Corrosion resistant Ti-Pd surface alloys produced by high intensity pulsed plasma beams Part 1. Deposition by pulsed erosion and vacuum evaporation/pulsed implantation doping modes

Electron beam processing is an efficient technology to reduce emissions of pollutants from flue gases of industrial plants. The present study examines the use of high intensity pulsed plasma beams for surface alloying of the electron-transparent, titanium foil window, through which electrons enter into the flue gas, with the purpose of increasing its resistance to corrosion. The surface alloying, with palladium, to depth of a few hundred nanometres, is carried out under two modes of operation of a rod plasma injector: pulsed implantation doping (PID) and deposition by pulsed erosion (DPE) modes, using nitrogen as the working gas. The performance of the resultant alloys is evaluated in 0.1 M H2SO4 at 80 degrees C. The corrosion resistance of the titanium foil is substantially improved by the surface alloying, with a shift in the opencircuit potential of the treated foil toward the region of passivity of titanium. Corrosion rates were slightly lower for the DPE mode of alloying than for the PID mode. The changes in surface regions of the alloyed layers following immersion in the test environment were determined by analytical scanning electron microscopy, Rutherford backscattering spectroscopy, nuclear reaction analysis and medium energy ion scattering revealing morphologically and compositionally non-uniform alloys and losses of palladium. (c) 2005 Elsevier B.V All rights reserved.