Filters

2012 - 20154

More filters

2019 - 20204
Reset filters

Settings

End date: 2015 × Start date: 2010 × Publisher: São Carlos : Universidade Federal de São Carlos ×

Search Results

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Carboxylated nitrile butadiene rubber/hybrid filler composites
    (São Carlos : Universidade Federal de São Carlos, 2012) Mousa, A.; Heinrich, G.; Simon, F.; Wagenknecht, U.; Stöckelhuber, K.-W.; Dweiri, R.
    The surface properties of the OSW and NLS are measured with the dynamic contact-angle technique. The x-ray photoelectron spectroscopy (XPS) of the OSW reveals that the OSW possesses various reactive functional groups namely hydroxyl groups (OH). Hybrid filler from NLS and OSW were incorporated into carboxylated nitrile rubber (XNBR) to produce XNBR hybrid composites. The reaction of OH groups from the OSW with COOH of the XNBR is checked by attenuated total reflectance spectra (ATR-IR) of the composites. The degree of curing ΔM (maximum torque-minimum torque) as a function of hybrid filler as derived from moving die rheometer (MDR) is reported. The stress-strain behavior of the hybrid composites as well as the dynamic mechanical thermal analysis (DMTA) is studied. Bonding quality and dispersion of the hybrid filler with and in XNBR are examined using scanning-transmission electron microscopy (STEM in SEM).
  • Thumbnail Image
    Item
    Viscoelastic behavior of multiwalled carbon nanotubes into phenolic resin
    (São Carlos : Universidade Federal de São Carlos, 2013) Botelho, E.C.; Costa, M.L.; Braga, C.I.; Burkhart, T.; Laukee, B.
    Nanostructured polymer composites have opened up new perspectives for multi-functional materials. In particular, carbon nanotubes (CNTs) have the potential applications in order to improve mechanical and electrical performance in composites with aerospace application. This study focuses on the viscoelastic evaluation of phenolic resin reinforced carbon nanotubes, processed by using two techniques: aqueous-surfactant solution and three roll calender (TRC) process. According to our results a relative small amount of CNTs in a phenolic resin matrix is capable of enhancing the viscoelastic properties significantly and to modify the thermal stability. Also has been observed that when is used TRC process, the incorporation and distribution of CNT into phenolic resin is more effective when compared with aqueous solution dispersion process.
  • Thumbnail Image
    Item
    Phase separation in rapid solidified Ag-rich Ag-Cu-Zr alloys
    (São Carlos : Universidade Federal de São Carlos, 2015) Niyomsoan, Saisamorn; Gargarella, Piter; Chomsaeng, Natthaphol; Termsuksawad, Preecha; Kühn, Utha; Eckert, Jürgen
    The microstructure and phase formation of rapid solidified Ag-rich Ag-Cu-Zr alloys were investigated. Two types of structure; interconnected- and droplet-type structures, were obtained due to phase separation mechanisms. The former was spinodal decomposition and the later was nucleation and growth mechanism. Depending on the alloy compositions, three crystalline phases; FCC-Ag, AgZr and Cu10Zr7 phases were observed along with an in-situ nanocrystalline/amorphous composite. Vickers hardness testing indicated a significant increase of hardness in the nanocrystalline/amorphous-composite alloy.
  • Thumbnail Image
    Item
    Phase formation, thermal stability and mechanical properties of a Cu-Al-Ni-Mn shape memory alloy prepared by selective laser melting
    (São Carlos : Universidade Federal de São Carlos, 2015) Gargarella, Piter; Kiminami, Cláudio Shyinti; Mazzer, Eric Marchezini; Cava, Régis Daniel; Basilio, Leonardo Albuquerque; Bolfarini, Claudemiro; Botta, Walter José; Eckert, Jürgen; Gustmann, Tobias; Pauly, Simon
    Selective laser melting (SLM) is an additive manufacturing process used to produce parts with complex geometries layer by layer. This rapid solidification method allows fabricating samples in a non-equilibrium state and with refined microstructure. In this work, this method is used to fabricate 3 mm diameter rods of a Cu-based shape memory alloy. The phase formation, thermal stability and mechanical properties were investigated and correlated. Samples with a relative density higher than 92% and without cracks were obtained. A single monoclinic martensitic phase was formed with average grain size ranging between 28 to 36 μm. The samples exhibit a reverse martensitic transformation temperature around 106 ± 2 °C and a large plasticity in compression (around 15±1%) with a typical “double-yielding” behaviour.