8369 research outputs found
Sort by
Enhanced thermoelectric performance of mechanically hard nano-crystalline-sputtered SnSe thin film compared to the bulk of SnSe
No full textThermoelectric thin-film architecture has the advantage over bulk by reducing further the thermal conductivity and increasing the figure of merit. The present work demonstrates the structural requirement to enhance the figure of merit and hardness of a SnSe thin film over bulk. The SnSe thin films were deposited over the glass substrate at different substrate temperatures (Ts) using the magnetron-sputtering technique. The bulk and the deposited films of SnSe were characterized by XRD, SEM, EDS, Raman spectroscopy, HRTEM, Nano-indentation, and thermoelectric properties (Seebeck coefficient, electrical, and thermal conductivities) measurement techniques. The structural, compositional, thermoelectrical, and mechanical analyses of films were used to establish the structure-property relationship for SnSe. The microstructure of the SnSe films was significantly affected by Ts. The well-evolved single-phase polycrystalline structure of the SnSe films was observed at high Ts (>= 400 degrees C). The planar orientations overlapping induced dislocations were observed at high Ts. The maximum ZT (0.83), power factor (similar to 2.43 mu Wcm(-1) K-2), and hardness (7.1 GPa) values were obtained for the SnSe film deposited at Ts = 500 degrees C. The structural modifications of SnSe thin film at high temperatures implemented by nano-crystallization, preferred orientation (111), grain boundaries, and competitive growth-induced dislocations were responsible for enhancing the figure of merit and hardness compared to bulk SnSe
Monitoring of machining process anomalies in diamond turning of Ti6Al4V alloy using transfer learning-based algorithms
No full textIn-process monitoring of anomalies in Ultra Precision Machining (UPM) can improve and ensure product quality and lower manufacturing costs, which is essentially important for industrial-scale ultraprecision manufacturing. UPM is found to be extremely sensitive towards minute instabilities; if such nascent anomalies are not detected can cause irrecoverable defects. However, the classification of the diamond-turning process through conventional monitoring techniques is challenging. This study explores the use of spectrogram-based deep learning to enable real-time, intelligent process monitoring in UPM. The vibrational signals obtained from machining are transformed into log-spectrogram images. These images obtained during machining allow the rendering of more accurate and richer features of signals, as most of the time domain signal obtained in UPM is susceptible to noise and exhibits several non-linearities. The current approach also uses Transfer Learning (TL) to address the feature selection problem. TL is adopted by using the deep learning (DL) models, which have already been developed for classifying different Images. DL pre-trained networks, including VGG19, ResNet50 and Densenet201, are studied for classifying the anomalies. These TL models are applied to the spectrogram images for the classification of normal and abnormal machining in UPM. Among the TL models, the VGG19 model yields the highest classification accuracy at 90%, which demonstrates the potential feasibility of the TL for monitoring process anomalies in UPM
Design Guidelines for Thin Diaphragm-Based Microsystems through Comprehensive Numerical and Analytical Studies
No full textThis paper presents comprehensive guidelines for the design and analysis of a thin diaphragm that is used in a variety of microsystems, including microphones and pressure sensors. It highlights the empirical relations that can be utilized for the design of thin diaphragm-based microsystems (TDMS). Design guidelines developed through a Finite Element Analysis (FEA) limit the iterative efforts to fabricate TDMS. These design guidelines are validated analytically, with the assumption that the material properties are isotropic, and the deviation from anisotropic material is calculated. In the FEA simulations, a large deflection theory is taken into account to incorporate nonlinearity, such that a critical dimensional ratio of /ℎ or 2/ℎ can be decided to have the linear response of a thin diaphragm. The observed differences of 12% in the deflection and 13% in the induced stresses from the analytical calculations are attributed to the anisotropic material consideration in the FEA model. It suggests that, up to a critical ratio (/ℎ or 2/ℎ), the thin diaphragm shows a linear relationship with high sensitivity. The study also presents a few empirical relations to finalize the geometrical parameters of the thin diaphragm in terms of its edge length or radius and thickness. Utilizing the critical ratio calculated in the static FEA analysis, the basic conventional geometries are considered for harmonic analyses to understand the frequency response of the thin diaphragms, which is a primary sensing element for microphone applications, and many more. This work provides a solution for microelectromechanical system (MEMS) developers to reduce cost and time while conceptualizing TDMS designs
Effect of inter-critical annealing atmosphere on microstructure and subsequent corrosion behavior of hot-dip galvanized Mn containing high-strength steel
