Advanced Materials Research Vol. 717

Abstract: This research proposes a new application of Electrical Discharge Machine (EDM) for cutting the rubber carbon black. The new material of this study was a natural rubber mixed with carbon black for increased electrical conductivity of natural rubber. was accomplished through the technique of design and analysis of experiment and statistical analysis. The 2⁴ Full factorial design was selected to conduct the experiment to determine the optimal mixed rubber cutting process parameters. The study has been carried out on the influence of design factors of the concentrate amount of carbon black per hundred of natural rubber (PHR), the voltage across the gap between and electrode tool and workpieces (Volt), the value of the discharge current (Ampere), and the duration of time (On-time, μs) that current is allowed to flow per cycle over response variables arithmetic surface roughness and material removal rate. The experimental results have shown the value of the discharge current that significantly affect to the degree of material removal rate of rubber mixed with carbon black and the duration of time that significantly affect to the degree of arithmetic surface roughness.

Abstract: Duplex Stainless Steel (DSS) is well known for their higher mechanical strength and better corrosion resistance. DSS is commonly used for marine construction, petrochemical and chemical industries. DSS (2205) is having equal amount of α and γ phases.The present study was conducted on12mm diameter rod of the UNS S32205 duplex stainless steel subjected to equal channel angular pressing (ECAP). The refinement of original grains was observed. Effect of microstructure change on the corrosion behavior of equal channel angular pressed (ECAP) UNS S32205 duplex stainless steel was investigated. After single pass ECAP process and study about the pitting corrosion resistance. The mechanical properties of UNS S3 2205 duplex stainless steelwere evaluated. The amount of ferrite after ECAP and before ECAP for the two different conditions was investigated. Also observed percentage of ferrite content reduces 3.32% after ECAP.

Abstract: The Cu_0.95Pt_0.05Fe_0.97Sn_0.03O₂ sample has been synthesized by a solid-state reaction to investigate optical properties of materials of transparent conducting oxide. Crystal structure was characterized by XRD. The Seebeck coefficient and electrical conductivity were measured in the high temperature (300 to 860 K), while the XPS and UV-VIS-NIR spectra were analyzed at room temperature. The XRD peaks confirm the samples forming the delafossite structure phase. The Seebeck coefficient reveals the samples displays the p-type conducting. The XPS spectra show the Sn²⁺ state stabling in this compound. The optical direct gap is 3.45 eV as a visible-transparent material. These results support that the Cu_0.95Pt_0.05Fe_0.97Sn_0.03O₂ oxide compounds, of which the Cu¹⁺ and Fe³⁺ sites are substituted by the Pt¹⁺ and Sn²⁺ ions respectively, are p-type transparent conducting oxide materials.

Abstract: The aim of the present study is to assess the incorporation of kaolin processing waste as partial substitute for aggregates in asphalt concrete. Mixtures elaborated from the conventional mixture with the gradual incorporation of kaolin processing waste (5 to 40%) were evaluated by volumetric composition, mechanical behavior and susceptibility to moisture tests, obeying current Brazilian norms, according with international standards. The results show that the coarse kaolin waste displays grains with varying diameters, and, as such, can substitute part of the conventional aggregates and filler used in an asphalt mixture. Moreover, its mineralogical composition showed the same minerals in the composition of conventional aggregates used in paving. The assessment of the mechanical behavior of these mixtures indicate that the increased waste levels in the mixtures studied caused an increase in stability and a reduction in tensile strength. When susceptibility to moisture was considered, the results indicate that up to 25% of residue can be used as a substitute for conventional aggregates.

