Green fire retardant finishing and combined dyeing of proteinous wool fabric

Flame retardancy was imparted to a scoured and bleached, proteinous woollen textile by using banana pseudostem sap, an ecofriendly waste agricultural product, at different pH levels. The flame retardancy characteristics of both the control and the treated fabrics were analysed in terms of the limiting oxygen index and the vertical flammability measurement. Thermal degradation and fire retardancy mechanisms were studied using thermogravimetry, scanning electron microscopy, and energy dispersive X‐ray analysis. Moreover, the charring mechanism of both the control and the banana‐pseudostem‐sap‐treated fabrics with varying pH was analysed and reported in detail. The wool fabric was also dyed with CI Acid Blue 25 using banana pseudostem sap as well as water as the medium. The fabric dyed with the banana pseudostem sap medium at pH 5.5 showed more colour exhaustion, colour strength, and thermal stability compared with the control wool fabric. The mechanism by which superior fire retardancy and colour strength are imparted to the woollen textile by the application of banana pseudostem sap is proposed.     

Tape Cast Multilayer Composite of Nano Zirconia with High Toughness

During the last decade, worldwide attention of researchers has focused on nano-ceramic composites with superior mechanical behavior and improved reliability for structural applications. Here we report the development of a multi-layer composite (MLC) of tape cast nano zirconia with high failure energy. The MLC samples were fabricated by thermocompression of green tapes prepared from 3 mole % yttria stabilized zirconia (3-YSZ) powder with a primary crystallite size of 27 nm. Depending on the number of layers, the MLC samples exhibited failure energy (238.97 KJm^-3) more than two times higher than that of the single tape (≈107 KJm^-3) with a reasonably high bi-axial flexural strength (≈630 MPa), high hardness (≈ 13 GPa at 49 N), and indentation fracture toughness nearly four times as high as that of the single tape. In addition, these MLC materials showed the presence of a R-curve behavior.     

The polar cluster like behavior in Ti substituted BaZrO3 ceramics

In this paper we report the evolution of the polar cluster like behavior with the incorporation of Ti⁴⁺ ion in BaZrO₃ Ceramics. Dielectric behavior of BaZr_xTi_(1−x)O₃ (x = 1.00, 0.95, 0.90, 0.85) ceramics is studied in the temperature range from 300 to 30 K. Polar cluster like behavior becomes more prominent with the increase in content of Ti⁴⁺ ion. The dielectric relaxation is analyzed by Vogel–Fulcher relation and Arrhenius law. Frequency dependence of dielectric constant and low loss tangent of these materials can be useful for the potential applications at low temperature.     

MODE II STABLE CRACK GROWTH

Abstract Mode II stable crack extension has been examined for an aircraft grade aluminium alloy D16AT. Both theoretical and experimental results are presented. The experimental observations include load displacement diagrams, plastic wake, crack front tunnelling and scanning electron micrographs of the fracture surfaces. The crack shows a tendency for in-plane extension, and the fracture surface is very flat, smooth and free of any dimples. The crack front advances with neghgible tunnelling at all stages of extension. The span of mode II stable crack growth (SCG) is longer than in the case of mode I SCG reported earlier for the same material and there is also more extensive plastic deformation. In the presence of a slight mode I load, the crack grows out-of-plane and the fractured surface facets resemble that of a mode I or mixed-mode dimpled fracture. The theoretical study is based on a finite element analysis using small deformation theory and incremental plasticity. Some of the experimental results have been theoretically predicted using the COA criterion as the governing criterion. The theoretical results include load-displacement diagrams, crack edge displacement curves, plastic zones and the J resistance curves. There is good agreement between the load-displacement diagrams. The initiation and maximum loads differ by less than 15%. The J resistance curve has a constant slope over the whole span of stable crack growth.     

Studies on dielectric relaxation and defect generation for reliability assessments in ultrathin high-k gate dielectrics on Ge

In this work, we present the results of dielectric relaxation and defect generation kinetics towards reliability assessments for Zr-based high-k gate dielectrics on p-Ge (1 0 0). Zirconium tetratert butoxide (ZTB) was used as an organometallic source for the deposition of ultra thin (∼14 nm) ZrO₂ films on p-Ge (1 0 0) substrates. It is observed that the presence of an ultra thin lossy GeO_x interfacial layer between the deposited high-k film and the substrate, results in frequency dependent capacitance-voltage (C-V) characteristics and a high interface state density (∼10¹² cm⁻² eV⁻¹). Use of nitrogen engineering to convert the lossy GeO_x interfacial layer to its oxynitride is found to improve the electrical properties. Magnetic resonance studies have been performed to study the chemical nature of electrically active defects responsible for trapping and reliability concerns in high-k/Ge systems. The effect of transient response and dielectric relaxation in nitridation processes has been investigated under high voltage pulse stressing. The stress-induced trap charge density and its spatial distribution are reported. Charge trapping/detrapping of stacked layers under dynamic current stresses was studied under different fluences (−10 mA cm⁻² to −50 mA cm⁻²). Charge trapping characteristics of MIS structures (Al/ZrO₂/GeO_x/Ge and Al/ZrO₂/GeO_xN_y/Ge) have been investigated by applying pulsed unipolar (peak value - 10 V) stress having 50% duty-cycle square voltage wave (1 Hz-10 kHz) to the gate electrode.     

Removal of congo red using activated carbon and its regeneration

Activated carbon is used for the removal of colored toxic congo red dye. The effects of different operating conditions like, initial dye concentration, contact time, pH and temperature are studied for adsorption of congo red by a known amount of activated carbon (1.0g/L) under stirred batch condition. The zero point of charge of the activated carbon is found about 6.6. About 90% dye is removed for initial concentration of 50 and 100mg/L, it is about 80% at pH 7.0. Maximum adsorption (about 100%) of dye is observed at pH 2.0 for the concentration range studied here. Freundlich isotherm is found to fit the equilibrium data more adequately. Pseudo second order kinetic model explain successfully the kinetic data. The surfactant enhanced carbon regeneration (SECR) technique using both cationic and anionic surfactants is adopted for the regeneration of spent carbon by desorbing the dye. A kinetic model for dye desorption from the commercial activated carbon (CAC) is also proposed. Anionic surfactants show better performance than the cationic ones. Efficiency of dye desorption using surfactants is also compared with the desorption using pH change.