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Influence of ageing on high temperature tensile deformation of a Ni- based superalloy, HAYNES 282
No full textThe effect of ageing time and temperature on the deformation mechanism and corresponding tensile properties are investigated in a gamma/gamma ' Ni-based superalloy, HAYNES 282. Through a systematic variation in duration (24 h and 216 h) and temperature of ageing (650 degrees C and 760 degrees C), a significant variation in strengthening microstructural features was achieved in the resulting microstructures. While in one case (650 degrees C, 24 h ageing condition), a microstructure with no gamma ' was observed, for the rest of the cases, gamma ' precipitates of varied sizes were observed. In one specific case (760 degrees C, 216 h ageing condition), very fine (4-6 nm) MC carbides were observed along with gamma ' precipitates; in which these tiny MC carbides became the deciding factor for strength over gamma ' precipitates. While common knowledge of smaller gamma ' precipitates giving higher strength could explain the higher strength at 760 degrees C, 24 h ageing condition as compared to 650 degrees C, 216 h ageing condition, the further increase in strength in case of 760 degrees C, 216 h ageing condition, even with much larger gamma ' precipitates was something quite interesting and counterintuitive. This paper elucidates this puzzling observation. The variation of tensile properties of these wide varieties of microstructures will be described in this paper in light of the underlying deformation mechanisms. A change in deformation mechanism from planar slip (microstructure with no gamma ') to twinning (microstructure with gamma ') and Orowan-looping (microstructure with gamma ' along with fine nano carbides) as a function of microstructure explains the difference in strength, ductility, and strain hardening phenomena among the varied ageing conditions.(c) 2022 Elsevier B.V. All rights reserved
Synthesis and characterization of sputter-deposited Ni-rich Ni3Al hard coatings
No full textNi3Al and Nickel (Ni) rich Ni3Al thin films were deposited on Si (100) substrate by magnetron sputtering and co-sputtering process respectively. Variations in elemental composition, microstructure, surface topography, and mechanical properties were investigated as a function of Ni enrichment via EDS, SEM, AFM, and nanoindentation respectively. Results revealed that the hardness and young's modulus decrease with increase in Ni content in the film. A maximum hardness of 12.75 GPa was achieved with the elemental composition of Al (20.8 at%) and Ni (79.2 at%). The increase in surface roughness as a result of Ni enrichment led to the increase in hydrophobic properties up to the elemental composition of Al (14.9 at%) and Ni (85.1 at%) beyond which it declined. This study shows that the surface roughness, microstructure, and elemental composition influence the mechanical and hydrophobic properties of the Nickel rich Ni3Al coatings. (C) 2022 Elsevier B.V. All rights reserved
Pyrolysis Pre-treatment of PCBs: A Sustainable Solution to Convert Encapsulation into Marketable Product and Separation of Metallic Concentrate
Get PDFPrinted circuit boards (PCBs) are the essentially required component of all the electronic goods, containing a variety of metals. PCBs are made up of several layers of epoxy resins, thin metallic sheets, etc. The metallic sheet encapsulated with resin hinders the hydrometallurgical metal dissolution process. The mechanical pre-treatment process is not feasible due to high energy consumption and non-availability of a compatible machine. Therefore, pyrolysis studies were conducted for the removal of capsulation of resin on metals present in PCBs. Various experimental
parameters were studied to optimize the pyrolysis process. The gas generated during the pyrolysis was
condensed to get Low Density Oil (LDO).And the metal depleted poly-cracked carbon was converted
to activated carbon and the metallic fractions processed for metal recovery using hydrometallurgy.
