Corrosion Behavior of Bare,Cr3C2-25%(NiCr), and Cr3C2-25%(NiCr)+0.4%CeO2-Coated Superni 600 Under Molten Salt at 900 °C

Cr₃C₂-25(NiCr) and Cr₃C₂-25(NiCr)+0.4%CeO₂ coatings were deposited on nickel-based superalloy Superni 600 by Detonation-gun technique. Studies were conducted on bare and coated alloys in molten salt environment (Na₂SO₄-25%NaCl) at 900 °C under cyclic condition. Characterization of the corrosion product was done using field emission scanning electron microscopy/energy dispersive spectroscopy and x-ray diffraction techniques. The bare Superni 600 shows penetration of corrosion beneath the metal layer thereby indicating internal oxidation. The coating of Cr₃C₂-25(NiCr) with 0.4%CeO₂ leads to the formation of adherent scale.     

Effect of Ultrasonic Shot Peening on Microstructure and Mechanical Properties of High-Nitrogen Austenitic Stainless Steel

The effect of ultrasonic shot peening (USSP) was studied on microstructural modification and mechanical properties such as microhardness, yield strength, tensile strength, and low cycle fatigue (LCF) life of a nitrogen stabilized austenitic stainless steel, at room temperature. There was grain refinement up to nano scale in surface region of the shot peened specimens and the microhardness was increased markedly up to the depth of approximately 100 µm. There was insignificant increase in yield and tensile strength, but drastic reduction in LCF life, particularly at low strain amplitude, from USSP. The nominal increase in yield and tensile strength was due to grain refinement in the surface region and drastic fall in LCF life was due to surface cracking resulting from USSP.     

Corrosion Behavior of 9Cr-1Mo Steel in Sulfur Dioxide Environment

Corrosion behavior of annealed 9Cr-1Mo steel was studied in SO₂ environment at 1173 K, at flow rates from 8.33 × 10^?7 to 33.33 × 10^?7 m³/s, and parabolic rate law was followed. The rate constants were found to be independent of flow rate, within the range of flow rate investigated. Corrosion at temperatures from 973 to 1173 K, at a constant flow rate of 16.66 × 10^?7 m³/s, at 1 atmospheric pressure, for 6 h also exhibited parabolic law, however, the rate constants were observed to increase significantly with rise in temperature. The outer layer of the scale formed at 973 K was essentially of iron oxide, with small amount of chromium oxide whereas the inner layer was predominantly of chromium sulphide and chromium oxide. The scale formed at 1173 K was multilayered, in contrast to double layered formed at 973 K and 1073 K. The outer thick layer of the scale formed at 1173 K, consisted of iron oxide followed by thin substrate of chromium sulphide, iron sulphide/iron oxide, and chromium sulphide/chromium oxide toward the substrate. A model is proposed for the process of corrosion of 9Cr-1Mo steel in SO₂ environment, based on the present investigation.     

Ternary polymer electrolyte with enhanced ionic conductivity and thermo-mechanical properties for lithium-ion batteries

Cellulose is the main building block of plant's cell wall that provides structural stability. This idea inspired us to use modified cellulose (Networked cellulose) to provide thermal and mechanical stability to a polymer electrolyte system. The system composed of polyethylene glycol (PEG) (or tetraethylene glycol dimethyl ether (TEGDME)), polyethylene oxide (PEO), networked cellulose (NC) and LiClO₄ as a salt. The PEG (or TEGDME) was used as a high mobility phase for lithium ions, PEO acted as a binder and NC provided structural support for the quasi-solid polymer electrolytes. A high conductivity of the order of 10⁻⁴ S cm⁻¹ was obtained at room temperature. Dynamic mechanical analysis of PEG (or TEGDME):PEO:NC (70:20:10 wt%) showed an improvement of storage modulus as compared to the pristine PEO in the 60–120 °C temperature range. Differential scanning calorimetry (DSC)/Thermal gravimetry analysis (TGA) revealed that the developed ternary polymer electrolyte is thermally stable in the lithium-ion battery operational temperature range.     

Effect of microwave pretreatment of mixed culture on biohydrogen production from waste of sweet produced from Benincasa hispida

To enhance the production of biohydrogen from biomass, various pretreatment methods play important role. In this study, effect of microwave irradiation on the culture was studied on biohydrogen production from Benincasa hispida (Petha) solid waste at different powers for a fixed interval of time. The highest power studied was 800 W with a frequency of 2450 MHz. The amount of soluble sugars found in the waste was 13.9 mg/L having the chemical oxygen demand (COD) of 3000 mg/L. Studies have been performed in batch reactors using mixed consortia and results were also compared with the reactor operated at the normal conditions i.e. without any inoculum pretreatment. Maximum hydrogen produced was 14 mmol H₂ per mol of soluble sugar consumed in the reactor in which the inoculum was exposed to 320 W of microwave for 5 min. SEM analysis of this microwave pretreated culture was done.     

