Department of Mechanical Engineering

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IIT Jodhpur

This paper elaborates manufacture and performance analysis of new clay ceramic (CC) water filtration materials. The CC is manufactured from clay and sawdust mix. Waste marble powder and machined iron fines are used as additives to the mix for manufacturing the new modified materials. An equal volume of clay and sawdust were used to manufacture the control CC. Another ceramic, marble clay ceramic (MCC), was manufactured with distinct volume fractions of clay, sawdust, and marble (40:40:10). Third ceramic, ferrous clay ceramic (FCC), was manufactured from an equal volume of clay and sawdust and five percent by volume of iron fines. FCC showcased better arsenic (As (V)) contaminant removal from water at acidic pH while MCC showcased best As (V) removal at around pH of 8. Average flexural strength of MCC was comparatively better than FCC and CC. The modified materials showcased similar percolation rates at par with control CC. MCC showcased comparatively better E. coli removal capabilities than FCC and CC. Only limited volumetric addition of marble powder and iron fines were found to positively affect compressive strength. The results demonstrate new low-cost ways of modifying strength and specific water treatment characteristics of CC using waste materials from local marble-processing and iron-machining industries. © 2019 Desalination Publications. All rights reserved.

World University root node

Desalination and Water Treatment

Use of marble and iron waste additives for enhancing arsenic and E. Coli contaminant removal capacity and strength of porous clay ceramic materials for point of use drinking water treatment

Re-Use and Recycling of Materials: Solid Waste Management and Water Treatment

Effect of local industrial waste additives on the arsenic (V) removal and strength of clay ceramics for use in water filtration

Pipeline steels are extensively used in various applications like oil and gas transmission, offshore oil drilling and pressure vessels due to its higher toughness and strength values. To provide higher atmospheric corrosion protection and to improve mechanical properties than normal steels, wide variety of pipeline steels are manufactured using different heat treatment procedure. In present work, a heat treatment procedure was used to alter the microstructure of base metal and to study its effect on the electrochemical corrosion behaviour of X70 pipe line steel. Heat treatment of X70 steel was performed at two austenitizing temperatures (e.g. 1000 °C and 850 °C) followed by quenching and subsequent tempering at 300 °C, 450 °C and 600 °C. Linear Sweep voltammetry technique of electrochemical corrosion was used to study the corrosion behaviour of heat treated specimens in sea water pH-8.2, 5%NaCl+10 −2 mol/l sodium thiosulphate pH-3 and 5%NaCl+10 −3 mol/l sodium thiosulphate pH-5 solution. Microstructure of different heat treated samples shows the presence of different phases developed during heat treatment. Polygonal ferrite and fine grained ferrite microstructures (at 600 °C) developed during heat treatment inhibits the corrosion rate as compared to the tempered martensitic (300 °C) microstructure. © 2019 Elsevier Ltd

International Journal of Pressure Vessels and Piping

Microstructure evolution and electrochemical corrosion behaviour of API X70 linepipe steel in different environments

The solid solution strengthened P91 steel shows excellent physical and mechanical properties at high temperature. However, degradation in mechanical properties due to softening of martensitic matrix and coarsening of precipitates are still observed. In this paper, initially P91 steel (normalized+tempered) is thermally aged at 650 °C for 4000 h. The microstructural feature and mechanical behavior were investigated for aged sample. The ageing resulted in degradation in mechanical properties. After the ageing, sample was subjected to two heat treatments: (1) tempering (AT), (2) normalizing+tempering (ANT). The main aim was heat treatment to regain the original mechanical properties of the aged P91 steel. The mechanical properties measured for ANT sample was similar to than that of base metal (NT). © 2019 IOP Publishing Ltd.

Materials Research Express

Effect of heat treatment on mechanical behavior and microstructure feature of the thermal aged P91 steel

Thermally sprayed 75Cr3C2-25NiCr coating is applied on structural components to improve corrosion, oxidation and erosion behaviour at high temperature. In order to understand the microstructural and mechanical behaviour of coating a long term investigation was carried out at 650 °C. The Objective of the present work is to study the effect of long term heat treatment (i.e. 650 °C/ 3000 h) on various characteristics of the detonation gun sprayed 75Cr3C2-25NiCr coating. Hardness and nanoindentation studies were carried out on Cr3C2-NiCr coating after fixed time intervals. The morphological and microstructural features of the coated surface were characterized using scanning electron microscope (SEM). The phases formed during the long term exposure were identified by x-ray diffraction (XRD) technique. The coating showed the presence of various Cr, Ni, based oxides, Fe and Ni based spinels. Vanadium, niobium, and molybdenum showed maximum tendency to diffusion from substrate to the coating. Hardness of the coating reached a maximum value of 870 HV after 2160 h of exposure. The hardness of coating observed an initial drop in hardness due to carbide coarsening which was recovered by precipitation of carbides from the solid solution. © 2019 IOP Publishing Ltd.

