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Influence of rare earth metals on inclusion modification of dual phase steel Influence des metaux de terres rares sur la modification des inclusions de l'acier biphase
No full textInclusions are very critical in advanced high-strength steels as they are used in automobile and aerospace industries in which modification of inclusions is required. In this investigation, Rare Earth Metals (REM) have been used to control and modify the inclusions in the steel. With the addition of REMs, the total sulphur content present in the steel has been reduced by 22%. An inclusion study has been performed using the inclusion classifier and ISO-4967 method. Total inclusions and the number of inclusions at higher indexes (severity) are reduced by adding REM. The chemistry of the modified inclusions, such as oxides, sulphides, and oxysulphides of REM, is compatible with the steel matrix and does not have harmful effects. With the addition of REM, the global cleanliness index value at 1.5, 2, 2.5, and 3 indexes are decreased. This may be attributed to the REM breaking down the stringers. Whereas value has been increased at 0.5 and 1 indexes after the addition of RE metals, inclusions sizes are reduced, which is not harmful to the properties of the steel
Design and characterization of Cameroonian pegmatite-calcined clay binary mortars via geopolymerisation
No full textIn this work, geopolymer binders obtained from a mixture of Cameroonian pegmatite and type 1/ 1 calcined clays (metakaolin and metahalloysite) at different proportions (10-30 wt%) were used for the formulation of mortars. The kinetic parameters of the reactivity of the pegmatite mixed with different calcined clays in an alkaline medium were evaluated via the heat of reaction data measured at an isothermal conduction calorimeter (ICC) at 27 degrees C for the first 24 h. As feedstock precursors, the different products obtained were characterized by means of mechanical flexural and compressive resistances (dry and wet), physical properties, Fourier Transform infrared spectroscopy and Scanning Electron Microscope. The results showed that the compressive strength values vary with the type and percentage of calcined clays. The highest values were achieved with mortars containing 30 wt% of the different calcined clays, ranging from approximately 25-35 MPa in dry conditions. The flexural strength values of the mortars increase also with the incorporation of calcined clay and vary from 1.0 to 4.5 MPa. After 72 h of immersion of these samples in water, they lost less than 60% of their mechanical performance. The water absorption rate of the mortars decreases with the incorporation of calcined clays and ranges from 7.5 to 13.8%. FT-IR indicated the reactivity of pegmatite during the geopolymerisation process while SEM micrographs exhibited a better cohesion between the aggregates (river sand, 200 & mu;m & LE; ɸ & LE; 2000 & mu;m) and the binder. The above-mentioned pegmatite-calcined clay mortars appear to be a suitable candidate for engineering applications (civil engineering)
Efficacy of Pilot Scale Batac Jig on LVC Coal Utilization for Coke Making
No full textThe focus of present research is to see the effectiveness of Pilot scale Batac jig for beneficiation of coarse (− 13 + 1 mm) low volatile coking coal from Jharia through a series experimentation wherein appropriate diverse process parameters were exploited for definitive study. The feed coal properties were measured in terms of proximate and ultimate analysis. The gross calorific value was observed as 5784 kcal/kg. The performance of jigging process observed layer wise, evidenced that the stroke length and air pressure of the process parameters were impressively provoking generation in potency of the process. The jigging experiments revealed that 24.6% ash content of concentrate was achieved with 76% yield from the feed ash content of 32.5% in top layers under optimum process conditions, whereas bottom layer contained 57.4% ash as the final reject. The jig product is promising and practicable for assured usage as blendable coking coal for making metallurgical coke
Influence of Scanning and Building Strategies on the Deformation Behavior of Additively Manufactured AlSi10Mg: CPFEM and Finite Element Studies