No full textA systematic study is performed on the development of hot-dip galvanized coatings on an Mn-containing high-strength steel sheet by varying the dew point (- 50, - 10, and + 10 degrees C) during inter-critical annealing of the steel strip at 800 degrees C. It also studies the effect of dew point on the corrosion behavior of the coatings in freely aerated 3.5 wt% NaCl solution. The reducing gas atmosphere consists of 95% N-2 and 5% H-2, where inter-critical annealing is carried out. Surface oxidation of the steel has a strong effect on the development of sound coating. A defect-free adherent galvanized coating is obtained on the annealed steel surface at a fixed dew point of + 10 degrees C, and it is attributed to the fine and continuous compact Fe-Al crystals compared to galvanized coatings produced at other dew points as well as the highest atomically dense (0002) basal plane. This also leads to the lowest corrosion rate (similar to 0.164 mm y(-1), where mm and y stand for millimeter and year, respectively) of the galvanized coating produced at a dew point of + 10 degrees C when compared with galvanized coatings produced at dew points of - 50 degrees C (similar to 0.279 mm y(-1)) and - 10 degrees C (similar to 0.259 mm y(-1)). The lowest corrosion rate of the galvanized specimen developed at + 10 degrees C dew point can be attributed to the uniform and defect-free coating surface, together with the dominance of the more atomically dense (0002) basal plane
Influence of tool rotational speed on mechanical and corrosion behavior of friction stir processed AZ31/Al2O3 nanocomposite
No full textNano-sized reinforcements improved the mechanical characteristics efficiently by promoting more implicit particle hardening mechanisms compared to micron-sized reinforcements. Nano-sized particles lessen the critical particle solidification velocity for the swamp and thus offer better dispersal. In the present investigation, friction stir processing (FSP) is utilized to produce AZ31/Al2O3 nanocomposites at various tool rotation speeds (i.e., 900, 1200, and 1500 rpm) with an optimized 1.5% volume alumina (Al2O3) reinforcement ratio. The mechanical and corrosion behavior of AZ31/Al2O3-developed nanocomposites was investigated and compared with that of the AZ31 base alloy. The AZ31 alloy experienced a comprehensive dynamic recrystallization during FSP, causing substantial grain refinement. Grain-size strengthening is the primary factor contributed to the enhancement in the strength of the fabricated nanocomposite. Tensile strength and yield strength values were lower than those for the base metal matrix, although an upward trend in both values has been observed with an increase in tool rotation speed. An 19.72% increase in hardness along with superior corrosion resistance was achieved compared to the base alloy at a tool rotational speed of 1500 rpm. The corrosion currents (Jcorr) of all samples dropped with an increase in the rotational speed, in contrast to the corrosion potentials (Ecorr), which increased. The values of Jcorr of AZ31/Al2O3 were 42.3%, 56.8%, and 65.5% lower than those of AZ31 alloy at the chosen rotating speeds of 900, 1200, and 1500 rpm, respectively. The corrosion behavior of friction stir processed nanocomposites have been addressed in this manuscript which has not been given sufficient attention in the existing literature. Further, this work offers an effective choice for the quality assurance of the FSP process of AZ31/Al2O3 nanocomposites. The obtained results are relevant to the development of lightweight automobile and aerospace structures and components.& COPY; 2023 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open-access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ) Peer review under responsibility of Chongqing Universit
A Review on Recovery of Terbium from Primary and Secondary Resources: Current State and Future Perspective
No full textRare earth elements (REEs) are essential for high-tech and low-carbon economies. Achieving global net-zero emissions by 2050 would require a significant increase in mineral input, including 3-7 times more REEs. At present, there are no direct high-grade ores of heavy REs like terbium. Bastnasite, monazite, and xenotime are the primary sources of terbium, while southern Chinese ion-adsorption clays are the richest commercial sources. To address the scarcity of rare earth resources, countries lacking RE deposits should focus on developing innovative and economically viable recycling techniques for the recovery of REs like terbium from different secondary resources. Spent fluorescent lamp phosphor powder represents a potential secondary resource for terbium recovery, although research efforts have been focused mostly on other REEs than Tb as value-added products. Hydrometallurgical processing is widely employed to extract terbium from different resources. The present review systematically summarizes in detail the major recovery/separation techniques used and critically evaluates the potential of terbium recovery from mineral resources and end-of-life fluorescent phosphor wastes. The advantages and limitations of each of these technologies have been provided. The objective is to foster valuable insights for researchers and the development of economical and promising extraction technologies for the recovery of terbium
Low-density nano-precipitation hardened Ni-based medium entropy alloy with excellent strength-ductility synergy
