Junping Zhao

To meet the demands of high-voltage power electronics, this study elucidates the role of ion flux in plasma-enhanced chemical vapor deposition in governing the sp3/sp2 ratio of diamond-like carbon (DLC) films on alumina particles, which is believed to have the potential to improve the interface between epoxy and filler particles. Independent control of ion flux revealed a non-monotonic trend in the sp3/sp2 ratio: it initially increases due to suppressed carbon relaxation at moderate flux, then decreases beyond a critical threshold due to thermal graphitization from excessive energy deposition. By integrating the subplantation model with energy analysis, this study clarifies the competition between kinetic stabilization and thermal degradation. This work provides a mechanistic understanding and a practical guideline for optimizing DLC-coated fillers in high-performance composites.

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.

Depositing diamond-like carbon (DLC) film is considered to be more promising for surface modification of microparticles. The development of reliable and precise measurement techniques for DLC coatings on microparticles is crucial for advancing research in this field. This paper introduces a methodological approach for quantifying the thickness of the film on microparticles. The thickness of the film is obtained by establishing the quantitative relationship between the energy lost when electrons pass through the film and the thickness of the film. The proposed method allows for the estimation of film thickness by assessing solely the elemental abundance on the particle surfaces.