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Tailoring of Visible to Near-Infrared Active 2D MXene with Defect-Enriched Titania-Based Heterojunction Photocatalyst for Green H2 Generation
No full textA wide solar light absorption window and its utilization, long-term stability, and improved interfacial charge transfer are the keys to scalable and superior solar photocatalytic performance. Based on this objective, a noble metal-free composite photocatalyst is developed with conducting MXene (Ti3C2) and semiconducting cauliflower-shaped CdS and porous Cu2O. XPS, HRTEM, and ESR analyses of TiOy@Ti3C2 confirm the formation of enough defect-enriched TiOy (where y is < 2) on the surface of Ti3C2 during hydrothermal treatment, thus creating a third semiconducting site with enough oxygen vacancy. The final material, TiOy@Ti3C2/CdS/Cu2O, shows a broad absorption window from 300 to 2000 nm, covering the visible to near-infrared (NIR) range of the solar spectrum. Photocatalytic H-2 generation activity is found to be 12.23 and 16.26 mmol g(-1) h(-1) in the binary (TiOy@Ti3C2/CdS) and tertiary composite (TiOy@Ti3C2/CdS/Cu2O), respectively, with good repeatability under visible-NIR light using lactic acid as the hole scavenger. A clear increase of efficiency by 1.53 mmol g(-1) h(-1) in the tertiary composite due to NIR light absorption supports the intrinsic up conversion of electrons, which will open a new perspective of solar light utilization. Decreased charge-transfer resistance from the EIS plot and a decrease in PL intensity established the improved interfacial charge separation in the tertiary composite. Compared to pure CdS, H-2 generation efficiency is 29.6 times higher on the noble metal-free tertiary composite with an apparent quantum efficiency of 12.34%. Synergistic effect of defect-enriched TiOy formation, creation of proper dual p-n junction on a Ti3C2 sheet as supported by the Mott-Schottky plot, significant NIR light absorption, increased electron mobility, and charge transfer on the conductive Ti3C2 layer facilitate the drastically increased hydrogen evolution rate even after several cycles of repetition. Expectantly, the 2D MXene-based heterostructure with defect-enriched dual p-n junctions of desired interface engineering will facilitate scalable photocatalytic water splitting over a broad range of the solar spectrum
Effect of Weld Line Energy on Mechanical Properties and Formability of Cold Metal Transfer-Welded Dissimilar DP600-780 Thin Sheets
No full textIn this study, the effect of weld line energy (WLE) and root gap on the mechanical properties and formability of cold metal transfer-welded dissimilar dual-phase (DP) steel thin sheets was investigated. 1.2-mm sheets of DP600 and DP780 were joined with varying WLE 66.45 J/mm to 219.34 J/mm at zero and 0.2-mm root gap. The microstructural features and mechanical properties were analyzed through field emission scanning electron microscopy, Vickers microhardness analysis, uniaxial tensile test and Erichsen cupping tests. The results indicate that WLE and root gap significantly affect the bead shape, formability, tensile strength and microhardness. The joints with root gap exhibited superior mechanical properties and formability compared to zero-gap joints. The highest tensile strength (668.35 MPa) and hardness (367 HV0.5) were achieved for joints with 0.2-mm gap at 66.45 J/mm. This joint also achieved the highest joint efficiency (102.59 %) and the least heat-affected zone (0.828 mm). The highest Erichsen index (6.82 mm) was achieved for 219.34 J/mm joint with 0.2-mm root gap. Fractography results confirmed ductile fracture
Elimination of Wettability Issues in Interstitial Free High Strength (IFHS) Steel by Controlling the Annealing Atmosphere
No full textIn this investigation, a thermodynamic study was performed to predict the type and amount of possible oxides formed on interstitial-free high-strength (IFHS) steel substrate surface during the annealing treatment prior to dipping in a liquid zinc alloy bath. This study was carried out based on the CALPHAD approach using the thermodynamic simulation software package Thermo-Calc by varying the annealing temperature and annealing atmosphere (dew point and gas composition). The experiments were performed on IFHS-350 grade steel substrate using hot-dip process simulator (HDPS) for varying annealing conditions (temperature: 780-830 degrees C and dew point: - 30 to + 10 degrees C). The specimens were characterized in as-annealed condition as well as after hot dipping in the galvanizing bath. This investigation was performed to find out the suitable combinations of annealing temperature and dew point for developing a good quality coating on IFHS grade steel substrate by eliminating the wettability issues. Good quality coating, free from bare spots, was obtained using an annealing gas atmosphere having 5%H2 and 95%N2 at (a) 780 degrees C with - 30 degrees C dew point, (b) 805 degrees C with - 10 degrees C dew point and (c) 830 degrees C with + 10 degrees C dew point. In general, coating quality was improved with low annealing temperatures and low dew point or high annealing temperature and high dew point conditions
