceramic, however, is difficult to sinter to high density. In contrast, ZrP 2 O 7 ceramics with MgO and Al 2 O 3 sintering additives can be liquid‐phase sintered to relative densities of 90%–96% at sintering temperatures of 1250°–1500°C, without significant decomposition. The microstructure is observed by scanning electron microscopy. The effect of density, phosphate glass phase, and grain growth on bending strength is analyzed. Because of the abnormal grain growth and microcracking of ZrP 2 O 7 ceramics, the bending strength first increases and then decreases as a function of the sintering temperature.