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Microstructure and Properties of Spark Plasma‐Sintered ZrO 2 –ZrB 2 Nanoceramic Composites
Author(s) -
Basu Bikramjit,
Venkateswaran T.,
Kim DohYeon
Publication year - 2006
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.1551-2916.2006.01083.x
Subject(s) - materials science , spark plasma sintering , composite material , microstructure , nanoceramic , toughness , indentation , fracture toughness , composite number , ceramic , nanoindentation , nanocomposite , ceramic matrix composite , yttria stabilized zirconia , cubic zirconia
In a recent work, 1 we have reported the optimization of the spark plasma sintering (SPS) parameters to obtain dense nanostructured 3Y‐TZP ceramics. Following this, the present work attempts to answer some specific issues: (a) whether ZrO 2 ‐based composites with ZrB 2 reinforcements can be densified under the optimal SPS conditions for TZP matrix densification (b) whether improved hardness can be obtained in the composites, when 30 vol% ZrB 2 is incorporated and (c) whether the toughness can be tailored by varying the ZrO 2 –matrix stabilization as well as retaining finer ZrO 2 grains. In the present contribution, the SPS experiments are carried out at 1200°C for 5 min under vacuum at a heating rate of 600 K/min. The SPS processing route enables retaining of the finer t ‐ZrO 2 grains (100–300 nm) and the ZrO 2 –ZrB 2 composite developed exhibits optimum hardness up to 14 GPa. Careful analysis of the indentation data provides a range of toughness values in the composites (up to 11 MPa·m 1/2 ), based on Y 2 O 3 stabilization in the ZrO 2 matrix. The influence of varying yttria content, t ‐ZrO 2 transformability, and microstructure on the properties obtained is discussed. In addition to active contribution from the transformation‐toughening mechanism, crack deflection by hard second phase brings about appreciable increment in the toughness of the nanocomposites.