Effect of Particle Size on Tribological Behavior of Rice Husk Ash–Reinforced Aluminum Alloy (AlSi10Mg) Matrix Composites

Rice husk ash of three different particle size ranges (50–75, 75–100 and 100–150 μm) a 3, 6, 9, and 12% by weight is reinforced with an aluminum alloy (AlSi10Mg) using the liquid metallurgy method. The dry sliding wear behavior of the composites in the cast conditions is examined using the pin-on-disc tribotesting machine for three different loads (20, 30, and 40 N) with three different sliding velocities (2, 3, and 4 m/s). The results reveal that the composite reinforced with the coarse rice husk ash particles exhibits superior wear resistance compared to the fine rice husk ash particles. The wear rate of the composite decreased with an increase in the weight percentage of rice husk ash particles for all size ranges. Finally, the wear mechanism was investigated with the worn surface using a scanning electron microscope.     

Effect of initial preform geometry and friction on the cold deformation behaviour of sintered titanium carbide composite steel

Cold upsetting experiments were carried on sintered titanium carbide composite steel preforms in order to assess their deformation characteristics. The effect of aspect ratio and frictional constraints on deformation behaviour have been investigated thoroughly. Cylindrical compacts with different aspect ratios were prepared, sintered and upset forged at room temperature. The above cold deformation work was carried out using 1.0 MN capacity Universal Testing Machine. Cold deformation experiments were carried out in several steps. Dimensions such as height, contact, and bulged diameters and densities were measured for each test. In general, each compact was subjected to an incremental compressive loading in steps of 0.005 MN until fine cracks appeared on its free surface. Effect of various upsetting parameters, namely, axial strain, axial stress, Poisson’s ratio on the densification has been studied.     

Preparation of activated carbon from sorghum pith and its structural and electrochemical properties

The cost effective activated carbon (AC) has been prepared from sorghum pith by NaOH activation at various temperatures, including 300 °C (AC1), 400 °C (AC2) and 500 °C (AC3) for the electrodes in electric double layer capacitor (EDLC) applications. The amorphous nature of the samples has been observed from X-ray diffraction and Raman spectral studies. Subsequently, the surface functional groups, surface morphology, pore diameter and specific surface area have been identified through FT-IR, SEM, histogram and N₂ adsorption/desorption isotherm methods. The electrochemical characterization of AC electrodes has been examined using cyclic voltammetry technique in the potential range of −0.1-1.2 V in 1.0 M H₂SO₄ electrolyte at different scan rates (10, 20, 30, 40, 50 and 100 mV/s). The maximum specific capacitances of 320.6 F/g at 10 mV/s and 222.1 F/g at 100 mV/s have been obtained for AC3 electrode when compared with AC1 and AC2 electrodes. Based on the characterization studies, it has been inferred that the activated carbon prepared from sorghum pith may be one of the innovative carbon electrode materials for EDLC applications.     

The effect of humidity, fabric surface geometry and dye type on the colour of cotton fabrics dyed with a select range of anionic dyes

Four C.I. Solubilised Sulphur dyes were applied to cultivated silk fabric using sodium thioglycolate at pH 7, for 30 min at 60 °C in the absence of electrolyte. Medium/deep shades were obtained that displayed good/excellent fastness to washing at 40 °C and little or no sensitivity to oxygen bleach fading. The dry rub fastness of the dyeings ranged from moderate to good whilst the wet rub fastness varied from poor to moderate; light fastness of the 10% omf dyeings varied from low to moderate. The mild application conditions used had little effect on the tensile strength of the fabric.     

An analysis of the general benefits of a centralised VMI system based on the EOQ model

Within a vendor-managed inventory (VMI) agreement, the upstream supply chain member (the vendor) takes responsibility for managing the inventory of the downstream member (the customer) within specific levels previously agreed upon without the need of orders from the customer side to be placed. Therefore, the vendor can focus on optimising production efficiency and capacity planning, while the customer has to improve forecast accuracy. This paper analyses the benefits a VMI agreement could bring for a one-supplier, multiple-customer case through analysing two cases: a supply chain managed in a traditional manner and VMI when both the vendor and the customers belong to the same organisation. The analysis is based on the economic ordering quantity (EOQ) formula and its related total cost, and the novelty is captured by evaluating one vendor, multiple buyers, and multiple product situations. The modelling is done so as to capture the needs and factors which occur within the pharmaceutical industry and a numerical application will be executed with data from one of the main leaders within the pharmaceutical field.     

Combustion synthesis and characterization of spherical α-MnMoO4 nanoparticles

In this study, α-MnMoO₄ nanoparticles were prepared by combustion synthesis method. The structural, morphological and electrical characteristics of α-MnMoO₄ were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, transmission electron microscopy and impedance spectroscopy. The structural parameters were calculated from XRD pattern which confirmed the monoclinic structure of α-MnMoO₄. FT-IR and Raman spectroscopy results revealed the presence of MoO₄ surface functional groups. The TEM and HRTEM investigations evidenced the presence of homogeneous distribution of spherical nanoparticles and high crystallinity of α-MnMoO₄. Moreover, the SAED patterns clearly revealed the polycrystalline nature of the material. The conductivity measurements had inferred the semiconducting property of α-MnMoO₄ and the maximum conductivity of 1.94 × 10^? 6 S/cm was attained at 540 °C.     