No full textThe development of advanced structural materials with a synergistic combination of strength and ductility is currently one of the thrust areas of research for material scientists. An alloy design strategy for such materials takes into consideration the ease of processing, density reduction, and economic viability along with unprecedented mechanical properties. The present study reports a low-density, low-cost medium entropy alloy, designed based on the CALPHAD approach, for structural applications. The designed Ni-Fe-Cr-Al based alloy was cast, homogenized and cold rolled to 75% thickness reduction. The cold-rolled full hard material was isothermally annealed at 900 degrees C for varying duration with a quest for an in-depth understanding of static recrystallization mechanisms. The specimens annealed at 900 degrees C for varying durations were aged at 600 degrees C for 5 h. Based on the systematic understanding of recrystallization and precipitation mechanisms involved, a suitable thermomechanical process route was judicially selected for the designed alloy, which contributed to an excellent combination of high tensile strength of > 1 GPa accompanied by an appreciable total elongation of > 50%. This superior strength-ductility synergy surpassed the strength-ductility combination of many existing medium and high entropy alloys and can be investigated further to assess its potential applications in challenging existing solid solution (SS) strengthened superalloys
Corrosion and in vitro characteristics of cerium phosphate-based chemical conversion coating on AZ31 magnesium alloy
No full textA two-stage chemical conversion coating procedure was proposed for cerium phosphate-based coating on Mg alloys. Initially, a layer of magnesium phosphate was obtained and the cerium phosphate-based coatings were achieved by immersing the precoated sample in a cerium nitrate solution prepared in either water or ethanol. The resultant coating obtained from a water-based nitrate bath consisted of oxides and hydroxides of cerium in addition to cerium phosphate. On the other hand, due to the lack of OH- ions in ethanol-based nitrate bath, oxides, and hydroxides were suppressed and cerium phosphate-rich coating was obtained. Scratch test and scanning vibrating electrode analysis confirmed the self-healing characteristics of the water-based coating due to the presence of cerium oxide and hydroxide in the coating. The detailed corrosion studies revealed that the ethanol-based coating exhibited superior corrosion resistance in both 1 wt% NaCl as well as in simulated body fluid due to the high stability of cerium phosphate in both test conditions. Both the coatings displayed acceptable cell viability (MG63 cell line) under physiological conditions and hence have the potential for both engineering and biomedical applications
Souvenir of One Week One Lab - CSIR-NML
No full textHon’ble Minister of Science and Technology and earth Sciences, Dr. Jitendra Singh highlighted that every 37 CSIR laboratory is unique and their focus in the diverse areas including minerals to materials, genome to geology, food to fuel, and many more. To showcase and publicize such diversity in the CSIR’s technological breakthroughs and innovations across society, Hon’ble Minister announced “One Week One Lab (OWOL)" campaign nationwide to showcase the in the CSIR labs. In order to fulfil the objectives of the OWOL campaign, CSIR-National Metallurgical Laboratory, Jamshedpur, India is participating to demonstrate its technologies, innovations, and undergoing and futuristic ideas for the benefit of the society. The CSIR-NML OWOL is comprises of the various activities including displaying of existing technologies and futuristic ideas, Shilpakar Mela, workshops
on (1) rare earth materials, (2) materials challenges in unlocking the hydrogen era, Jigyasa program for students-scientists interactions, academic-industry-entrepreneur-scientist meet to bridge the gap between them so that the hands can be joined to work collaboratively.
The purpose of the CSIR-NML OWOL event is to identify the needs of regions, industry – develop and provide desired scientific solutions, to develop collaboration with states and industry for deployment and commercialization, to identify the potential industry for the co-development of next-gen technologies & products, to create networks of government-academia-industry for faster delivery and
deployment, to motivate youngsters and budding entrepreneurs to create start-ups and many more
Facile Synthesis of Citric Acid Functionalized Fe3O4@Activated Carbon Magnetic Nanocomposite for Efficient Adsorption of Brilliant Green Dye from Wastewater
No full textOwing to the impact of brilliant green dye on potable water contamination, citric acid functionalized magnetic nanocomposite in the presence of activated carbon was prepared for easy, quick, and efficient removal of the dye from water. Batch adsorption studies were conducted to maximize the adsorption efficiency by optimizing contact time, initial dye concentration, pH, dosage, and salt concentration. The maximum efficiency of the citric acid functionalized Fe3O4@activated carbon was found to be 773 mg g(-1). The efficiency of the monolayer adsorption process as depicted in the Langmuir model is explained based on the hydrogen bonding, electrostatic interaction, and porosity of the adsorbent. The adsorption process follows a pseudo-second-order kinetics model which can also be correlated to the relatively quick adsorption process. The saturation magnetization of the nanocomposites prepared in the presence of activated carbon was found to be 35.2 emu/g, which makes it effective for quick magnetic separation. Built on the findings, we report an economical, efficient, and satisfactory alternative adsorbent for the abatement of brilliant green dye from colored wastewater and contaminated water sources