Microstructure and mechanical properties of D-Gun sprayed Cr3C2-NiCr coating on P91 steel subjected to long term thermal exposure at 650 °c

The microstructural evolution and mechanical properties of gas tungsten arc welded creep strength enhanced martensitic (CSEM) and austenitic stainless steel (SS) dissimilar welded joint is explored in the as welded (AW) and post weld heat treated (PWHT) conditions. The as received normalized and tempered P91 steel has been welded with SS304 L by preparing a conventional groove and employing a P91 GTAW filler wire. The welded plate is subjected to PWHT at 760 °C for 120 min followed by air cooling. The P91 steel in as received condition exhibited fully martensitic (tempered) structure with lathe morphology and prior austenite grain boundaries while SS304 L have austenitic structure with twins. The heterogeneity (as-welded condition) across the welded joint were produced in terms of microstructure and mechanical properties (hardness, Charpy toughness and tensile strength). The variation in mechanical properties has been minimized after the PWHT. PWHT has observed a drastic influence on mechanical properties and microstructure of weld fusion zone and HAZ of P91 side however, remain unaffected for the SS304 L side HAZ. The strength of the welded joint have been measured 1016 ± 2.5 MPa and 906 ± 6.5 in as-welded and PWHT condition with joint efficiency of 140 % and 125 %, respectively. © 2019 The Society of Manufacturing Engineers

Journal of Manufacturing Processes

An assessment for mechanical and microstructure behavior of dissimilar material welded joint between nuclear grade martensitic P91 and austenitic SS304 L steel

Ceramic coatings are widely used as thermal and environment barrier coatings due to their inert properties and capability to withstand high temperature. Ceramic coatings are commonly deposited by air plasma spray process and electron beam physical vapor deposition. In the present work, a cost-effective, slurry-based dip coating technique was developed to deposit mullite-based ceramic coating on the P91 steel substrate. The coating has been characterized by X-ray diffraction technique and scanning electron microscopy. Sintering of coatings was carried out in the temperature range of 900–1000 °C. Sintering time was varied between 0.5 and 1 h. Energy dispersive spectroscopy was carried out to study the distribution and diffusion of constituent elements during high-temperature sintering. Potentiodynamic polarization tests and thermo-gravimetric analysis were performed to investigate the corrosion behavior of the coating. The coating sintered at 1000 °C was found to be free from cracks and other microdefects. The corrosion rate of coating sintered at 1000 °C was found to be 26.06 mpy whereas the uncoated sample showed a higher corrosion rate of 153.7 mpy. © 2018, Australian Ceramic Society.

Journal of the Australian Ceramic Society

Characterization of slurry-based mullite coating deposited on P91 steel welds

This paper investigates the starting transients in vacuum ejector and its dependence on various geometric configurations. Various geometric parameters investigated were the ratio of diffuser to primary duct height (D∕d), diffuser length–to–diffuser height ratio (L∕D), and secondary chamber height–to–secondary jet thickness ratio (hs∕ts). It is seen that the vacuum ejector start-up is associated with a gradual initial vacuum generation stage, which is followed by a rapid vacuum generation. The gradual vacuum generation is found to be caused by the mass supply by the recirculation bubble (existing in the diffuser) to the secondary chamber exit plane. The rapid evacuation happens when the initial recirculation bubble splits up, which results in a rapid reduction of the amount of reverse flow mass reaching the secondary chamber. It is found that with reduction in the D∕d ratio and increase in the L∕D ratio, the rapid evacuation stage reduces and eventually vanishes. The present investigation shows that both these configuration changes reduce the mass supply by reverse flow to the secondary chamber and this is attributed to the cause of the reduction in rapid evacuation stage. The present study also shows that the nature of vacuum generation does not vary with change in secondary chamber height. © 2019 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

AIAA Journal

Effect of geometric configurations on the starting transients in vacuum ejector

In present research work, discussions have been made to predict the bead geometries and shape profiles of weldments using statistical regression modeling and fuzzy logic techniques. However, the regression and fuzzy logic modeling techniques do not take into account the actual physical properties and phenomena that occur in welding. Moreover, techniques such as regression and fuzzy logic modeling are not suitable for predicting the transient temperature distribution and distortion of arc welded joints. To predict the transient temperature distributions, peak temperature distribution, and residual deformation in welding, deterministic modeling techniques such as thermomechanical analysis are preferred. However, while performing thermomechanical analysis of welded joints, size and reinforcement dimensions of the weld bead need to be incorporated into the model for accurate prediction of transient temperature distributions and distortions. In this work, circularly spread moving heat source has been used for transient thermal modeling of tungsten inert gas (TIG) welding process. In the subsequent sections of this article, the weld thermomechanical analyses for TIG square butt joints are discussed to predict the temperature distributions and angular distortion. The weld dimensions such as weld width, weld depression, and weld bulging have shown great influence on the angular distortion patterns. © 2019 Society of Naval Architects and Marine Engineers. All rights reserved.

Journal of Ship Production and Design

Thermomechanical analysis of tungsten inert gas welding process for predicting temperature distribution and angular distortion

This paper proposes a method for global active noise control in vibro-acoustic cavities using acoustic sensing under the presence of both structural and acoustic disturbances. Global active noise control has earlier been carried out by minimizing the acoustic potential energy in the cavity expressed as the sum of squares of the acoustic pressures at discrete microphone locations. However, this approximation though holds well for a rectangular box cavity, is not applicable for the cavities of other shapes. This calls for development of an active noise control method based on the estimation of the acoustic potential energy applicable to the cavities of arbitrary shapes as encountered in practice. Virtual sensing of the acoustic potential energy has been reported in the literature based on measurement of vibration by the structural sensors. However, such approaches are applicable when only the structural disturbances act on the cavity, but cannot be used if the acoustic disturbances are also present in the cavity. This paper presents development of a global active noise control method based on virtual sensing of the acoustic potential energy in the cavity under the presence of structural and acoustic disturbances. Minimisation of the estimated acoustic potential energy through a feedforward control law is developed. Numerical studies on an irregular-shaped vibro-acoustic cavity and a car cavity are presented to evaluate the performance of the proposed technique. The results are also compared with the maximum possible reduction in the acoustic potential energy obtained using the optimal control inputs. The levels of reduction in the acoustic potential energy obtained with the proposed method are found to be close to the maximum possible reduction using the optimal control inputs. The proposed method is then also validated through an experimental study on a rectangular box cavity. © 2019 Elsevier Ltd