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Al 6061 alloy is widely used for commercial applications in the transportation

Layered two-dimensional transition metal dichalcogenides, due to their semiconducting nature and large surface-to-volume ratio, have created their own niche in the field of gas sensing. Their large recovery time and accompanied incomplete recovery result in inferior sensing properties. Here, we report a composite-based strategy to overcome these issues. In this study, we report a facile double-step synthesis of a MoS 2 /SnO 2 composite and its successful use as a superior room-temperature ammonia sensor. Contrary to the pristine nanosheet-based sensors, the devices made using the composite display superior gas sensing characteristics with faster response. Specifically, at room temperature (30° C), the composite-based sensor exhibited excellent sensitivity (10%) at an ammonia concentration down to 0.4 ppm along with the response and recovery times of 2 and 10 s, respectively. Moreover, the device also exhibited long-term durability, reproducibility, and selectivity toward ammonia against hydrogen sulfide, methanol, ethanol, benzene, acetone, and formaldehyde. Sensor devices made on quartz and alumina substrates with different roughnesses have yielded almost an identical response, except for slight variations in response and recovery transients. Further, to shed light on the underlying adsorption energetics and selectivity, density functional theory simulations were employed. The improved response and enhanced selectivity of the composite were explicitly discussed in terms of adsorption energy. Lowdin charge analysis was performed to understand the charge transfer mechanism between NH 3 , H 2 S, CH 3 OH, HCHO, and the underlying MoS 2 /SnO 2 composite surface. The long-term durability of the sensor was evident from the stable response curves even after 2 months. These results indicate that hydrothermally synthesized MoS 2 /SnO 2 composite-based gas sensors can be used as a promising sensing material for monitoring ammonia gas in real fields.

Mathematical models for tracking the melting of cored wire during its injection into the steel bath have been developed in the past though important aspects of the formulations have not been discussed in sufficient detail. As a result, it is difficult to use the results of these models to derive benefits for a specific steel melting shop.A general purpose mathematical model has been developed at R & D, Tata Steel, using the finite difference approach with a fully implicit scheme to simulate the process of cored wire injection taking into account the different operating practices encountered in the steel shop. Numerical simulation of this kind of problem, involving moving boundary, typically suffers from the limitation that the progressive solidification of frozen layers that takes place is not made part of the thermal balance till it attains the size of a full node and thus the heat gained or lost by this "partial node" is not accounted for till such time. An alternative numerical formulation has been developed to rectify this.Owing to the difficulty in making a direct validation, this model has been verified through a novel approach. This work suggests that the use of different wire dimensions (13-18 mm diameter and 0.4-0.6 mm casing), depending on the steel grades to be processed, is necessary in order to extract the maximum benefit.KEY WORDS: mathematical model; steelmaking; calcium treatment; cored wire; injection metallurgy; deoxidation; alloy addition.

As a typical volatile organic compound (VOC), N,N-dimethylformamide (DMF) is a popular solvent and tracer for environmental air quality monitoring. Highly selective detection with low electrical noise, quick response/recovery times, and superior sensitivity at room temperature against VOCs, especially at the parts per billion (ppb) level, continues to be a significant challenge in gas-sensing applications. To address the issue, herein we demonstrate an MoSe2/multiwalled carbon nanotube composite based chemiresitor sensor for the detection of DMF. MoSe2 with a layered sheetlike structure supports MWCNTs to enhance the specific surface area, thereby increasing the sensitivity (down to 0.1 ppm for DMF) and selectivity and improving the response over a wider range of relative humidities (30–80%). The composite-based sensor shows good sensitivity (12.3% for 5 ppm of DMF), better selectivity, and faster response (65 s) and recovery (90 s) times in comparison to the MoSe2 sensor (192, 392 s), respectively, and a consistent response over 35 days. Density functional theory simulations were employed to understand the adsorption process and sensing mechanism. An analysis revealed a negative adsorption energy of −716 meV, implying that the adsorption process is spontaneous and exothermic. Further, charge transfer (0.013 e) using the Bader scheme confirms the process to be physisorption in nature. The results were further supported using an electrochemical impedance spectroscopy analysis. These results indicate the great potential of the composite for selective and stable sensing of DMF over a wider range of relative humidities. The present work suggests that a composite of MoSe2 with MWCNTs could be useful to design DMF sensors with improved sensitivity and selectivity under various environmental conditions.

In the present day competitive market scenario, steel producers are striving for high speed continuous casting with stringent and consistent quality as well as reduced production cost. The ladle furnace (LF) is a key unit for achieving the above objectives during secondary steelmaking. Proper control of process parameters during LF processing of liquid steel is essential. The paper reports development of a model based advisory system, called ladle furnace on-line reckoner (LFOR), for the prediction and control of temperature and composition of steel in a LF. The thermal and chemistry models employed in the LFOR system are based on simplified physics, material and heat balance, and statistical analysis of plant data. The LFOR system is provided with graphical user interface (GUI) to display the predicted composition and temperature profile. The control advice displayed on the screen provides guidance for arcing and addition to achieve the target temperature and composition. The LFOR system has been commissioned at LF No. 2 of the LD2 and Slab Caster Shop of Tata Steel, Jamshedpur and is designed to meet the requirements of sequence casting as well as to optimise the energy input and cost of alloying additions. The performance of the LFOR system was analysed and validated with data taken over 100 heats and was noted to be satisfactory.

Iron ore sintering is an extremely complex process involving fuel combustion to generate heat and reducing gases like CO. This heat allows physicochemical, solid and solid-liquid reactions to form liquids of complex components as fuel particles are consumed and cooling processes allow the formation of solid mineral phases. At JSW coke breeze from coke ovens is used as solid fuel in sinter. The properties (size) of the solid fuel play a very important role in determining the sinter microstructural properties and sinter quality. The microstructure of the sinter is a basic necessity and also the first step towards establishing the structural property relationship. Microstructural studies have been carried out to understand the effect of coke breeze particle size on sinter microstructure and sinter properties. The present paper is an attempt to understand and correlate the physical and metallurgical properties of sinter with varying size of the coke breeze particle in sinter mix. It was observed that as the proportion of coke breeze below 3 mm in the sinter mix increased from 53?0 to 90?0% the calcium ferrite phase increased, the number of bigger size pores decreased, and thereby decreased the reduction degradation index (23?15 mm) of sinter from 39?7 to 23?5%. Superior sinter properties were obtained with the 23 mm coke breeze size ,90% in the sinter mix.

Pellet plant (4?2 MPta capacity) of JSW Steel Ltd imports iron ore fines from different mines to produce pellets for its Corex and Blast Furnace plants. The pelletisation process involves drying the ore fines to reduce the moisture content to less than 1%, grinding in open circuit ball mills to get required fineness. To produce good quality of pellets certain additives are important and limestone is employed for modifying the pellet basicity. Iron ore fines of 210 mm size and limestone are ground together in a ball mill to get sufficient fineness for the balling process. However, as limestone is harder than iron ore fines the z100 mesh size limestone particles is higher than required and not all the limestone is fully consumed in the reaction for melt formation. Microstructural studies were conducted under a Leica DMRX polarized microscope at different level fineness (2325# 2 56, 58 and 60%) to investigate its effect on the pellet quality. The cold crushing strength of the pellet improved from 203 to 220 kg p 21 with increase in fineness. With increase in percentage of 2325# particle size in the ground product RDI of the pellet decreased from 13?8 to 11?9% with increased melt formation from 5 to 9%. With increase in fineness 2325# from 56 to 60% the 150 to 500 mm size pores decreased from 51?8 to 13?6%.