Features of materials alloying under exposures to pulsed plasma streams
Institute of Plasma Physics of the NSC KIPT, Akademicheskaya str.1, 61108 Kharkov, Ukraine
Corresponding author: a email@example.com
Revised: 19 January 2009
Published online: 21 May 2009
Surface modifications and features of materials alloying under pulsed plasma exposures are investigated in this paper. The experiments were carried out with a pulsed plasma gun, which generates plasma streams with ion energies of up to 2 keV, a plasma density of (2–20)× 1014 cm-3, an average specific power of 10 MW/cm2 and plasma energy densities in the range of (5–40) J/cm2. Nitrogen, helium, hydrogen, oxygen and different mixtures can be used as working gases. Modification of thin (1–2 μm) PVD coatings of molybdenum coating mixed with substrate in liquid phase under the pulsed plasma processing are analyzed. After alloying of ferritic/martensitic steel EP-823 with Mo the concentration of molybdenum in the modified layer of 15–20 μm achieved 20% for single treatment cycle and 30% after two cycles. Decrease of grain sizes (from tens of μm to hundreds of nm), roughness and porosity were obtained by plasma irradiation of thick (~0.1–0.3 mm) plasma sprayed coatings of Co-32Ni-21Cr-8Al-0.5Y and Ti64. A modified layer with homogeneous structure and thickness up to 50 μm is formed as a result of plasma treatment. Mechanisms of surface modification of WC-Co under irradiation with pulsed plasma streams of different ions are discussed.
PACS: 52.40.Hf – Plasma-material interactions; boundary layer effects
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2009