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This paper evaluates the deposition of silica layers at atmospheric pressure as a pretreatment for the structural bonding of titanium (Ti6Al4V, Ti15V3Cr3Sn3Al) in comparison to an anodizing process (NaTESi process). The SiO2 film was deposited using the LARGE plasma source, a linearly extended DC arc plasma source and applying hexamethyldisiloxane (HMDSO) as a precursor. The morphology of the surface was analyzed by means of SEM, while the characterization of the chemical composition of deposited plasma layers was done by XPS and FTIR. The long-term durability of bonded samples was evaluated by means of a wedge test in hot/wet condition. The almost stoichiometric SiO2 film features a good long-term stability and a high bonding strength compared to the films produced with the wet-chemical NaTESi process.

Fatigue variation of surface properties of silumin subjected to electron-beam treatment S V Konovalov, K V Aksenova, V E Gromov et al. -The effect of erosion and abrasion on surface properties of composite resin S Stoleriu, S Andrian, G Pancu et al. Abstract. A commercially available carbon fiber (CF) with an epoxy-based sizing (EP-sized CF) and an unsized CF have been plasma treated to study the effect on the fiber-matrix adhesion towards a polypropylene matrix. The EP-sized fiber was chosen because of its predictable low adhesion in a polypropylene (PP) matrix. The fibers have been modified using a microwave low-pressure O 2 /CO 2 /N 2 -gas plasma source (Cyrannus ® ) developed at IWS in a batch process. One aim of this study was the evaluation of parameters using high energies and short time periods in the plasma chamber to see the effect on mechanical performance of CF. These results will be the fundamental work for a planned continuous plasma modification line. The CF surface was characterized by determining the surface energies, single fiber tensile strength and XPS analysis. The adhesion behavior before and after plasma treatment was studied by single fiber pull-out test (SFPO) and scanning electron microscopy (SEM). It was shown that the CO 2 -and O 2 -plasma increases the number of functional groups on the fiber surface during short time plasma treatment of 30 s. Carboxylic groups on the unsized CF surface resulting from O 2 -plasma treatment lead to an enhanced fiber-matrix adhesion, whereas the fiber strength was merely reduced.

In this contribution the Al x CoCrFeNi alloy system is explored thoroughly over a wide compositional range of x = 0.2 to 1.5 (5 to 30 at% Al). For this alloy system compositional gradient structures were produced by laser metal deposition of pre-alloyed CoCrFeNi and elemental Al powders using an in-house developed coaxial cladding system COAXpowerline. The evolution of the microstructure with increasing Al content was analyzed in the as built as well as the homogenized condition (1350 K for 20 h). Metallographic cross sections were prepared and thoroughly analyzed by means of scanning electron microscopy, energy dispersive X-ray spectroscopy, and electron backscattered diffraction. Additionally, the evolution of the sample hardness with increasing Al contents was determined for both sample conditions. In the Al x CoCrFeNi alloy system the lattice structure as well as the sample hardness can easily be adjusted by the variation of Al. With increasing Al content a phase transition from a solid solution fcc phase toward a multiphase bcc microstructure consisting of a Fe and Cr rich solid solution bcc phase and an ordered Al and Ni rich bcc B2 phase can be observed. This is combined with an increase in sample hardness from around 200 HV up to around 500 HV in the as built condition. The compositional regions of the phase transitions for both sample conditions were compared to ab initio thermodynamic calculations done using a CALPHAD approach. For the as built condition a strong deviation from the calculated transition regime could be observed. After homogenization the experimental and calculated data are in good agreement.