Premium
Reaction Bonding and Mechanical Properties of Mullite/Silicon Carbide Composites
Author(s) -
Wu Suxing,
Claussen Nils
Publication year - 1994
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.1151-2916.1994.tb04521.x
Subject(s) - materials science , mullite , composite material , silicon carbide , sintering , compaction , fracture toughness , shrinkage , cubic zirconia , flexural strength , ceramic
Based on the RBAO technology, low‐shrinkage mullite/SiC/ Al 2 O 3 /ZrO 2 composites were fabricated. A powder mixture of 40 vol% Al, 30 vol% A1 2 O 3 and 30 vol% SiC was attrition milled in acetone with TZP balls which introduced a substantial ZrO 2 wear debris into the mixture. The precursor powder was isopressed at 300–900 MPa and heattreated in air by two different cycles resulting in various phase ratios in the final products. During heating, Al oxidizes to Al 2 O 3 completely, while SiC oxidizes to SiO 2 only on its surface. Fast densification (at >1300°C) and mullite formation (at 1400°C) prevent further oxidation of the SiC particles. Because of the volume expansion associated with the oxidation of Al (28%), SiC (108%), and the mullitization (4.2%), sintering shrinkage is effectively compensated. The reaction‐bonded composites exhibit low linear shrinkages and high strengths: shrinkages of 7.2%, 4.8%, and 3%, and strengths of 610, 580, and 490 MPa, corresponding to compaction pressure of 300, 600, and 900 MPa, respectively, were achieved in samples containing 49–55 vol% mullite. HIPing improved significantly the mechanical properties: a fracture strength of 490 MPa and a toughness of 4.1 MPa . m 1/2 increased to 890 MPa and 6 MPa . m 1/2 , respectively.