Papers by Keyword: Modification

Abstract: In order to develop more suitable anticorrosive coatings for hydraulic engineering metal structures, studies were carried out on the modification of water-borne inorganic zinc-rich coatings in this paper. Through effective regulation of the type and dosage of various ingredients, such like potassium silicate solution, silicone-acrylate emulsion, zinc powder and additive agent, modified water-borne inorganic zinc-rich coatings equipped with enhanced water and impact resistance were prepared. Coupled with the inherent anti-corrosion and electrochemical protection property, this modified new coating possesses a broader application prospect in hydraulic engineering metal structures.

Abstract: The morphology of eutectic and primary silicon phases was analyzed by OM and SEM. OM and SEM results show that pure Nd can significantly refine both eutectic and primary silicon of hypereutectic Al-20%Si alloy. Morphology of primary silicon is transformed from star-shaped and irregular morphology to fine polyhedral and grain size of primary silicon is refined from 80~120 μm to 20~50 μm. Friction and wear resistance tests show that friction coefficient of Al-20%Si alloy reduces after Nd modification. Wear resistance of Al-20%Si alloy after modification is significantly improved as compared to the initial sample. The dominant wear mechanism for 0.3% Nd modified alloy is abrasive wear, adhesive wear and oxidative wear mechanism, but wear mechanism for unmodified alloy is abrasive wear and adhesive wear mechanism.

Abstract: The modification mechanism was studied by OM, SEM, XRD and Trace Element Analysis. The results of OM and SEM analysis show that pure Nd can effectively refine primary and eutectic silicon in hypereutectic Al-20%Si alloy. Morphology of primary silicon is transformed from pentalpha to block and the average grain size of primary silicon is reduced from 80~120μm to 20~50μm after modification. Trace Element Analysis results show that Nd can purity base metal and reduce impurity contents. XRD patterns show that no new phase formed after Nd modification. The results of mechanical properties test show that whole properties of modified sample are significantly improved. Tensile strength increases about 35.8% from 117 MPa to 148 MPa after modification, Elongation change increases about 193% from 0.56% to 1.64%. The improvement of mechanical properties should be attributed to fine primary Si phase and eutectic silicon phase and purification of base metal after modification.

Abstract: The modification mechanism of hypereutectic Al-17.5%Si alloy with Nd was studied by OM and XRD. The results of OM analysis show that pure Nd could effectively refine primary in hypereutectic Al-17.5%Si alloy. When Nd addition is 0.3%, the average grain size of primary silicon reaches its minimum. The average grain size of primary silicon is reduced from 40~60μm to 10~30μm after modification. XRD patterns show that no new phase forms after Nd modification. The results of mechanical properties tests show that whole properties of modified samples are significantly improved. When Nd addition is 0.3%, tensile strength of the alloy reaches its maximum. Tensile strength is increased about 35.8% from 120 MPa to 163 MPa. Elongation was increased about 175% from 0.8% to 2.2%. The improvement of mechanical properties should attribute to fine primary after modification.

Abstract: Fe-diatomite was prepared and applied for the sorption of Pb (II) from aqueous solution. The samples before and after modification were characterized by SEM and XRF. The results showed that iron hydroxide compound has been successfully loaded at the diatomite. Lead adsorption characteristics were studied in a batch system with respect to changes in initial concentration of lead, pH of solution, adsorbent dosage and temperature. It showed that the removal rate increased with pH, adsorbent additive amount, the temperature and decreased with the initial concentration.

