Table of Contents - Volume 14 Number 1

Ceramic hard Coatings  based on Si, C , N, Ti and  B were developed using magnetron sputtering, applicable for protecting the underlying substrate. Different morphological patterns were observed on the coating surface due to sputtering. Nanoindentation was used to determine the hardness and modulus of the coatings. The deviations in H and E values were attributed to indentation positions, thin film stress and anisotropy. Evidence of strain hardening was found during loading.

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This work presents a comprehensive study on the optical behavior of cadmium sulphide (CdS) nanoparticles under the effect of nickel (Ni²⁺ ions) doping. The pristine and Ni-doped CdS nanoparticles (CdS:Ni) have been synthesized via. conventional co-precipitation technique and analyzed using UV-visible spectrophotometer. Ni²⁺ ions with different concentrations (2% and 4%) incorporate in CdS structure, modify it and hence, exhibit a red shift of absorption edge. The increase in Ni²⁺ ions concentration from 0% to 4% leads to tailor the optical band gap of CdS from 2.70 eV to 2.47 eV. These band gap values are higher than that of bulk CdS which confirm a quantum size effect in the synthesized nanoparticles.

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Over the last two decades, the design of multicomponent molecular crystals or cocrystals has grown out to be an interesting and promising area of research in pharmaceuticals and material science. Cocrystallization is at the interface of crystal engineering and supramolecular chemistry and allows us to vary the physicochemical properties of solids according to the need, through manipulation of various intermolecular interactions. In this short review, we focus on some recent reports on pharmaceutical cocrystals and emerging subclasses of cocrystals, namely: Charge transfer cocrystals, Energetic cocrystals, and Ternary cocrystals and discuss about their methods of characterization and applications of importance in the industry.

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Attempts were made to synthesize high quality graphite oxide (GO) and reduced graphene oxide (rGO) by using successive oxidation-reduction process of high quality vein graphite from Sri Lanka. We report the lowest optimum reduction temperature for converting GO to rGO which has been systematically studied using X-ray diffraction spectroscope (XRD) with the high temperature heating attachment (HTA) for the first time. The effect of particle size of graphite on properties of GO and rGO is also compared using commercially available graphite of particle size of ~111 mm  and ball-milled graphite  of particle size ~37 mm. The GO and rGO were characterized using XRD, UV-Visible spectroscopy, Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The GO and rGO synthesized from ball-milled graphite showed higher oxidation and reduction properties as verified through the UV-Vis and FTIR analysis. The SEM analysis revealed that the splitting of graphene layers is efficiently taken place in GO from ball-milled graphite. The lowest optimum temperature for thermal reduction of GO to rGO was found to be at 475 °C. FTIR confirmed the removal of most of the functional groups in rGO and according to the BET surface area analysis few layers, supposed to be 2-6 is formed. The efficient oxidation and reduction process of smaller particle size graphite has led to yield highly oxidized GO and high quality rGO which can be used to prepare high quality graphene for future applications.

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This is a report on large scale synthesis of nickel oxide (NiO) using polyethylene glycol as a fuel employing self-propagating combustion reaction with nickel oxalate as precursor. The synthesized NiO is characterized for its crystal structure, morphology and bonding via XRD, SEM and FTIR respectively. Thermal behavior of the synthesized NiO is studied employing TGA and DSC. Super paramagnetic behavior of the synthesized is studied by magnetic hysteresis.

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This manuscript shows the recrystallization of micro Pentaerythritol tetranitrate (mcPETN) through solvent anti solvent technique by changing some important parameters viz., rotations per minute, temperature of crystallization, while keeping the concentration of PETN constant as  in solvent acetone. The synthesized mcPETN is characterized for its crystal structure and morphology. The enhanced performance to its macro sized PETN is reported herewith the results.

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Carbon fiber is composed of carbon atoms bonded together to form a long chain. The fibers are extremely stiff, strong, and light, and are used in many processes to create excellent building materials. Carbon fiber material comes in a variety of "raw" building-blocks, including yarns, uni-directional, weaves, braids, and several others, which are in turn used to create composite parts. The properties of a carbon fiber part are close to that of steel and the weight is close to that of plastic. Thus the strength to weight ratio (as well as stiffness to weight ratio) of a carbon fiber part is much higher than either steel or plastic. Carbon fiber is extremely strong. It is typical in engineering to measure the benefit of a material in terms of strength to weight ratio and stiffness to weight ratio, particularly in structural design, where added weight may translate into increased lifecycle costs or unsatisfactory performance.

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Sialon is an excellent material belonging to the oxynitride ceramics. It has high strength, wear resistance, and other mechanical and chemical properties.   β–sialon has the general formula of Si_6-ZAl_ZO_ZN_8-z,where z=0  to 2.1. In the present work in total nine different Sialon samples with different compositions were sintered at 7 different temperatures viz., 1575 to 1840^oC. Green density, fired density, % linear shrinkage at different temperatures and compositions were reported. Theoretical density of 3.2 gm/cc. was almost reached. The properties were compared and various parameters were corroborated In terms of at% N.

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A parametric approach has been used to derive an approximate formula for the prediction of the radius of curvature of a thin bimetallic strip that at initial ambient temperature, is both flat and straight, but at above ambient temperature, forms into an arc of a circle. The formula enables the evaluation of the radius of curvature of the strip as a function of heating or cooling. A formula for calculating the radius of curvature of a bimetallic strip already exists, and was produced by Timoshenko in his paper on Bimetallic Thermostats. The formula by Timoshenko has been vigorously tested, tried and proven and accepted in countless papers and journals since its original publication. The parametric approach solution introduced in this work gives an approximate solution to the Timoshenko formula for equal thicknesses of two mating metals within the bimetallic. The Khatkhate Singh Mirchandani (KSM) formula presented here is taken from the first order approximation derived by Angel and Haritos by incorporating the ratio of Young's modulus of the bimetallic materials. Furthermore, researchers in this area have proven that the Young's modulus does not have a significant effect on the radius of curvature. Taking this fact into consideration, the authors have suitably incorporated a correction modifier purely based on the coefficient of thermal expansion (CTE) of the materials. The simulation results and the overall close agreement with the Timoshenko formula has been put forward here. Also, the solution derived by the authors Khatkhate et.al shows better prediction as compared to the solutions derived by other researchers.

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