Dual phase high temperature Si₃N₄/Al(Ti)N films with tunable thermal conductivity

Area of Science:

• Materials Science
• Nanotechnology
• Thermal Engineering

Background:

• Tunable thermal conductivity in amorphous dielectric films is crucial for advanced thermal management in electronics and aerospace.
• Understanding phonon transport mechanisms in nanocomposites is key to designing materials with tailored thermal properties.

Purpose of the Study:

• To investigate the effect of incorporating amorphous Al(Ti)N and crystalline TiN nanoparticles on the thermal conductivity of amorphous Si3N4 matrix.
• To evaluate the thermal stability of Si3N4/AlN and Si3N4/TiN dual-phase nanocomposite coatings at high temperatures.

Main Methods:

• Fabrication of amorphous Si3N4 matrix nanocomposite coatings with varying volume fractions of dispersed amorphous Al(Ti)N nanoparticles (1 nm or larger).
• Incorporation of crystalline TiN phases (5-15 nm) into the amorphous Si3N4 matrix.
• Thermal conductivity measurements and assessment of thermal stability via high-temperature exposure in ambient air.

Main Results:

• Amorphous Al(Ti)N nanoparticles (6-70% volume fraction) had a negligible impact on the intrinsic thermal conductivity of the Si3N4 matrix (~2 W m⁻¹K⁻¹).
• Crystalline TiN phases (5-15 nm) significantly increased thermal conductivity up to 15 W m⁻¹K⁻¹.
• The developed Si3N4/AlN and Si3N4/TiN nanocomposite coatings demonstrated excellent thermal stability at 1000°C for 50 hours.

Conclusions:

• The size and crystallinity of the second phase critically influence phonon transport and thermal conductivity in amorphous dielectric nanocomposites.
• Engineering crystalline TiN inclusions offers a viable pathway to enhance thermal conductivity in amorphous Si3N4 coatings.
• These findings provide insights into phonon scattering mechanisms and guide the design of high-performance thermal management materials.