Creep rupture study of dissimilar welded joints of P92 and 304L steels
No full textThe present work investigates the high-temperature tensile and creep properties of the dissimilar metal weld joints of 304L austenitic stainless steel (SS) and P92 creep strength-enhanced ferritic-martensitic (CSEF/M) steel under different testing conditions. Thermanit MTS 616 filler rod (P92 filler) and the multi-pass tungsten inert gas (TIG) welding process were used to create the dissimilar weld connection. The ultimate tensile strength (UTS) was evaluated in the temperature range of 450-850 degrees C. Creep testing was conducted at a temperature of 650 degrees C while applying stress levels of 130 MPa, 150 MPa, 180 MPa, and 200 MPa. The shortest creep life (2.53 h) was recorded for the specimen tested at 650 degrees C and subjected to 200 MPa, whereas the longest creep life (similar to 242 h) was observed for the specimen tested at 650 degrees C with a stress of 130 MPa. The linear regression model was developed using an applied stress (sigma) v/s rupture time (t(R)) plot at 650 degrees C. The applied stress and rupture time followed the logarithmic equation: log(t(R)) = 22.57566 + (-9.55294) log (sigma). The detailed microstructural characterization and micro-hardness distribution across the fractured specimens was carried out. The findings demonstrated that the service life span of this weld joint at high temperature and stress conditions is influenced by the undesired microstructural changes at elevated temperature, such as coarsening of the precipitates, development of the Laves phase, softening of the matrix, and strain-aging phenomenon
Making low-carbon energy sustainable
No full textLow-carbon energy capacity continues to grow, facilitating the much-needed transition away from fossil fuels. However, broader sustainability issues remain
CSIR-NML Annual Report 2023-2024
Get PDFIt contains the statement of R&D works undertaken, achievements made, and the expenditure by the laboratory during the financial year 2023-2024
Creep and High-Temperature Tensile Deformation Behavior of the TIG Welded P92/304L Dissimilar Steel Weld Joints
No full textCreep life, high-temperature tensile properties of creep strength enhanced ferritic-martensitic P92 steel and austenitic 304L stainless steel (SS) dissimilar weld joint were investigated. DWJ was prepared using tungsten inert gas welding process employing ERNiFeCr-2 (Inconel 718) filler metal. The creep tests were conducted at 650 degrees C under stresses ranging 80-180 MPa; and rupture times 1789.8 and 25.4 h were measured at 80 and 180 MPa, respectively. The micro-hardness investigations showed failure from base metal, P92 steel, irrespective of the creep testing condition. The early creep failure observed in P92 steel was mainly due to the formation of the laves phase and precipitation strengthening from coarsening of precipitates. The tensile and yield strengths were evaluated at temperatures ranging 450-850 degrees C to examine P92/304L weld joint strength; and strengths were found to decrease with the rise in temperature. From tensile test, it was observed that there were two types of fracture locations, which were base metals of 304L SS and P92 steel, respectively. The specimens failed from the base metal of 304L at 450 and 550 degrees C. P92 steel underwent significant strength reduction at 650 degrees C, and similar failure was also noticed in the base metal of P92 steel at 650-850 degrees C
Distribution of trace elements and rare earth elements in coal from the Bhalukasba Surni coal block, Rajmahal coalfield, Eastern India
