Synthesis and Characterization of Double Solid Solution (Zr,Ti)2(Al,Sn)C MAX Phase Ceramics
Bensu Tunca1,2, Thomas Lapauw2, Rémi Delville1
1SCK•CEN , Boeretang 200 , B-2400 Mol , Belgium.
Inorganic Chemistry
|May 2, 2019
Summary
This study synthesized novel MAX phase ceramics with high phase purity using tin. These materials exhibit tunable thermal expansion properties, crucial for advanced ceramic applications.
Area of Science:
- Materials Science
- Ceramic Engineering
- Solid-State Chemistry
Background:
- MAX phases are a unique class of layered ternary carbides and nitrides with exceptional properties.
- Achieving high phase purity in MAX phase solid solutions, especially with multiple metallic elements, presents significant challenges.
- Understanding the role of additives like tin in stabilizing MAX phase structures is critical for material design.
Purpose of the Study:
- To synthesize quasi phase-pure MAX phase solid solutions with (Zr,Ti)2(Al0.5,Sn0.5)C stoichiometry.
- To investigate the influence of tin on phase purity, crystal structure, and thermal expansion behavior.
- To explore the effect of varying Zr/Ti ratios on the properties of these novel MAX phases.
Main Methods:
- Synthesis via reactive hot pressing and pressureless sintering of ZrH2, TiH2, Al, Sn, and C powders.
- Phase purity and microstructure analysis.
- Crystal structure characterization using synchrotron X-ray diffraction and Rietveld refinement.
- Thermal expansion coefficient measurements at high temperatures.
Main Results:
- Successfully synthesized quasi phase-pure (>98 wt %) (Zr,Ti)2(Al0.5,Sn0.5)C MAX phase solid solutions.
- Tin addition was identified as crucial for achieving high phase purity in the (Zr,Ti)2AlC system.
- Sn-containing MAX phases exhibited reduced M6A prismatic distortion compared to Sn-free counterparts.
- Measured thermal expansion coefficients along the a and c directions for various Zr/Ti ratios.
- Observed increased thermal expansion anisotropy in double solid solutions compared to end-members.
Conclusions:
- Tin is essential for the formation of phase-pure (Zr,Ti)2(Al,Sn)C MAX phases.
- The incorporation of Sn influences the crystal structure and reduces steric strain.
- The synthesized MAX phase solid solutions demonstrate tunable thermal expansion properties, with anisotropy increasing with Zr/Ti ratio variation.
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