Structural,morphological, and optical properties of strontium doped lead-free BCZT ceramics

We report the synthesis of Sr²⁺ doped Ba_0.9-xCa_0.1Sr_xTi_0.8Zr_0.2O₃ nano-ceramics by the conventional solid-state reaction method. Phase formation of single-phase orthorhombic ABO₃ type structure with space group P2mm was confirmed through X-ray diffraction (XRD). The crystallite size increased with increasing doping concentration from 25.46 nm to 52.96 nm as calculated by the Scherrer formula and from 47.1 nm to 88.5 nm by the Williamson-Hall method. The lattice parameter, dislocation density, and apparent density decreased with doping, except for when x = 0.05. The porosity was found to increase up to 16.8% with increasing doping. Field emission scanning electron microscopy (FESEM) shows that samples exhibit a flake-like structure. X-ray photoelectron spectroscopy (XPS) analysis confirms that Sr-ions occupy the Ca-site, for x = 0.05, and force the Ca ions to occupy the Ti-sites. For the higher concentration of Sr, i.e. x ≥ 0.15, no more forced substitution is observed and Sr-ions occupy the Ba-site only, which decreases oxygen vacancies. Diffused rings observed in selective area electron diffraction (SAED) patterns indicate the high crystalline order of the samples. The Fourier-transformed infrared spectroscopy (FTIR) measurements show a single broad peak between 544 and 594 cm^?1 for all the compositions, while two prominent peaks are observed for the composition x = 0.05 at 528 cm^?1 and 592 cm^?1. The Raman spectra show a shift in the most prominent peak, observed approximately 517 cm^?1.     

An investigation of molybdenum surface reinforcement on the hardness and wear properties of AISI 630

AISI 630 stainless steel (SS) surface has been reinforced with molybdenum (Mo) using gas tungsten arc (GTA) as a heat source. The optimum GTA heat source conditions have been finalised based on the proper fusion of base metal. The microhardness of the Mo-reinforced AISI 630 SS was found to be 502?HV which shows an improvement of 35% with respect to the base metal (371?HV). To improve the properties, the reinforced alloy was heat treated. The microhardness of the reinforced and aged AISI 630 was 725?HV, which was higher than the base metal by 95%. Dry sliding wear tests using a Pin-on-Disc machine were performed and it was found that the wear resistance of the reinforced surface was improved by 52% with respect to base metal. Characterisation techniques such as optical microscopy, scanning electron microscope, energy-dispersive X-ray spectrometry and XRD were used to establish morphology, structure and composition, and the presence of Mo was confirmed.     

Above-ground morphological predictors of rooting success in rooted cuttings of Jatropha curcas L.

Cuttings of 1–3 cm diameter and 45 cm length were collected during the first week of February from branches of previous year’s growth in a mature plantation of Jatropha curcas. The cuttings, without application of any growth regulator, were planted in nursery beds having loam: gravel (1:1 v/v) mixture rooting media. The nursery beds existed inside a polyethylene tunnel where intermittent misting was done. When sprouting percentage had stabilised, sprouted cuttings were removed from the media, and root and shoot characteristics of the cuttings were recorded. The number of roots and root length were found to be significantly correlated (P < 0.01) with one another as well as with sprout length, number of sprouts and number of leaves. The following equations were fitted for prediction of root characteristics of a cutting from of its above-ground characteristics: (i) No. of roots = −0.409 + 0.452 (no. of leaves) + 0.395 (sprout length), and (ii) Root length = 2.656 + 0.206 (no. of leaves) + 0.270 (sprout length); the sprout length and root length are in centimetres in both equations. Thicker cuttings possessed better root and above-ground characteristics.     