Effect of particulate fillers on thermal expansions and other critical performances of polycarbonate‐based compositions

Influence of different inorganic particulate mineral fillers on polycarbonate composites was explored. Among all the fillers assessed here only boron nitride and mica could appreciably reduce the thermal expansion of polycarbonate, particularly along the direction of flow. While measured in the normal to flow (cross‐flow) direction, the coefficient of thermal expansion (CTE) values decreased marginally in presence of boron nitride and mica as compared to the unfilled specimen. The anisotropicity in CTE is presumable due to preferential orientation of boron nitride and mica along the direction of flow in the injection molded samples. The effectiveness of fillers in reducing CTE of the polycarbonate composites was correlated to the dispersion of fillers in the polymer matrix. Better dispersion of boron nitride and mica, as observed through SEM, ensured their improved interaction with the matrix and thereby reducing the CTE. It was observed that in presence of particulate fillers the impact performance of the composites decreased appreciably with an increase in tensile modulus, in general. The flow behavior of the composites was by large dependent on the types of fillers used. In presence of some of the fillers such as BaSO₄, ZnO, ZnS, TiO₂, and alumina, flow of the composites increases significantly, primarily associated to appreciable reduction in molecular weights of the polycarbonate. On the other hand, with boron nitride flow remained almost unchanged upon its addition of 5 vol %. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Optimization of spinning parameters influencing the characteristics of structurally modified viscose yarn

Yarn structure influences the configuration of the constituent fibers in the yarn and the comfort properties of the fabrics to a great extent. The fiber arrangement in the yarn has a major influence on the comfort-related properties such as thermal conductivity, air permeability, wickability, and moisture vapor permeability. This study dealt with the influence of process and material variables namely, polyvinyl alcohol (PVA) proportion, twist multiplier (TM), and spindle speed on microporous viscose yarn properties. Three-variable three-factor Box and Behnken method was used to investigate the individual and interaction effects of selected variables on yarn properties. The selected variables have a significant influence on all the yarn properties. The increase in PVA%, spindle speed, and TM reduces the specific volume and wickability of yarns and increases the tenacity and packing factor of yarns before dissolving the PVA fibers. With increase in spindle speed and TM, same trend was noticed after dissolving the PVA also. But the trend reverses with increase in PVA percentage after dissolution of PVA fiber. The increase in PVA percentage increases the specific volume and wickability of yarns and decreases the tenacity and packing factor of yarns after dissolution of PVA fiber. The optimized process parameters were obtained, and yarn was spun with the optimized parameters to validate the model.     

Optimizing Diffusion Bonding Parameters in AA6061-T6 Aluminum and AZ80 Magnesium Alloy Dissimilar Joints

The main difficulty when joining magnesium (Mg) and aluminum (Al) alloys by fusion welding lies in the formation of oxide films and brittle intermetallic in the bond region which affects the integrity of the joints. However, diffusion bonding is a suitable process to join these two materials as no such characteristic defects are produced at the joints. The diffusion bonding process parameters such as bonding temperature, bonding pressure, holding time, and surface roughness of the specimen play a major role in determining the joint strength. In this investigation, an attempt was made to develop empirical relationships to predict the strengths of diffusion bonded AZ80 magnesium and AA6061 aluminum alloys dissimilar joints from the process parameters based on central composite factorial design. Response surface methodology was applied to optimize the process parameters to attain the maximum shear strength and bonding strength of the joint. From this investigation, it was found that the bonds produced with the temperature of 405.87?°C, pressure of 7.87?MPa, holding time of 29.02?min and surface roughness of 0.10???m exhibited maximum shear strength and bonding strength of 57.70 and 76.90?MPa, respectively. The intermetallic formation at the interface was identified.     

Studies on the structural,electrical and magnetic properties of LaCrO3, LaCr0.5Cu0.5O3 and LaCr0.5Fe0.5O3 by sol–gel method

The structural, electrical and magnetic properties of LaCr_0.5M_0.5O₃ (M = Cr³⁺, Cu²⁺ and Fe³⁺) synthesized by a sol–gel technique were studied. The X-ray diffraction pattern shows the structure to be orthorhombic and the size of the particles is around 100 nm as seen from the TEM images. The effects of Cu²⁺ and Fe³⁺ on the electrical properties of LaCrO₃ were studied using impedance spectroscopy at room temperature (RT). The properties of LaCr_0.5Cu_0.5O₃ were studied over a wide range of temperature from RT to 533 K. A maximum conductivity of 1.7 × 10^?3 S cm^?1 was observed for LaCr_0.5Cu_0.5O₃ at a measured temperature of 533 K. The impedance spectra indicate a negative temperature coefficient of resistance (NTCR) and also imply the conduction is through bulk of the material. The magnetic studies performed using a SQUID magnetometer interpret the antiferromagnetically ordered LaCrO₃ to behave ferromagnetically on the addition of Cu²⁺ and Fe³⁺, and the magnetization was found to be enhanced in the LaCr_0.5Fe_0.5O₃.