Surface modification and characterization of zirconium carbide particulate reinforced C70600 CuNi composite fabricated via friction stir processing

In the present research work, Friction stir processing (FSP) technique has been applied to develop a C70600 graded copper-nickel (CuNi) Surface metal matrix composite (SMMC) reinforced with and without addition of ZrCp. Rotational and traverse speeds were set as 1200 rpm and 30 mm/min, respectively. The fabricated SMMC were metallurgically characterized by using Optical microscope (OM) and Field emission scanning electron microscope (FESEM). The homogeneous distribution of ZrC particles and good interfacial bonding between matrix/reinforcement were observed via OM and FESEM microscopes. The microhardness of the CuNi/ZrC surface composite was observed by using microhardness tester at the cross section of the sample. The average higher microhardness of 148 Hv at CuNi/ZrC SMMC and lower microhardness of 115 Hv at FSPed CuNi was found. The Ultimate tensile strength (UTS) value was measured by using micro tensile testing machine. The UTS value of CuNi/ZrC composite and FSPed CuNi were observed to be 310 MPa and 302 MPa, respectively. The mode of fracture was also observed via FESEM. The X-ray diffraction (XRD) test was carried out to confirm the presence of CuNi & ZrC in the SMMC layer.     

Effect of Traverse Speed on Microstructure and Microhardness of Cu/B4C Surface Composite Produced by Friction Stir Processing

Friction stir processing (FSP) has evolved as a potential candidate to fabricate surface composites. This paper investigates the influence of traverse speed on microstructure and microhardness of Cu/B₄C surface composite fabricated using FSP. The traverse speed was varied from 20 to 60 in steps of 20 mm/min. The tool rotational speed, axial force and groove width were kept constant. Optical microscopy and scanning electron microscopy were employed to study the microstructure of the fabricated surface composites. The results indicated that the traverse speed significantly influenced the area of the surface composite and distribution of B₄C particles. The area of the surface composite was found to bear an inversely proportional relationship to traverse speed. Lower traverse speed exhibited homogenous distribution of B₄C particles while higher traverse speed caused poor distribution of B₄C particles in the surface composite.     

喷雾热解法在硅衬底上生长定向碳纳米管阵列(英文)

以向日葵油的甲基酯为碳源,二茂铁为催化剂前驱体,Ar为载气,通过喷雾热解法在硅衬底上合成定向碳纳米管阵列。结果表明,在硅衬底上原位形成Fe催化剂纳米颗粒。由拉曼光谱、透射电镜图和X-射线衍射谱图显示所制定向碳纳米管阵列具有较好的石墨化程度,其直径为1 0～3 0 nm,管壁约为1 0 nm。所制定向碳纳米管阵列中残留的催化剂含量可以忽略。     

A micromechanical fracture analysis to investigate the effect of healing particles on the overall mechanical response of a self‐healing particulate composite

A computational fracture analysis is conducted on a self‐healing particulate composite employing a finite element model of an actual microstructure. The key objective is to quantify the effects of the actual morphology and the fracture properties of the healing particles on the overall mechanical behaviour of the (MoSi₂) particle‐dispersed Yttria Stabilised Zirconia (YSZ) composite. To simulate fracture, a cohesive zone approach is utilised whereby cohesive elements are embedded throughout the finite element mesh allowing for arbitrary crack initiation and propagation in the microstructure. The fracture behaviour in terms of the composite strength and the percentage of fractured particles is reported as a function of the mismatch in fracture properties between the healing particles and the matrix as well as a function of particle/matrix interface strength and fracture energy. The study can be used as a guiding tool for designing an extrinsic self‐healing material and understanding the effect of the healing particles on the overall mechanical properties of the material.     

Studies on the effect of weld defect on the fatigue behavior of welded structures

Structural integrity isstated as the science and technology of margin between safety and disaster. Systematic prediction of structural integrity of critical structures such ascombustion chambers,pressure vessels,nuclear reactor components,boilers etc.,ensures the human safety,environmental protection,and the economical considerations.The present work aims at prediction of fatigue behaviour of symmetric structures like pressure vessels in the presence of common welding defects such as lack of fusion( LOF),lack of penetration( LOP) and porosity.A ring type specimen which replicates the stress pattern in thepressure vessel is considered for the study of severity of weld imperfections. Initial dimensions of weld defects are arrived by performing NDT inspection.Crack growth analysis is carried out to determine the remaining life of the welded joint with defects.     

Influence of materials and machining parameters on WEDM of Al/AlCoCrFeNiMo0.5 MMC

The current study intends to optimize the wire electric discharge machining (WEDM) parameters while machining the newer AlCoCrFeNiMo_0.5 high entropy alloy (HEA) particles-reinforced aluminum composites. AlCoCrFeNiMo_0.5 HEA particles produced through arc melting technique are reinforced here for different weight % (0%, 3%, 6%, 9%, 12%, and 15%) along with pure aluminum by the way of powder metallurgy. WEDM studies were conducted by varying the appropriate parameters, namely, pulse ON time, pulse OFF time, and wire feed. Based on the selected parameters, through Taguchi method L18 orthogonal array is designed; the optimal parameter combination for better surface finish, material removal rate (MRR), and reduced kerf width (KW) is identified. For better understanding, through ANOVA, also the effect of each input variables over these adopted response variables was analyzed. The yielded results reveal that addition of AlCoCrFeNiMo_0.5 HEA as reinforcement has considerable effect over the response variablessuch that MRR and KW reduces; surface roughness increases with increase in HEA %. ANOVA results confirm that pulse ON time has higher effect over the response variables than any other parameters involved for the study. Multi-objective optimization done through Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) methodology answers that MRR and surface finish have improved, whereas KW gets reduced noticeably.     