Predicting the properties of needlepunched nonwovens using artificial neural network

Needlepunching is a well‐known nonwoven process of converting fibrous webs into self‐locking or coherent structures using barbed needles. In this study, Artificial Neural Network (ANN) modeling technique has been used to predict the bulk density and tensile properties of needlepunched nonwoven structures by relating them with the main process parameters, namely, web area density, punch density, and depth of needle penetration. The simultaneous effect of more than one parameter on bulk density and tensile properties of needlepunched nonwoven structures have been investigated based upon the results of trained ANN models. A comparison is also made between the experimental and predicted values of fabric bulk density and tensile strength in the machine and crossmachine directions in unseen or test data sets. It has been inferred that the ANN models have achieved good level of generalization that is further ascertained by the acceptable level of mean absolute error obtained between predicted and experimental results. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Tensile behaviour of thermally bonded nonwoven structures: model description

Nonwovens are complex three-dimensional anisotropic structures and consisting of fibres orientated in certain directions, which are bonded by thermal, chemical, mechanical entanglement or a combination of these techniques. Thermally bonded are further classified in two categories, i.e. through-air and calendared nonwoven structures. In this study, a modified micromechanical model describing the tensile behaviour of thermally bonded nonwovens is proposed by incorporating the effect of fibre re-orientation during the deformation. The anisotropic behaviour of through-air bonded structures is demonstrated through theoretical stress–strain curves and the relationship between the fibre re-orientation and fabric strain is also analysed. Furthermore, the failure criterion of thermally bonded nonwovens is analysed using pull-out behaviour of fibres in the system. A parametric study revealing the dependencies of various structural and geometrical characteristics of fibres on pull-out behaviour of fibres in thermally bonded nonwovens is also discussed.     

Tensile behaviour of nonwoven structures: comparison with experimental results

Nonwoven structures have been recently explored for numerous novel applications ranging from composites to scaffolds. The tensile property of nonwovens is a pre-requisite and indeed, one of the main parameters to determine their performance for such applications. In the first part, a modified micromechanical model describing the tensile behaviour of thermally bonded nonwovens was proposed by incorporating the effect of fibre re-orientation during the deformation (Rawal et al., J Mater Sci 45:2274, 2010). In this study, an attempt has been made to compare the theoretical and experimental stress–strain curves of thermally bonded and spunbonded nonwoven structures. These theoretical findings have been obtained from the most popular analytical tensile models of nonwovens available in the literature in addition to our modified tensile model. Poisson’s ratio has also been determined experimentally in order to predict the stress–strain behaviour of nonwoven, and its relationship with longitudinal strain has clearly distinguished between the randomly and preferentially orientated types of structures. In thermally bonded nonwovens, the tensile strength in various test directions is computed through pull-out stress and a comparison is made with the experimental results.     

Perturbation Theory for the Transport Properties of Multicomponent Glass Melts

A first-order theory is presented for the calculation of the effects of compositional variation on the transport properties of glass melts. The theory is based upon the modified Enskog theory applied to the high-temperature expansion of the free energy. The theory is applied to a simple two-component glass system and compared to experimental and previous theoretical results.     

Large,Switchable Electrochromism in the Visible Through Far‐Infrared in Conducting Polymer Devices

Advanced materials with large and dynamic variation in thermal properties, sought for urgent defense and space applications, have heretofore been elusive. Conducting polymers (CPs) have shown some intrinsic variation of mid‐ to far‐infrared (IR) signature in this respect, but the practical utilization of this has remained elusive. We report herein the first significant IR electrochromism in any material, to our knowledge, in the 0.4 through 45 μm region. This is seen in practical CP devices in the form of thin (<0.5 mm), flexible, entirely solid‐state, variable area (1 cm² to 1 m²) flat panels. Typical properties include: very high reflectance variation; switching times <2 s; cyclabilities of 10⁵ cycles; emittance variation from 0.32 to 0.79; solar absorptance variation from 0.39 to 0.79; operating temperatures of –35 to +85 °C; durability against γ‐radiation to 7.6 Mrad, vacuum to 10^–6 torr, and simulated solar wind (e.g., 6.5 × 10¹⁶ e/cm² @ 10 keV).