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Utilizing a sustainable surfactant from Cucurbita pepo seeds for eco‑friendly flotation of non‑coking coal in sustainable energy applications
No full textFatty acids are being explored as promising collectors in coal flotation as they consist of both polar heads and non-polar aliphatic tails. In the present study, the fatty acid–rich oil extracted from Cucurbita pepo (Cp) seeds by Soxhlet extraction was used as a bio-based surfactant to reduce ash in non-coking coal by flotation. The FTIR and GCMS were used to investigate the functional groups and free fatty acid composition of the extracted oil respectively. The molecular conformation was identified using NMR spectroscopy. The extracted Cp oil was primarily composed of linoleic acid (64.17%) and oleic acid (11.54%). The extracted oil was utilized as a bio-based surfactant to float high ash non-coking coal, taking advantage of the oil’s fatty acid content. Taguchi’s design of experiments was used to optimize flotation process parameters such as collector dosage (extracted Cp oil), frother dosage (MIBC), and airflow rate. ANOVA analysis was conducted to determine
the significance of the process parameters. It was observed that frother dosage played the most significant role in achieving optimal ash rejection, followed by collector dosage and airflow rate. The optimized conditions for combustible recovery were an airflow rate of 2.0 l pm, collector dosage of 3.5 ml, and frother dosage of 0.35 ml. For optimal combustible recovery (92.15) and separation efficiency (67.77), the airflow rate had the highest impact, followed by collector and frother dosages. From the XRD analysis, it was found that the major gangue, namely, quartz and kaolinite present in the non-coking coal, were significantly reduced in the final concentrate (float). Thus, the oil extracted from the seeds of Cucurbita pepo can be used as a bio-based surfactant in high ash, non-coking coal flotation
Implementation of different scanning strategy to improve the mechanical and wear properties of 15-5 PH stainless steel fabricated by laser-directed energy deposition
No full textIn this work, the effect of three different scan patterns (island scan pattern, island alternative scan pattern, and cross-hatch pattern) on mechanical and wear properties is investigated for 15-5 Precipitation-hardened (PH) stainless steel by using laser-directed energy deposition (L-DED). Six rectangular blocks are deposited with constant laser power and scanning speed. Currently, studies on the control of anisotropic behavior to improve the mechanical and wear properties by using different scan strategy, especially in the case of 15-5 PH grade stainless steel is relatively sparse. Therefore, it is necessary to learn how mechanical and wear properties are improving in these three different scan pattern samples. At first, the temperature data at a specific point is captured by using a non-contact type pyrometer during printing and the detailed microstructural characterization of that particular region is analyzed. All three different scan pattern samples mostly show delta-ferrite and lath martensite (alpha') structure. The X-ray diffraction shows, there is the formation of secondary precipitation phases like NbCr2, NbC, and Cu-rich precipitation in all three different scan pattern samples. The electron back-scattered diffraction (EBSD) result exhibits that the island alternative scan pattern samples have mostly mixed orientation direction, a high fraction of retained austenite ((similar to)0.004), and high angle grain boundaries (HAGBs) compared to the island scan pattern and cross-hatch pattern samples. The island alternative scan pattern samples show maximum improved mechanical properties i.e. average ultimate tensile strength (UTS) of 1316 MPa and up to 20% elongation amongst all deposited samples. Similarly, the alternative island scan pattern samples exhibit a high coefficient of friction (COF) irrespective of the applied load. The SEM image of the worn surfaces demonstrates abrasion and adhesion type wear in all three different scan pattern samples
A data-driven approach to model the martensitic transformation temperature in strain-induced metastable austenitic steels