Abstract: 1-x)[(Na_0.515K_0.485)_0.96Li_0.04(Nb_0.8Ta_0.2)O₃]-xBiMnO₃ (x = 0, 0.002, 0.004, 0.006, 0.008 and 0.010) lead-free ceramics were prepared using a conventional mixed-oxide method. The result indicated that the highest density of 4.89 ± 0.01 g/cm³ was found in 0.6 mol% BiMnO₃ - doped sample sintered at 1060 C. Grain size decreased with increasing of BiMnO₃ content. In the composition range studied, the perovskite phase with the coexistence of the orthorhombic and tetragonal phases was identified at approximately 0 x 0.006 by the X-ray diffraction analysis, which led to a significant enhancement of the piezoelectric properties. The temperature dependence of dielectric properties showed that the addition of BiMnO₃ markedly decreased the ferroelectric tetragonal-paraelectric cubic phase transition temperature (T_C), and greatly shifted the polymorphic phase transition from the ferroelectric orthorhombic to the ferroelectric tetragonal phase (T_OT) to near room temperature. Sample with x = 0.002 exhibited excellent electrical properties: the dielectric constant (ε_r) = 1228, dissipation factor (tan δ) = 0.0244, piezoelectric constant (d₃₃) = 235 pC/N, and Curie temperature (T_C) = 286 °C. These results clearly showed that the 0.998(Na_0.515K_0.485)_0.96Li_0.04(Nb_0.8Ta_0.2)O₃ - 0.002BiMnO₃ ceramics are very promising lead-free piezoelectric candidates.

Abstract: o-LiMnO₂ was successfully synthesized by the hydrothermal method at Li⁺/Mn³⁺=4:1. The influence of Li⁺/Mn³⁺ ratios, hydrothermal temperature and time to the purity of o-LiMnO₂ was researched. The particles as-prepared were well-dispersed and near-spherical.

Abstract: Barium hydrogenphosphate, BaHPO₄ was synthesized for the first time through simple and rapid method using BaCO₃-H₃PO₄-NaOH, pH =9.0 at room temperature for 30 min. The studied BaHPO₄ decomposed in a single well-defined stage via deprotonated hydrogenphosphate reactions, revealed by TG/DTG and DSC techniques. The calculated wavenumbers based on DSC peak were comparable with FTIR results, which support the breaking bonds of P-OH (HPO₄^2-) in the deprotonated hydrogenphosphate reactions. The thermodynamic functions (ΔH*, ΔG*, and ΔS*) for the deprotonated hydrogenphosphate reactions calculated from DSC data indicate that the deprotonated HPO₄^2- reaction occur a lower-energy pathway and spontaneous process. The FTIR, XRD and SEM data of the studied BaHPO₄ and its decomposed product Ba₂P₂O₇ are also reported.

Abstract: A binary calcium iron pyrophosphate CaFeP₂O₇ was synthesized by solid state route using the mixing of calcium carbonate, iron metal and phosphoric acid in aqueous-acetone media at 600 °C. The XRD datum indicates the formation of CaFeP₂O₇ phase without the presence of any phase impurities. FTIR result indicates the presence of the P₂O₇^4- anion in the structure. Sheet-like microparticle of CaFeP₂O₇ was revealed by SEM. Room temperature magnetization result showed ferromagnetic behavior of the synthesized CaFeP₂O₇, with saturation-specific magnetization value of 11.067 emu g^-1 at 10kOe. The magnetic feature of the synthesized CaFeP₂O₇ in this work compared with M₂P₂O₇ (M = Ca and Fe), its isotypic (CaMP₂O₇ (M= Mn and Co) and CFeP₂O₇ (C= Co and Cu) reported in our previous works is important properties for specific applications.

Abstract: Spherical-like calcium dihydrogenphosphate monohydrate (Ca (H₂PO₄)₂H₂O) nanostructure was successfully prepared by the mixing of calcium carbonate and phosphoric in aqueous-methanol media at ambient temperature for 30 min. Three thermal decomposition step and higher stability at over 800 °C of the prepared sample are different from the earlier works. Spherical-like Ca (H₂PO₄)₂H₂O nanostructure with diameter < 100 nm confirmed by SEM may be important for potential applications. This method of synthesis by aqueous-methanol media is a fast and simple method and it is expected to be applicable for the synthesis of other nanocrystalline calcium phosphates.