No full textExploration of secondary resources for isolation of valuable constituents, such as rare earth elements (REEs) and trace elements (TEs), is of importance owing to the need to identify new domestic sources and reduce reliance on imports. The present study systematically discusses the distribution of REEs and TEs in core samples from the coal block of Bhalukasba Surni {(B1(125 m)-B9 (409 m)} located in Rajmahal coalfield, Jharkhand, India, which has not been investigated previously for its geochemistry. The studied coal samples were found to be enriched in TEs whose abundances were in the order of Mn > Mo > Zr > Ni > Cr > V > Cu > Zn > Pb, and REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er, Tm, Yb, Lu) along with Sc and Y. The average concentration of REEs with yttrium (ΣREY) on an ash basis was 528 ppm, which is significantly higher than the world average for coal ash (435 ppm). Of the samples investigated, B3 (182–184 m) and B8 (396–399 m) demonstrated relatively higher concentrations of potentially economic elements, with B3 containing a higher proportion of middle to heavy REEs Gd, Dy, Ho and Er, and B8 showing relative enrichment in Nd and Y. On dry whole coal basis, B6 (275–278 m) showed a considerably higher concentration of Ge (55 ppm) than other samples, whereas the concentration of Zr varied in the range of 90–160 ppm in the whole coal block. X-ray diffraction studies revealed the presence of quartz, keatite, hematite, zircon, anatase and orthoclase in the coal ash samples prepared at 815 °C. REEs exhibited prominent positive correlation with Al2O3 (0.4 0.9) which is supportive of their residence in primary clay minerals such as kaolinite and illite-smectite. Additionally, a positive correlation of REEs with P2O5 (0.4 0.9) suggests their association with phosphate minerals (such as monazite, xenotime, apatite). Positive correlation with TiO2 (r > 0.7) corroborates the possible association of REEs with anatase. The morphology of the coal ash samples viewed in SEM showed the presence of Al2O3 and SiO2 enriched irregular-sponge particles likely derived from partly-fused clay minerals, which accounted for the lower extent of REE encapsulation. The Bhalukasba Surni coal block is potentially of economic importance due to its enrichment in Ge, Zr, and the REEs
Microstructure, mechanical and electrochemical behavior of magnetron-sputtered carbothermic reduced iron-boride ceramic coatings
No full textIn this study, magnetron sputtered carbothermic reduced iron boride (FeB) coatings were developed on grey cast iron (GCI) substrates at different substrate temperatures. The impact of substrate temperature on structural, mechanical, and corrosion behavior was examined for two FeB deposition scenarios: FeB coatings deposited at room temperature (RT) and at 500 degrees C substrate temperature. The evolution of phases and microstructure was studied using XRD and FESEM, respectively. The mechanical properties, creep, deformation behavior, and adhesion strength (scratch test) of the deposited coatings were investigated using nanoindentation at ambient temperature. The highest hardness and Young's modulus of 16 GPa and 231 GPa respectively, were achieved at 500 degrees C due to microstructural enhancement. Potentiodynamic polarization and electrochemical impedance spectroscopy were used to evaluate the corrosion behavior of the coatings. The results show that substrate temperature strongly influences the surface morphology of the coatings, which in turn governs the mechanical and corrosion behavior of the FeB coating. The FeB-coated GCI at 500 degrees C substrate temperature showed higher resistance to scratching, better mechanical properties, and improved corrosion resistance which is attributed to the enhanced adhesive strength, refined microstructure, and formation of protective oxide layers of FeB on the surface of the coatings
Outlook of Solid-State Electrolytes: A Boost in Next-Generation Li-Metal-Based Solid-State Batteries
No full textSolid-state electrolytes (SSEs) are emerging as highly promising alternatives to conventional organic liquid electrolytes due to their exceptional performance across a broad spectrum of temperatures, enhanced safety profiles, and superior energy densities. Their intrinsic properties, including thermal and electrochemical stability, significant ionic conductivity, and notable energy density, position SSEs at the forefront of next-generation rechargeable battery technologies. This review provides a comprehensive examination of the latest advancements in SSE technology, encompassing a diverse array of materials including thioborates, hydroborates, silicates, lithium nitrogen sulfides (LNS) with antifluorite structures, double perovskites, double antiperovskites, and composite polymer electrolytes. Moreover, this review depicts a brief overview of various fabrication techniques for thin-film electrolytes, highlighting the intricacies of each method and thereby offering insightful perspectives that are valuable for future researchers and scientists aiming to advance this field