Get PDFStrain-induced metastable austenitic stainless steels form an important class of materials in metallurgical industries for their wide range of applications. These steels undergo austenite-martensite phase transformation at temperatures above martensite start temperature, Ms, at which martensite is formed on mechanical deformation, also known as the Md temperature. Md temperature depends on several factors related to the steel and is important from alloy design perspective. In the literature, there are quite a few equations based on composition of the steels for the prediction of Md temperature. However, it is well known that the transformation from austenite to martensite is dependent on the austenite grain size as well as deformation conditions i.e. strain, strain rate and temperature of deformation. In the present work, the role of those parameters has also been considered. The model is implemented using fourteen input parameters viz., composition, grain size, amount of strain, temperature of deformation, and strain rate. The architecture of the neural network model is optimized rigorously to predict the Md temperature on a par with actual value. It has been shown that grain size and strain rate have very negligible influence whereas strain and temperature of deformation have quite strong role. Md temperature is increased with increasing strain whereas the temperature of deformation shows opposite dependence on it. An empirical equation thus, has been established to calculate the Md temperature of a steel as a function of its composition, grain size, temperature of deformation and strain. The final optimized model is then deployed to predict the Md temperature of different steels and predictions are found to be in close agreement to the experimentally measured Md temperatures. The developed model is general and can be extended to include other parameters as well as various other steel alloys
Enhancing the tribological characteristics of the biocompatible Ti-6Al-4 V alloy via heat treatment: An experimental analysis
No full textThe tribological behaviour of the Ti-6Al-4 V biocompatible alloy fabricated using laser powder bed fusion (LPBF) was experimentally investigated for prosthesis implants. Annealing heat treatment was executed to improve its tribological performance. The microstructure and microhardness characterization were performed using scanning electron microscope (SEM) and Vickers microhardness. The wear test was processed using a SS304 spherical ball in simulated body fluid (SBF) at body temperature. The ball on a flat tribometer was used to determine wear rate, depth, width, and friction coefficient at 15 N. The results revealed that a needle-like martensite alpha' structure was noticed on the as-deposited sample. Microstructural characterization significantly affects wear morphologies. The heat-treated specimen showed a more desirable wear performance than the as fabricated
Sputter-deposited zirconium doped nickel-aluminide coatings for high-temperature oxidation-resistant applications
No full textZr-Ni3Al coatings were deposited over the Inconel-718 substrate using DC cosputtering. The deposition was carried out in a custom-designed chamber at a substrate temperature of 400 degrees C. The evolution of phases, microstructure, surface topography, and elemental composition were characterized using x-ray diffraction, field emission scanning electron microscopy (FESEM), atomic force microscopy, and energy dispersive spectroscopy (EDS), respectively, whereas the adhesion strength and the mechanical properties of the coatings were characterized using nanoindentation. The oxidation properties of the coatings were studied at 900, 1000, and 1100 degrees C in open air to determine the kinetics of oxidations. The results reveal that with the increase in Zr concentration in the host Ni3Al matrix, the adhesive strength and mechanical properties of the films increase. The highest hardness and Young's modulus of similar to 9.2 and similar to 150.3 GPa, respectively, are observed for 30 W Zr-Ni3Al coatings. Additionally, 1.51 at. % of Zr in Ni3Al coatings has shown the best oxidation resistance properties at all temperatures. However, an increase in the rate of oxidation has been observed with an increase in exposure temperature. The formation of different oxide layers after oxidation has been elucidated using FESEM and EDS after looking into the surface morphologies of the oxidized coatings
Efect 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 a Mn-containing high-strength steel sheet by varying the dew point (− 50, − 10, and +10 °C) during inter-critical annealing of the steel strip at 800 °C. It also studies the efect 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% N2 and 5% H2, where inter-critical annealing is carried out. Surface oxidation of the steel has a strong efect on the development of sound coating. A defect-free adherent galvanized coating is obtained on the annealed steel surface at a fxed dew point of +10 °C, and it is attributed to the fne 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 (~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 °C when compared with galvanized coatings produced at dew points
of − 50 °C (~0.279 mm y−1) and −10 °C (~0.259 mm y−1). The lowest corrosion rate of the galvanized specimen developed
at +10 °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
Improving the energy efficiency in a walking hearth type reheating furnace by energy balance method and optimizing the resources
