[en] Recently, Oxide Dispersion Strengthened(ODS) ferritic alloys have been considered for the critical component materials of ultra-super critical pressure power plants or nuclear power plants. The strength properties of ferritic 12%Cr ODS alloys with the addition of Ti and W were investigated in comparison with those of 17% Cr ODS and 12%Cr ODS alloys in the range of room temperature to 1323K. Nano-sized oxide dispersoids in the alloys suppressed the grain growth during annealing at a 1323K and resulted in a remarkable improvements of the strength. The fine particles in 12%Cr ODS alloys with the addition of Ti and W was identified to be a complex oxide type of Y-Ti-O. The complex oxides containing Ti was the finest and showed the most uniform dispersion

[en] In the past few years, Oxide Dispersion Strengthened(ODS) alloys produced by Mechanical Alloying(MA) techniques have become increasingly interesting for structure applications in nuclear fission and fusion power plant. The mechanical properties of ferritic 17% Cr ODS alloys with and without the addition of Ti and Mo and 17% Cr ODS were investigated and comparison with those MA-956 alloys in the temperature range of 973K to 1573K. Nano-sized oxide dispersoids in the 17Cr-3Mo-1Ti-0.25Y₂O₃ alloys suppressed the grain growth during annealing at high temperature and resulted in a remarkable improvement of the high temperature strength. The oxides containing Ti was the finest and showed the most uniform dispersion

[en] The effect of the phases of γ, α^' and ε martensites, which constitute the structure of the 316L stainless steel with austenite structure at room temperature, on the damping capacity at room temperature has been investigated. As a result, various fractions of these phases were formed depending on the degree of cold work. The largest volume fraction of ε martensite phase is obtained by 20% cold rolling and showed the highest damping capacity. The damping capacity is strongly controlled by the volume fraction of ε martensite with linear relationship, while the other phases of α^' and γ have actually no effect on the damping capacity

[en] This study investigated the effect of the tempering before aging on the precipitation of Laves phase and mechanical properties of 10Cr-6W and 10Cr-6W-3Co ferritic heat-resistant steels. Laves phase was precipitated by aging, which increased tensile strength but decreased elongation and impact value. Toughness was rapidly decreased by the presence of the very fine disk-like Laves phase precipitated at early aging stage. Strength and impact value were decreased by tempering treatment and that is due to the increase of the particle number per unite area and to larger particle size of Laves phase. Laves phase increased by adding Co, and consequently strength was increased and elongation and toughness were decreased

[en] The damping capacity was the most important factor for development of industrial apparatus and precision apparatus. In this research, we developed Fe-12Cr-22Mn alloy having alloying elements and investigated the damping property and strength. Particularly, the effects of the phases of alpha, gamma and epsilon martensite on the damping capacity at room temperature has been investigated. Various fractions of these phases were formed depending on the Co and Si contents and degree. It was found that the combination of 22Mn-4Co-0.4Si and 50% cold rolling formed the largest volume fraction of epsilon martensite phase and showed the highest damping capacity. The other phases of alpha and gamma had actually no effect on the damping capacity. It was also found that 50% clod worked Fe-12Cr-22Mn-Co-0.4Si alloy indicated the largest Vickers hardness

[en] The interaction between halloysite nanotubes (HNT) and poly(styrene sulfonate) (PSS) in aqueous solution was investigated by dynamic light scattering. Dynamic behavior of HNT/PSS was observed with different salt, HNT, and PSS concentrations. The HNT colloids were stabilized by PSS over a wide range of HNT concentrations, and HNT suspension in dilute solution formed stable HNT/PSS particles. On the other hand, HNT particles aggregated as sediments at higher concentrations due to strong attraction among HNT rods, and HNT aggregates were stabilized by additional PSS. The interactions between HNT and PSS are described by the van der Waals–London force (VDWL). The stabilization process of HNT/PSS particles in salt solution was proposed by comparing the hydrodynamic radii and apparent intensities of samples. The results demonstrate that electrostatic, steric, and depletion stabilization processes are responsible for the stable dispersion of HNT even at high concentration

