Browsing by Keyword "Microhardness"
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Item Effect of ethylene glycol dimethacrylate on VOC reduction, rheological, mechanical and anticorrosion properties of a hybrid sol-gel coating on AA2024-T3 and sulfuric acid anodized AA2024-T3(2021-10) Agustín-Sáenz, Cecilia; Martín-Ugarte, Eider; Pérez-Allende, Beatriz; Izagirre-Etxeberria, Usoa; VALORIZACIÓN DE RESIDUOS; POLIMEROS; INGENIERÍA DE SUPERFICIESAn inorganic–organic coating based on methacrylic-functionalized silica and zirconia was synthesized by sol-gel technology as replacer of Cr(VI)-based treatments used to protect both unconverted and electrically converted AA2024-T3 for aeronautic application. The effect of a bi-methacrylate organic precursor in the formulation was studied with the aim to reduce the sol viscosity and coating thickness while crosslink was increased and volatile organic compounds (VOC) were diminished in the formulation. The viscoelastic behavior was studied by rheometry, and the properties of the coating material were related to its corrosion protection capability, studied by electrochemical impedance spectroscopy and neutral salt spray tests. The mechanical properties of the resulting coatings were studied by dynamic microindentation and rotary wear tests. The formulations containing the organic precursor provided coatings with higher degree of crosslinking and lower VOC. The derived coatings were thinner and provided outstanding corrosion protection with low thickness on unconverted AA2024-T3 and as sealant of hard sulfuric acid anodized AA2024-T3. The hardness was improved in comparison to coatings without the organic precursor although abrasion resistance was better for coatings with higher inorganic character.Item Fabrication of Cu-W nanocomposites by integration of self-propagating high-temperature synthesis and hot explosive consolidation technologies(2018) Aydinyan, S. V.; Kirakosyan, H. V.; Zakaryan, M. K.; Abovyan, L. S.; Kharatyan, S. L.; Peikrishvili, A.; Mamniashvili, G.; Godibadze, B.; Chagelishvili, E. Sh; Lesuer, D. R.; Gutierrez, M.; SGManufacturing W-Cu composite nanopowders was performed via joint reduction of CuO and WO3 oxides with various ratios (W:Cu = 2:1, 1:1, 1:3, 1:13.5) using combined Mg–C reducer. Combustion synthesis was used to synthesize homogeneous composite powders of W-Cu and hot explosive consolidation (HEC) technique was utilized to fabricate dense compacts from ultrafine structured W-Cu powders. Compact samples obtained from nanometer sized SHS powders demonstrated weak relation between the susceptibility and the applied magnetic field in comparison with the W and Cu containing micrometer grain size of metals. The density, microstructural uniformity and mechanical properties of SHS&HEC prepared samples were also evaluated. Internal friction (Q-1) and Young modulus (E) of fabricated composites studied for all samples indicated that the temperature 1000 °С is optimal for full annealing of microscopic defects of structure and internal stresses. Improved characteristics for Young modulus and internal friction were obtained for the W:Cu = 1:13.5 composite. According to microhardness measurement results, W-Cu nanopowders obtained by SHS method and compacted by HEC technology were characterized by enhanced (up to 85%) microhardness.