Effective removal of cationic methylene blue dye using nano-hydroxyapatite synthesized from fish scale bio-waste

Nano-hydroxyapatite (NHAp) with a novel rod shape was synthesized from an economical and easily accessible Labeo rohita fish scale bio-waste by facile and straightforward alkaline heat treatment method. The purity, functionality, morphology, and surface area of the green synthesized NHAp powder were well-characterized via X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET). The TEM and BET results indicate that the apatite is prepared as a rod-like particle and highly porous with high surface area (112.36 m² g⁻¹). The NHAp powder was used for the adsorptive removal of cationic dye-methylene blue (MB) from the aqueous samples. Batch experiments were performed to evaluate the mechanism of adsorption and kinetic models. The NHAp achieved an enhanced adsorption efficiency (666.67 mg g⁻¹) for the adsorption process. The obtained results perfectly obeyed the pseudo-second-order model, and the Langmuir isotherm exhibited an excellent relationship with the experimental data. Furthermore, thermodynamic studies reveal that the adsorption process was exothermic and spontaneous. Thus, the results proved that Labeo rohita fish scale bio-waste derived NHAp can be inventively utilized as a cost-effective and eco-friendly adsorbent for wastewater treatment.     

Effects of Silt Content and Void Ratio on the Saturated Hydraulic Conductivity and Compressibility of Sand-Silt Mixtures

The hydraulic conductivity, the coefficient of consolidation, and the coefficient of volume compressibility play major roles on the pore pressure generation during undrained and partially drained loading of granular soils with fines. This paper aims to determine how much these soil parameters are affected by the percentage of fines and void ratio of the soil. The results of a large number of flexible wall permeameter tests performed on 60 specimens of two poorly graded sands with 0, 5, 10, 15, 20, and 25% nonplastic silt are presented and discussed. Hydraulic conductivity measurements were done at effective confining stresses of 50–300 kPa. The evaluation of the data shows that the hydraulic conductivity and the coefficient of consolidation of sands with 25% silt content are approximately two orders of magnitude smaller than those of clean sands. The coefficient of volume compressibility of the sand-silt mixtures is affected in a lesser degree by void ratio, silt content, and confining stress. The influence of the degree of saturation on the laboratory-measured k values is also discussed.     

Laser damage threshold,antimicrobial efficacy and physicochemical properties of an organometallic L-proline lithium chloride monohydrate single crystal for NLO application and optoelectronic device fabrication

The potential metalorganic L-proline lithium chloride monohydrate single crystal was grown by slow evaporation method for evaluating optoelectronic device fabrication. From the single crystal XRD studies, the grown crystal was confirmed the molecular packing in monoclinic crystal lattice. The powder XRD data confirm the phase purity of the grown crystal. Vibrational absorption band assignments were recognized by FTIR and FT-Raman spectrum and they confirmed the presence of multiple functional groups in the grown crystal structure. Optical properties of the grown crystal were studied by using transmittance and absorption spectrum of UV–Vis–NIR analysis. The dielectric response of the grown crystal was studied in the frequency range between 50 Hz and 2 MHz for four temperature gradients. From the microhardness study, some mechanical parameters such as fracture toughness, brittleness index and yield strength were calculated. The photoluminescence activity of the grown crystal was deliberate in terms of optical peaks. The amino group participation over the optical scattering nodal regions for generating radiation absorption process to fascinate optical endurance was studied. TG/DTA curve shows that the LPLCM crystal was thermally stable up to 132 °C. The laser damage threshold value of the grown crystal was measured using multishot mode and it was found to be 7.78 GW/cm². The fractionation of the etching time prevents lattice from over etching and degradation of the mechanical properties of the grown crystal. LPLCM crystal showed higher antibacterial activity against one gram positive and one gram negative bacterial species. Second order nonlinear optical efficiency of the LPLCM crystal was studied at 1064 nm generated by a nanosecond pulsed Nd:YAG laser source.

     

Influence of friction stir processing parameters on surface modified 90Cu-10Ni composites

Friction Stir Processing (FSP) has emerged as a distinctive and pioneering solid state technique to produce surface composites. The objective of the present research is to produce reinforced 90/10 Copper–Nickel surface composites with different carbide-based ceramic particles through FSP and study the relationship of its dynamic parameters including tool rotational speed, tool traverse speed, and width of the groove over the surface behavior. Responses such as sliding wear, microhardness, and surface modified area in the friction stir processed region are modeled using polynomial, nonlinear, multiple regression based on the central composite design of experiment. Analysis of the developed models showed that the FSP parameters; traverse speed, rotational speed, and groove width have significant influence on both the sliding wear and microhardness of developed surface composite. And furthermore, tool rotational speed and tool traverse speed, simultaneously control dispersion of reinforcement in the surface. To validate the abovementioned noteworthy results and to study the microstructural aspects, selected specimens were carried over metallurgical analysis and the obtained results were put forward in detail in this paper.