Fractional deposition: Enhancing the bond strength between diamond-like carbon with high sp3/sp2 ratio and alumina

To enhance the thermal conductivity of epoxy composites, it is proposed to deposit diamond-like carbon (DLC) with strong bonding and a high sp3/sp2 ratio on the surface of filler particles. When plasma-enhanced chemical vapor deposition (PECVD) is employed, there exists a discrepancy between the optimal ion energy range for maximizing the DLC film's sp3/sp2 ratio and the bond strength between DLC and alumina. Parameter optimization methods cannot simultaneously optimize both properties. This paper introduces a fractional deposition approach. Specifically, by selecting the corresponding optimal parameters during the initial and prolonged deposition stages, this method ensures that the DLC film exhibits both a high sp3/sp2 ratio and excellent adhesion to alumina. The growth process of DLC on the alumina surface was investigated, revealing that the limited ion energy range is the rationale behind the phased regulation method. Compared to the conventional approach, the fractional deposition method enhances the bonding strength between DLC films with a high sp3/sp2 ratio and alumina substrates by approximately 48 %. This approach is anticipated to expand the application scope of DLC deposition technology.