Influence of interface structure on the bonding strength between alumina and diamondlike carbon deposited by plasma-enhanced chemical vapor deposition

The incorporation of diamondlike carbon (DLC)-coated alumina particles as filler offers a viable approach to enhance the thermal conductivity and mechanical properties of epoxy composites. The bonding strength of alumina and DLC film is the key index to evaluate the modification effect. The deposition of diamondlike films onto the alumina surface was achieved through plasma-enhanced chemical vapor deposition. It has been observed that the DLC film exhibits a stratified structure, with a transition region containing carbon, oxygen, and aluminum at the interface between the DLC and alumina. The DLC and alumina can be combined due to the existence of the transition region. The process of DLC film deposition of hydrocarbon ions with different energies on the alumina surface was simulated by the molecular dynamics method. The formation of the transition region is contingent upon the introduction of energetic ions into the alumina. The transition region will have a larger geometric size in the deposition by high-energy ions, which explains the higher film-base bonding strength of DLC films formed by high-energy ions. The experimental measurement of the bonding strength between DLC and alumina under various conditions revealed that an increase in the number of ions with energy exceeding 200 eV enhances the bonding strength.