[en] Antibacterial products have paid much more attraction all over global world. In this study, a novel and economical rout has been studied for antibacterial product, ultrafine nylon-6 (NY-6 NFS) nanofibers impregnated into garlic sour was synthesized by electrospinning method. The morphology of impregnated nanofiber mats was characterized by electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) was used to analyze the chemical interaction of Nylon-6 nanofiber mats and garlic sour. The antibacterial activities of impregnated garlic sour samples G-1, G-2 and G-3 were evaluated against Escherichia coli and Staphylococcus aureus bacteria by using disc diffusion method. It was found that the garlic sour has played a vital role for antibacterial activity. The nanofiber mats impregnated into garlic sour showed excellent antibacterial activity. It was observed that the antimicrobial effect for Escherichia coli and Staphylococcus aureus was more than 99 %. The excellent hydrophobic property which revealed water contact angle was examined with dropping method and TGA were examined excellent thermal degradation rate of NY-6 NFS and impregnated garlic sour samples. NY-6 NFS showed good mechanical strength according to ASTM D-638 standard. The obtained results indicate that the NY-6 NFS impregnated in garlic sour is a promising antibacterial product that can be utilized as antibacterial wound dressing.

[en] The dispersion characteristics of the nano-sized Y₂O₃ powders in molten aluminum were investigated from the viewpoint of changes in microstructure and mechanical property as a function of oxide contents. As the solidification structure, the oxide nanoparticles dispersed in the columnar crystal was mainly segregated on the grain boundary, whereas the oxide nanoparticles dispersed in the equiaxed crystal was uniformly dispersed on both grain boundary and inside the crystal. The most uniform dispersion of oxide nanoparticles was observed at Y₂O₃ content of 2 mass%. As Y₂O₃ content of 3 mass%, the size of oxide nanoparticles in metal matrix increased due to the particle aggregation, as confirmed by SEM analysis. Moreover, it was found that the mechanical properties such as hardness and tensile strength were improved at Y₂O₃ content of 2 mass%, indicating the well-dispersion of nano-sized Y₂O₃ powders in cast aluminum. The hardness was increased by 1.2 times up to 57 H_V and tensile strength was increased by 1.55 times up to 80 MPa, compared with the case of pure aluminum. However, at Y₂O₃ content of 3.0 mass%, tensile strength was sharply decreased by 0.6 times due to aggregation of oxide nanoparticles, while the hardness was increased to 57 H_V, which is the same as the case of Y₂O₃ content of 2.0 mass%. (author)

[en] Highlights: • N-halamine precursor APDMH was grafted on the surface of graphene oxide (GO) via in-situ polymerization. • Using GO as the carrier of polymeric APDMH greatly slowed down the release rate of oxidative chlorine. • The GO-PAPDMH-Cl composites exhibited good antimicrobial efficacies against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli O157:H7). -- Abstract: N-halamine compounds have been applied as antibacterial agents owing to the oxidative chlorine. In this work, graphene oxide (GO) as carrier was used to load N-halamine compounds for the sustained-release of chlorine in order to maintain long-term biocidal efficacies. 3‑(3′‑Acrylic acid propylester)‑5,5‑dimethylhydantoin (APDMH) was synthesized using 5,5‑dimethylhydantoin as a heterocyclic precursor and attached on the surface of GO nanosheets via in-situ polymerization. The modified GO composites were characterized by Fourier transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The chlorinated GO nanosheets modified with polymerized APDMH (PAPDMH) were very stable and possessed long-term antibacterial properties. The GO-PAPDMH-Cl composites exhibited good antimicrobial efficacies against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli O157:H7) with log reductions of 7.20 and 7.06 within 30 min of contact time, respectively.

[en] Herein we present our research on synthesis of silver nanoparticles (AgNPs) on cellulose nanofibers (CN) by a facile procedure using dopamine hydrochloride (Dopa), as reducing agent. The CN were produced by deacetylation of electrospun cellulose acetate (CA) nanofibers. The CN were then treated with 2 mg/mL of Dopa in 1 M Tris HCl buffer (pH 8.5) followed by soaking in 150 mM AgNO₃ solution for generation of AgNPs. The samples were characterized with SEM, XRD, FESEM, EDX, XPS, TEM, FTIR analysis and antibacterial assays. Synthesis of AgNPs was confirmed by XRD, XPS and TEM analysis. The TEM images demonstrated CNAgNP samples well decorated with AgNPs. Sizes of the spherical AgNPs, calculated by Debye–Scherrer method, were 20 nm. Antibacterial test results confirmed excellent bacterial growth inhibition properties of CNAgNP on agar plates and in liquid medium against E. coli and S. aureus strains. The relative cell viability (CFU/mL) test results demonstrated excellent bactericidal potential of the CNAgNP samples against the tested strains. The CNAgNP prepared by an environmentally benign process would thus be a promising nano-biocomposite for antibacterial applications.