Ion implantation into inner wall surface of millimeter size diameter steel tube by plasma source ion implantation

Nitrogen and carbon ions were implanted into the inner wall surface of 304 austenitic type stainless steel and Ni tubes with inner diameters of 0.9, 2 and 1.6 mm, by a plasma source ion implantation (PSII). These 30 mm long substrate tubes were fixed to an alumina ceramic tube in a vacuum chamber, fed with nitrogen and acetylene gases. A 2.45 GHz microwave was supplied to an antenna in the alumina ceramic tube and plasma was produced by a coaxial electron cyclotron resonance (ECR) discharge in this tube. A negative high voltage pulse of 15 kV (1 kHz, 10 μs) was applied to the steel and Ni tubes to extract ions from the generated plasma. The compositional and structural characterizations of the implanted surfaces were carried out using Auger electron spectroscopy and Raman spectroscopy. The results showed that uniform nitrogen ion implantation into the millimeter size inner wall surface of metal tubes was achieved by the PSII. Carbon implantation and subsequent diamond like carbon (DLC) coating was confirmed for the inner wall surface treated by acetylene PSII.