Abstract: Aiming at inadequate mechanical properties of Glass ionomer cement (GIC) commonly used in dental clinic, commercial and melt quenched GIC powders as control groups, homemade GIC powder was prepared by sol–gel route and modified by Nb₂O₅. The GIC samples were characterized by X-ray Diffraction (XRD), particle size analysis, Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FT-IR). The compressive strength, Vickers hardness, working and net setting time were tested. The data was analyzed by one-way ANOVA. The XRD results showed that commercial, melt quenched and sol gel GIC powders were similar amorphous. D90 of three GIC powders and Nb₂O₅ powder were 26 μm, 17 μm, 29 μm and 19 μm respectively. 5% Nb₂O₅-GIC exhibited the highest values of compressive strength and Vickers hardness, which were 112.93 Mpa, 139.48 MPa and 142.25 MPa respectively, increased 19.11%, 30.56% and 16.51% (P <0.05); the Vickers hardness were 35.15 MPa, 36.23 MPa and 37.62 MPa, increased 18.03%, 29.95% and 16.32% (P <0.05) compared to those of unmodified GICs as well. There was no significant change of the FT-IR characteristic peaks of modified GIC. The working time of three kinds of GIC were 4'58 ", 3'28" and 4'10 ", the net setting time were 5'16", 3'15 "and 4'38" (standard is 1.5-6 minutes). It was concluded that the dispersion stiffened effect of niobium oxide could improve the mechanical properties of the filling GIC without affecting the clinical operating performance.

Abstract: With an analysis on the structure of water-soluble sodium silicate and its polymerization, it was found that the poor stability of silicate drilling fluids lies in the relevance between the inherent nature and the pH value of sodium silicate. The modification of water-soluble sodium silicate in this paper was to improve its stability and keep the inhibitive property simultaneously. The a-olefin sulfonate (AOS) was employed as the modifer agent acted on the water-soluble sodium silicate monomer and oligomers. Furthermore, the modification mechanism was discussed through FTIR, Laser particle size, Zeta potential and SEM. A stable sodium silicate drilling fluids with better inhibitive property was obtained by the comparison of modified sodium silicate and unmodified ones.

Abstract: Vanadium-sol modified LiFePO₄ material was prepared by 300 °C calcination in a tube furnace. The modified LiFePO₄ material was characterized by X-ray diffraction, field emission scanning electron microscopy, energy disperse spectroscopy and electrochemical impedance spectroscopy. The results indicated that vanadium-sol modified LiFePO₄ had higher first cycling efficiency, lower impedance and polarization, and better electrochemical properties at high charge/discharge rates.

Abstract: This paper presents an overview of various innovative fabrication approaches and the potential applications of ionic polymer metal composites (IPMC), which is a composite material consisting of a polymer membrane sandwiched between two thin electrode layers. When given a voltage within a range of 1-5V, cations inside accompanying with water molecules of IPMC move across the width of the material causing a uniform water distribution and finally to achieve it’s bending motion. In addition to a classical processing method, three innovative modification approaches are recommended to fabricate IPMC, particularly to settle water electrolysis and leakage for multiple practical applications. Also, three applications are extensively highlighted in the later pages of the paper. This is a very new field and with the research done so far, it is believed that IPMC has a potential which is worth research elaborately. This paper presents an overview of the manufacturing components, techniques, related problems and applications of IPMC. Additionally, it recommends innovative modification fabrication approaches to subdue the associated problems in the existing conventional fabrication processing.

Abstract: In a novel approach of task based conceptual design method by proper synthesis and analyzes tools mechanism and function entities are modified, turned into and considered as extendable and squeezable ones , so systemized search of optimal structural solutions inside those entities leads the designer to satisfaction of prior given set of functions. Conceptual design generation procedure includes task simplification phase where a key function (s) based mechanical model is composed and its further development into final concept requires gradual satisfaction of remained pre given functions. Two major sources of mechanical solutions are used for function satisfaction. First is existing knowledge on mechanism available as database and the second source is self-generation of mechanisms by granting DOF action, both procedures strictly implemented in a function targeted manner. The database itself is available in different formats depending on application, tutorial or systemizing purposes. Current study discloses the approaches and methods of modification of mechanisms from database into models and formats applicable and suitable for being used in proposed task based conceptual design method.