Energies and charge-state fractions of carbon plasma ions measured with Doppler-shifts in the pulsed arc-discharge system

The energies and charge-state fractions of carbon plasma ions produced with the pulsed arc-discharge system have been measured using the Doppler-shifts in the line spectra emitted by carbon ions. The arc-discharge voltages ranged from 3 to 4 kV and the corresponding currents from 7.5 to 10 kA. Pulse duration times were about 30 μs. Strong populations of doubly and triply ionized carbon ions were observed. The maximum ion energy for the triply ionised carbon ions was 250 eV. The Doppler-shift measurements were performed with a crossed-dispersion spectrograph (theoretical spectral resolution 0.01 nm) and the lines were photographed

Wear and Corrosion Behavior of Zr-Doped DLC on Ti-13Zr-13Nb Biomedical Alloy

Zirconium (Zr)-doped DLC was deposited on biomedical titanium alloy Ti-13Nb-13Zr by a combination of plasma-enhanced chemical vapor deposition and magnetron sputtering. The concentration of Zr in the films was varied by changing the parameters of the bi-polar pulsed power supply and the Ar/CH4 gas composition. The coatings were characterized for composition, morphology, nanohardness, corrosion resistance in simulated body fluid (SBF) and tribological properties. X-ray photoelectron spectroscopy (XPS) studies on the samples were used to estimate the concentration of Zr in the films. XPS and micro- Raman studies were used to find the variation of ID/IG ratio with Zr concentration. These studies show that the disorder in the film increased with increasing Zr concentration as deduced from the ID/IG ratio. Nanohardness measurements showed no clear dependence of hardness and Young�s modulus on Zr concentration. Reciprocating wear studies showed a low coefficient of friction (0.04) at 1 N load and it increased toward 0.4 at higher loads. The wear volume was lower at all loads on the coated samples. The wear mechanism changed from abrasive wear on the substrate to adhesive wear after coating. The corrosion current in SBF was unaffected by the coating and corrosion potential moved toward nobler (more positive) values