No full textA novel computational framework has been presented in this work for understanding the mechanical deformation behavior in additively manufactured parts. AlSi10Mg parts were additively manufactured and investigated for effects on microstructure due to changes in process parameters. The morphological characteristics of the printed parts were assessed, and 2D statistically equivalent representative volume elements (SERVEs) were created and analyzed for deformation under tension computationally with crystal plasticity finite element method (CPFEM) with a combined MATLAB and ABAQUS interactive framework. For assessing the CPFEM parameters, an interactive ABAQUS and MATLAB environment was implemented using MATLAB's genetic algorithm (GA) toolbox. Various results like von Mises stress distribution, maximum in-plane stress distribution, and L-2-norm of Green Lagrange's strain were compared, and it was found that the vulnerability of the structures is related to the change in process or build parameters. CPFEM analyses on 3D microstructures generated through DREAM. 3D further confirmed the validity of results for CPFEM in 2D. The developed 2D framework also predicted the texture that correlated well with the tension test findings. Parallely, a finite element framework was developed to study the localization effects on AM specimens due to the presence of pores. This work has reported two separate viewpoints in terms of porosity and microstructure
Finite element evaluation of fracture toughness and crack propagation in LB-PBF AlSi10Mg
No full textFracture toughness properties of additively manufactured (AM) AlSi10Mg were explored computationally in this work. FE investigation of a previous experimental work on AlSi10Mg involving varying building directions was explored through critical crack opening displacement (COD), stationary crack method and extended finite element method (XFEM). Load-displacement curves for each of the varying build cases were simulated using COD method. The knife-edge displacements from the COD models were used in separately created stationary crack models to simulate the J resistance behaviour of the models. The simulated J curves could capture the anisotropy due to the varying build conditions, and the fracture toughness values correlate well with experimental results. Further, XFEM models were created at specimen scale and a meso-scale, respectively, using a 'sub-modelling' approach. The meso-scale model could legitimately predict the crack path reported in the literature for similar build conditions. Also, a better understanding of the crack propagation behaviour in AlSi10Mg was achieved. A novel modelling strategy was established which could help in future for AM designs
Microwave-plasma induced one-step synthesis of Ni(PO3)2 nanosphere-loaded bio-waste derived N, P co-doped carbon for an asymmetric supercapacitor with prolonged life
No full textDespite significant advancements, supercapacitors are still struggling to showcase their successful commercial presence because they suffer either from low energy storage performances due to sluggish reaction kinetics or use complex and less affordable manufacturing processes. Therefore, here, we introduce a controlled microwave-plasma induced single-step process to produce a nitrogen (N) and phosphorus (P) co-doped sheet-like multilayer graphitic carbon (NPGC) coupled with an ultrasmall (average particle size of similar to 6.2 nm) nickel phosphate (NiP2O6) nanosphere (NiPO) based composite (NPGC-NiPO) electrode with optimized compositions which exhibits a remarkable capacitance (417 F g(-1) and 300.6 mF cm(-2) at 1 A g(-1)) with ultralong cycle life (93% capacitance retained even after 10000 cycles at 5 A g(-1)). Moreover, the fabricated all-solid-state asymmetric supercapacitor (ASC) of the NPGC-NiPO composite and NPGC exhibits a prolonged cycle life (96% capacitance retained even after 10000 cycles at 7.6 A g(-1)) with high capacitance values (48.1 F g(-1) and 383.3 mF cm(-2) at 0.6 A g(-1)) while operating within 1.6 V. This NPGC-NiPO composite is the first of its kind and easy to manufacture through a one-step, quick and affordable microwave process which can be further extended for developing different composites from different bio-wastes and transition metal precursors for various energy storage applications
Physics-informed machine learning models for the prediction of transient temperature distribution of ferritic steel in directed energy deposition by cold metal transfer
No full textIn-situ monitoring of the additive layer characteristics in the directed energy deposition (DED) process by any contact technology is cumbersome. A well-tested finite element (FE) model is often employed to extract transient temperature distribution during deposition. However, the numerical model pertaining to each deposition attribute is computationally expensive. In the present work, we have generated a dataset through an experimentally validated thermal model, and further multiple machine learning (ML) algorithms are applied to train datasets. Models with an accuracy of more than 99% are utilised for the prediction of transient temperature distribution. The validation of deposition attributes using experiments and numerical model suggests that the physics-informed machine learning models for cold metal transfer can be applied in the DED process
