TiN films deposition inside stainless-steel tubes using magnetic field-enhanced arc ion plating

• TiN film was deposited on the inner surface of stainless steel tubes.
• A magnetic field-enhanced arc ion plating (MFE-AIP) is developed.
• The films show relatively high axial thickness uniformity.

A magnetic field-enhanced arc ion plating (MFE-AIP) is utilized to deposit TiN films on the inner wall of a stainless-steel tube with inner diameter 36 mm and length from 108 to 288 mm. Three groups of magnetic field coils are designed and located at different positions, to produce axial magnetic field to focus and to guide the arc plasma beam to spread along the center axial direction of the tubular workpiece. Samples of AISI 304 stainless steel are horizontally placed inside the tube to investigate the structure and performance of the films. A pulse bias is applied to the substrate to accelerate the plasma. The structure, surface morphology, cross-sectional image, hardness and wear-resistant properties as a function of the position inside the tubes are investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), nanoindenter, friction-tester, respectively. The results show that the film structures change from a single TiN phase into mixed phases of TiN and Ti2N with the increase in the distance to the tube entrance. The thickness, hardness and sliding friction coefficient of the films decrease with the increase in the distance to the tube entrance. The magnetic field-enhanced arc ion plating is shown to be an effective tool to treat the inner surface of stainless-steel tubes.