Study on GDC-KZnAl composite electrolytes for low-temperature solid oxide fuel cells

Development of low-temperature solid oxide fuel cells (LTSOFC) is now becoming a mainstream research direction worldwide. The advancement in the effective electrolyte materials has been one of the major challenges for LTSOFC development. To further improve the performance of electrolyte, composite approaches are considered as common strategies. The enhancement on ionic conductivity or sintering behavior ceria-based electrolyte can either be done by adding a carbonate phase to facilitate the utilization of the ionic-conducting interfaces, or by addition of alumina as insulator to reduce the electronic conduction of ceria. Thus the present report aims to design a composite electrolyte materials by combining the above two composite approaches, in order to enhance the ionic conductivity and to improve the long-term stability simultaneously. Here we report the preparation and investigation of GDC-KAlZn materials with composition of Gd doped ceria, K₂CO₃, ZnO and Al₂O₃. The structure and morphology of the samples were characterized by XRD, SEM, etc. The ionic conductivity of GDC-KAlZn sample was determined by impedance spectroscopy. The composite samples with various weight ratio of GDC and KAlZn were used as electrolyte material to fabricate and evaluate fuel cells as well as investigate the composition dependent properties. The good ionic conductivity and notable fuel cell performance of 480 mW cm⁻² at 550 °C has demonstrated that GDC-KAlZn composite electrolyte can be regarded as a potential electrolyte material for LTSOFCs.     

Koko: an architecture for affect-aware games

The importance of affect in delivering engaging experiences in entertainment and educational games is well recognized. Yet, current techniques for building affect-aware games are limited, with the maintenance and use of affect in essence being handcrafted for each game. The Koko architecture describes a service-oriented middleware that reduces the burden of incorporating affect recognition into games, thereby enabling developers to concentrate on the functional and creative aspects of their applications. The Koko architecture makes three key contributions: (1) improving developer productivity by creating a reusable and extensible environment; (2) yielding an enhanced user experience by enabling independently developed games and other applications to collaborate and provide a more coherent user experience than currently possible; (3) enabling affective communication in multiplayer and social games. Further, Koko is intended to be used as an extension of existing game architectures. We recognize that complex games require additional third party libraries, such as game engines. To enable the required flexibility we define the interfaces of the Koko architecture in a formal manner, thereby enabling the implementation of those interfaces to readily adapt to the unique requirements of game’s other architectural components and requirements.     

Nano ZnO grafted on MAA/BA/MMA copolymer: An additive for hygienic coating

Nano ZnO particles were synthesized by treating zinc oxalate with glycol and amines. The treated nano particles were in-situ grafted on methacrylic acid/butyl acrylate/methyl methacrylate via solution polymerization technique to prevent aggregation in the coating. The characterizations of grafted and treated nano ZnO particles were performed by transmission electron microscopy, atomic force spectroscopy, X-ray diffraction and particle size analysis. The outcome of this surface modification and varying concentrations of nano ZnO has helped in establishing it as an antibacterial additive in hygienic coating.     

Hybrid polymer networks of unsaturated polyester–urethane as composite matrices for jute reinforcement

Reactions of unsaturated polyester resin and 4,4′ diphenyl methane diisocyanate were carried out at different NCO/OH ratios in presence of catalysts to form the hybrid polymer networks. Chain extender (1,4 butanediol) added in the hybrid network (NCO/OH ratio: 0.76) was optimized at a level of ～ 3 wt % only of the polyester resin. The curing of these networks was studied by a rigid body pendulum type (RPT) method in terms of reduced damping ratio and increased frequency. Lack of multiple glass transition temperatures, sharp Tan delta peak, and particulate composite type morphology clearly demonstrated the formation of phase mixed domains in the hybrid networks. The storage modulus and loss modulus master curves obtained by dynamic mechanical analysis indicate that hybrid polymer networks retained higher modulus at lower and intermediate frequencies over the polyester resin showing their superior time‐dependent response. Efficacy of these hybrid network resins was examined as matrices in the jute composites and compared with those of polyester resin and unsaturated polyester–polyurethane interpenetrating network matrices. It is found that the hybrid polymer network matrix composites exhibited superior physicomechanical properties under both dry and boiling water age test. Fractographic evidences such as fiber–matrix adhesion, hackle markings, and fiber breakage also supported their superior behavior over other composite matrices. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Frequency-truncated system norms

Some applications require norm computation of frequency-truncated systems. A typical frequency-truncated system is one whose frequency response is rational in certain frequency bands and is zero in others. This note explains how to compute the L² norm of such systems.