An experimental setup and segmentation method for CFU counting on an agar plate for the assessment of drinking water
No full textQuantification of bacterial colonies on an agar plate is a daily routine for a microbiologist to determine the number of viable microorganisms in the sample. In general, microbiologists perform a visual assessment of bacterial colonies which is time-consuming (takes 2 min per plate), tedious, and subjective. Some automatic counting algorithms are developed that save labor and time, but their results are affected by the non-illumination on an agar plate. To improve this, the present manuscript aims to develop an inexpensive and efficient device to acquire S.aureus images via an automatic counting method using image processing techniques under real laboratory conditions. The proposed method (P_ColonyCount) includes the region of interest extraction and color space transformation followed by filtering, thresholding, morphological operation, distance transform, and watershed technique for the quantification of isolated and overlapping colonies. The present work also shows a comparative study on grayscale, K, and green channels by applying different filter and thresholding techniques on 42 images. The results of all channels were compared with the score provided by the expert (manual count). Out of all the proposed method (P_ColonyCount), the K channel gives the best outcome in comparison with the other two channels (grayscale and green) in terms of precision, recall, and F-measure which are 0.99, 0.99, and 0.99 (2 h), 0.98, 0.99, and 0.98 (4 h), and 0.98, 0.98, 0.98 (6 h) respectively. The execution time of the manual and the proposed method (P_ColonyCount) for 42 images ranges from 19 to 113 s and 15 to 31 s respectively. Apart from this, a user-friendly graphical user interface is also developed for the convenient enumeration of colonies without any expert knowledge/training. The developed imaging device will be useful for researchers and teaching lab settings
Uranium extraction from sulphuric acid leach liquor by Cyanex®272 as intermediate in nuclear fuel cell
No full textThe uranium extraction from sulphate pregnant solution by Cyanex (R) 272 in kerosene diluent was examined. The influence of parameters affecting the extraction mechanism including Cyanex (R) 272 concentrations and equilibrium pH was investigated. At optimized conditions, the extraction efficiency of 97.1 +/- 3% U(VI) by 0.3 mol/L Cyanex (R) 272 at 27 +/- 2 degrees C in the equilibrium pH range of 3-4 was achieved from the pregnant solution containing admixtures of 3596.3 mg/L U(VI), 31.47 mg/L Th(IV), 11.01 mg/L Fe( III), 68.70 mg/L Al(III), 7.29 mg/L Mn(II), 0.57 mg/L Ce(IV), 0.49 mg/L La(III), and 0.10 mg/L Pr( IV), respectively. Maximum stripping of U(VI) from the loaded organic phase was achieved using 0.5 mol/L Na2CO3 solution. Finally, uranium from uranyl solution recovered as sodium diuranate ( Na2U2O7: 00-064-0473, density = 6.51 g/ cm(3), melting point = 1654 +/- 2 degrees C) is capable of serving as an intermediate in a nuclear fuel cell
Leaching of rare earth elements from coal ash using low molecular weight organocarboxylic acids: Complexation overview and kinetic evaluation
No full textThe study of thermodynamics and kinetics of leaching rare earth elements (REEs) is a fundamental aspect of understanding the mechanism behind the leaching process. Leaching of REEs from coal ash with an aqueous solution of organocarboxylic acid is a heterogeneous fluid-particle system. In the present study, the leaching mechanisms of these three potential organocarboxylic acids, tartaric acid, lactic acid, and citric acid were examined over a range of temperatures (30-90 degrees C) at various leaching durations. The kinetic data thus obtained were found to follow deviation from the conventional shrinking core model (SCM). A mixed mechanism model was deduced to be the optimum fit to the data with high precision (R-2 > 0.95) and desired graphical linearity with a closer interception to the origin. The aluminosilicate matrix remained unaltered after acid treatment which is the unchanged core concluded from the kinetic mechanism. Morphological analysis using Scanning Electron Microscope (SEM) and particle size determinations were suggestive of a significant reduction in grain size post-leaching with organocarboxylic acids, tartaric acid being the most effective of all