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Abstract: The removal rate of carbon from amorphous graphite–tungsten composite during cleaning in oxygen plasma was studied. The composite was prepared by sputter deposition from C and WC-targets in Ar atmosphere. A total thickness of deposited layer was about 1μm. The samples were treated in a weakly ionized highly dissociated oxygen plasma created in a microwave discharge at a power of 1kW. The gas flow was 13slh and the pressure was 200Pa. The temperature of the samples during treatment was about 580°C. After plasma treatment the samples were analyzed by AES (Auger electron spectroscopy) depth profiling, XPS (X-ray photoelectron spectroscopy), SEM (Scanning electron microscopy) and AFM (Atomic force microscopy). It was found that during the plasma treatment selective etching of the composite occurred. Carbon was preferentially removed from the composite. XPS results have shown that during the plasma treatment a layer of WO3 was growing on the surface. After about 15min, carbon was completely removed from the deposited composite layer. [Copyright &y& Elsevier]

Abstract: The stability of commercially available yellow (Bayferrox 3920) and red (Bayferrox 140) micronized iron oxide pigments against highly aggressive treatment with oxygen plasma is examined. The red pigment microparticles with hematite crystal structure are stable, while the yellow pigment changes colour during the treatment. Structural analysis with powder X-ray diffraction and X-ray absorption methods, EXAFS and XANES, shows that the yellow pigment microparticles recrystallize from goethite to hematite crystal structure. Larger hematite particles are composed of small highly anisotropic nano-domains. No nanoclusters or amorphous iron oxide phases are detected. The valence state of iron atoms in the pigments is not affected by the strongly oxidative plasma environment. [Copyright &y& Elsevier]

Abstract: Thrombosis and restenosis are the most common problems during insertion of biocompatible implants like titanium stents into human blood, due to aggregation of platelets on their surfaces. Because of this reason, we studied the response of blood platelets to a plasma treated titanium surface. The aim was to design a functionalized surface which would repel blood platelets or prevent their adhesion. Therefore, we functionalized surfaces with low-temperature inductively coupled oxygen plasma treatment, which in the first stage cleaned the surface of titanium, and in the second promoted incorporation of oxygen functional groups as well as the growth of a titanium dioxide film. In this paper we show that oxygen atoms or oxygen containing groups play an important role in the repulsion of platelets and their deactivation. At the same time, increased surface temperature of samples either through sequential thermal deactivation in oven at 150°C or heating the surface with ion bombardment during the treatment, lowers the oxygen content and the surface repulsion for platelets. [Copyright &y& Elsevier]