The process has potential for commercialization after feasibility studies
Extraction and Flotation Performance Evaluation of Bio-collector in High Ash Graphite Ore Beneficiation
Get PDFThe rapid depletion of high-grade ores and natural resources, utilization of low-grade ores by beneficiation becomes utmost importance for sustainable development and resource management. The increasing wide range of applications of graphite for electrode, lubricants, refractory applications especially the recent surging electric automobile industry, resulting in significant need of graphite in future. Graphite demand in the energy storage industry is expected to grow faster than today's demand in future. Most of the graphite ore deposits in India are of low grade containing high ash content. Graphite is a naturally hydrophobic mineral and froth flotation process involves separation of minerals based on its surface hydrophobicity. The chemical reagents commonly used in graphite flotation are hydrocarbon oils such as diesel, kerosene along with a frothing agent such as methyl isobutyl carbinol (MIBC) which are non-environment friendly, hazardous and not cost effective while used at large scale industrial processing of the ore. Hence, in this work, a new eco-friendly bio-collector was developed from the exocarp or rind of a shrubaceous plant as an alternate flotation reagent for graphite. The flotation performance efficacy of this bio-collector was evaluated in comparison to the existing practice of diesel-MIBC dual reagent system in graphite flotation. A high ash low-grade graphite ore from eastern India with 84.71% ash and 9.07% fixed carbon was beneficiated by flotation technique for recovering graphite with lower ash content. The ore characterization studies mineralogy (XRD, ore microscopy) and morphology (SEM) reveal that the graphite mineral phase with sheet like appearance was accompanied predominantly by quartz, with minor fractions of biotite, muscovite and kaolinite. The spectral analysis of the developed bio-collector was characterized (FTIR). Under similar flotation test conditions on processing the high ash graphite ore, a final concentrate graphite product with 11.40% ash using diesel & MIBC as flotation reagents and 11.74% ash using bio-collector was obtained which indicates that the developed bio-collector could be a potential replacement for diesel- MIBC reagents being used in graphite processing mineral industries. Also, this bio-collector has an added advantage of being a natural plant-based extract with environmental compatibility leading to a step towards clean ore processing
Flotation Studies on Optimization of Carbon Recovery from Steel Plant Sludge
Get PDFMining and mineral-based processing plant tailings and sludge from processing plants contain solids in water which can contaminate soil and water supplies resulting in environmental damage. However, these solids suspended in water (sludge) still contain valuable minerals which can be recovered for primary and secondary usage. Feed material goes through multiple processing stages in a processing plant. Thus, sludge contains gangue particles associated with valuable carbon values in a complex manner. In this study, flotation method has been studied as a method for carbon recovery from processing plant sludge residue. The objective is to recover maximum carbon value from the sludge and optimize the flotation process. Carbon and iron values in the sludge residue was found to be in the range of 18-26% and 35-38% respectively. Preliminary flotation studies were carried out using a number of collectors i.e. diesel oil, kerosene Oil and other synthesized reagents such as FBD, PBD etc. Methyl isobutyl carbinol (MIBC) was used as frother. Based on the results, operational conditions were selected for further experimentation. Response surface methodology (Box-Behnken design) approach of designing and optimization was selected for this purpose. Effects of input parameters i.e. collector dosage, frother dosage and rpm have been studied using advanced statistical method. ANOVA has been applied to determine the order of significance of input variables for different outputs of this investigation. Empirical models based on regression analysis were developed to establish relationship between optimum recovery and grade of carbon concentrate and input parameters. Optimized carbon recovery of 54.79% was obtained at cell rpm of 1200, frother dosage of 48 gpt and collector dosage of 430 gpt. The recovered carbon can be further used to supplement the carbon requirement for iron making
Ash analyses of bio‑coal briquettes produced using blended binder
No full textThe behaviour of ash of fuel afects its thermal efciency when in use. The ash analyses of bio-coal briquettes developed from lean grade coal and torrefed woody biomass have received limited intensive study. Therefore, the present study aims at analysing the ashes of briquette made from lean grade coal and torrefed woody biomass using blended coal tar pitch and molasses as the binder.
