Internal and External Modification of 0.6 cmØ Stainless Steel Tubes Using Plasma Immersion Ion Implantation (PIII) and Deposition (PIII&D) Techniques

Metallic tubes are widely used in industrial applications. However, the internal smoothness and chemical resistance of metallic tubes are often major concerns. In contrast to the widely studied large-diameter metallic tubes (typically > 4 cm internal diameter) commonly investigated for surface modifications in industrial applications, we have focused on modifying the internal sur-faces of much smaller SS304 tubes (0.6 cm internal diameter) using nitrogen and argon PIII, as well as acetylene PIII&D. This study demonstrated that high-quality internal surface modifica-tions can be achieved with a straightforward setup and appropriate analysis techniques, even in tubes of industrial relevance with such small dimensions. In addition to gaining insights into the characteristics of hollow cathode (HC) and dielectric barrier (DB) discharges in small-diameter tubes, we found that Ar-PIII can partially mitigate the poor surface quality of as-received tubes. The addition of an N-PIII step further enhanced the internal surface, resulting in a smoother fin-ish with fewer trapped impurities. Moreover, acetylene PIII&D enabled the rapid deposition of a thick (>300 μm) Glassy Carbon film. These findings highlight the potential of these techniques for various plasma-related applications and industrial processes, offering promising avenues for future development.