No full textMost metal industries use reheating furnaces (RHF) for their finishing operations. This RHF is highly energyconsuming equipment that heats the material inside the chamber for rolling or shaping using the by-product gases, natural gas, or oil as fuel. It is necessary to minimize or optimize the fuel consumption to the extent possible. By analyzing the plant operating data, plant measurements, and energy balance calculation, this work aims to determine the potential for decreasing the fuel consumption of a billet reheating furnace. Predictions are made by modeling operating data to reveal the hidden problems and uncover underlying issues. The study results in increasing productivity by 11 % while oil consumption was reduced by 14 %. These actions significantly decreased carbon emissions considerably and generated significant cost savings
Development of octahedral shaped Zn2TiO4 loaded Ti3C2-TiO2 ternary composite with excellent photocatalytic efficiency
No full textThe development of highly efficient and stable earth-abundant photoanode materials for photoelectrochemical
water splitting is crucial for a sustainable energy economy. Being earth-abundant, 2D Ti3C2 MXenes have recently emerged as promising candidate for efficient photocatalytic performances. However, pristine Ti3C2and its composites suffer from poor electron–hole separation and fail to prevent the spontaneous recombination process due to the poor conductivity derived from the serious agglomeration of MXene sheets during processing. Therefore, suitable heterojunction engineering of the MXene based composites is required for their efficient photocatalytic performances. Hence, in this work, we have developed a Ti3C2-TiO2 and octahedron-shaped, nanosized Zinc titanate (Zn2TiO4) based ternary nanocomposite with optimized composition via a simple process of alkalization followed by hydrothermal. As-synthesized Ti3C2-TiO2/Zn2TiO4 (1:0.5) nanocomposite shows
a 3.7 fold augmentation in photocurrent density as compared to alkali treated Ti3C2-TiO2 at a potential of 0.9 V
vs Ag/AgCl resulted due to the facile charge transfer evidenced from its impedance analysis having lowest charge
transfer resistance. Furthermore, the Mott-Schottky measurements reveal that the as-synthesized nanocomposites
possess n-type semi conductivity and the charge carrier concentration of Ti3C2-TiO2/Zn2TiO4 (1:0.5) is almost 5.2
times higher than that of alkali-treated Ti3C2-TiO2. This work may inspire more excellent work on developing
MXenes-based photoanodes
A Comprehensive Review on Occurrence and Processing of Phosphate Rock Based Resources- Focus on REEs
No full textIn general, the phosphatic rock contains around 0.05 wt% rare earth elements (REEs). The global com-mercial phosphatic rock output is anticipated to obtain 250 million tons per year, making phosphate rocks a significant source of REEs. The review discusses the geological aspects of phosphate rocks, their availability, and methodologies to convert them to phosphoric acid and ultimately to phosphogypsum. Phosphogypsum (PG) is a high-volume by-product of phosphate-based chemical industries that produce phosphoric acid. Because of the low radioactivity of radionuclide contaminants, roughly 85% of PG is stored in open fields. These PG stacks require enormous land areas, cause substantial upkeep expenses, and may create major environmental damage. Apart from the detailed analysis of metal worth in phosphogypsum, the efforts put forth by researchers in recovering valuable rare earth elements from PG have been discussed. Additionally, the processes for metal separation and purification are also discussed in vogue
Heat Transfer and Fluid Flow During Laser Powder Bed Fusion of SS316L Stainless Steel
No full textPowder bed fusion using a laser-based (PBF-LB) process offers design freedom with an acceptable surface finish in several industrial applications. The judicial selection of the process parameters in the PBF-LB process can result in better performance of the additively manufactured products. The bead shape and size obtained in the PBF-LB process depend on the melt pool dimensions, while experimentally investigating the melt pool to understand the effect of PBF-LB process parameters is expensive and exhausting. Therefore, in the present study, melt pool dimensions are numerically envisaged for different process parameters to comprehensively understand the effect of various process parameters on the temperature distribution and molten pool size during PBF-LB of SS316L alloy. In this regard, a three-dimensional heat transfer analysis using finite element method (FEM) is attempted, and furthermore, the heat and mass transfer phenomenon in the molten pool during solidification is also analyzed utilizing finite volume method (FVM). A systematic comparison of the simulated results obtained from both methods is carried out in detail to understand the need to opt for FEM or FVM approach in predicting molten pool characteristics. The numerically predicted molten pool size is in good agreement with the experimental results