Porosity Effect on Thermal Properties of Al-12 wt % Si/Graphite Composites

Area of Science:

• Materials Science
• Composite Materials
• Thermal Properties

Background:

• Composite materials offer tunable thermal properties.
• Porosity significantly impacts material performance.
• Aluminum-silicon alloys and graphite are key components in advanced materials.

Purpose of the Study:

• To determine the effect of porosity on thermal conductivity and thermal expansion.
• To analyze aluminum-silicon alloy-graphite composites.
• To evaluate the applicability of the Hasselman-Johnson model.

Main Methods:

• Fabrication of composite preforms using irregular graphite particles.
• Infiltration with Al-12 wt % Si alloy under varying pressures.
• Measurement of thermal conductivity and coefficient of thermal expansion.
• Modeling using the Hasselman-Johnson approach.

Main Results:

• Thermal conductivity increases with infiltration pressure due to reduced porosity.
• The Hasselman-Johnson model accurately estimates experimental thermal conductivity.
• Coefficient of thermal expansion shows a slight increase with saturation (86-100%).

Conclusions:

• Porosity reduction is crucial for enhancing thermal conductivity in these composites.
• The Hasselman-Johnson model provides a reliable estimation method.
• The observed thermal expansion behavior aligns with theoretical bounds.