In Situ Synthesis of (Mo,Cr)Si₂ Composites by Spark Plasma Sintering

Area of Science:

• Materials Science
• Ceramic Engineering
• High-Temperature Materials

Background:

• Molybdenum disilicide (MoSi2) based composites are crucial for high-temperature applications.
• Understanding the effect of alloying elements on MoSi2 properties is essential for material optimization.

Purpose of the Study:

• To investigate the influence of chromium (Cr) content on the properties of (Mo,Cr)Si2 composites.
• To analyze the impact of Cr addition on mechanical behavior and oxidation resistance.

Main Methods:

• Fabrication of (Mo,Cr)Si2 composites with varying CrSi2 molar fractions (0-10%) using spark plasma sintering (SPS).
• Systematic characterization of surface morphology, phase composition, mechanical properties (Vickers hardness, fracture toughness, flexural strength), and high-temperature oxidation resistance.

Main Results:

• The (Mo95,Cr5)Si2 composite sintered at 1400 °C showed improved mechanical properties: 11.6 GPa hardness, 4.6 MPa·m1/2 fracture toughness, and 397 MPa flexural strength.
• Oxidation at 1500 °C resulted in a protective oxide layer of SiO2 and Cr2O3 on (Mo,Cr)Si2 composites.
• Moderate Cr addition promoted the formation and thickening of this protective oxide layer.

Conclusions:

• The addition of Cr to MoSi2 significantly enhances mechanical properties and high-temperature oxidation resistance.
• The formation of a dual SiO2-Cr2O3 protective layer is key to the improved performance of (Mo,Cr)Si2 composites.
• Optimized Cr content in MoSi2 offers a promising route for developing advanced high-temperature materials.