Bio-coal briquettes were produced from coal and torrefed biomass in various hybrid ratios. Ashing of various briquettes was done in a mufe furnace at 850 °C for 3 h. Mineral phases of the ash were identifed using an X-ray Difractometer (XRD), while the mineral oxides were obtained using an X-ray Fluorescence Spectrometer. The AFT700 Furnace was used with its AFT700 software to evaluate the ash fusion temperatures of the ashes. The XRD patterns look similar, and quartz was found to be the dominant mineral phase present in the raw coal and bio-coal briquettes. The SiO2 (57–58%), Al2O3 (19–21%), and Fe2O3 (8–9%) were the major oxides observed in the ashes. The fnal fusion temperatures of the ashes range from 1300–1350 °C. The compositions of the ashes of the bio-coal briquettes are classifed as detrital minerals. It was concluded that the addition of torrefed biomass
(≤10%)and blended binder (≤ 15%) to coal gave a negligible impact on the ashes of the resultant biocoal briquettes
Recovery of Lithium (Li) Salts from Industrial Effluent of Recycling Plant
No full textTo cope up with the supply–demand gap of lithium (Li) an essential energy element, the recycling of waste industrial effluent (generated after cobalt recycling from waste Li-ion batteries) is targeted. In industry, after the recovery of Co, Cu, Ni, and graphite from one ton of black cathodic material of Li-ion batteries about 8 m3 of waste effluent containing 5–10 g/L Mn and 1–3 g/L Li is generated. Systematic precipitation studies were carried out using saturated alkaline solution varying Eh/ pH of the effluent. Settling time 30 min and pH ~12 were found to be optimum
conditions for maximum precipitation of Li (~90%) as salt. Precipitation studies for Mn/ Li with scientific validation were also carried out and discussed. The process developed has tremendous potential to be commercialized in industry after scale-up studies
Grain refinement in Fe-rich FeSiB(P)NbCu nanocomposite alloys through P compositional modulation
No full textThe progressive addition of P in Fe-rich FeSiB(P)NbCu nanocomposite alloy leads to grain refinement of α-Fe nanocrystals i.e, dense nucleation and grain growth inhibition. The P addition leads to linear reduction of α-Fe nanocrystallite size (D) and increases nucleation density (Nd) from ~ 30 nm and 2.5 × 1022 (0 at% P) to ~ 15 nm and 0.9 × 1023 for (8 at% P). The refined microstructure leads to coercivity reduction from 74 A/m (0 at% P) to 9.4 A/m (8 at% P), in agreement with Random-Anisotropy Model. The P assisted synergistic grain refinement mechanism is explained in the context of crystallization activation energy, selective solute re-distribution and enhanced stabilization of intergranular amorphous matrix. The 4 at% P alloy shows optimal soft-magnetic properties of 10.2 A/m and 1.64 T
Low cycle fatigue behavior and deformation mechanism of different microstructures in Ti-5Al-5Mo-5V-3Cr alloy
No full textTwo fundamental questions have been addressed on a recently developed high strength β Ti alloy, Ti-5Al-5V-5Mo-3Cr, with respect to two very different types of microstructures, one bimodal and the other fully lamellar, both having similar yield strength. Those are: 1) If and what would be the difference in their LCF response? 2) What would be the sequence of plastic deformation among the phases of different morphology, β, globular α and lath α? TEM based deformation micro mechanism explained the LCF response at various strain amplitudes. Crack path-microstructure interaction explained the difference in life, specifically observed at low strain amplitud
Effect of Finish Rolling Temperature on Microstructure and Mechanical Properties of Low-Si Steel After Quenching and Nonisothermal Partitioning
No full textThe quenching and nonisothermal partitioning process has been found to achieve excellent combinations of strength and ductility through the retention of austenite in the microstructure. Therefore, in the present study, the effect of grain size on phase transformations and ensuing mechanical properties has been investigated. A low-Si and Al-free steel was finish rolled at different temperatures which was subsequently quenched to a constant temperature below M-s for the formation of martensite with remaining untransformed austenite. This was followed by slow cooling to room temperature to simulate the condition of nonisothermal partitioning of carbon from martensite to the austenite. The results show that there is not much change in the average grain size with variation in the finish rolling temperature, as well as, no measurable differences are observed in the microstructural features and retained austenite content. The microstructure shows the presence of martensite, carbides, and a small amount of retained austenite. However, in terms of mechanical properties, the finish rolling at a lower temperature of 900 degrees C lead to higher hardness and strength with comparable ductility in comparison to the sample which has been finish rolled at a relatively higher temperature (940 degrees C). The above results will thus be helpful in designing the industrial processing schedule for low-Si steel to achieve enhanced performance