Activated Sintering of Cr₂O₃-Based Composites by Hot Pressing

Area of Science:

• Materials Science
• Ceramics Engineering
• Composite Materials

Background:

• Sintering chromium(III) oxide (Cr2O3)-based composites via hot pressing is challenging due to Cr2O3 decomposition above 1300 °C.
• Chemical reactions between composite components during sintering can lead to undesirable phase formations and property degradation.

Purpose of the Study:

• To develop a novel method for structure formation in Cr2O3-based composites during sintering.
• To overcome the decomposition issue of Cr2O3 at high sintering temperatures.
• To investigate the role of aluminum as an active agent in forming stable Cr2O3 composites.

Main Methods:

• Hot pressing of Cr2O3-based composites utilizing ultrafine aluminum powder.
• Controlled reaction between aluminum and Cr2O3 to form a liquid phase.
• Analysis of solid solution formation ((Cr,Al)2O3) with varying stoichiometry.

Main Results:

• A novel method successfully facilitated aluminum-Cr2O3 interaction, preventing Cr2O3 decomposition during sintering.
• The formation of (Cr,Al)2O3 solid solutions was observed, with stoichiometry dependent on aluminum content.
• The solid solution at phase boundaries significantly enhanced mechanical properties, achieving fracture toughness of 5-7 MPa m½ and bending strength around 500 MPa.
• The composite with 22 wt.% aluminum exhibited optimal mechanical performance.

Conclusions:

• The developed hot pressing technique effectively produces robust Cr2O3-based composites.
• The addition of aluminum as an active agent is crucial for stabilizing Cr2O3 during high-temperature sintering.
• The resulting composites demonstrate superior mechanical properties, making them suitable for demanding applications.