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Stabilization of porosity in reaction bonded aluminum oxide (RBAO) by coarsening in a reactive atmosphere
Publikationstyp
Journal Article
Date Issued
2024-10-01
Sprache
English
Journal
Volume
50
Issue
19
Start Page
37395
End Page
37401
Citation
Ceramics International 50 (19 Part C): 37395-37401 (2024)
Contribution to Conference
Publisher DOI
Scopus ID
Publisher
Elsevier
A coarsening treatment in an HCl containing atmosphere was performed to stabilize the porosity of Al2O3/ZrO2 composites up to elevated temperatures. There is minimal shrinkage during the reactive coarsening treatment and the porous microstructure is stable during subsequent heat treatments. The reaction bonding of aluminum oxide (RBAO) process was used to fabricate the samples. Coarsening was investigated as a function of initial density (40–60 % TD) and coarsening temperatures (1250–1400 °C). After the HCl coarsening step, samples were sintered in air to determine the effect of coarsening treatment on pore stability. Up to the temperature of the coarsening treatment no further densification is observed. Above the HCl coarsening temperature densification is significantly retarded. Thus, it is shown that the porosity in RBAO can be stabilized by heat treatment in a 10 vol % HCl containing atmosphere. During the coarsening treatment in HCl at 1300 °C, 1350 °C and 1400 °C little densification was observed (Δ ρ ≤ 2 % TD) in comparison with the densities that result from sintering reaction bonded samples in air at 1350 °C (Δ ρ ∼ 5–8 % TD). Therefore, the HCl coarsening is a promising approach to adjust a desired level of porosity for high temperature applications of porous materials. It is postulated that at a given density, the coarsened materials should exhibit increased strength compared to un-coarsened materials due to increased contact area between the particles.
Subjects
Coarsening
Density
Reaction bonding
Sintering
DDC Class
600: Technology