Advanced Materials Research Vol. 856

Abstract: Researches show that properties of semiconductor materials such as electrical, optical and antibacterial properties can be improved in the nanoscale. Among the semiconductor materials , zinc oxide with excellent electronic properties has been considered extremely. Application and properties of Zno nanoparticles depends on the size and morphology. In the present work, Zno Nanoparticles (NPs) were prepared by sonochemical method at a constant temperature and were applied on to the 100% cotton woven fabric using Insitu method. The results show that nanoparticles with average sizes of 20-100 nm with different morphologies were created on the surface of samples. Synthesis of ZnO-NPs were varied in the morphological transformation by changes in zinc acetate concentration. Characterizations were carried out, Scanning electron microscopy (SEM) and Spectrophotometery. The antibacterial activities of the fabrics were assessed semi-quantitatively by the coloneis count method. The results show that the finished fabric demonstrated significant antibacterial activity against S.aureus in antibacterial test.

Abstract: The sensitization of stainless steel type AISI304 (304SS) is evaluated as a function of pre-welding cold work and welding heat input. 304SS is cold rolled to various percentages of thickness reduction of up to 50% at ambient temperature before being TIG welded. The susceptibility of 304SS to sensitization (weld decay) is evaluated using ASTM A262, practice A and electrochemical potentiokinetic reactivation tests. The results indicate that the influence of pre-welding cold work on the degree of sensitization (DOS) is distinct and appreciable within the range of 10% to 35% CR. In addition, within this range the optimum level of cold work after which the DOS starts to decrease is found to be inversely related to the amount of welding heat input. At higher levels of cold work of ≥ 35% CR, it is found that neither the cold work nor the heat input significantly influences the amount of DOS. Microstructural investigation showed that the predominant intergranular corrosion (IGC) occurs at austenite grain boundaries and less likely at ferrite / austenite interfaces of the weld metal. Meanwhile, transgranular attack at austenite bulk matrix along the defects is rarely observed.

Abstract: Gum tragancanth based organic-inorganic hybrid ion exchanger has been synthesized using a mixture of sodium tungstate, orthophosphoric acid and potassium iodate. The different reaction conditions like reaction temperature, reaction time, pH of reaction medium, solvent volume, monomer concentration and initiator concentration were optimized in order to get the semi-IPN Gt-cl-poly (AA). Onto semi IPN, methylmethacrylate was incorporated using lipase-gluteraldehyde as the initiator-crosslinker system. The IPN finally was converted into ion-exchanger and was studied for its different physico-chemical properties. Ion exchange capacity was studied for Na⁺ and effect of different temperatures on ion exchange capacity was evaluated. Characterization was done using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and EDS techniques.

Abstract: This paper presents a comparative evaluation of three lignocellulosic residues (corn cobs, spent coffee grounds and Raphanus sativus press cake) as precursor materials in the production of activated carbons (ACs). Results indicate that the precursor material has a significant effect in both physical and chemical aspects of the adsorbent as well as on the adsorption mechanisms. Highest and lowest values of iodine number and density were observed for ACs based on press cake and corn cobs, respectively. Regardless of the observed differences in surface chemical make-up and adsorption mechanisms, all employed materials were deemed adequate for adsorbent production, since the prepared ACs presented adsorption capacities similar or even higher than those of commercial ACs and other residue-based adsorbents.

Abstract: In this paper, the tensile properties of plain-woven aramid fabric style 724 (Kevlar^® 129 fibre, 1000 denier, 24×24 yarns per inch) and the tensile properties of individual aramid yarn extracted from the fabric are presented. It was found that this fabric is balanced with less than 5% difference in strength between the warp and weft directions. The mechanical properties of the individual yarns were found to be lower than those reported for Kevlar^® 129 fibre, which is explained by the fact that the yarns were damaged during the extraction process or weaving process. A 3D finite-element model of the tensile testing of plain-woven fabric was built at the mesoscale in Abaqus/Explicit by modelling individual crimped yarns and taking into account friction. Material properties and yarn geometry for the model were obtained from experimental observations. An orthotropic elastic model with failure criterion based on the yield stress was used. Numerical results were analysed and compared with experimental results. It was found that the numerical model can reproduce the physical experimental observations, the yield strength and the failure strain.

Abstract: To investigate the effect of the additive agents such as polyethylene glycols (PEGs), melamine formaldehyde resin (MF-resin) and phenol formaldehyde resin (PF-resin) on the flow deformability of solid wood, free compression tests during heating were performed. Various molecular weights ranging from 200 to 20,000 for PEGs and almost similar molecular weight around 380 for MF-resin and PF-resin were applied. It was found from the compression tests that the yield stress indicating wood cell deformation resistance was drastically decreased with smaller molecular PEGs in wood, whereas the initiation of flow behavior, which is derived from detachment/slippage between cells, occurred at lower pressure with larger molecular PEGs. For generating the flow behaviors of solid wood, smaller molecular resin/substance was not always suitable. Thermosetting agents also act as a plasticizer during heating and especially the PF-resin showed better softening effect as well as a promoter of flow behavior than the MF-resin with almost similar molecular weight. This indicates that it is important for generating flow behavior to consider affinity/compatibility of resin to wood constituents. A maximum flow deformation ratio in the tangential direction of wood reached 180 % when using PEG 20,000 and MF-resin as an additive agent. It was also demonstrated that using PF-resin and MF-resin deep cup products shaped by a backward extrusion process had a better size stability against water, steam, and acetone.

Abstract: Welding with coated (covered) electrodes is a manual process in which an electric arc is generated between the electrode and work piece to melt the metals at the welding point whereby they are joined. Among the several ingredients that constitute the electrode coating, there is the binder, which is usually sodium or potassium silicate. Recently, studies were conducted where the usual binders were successfully replaced by hydrophobic polymers in solution, making the electrode waterproof, therefore of very low diffusible hydrogen content, and eliminating the need for a drying step during the preparation of the electrode. In the present work, the use of epoxidized vegetable oils as binders was evaluated in order to minimize negative environmental impacts since the binders are produced from a renewable source. The epoxidized vegetable oils were prepared from a variety of vegetable oils using acetic acid and hydrogen peroxide as reagents and an acidic ion exchange resin as catalyst. The prepared resins were dully characterized and used as a binder in the formulation for coating of basic-type electrodes. The produced electrodes were evaluated for the quality of the weld.

Abstract: Contact width is important design parameter for optimizing design of new metal gasket. The contact width was found have relationship with helium leak quantity. Increasing axial force, the contact width will increase and helium leakage will decrease. This study we conducted the surface roughness evaluation of 25A-size metal gasket before and after use. The results denote the real contact width after contact with flange having different surface roughness. The real contact width for the flange having smoother surface roughness is wider than the rougher one.

Abstract: An experimental investigation of the oscillatory flow and heat transfer in a vertical oscillating heat pipe (OHP) was conducted. The oscillating heat pipe was made of a copper-glass tube. Flow inside the oscillating heat pipe at different heat loads was recorded by a high speed camera. Through this research, the authors investigated the effect of utilizing nanofluids on heat transfer amount in heat pipes. The employed nanofluids in this study were water-Fe₂O₃, water-SiO₂ and water-TiO₂ with various volumetric concentrations. The results show that after adding nanoparticles in the base fluid (here water) heat transfer rate increases significantly. It's also noteworthy, of the all applied nanofluids, water-TiO₂ mixture presents the best enhancement in heat transfer amount.

Abstract: Removed at authors request.