Browsing by Author "Mandal A."

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Abrasive Wear Analysis of Plasma-Sprayed LaCeYSZ Nanocomposite Coatings Using Experimental Design and ANN
(2014) Mantry S.; Jha B.B.; Mandal A.; Chakraborty M.; Mishra B.K.
The abrasive wear characteristics of plasma-sprayed nanostructured yttria-stabilized zirconia (YSZ) coatings on Inconel 718 substrates was evaluated using AFS 50/70-grade silica sand as abrasives. This article depicts the dependence of abrasive wear characteristics of plasma-sprayed nanocomposite LaCeYSZ coatings on abrading distance, keeping the applied load constant. The influence of four operating parameters-that is, load, wheel speed, time, and temperature with four different levels each-on the performance output (i.e., abrasion wear rate) is studied using Taguchi's L16 orthogonal array design and analysis of variance (ANOVA). Out of the four parameters, load has been found to be most significant factor followed, by speed of the abrasive wheel and temperature influencing abrasion. The morphology of the worn-out surface also showed microcutting and small crater formation in the binder matrix caused by the repetitive impacts of abrasive particles. It was observed that coating with nano-LaCeYSZ grains exhibited higher wear resistance compared to conventional YSZ coating and the reason may be attributed to embedded crack-arresting nanozones, which toughen the coating. An artificial neural network (ANN) approach is then implemented taking into account training and test procedures to predict the triboperformance under different operating conditions. This technique helps in saving time and resources for a large number of experimental trials and successfully predicts the wear rate of the coatings both within and beyond the experimental domain. � 2014 Copyright � Society of Tribologists and Lubrication Engineers.
An alternate approach to synthesize TiC powder through thermal plasma processing of titania rich slag
(2016) Kasimuthumaniyan S.; Singh S.K.; Jayasankar K.; Mohanta K.; Mandal A.
This paper reports the preparation of fine titanium carbide (TiC) powder by using titania rich slag as a cheap raw material. The mixture of titania rich slag and activated charcoal was reacted in a thermal plasma reactor for 30�min under argon flowing atmosphere. The reaction product, a fused mass of Fe-TiC composite, was milled to fine powder at ambient atmosphere for 10�h then chemically leached for the removal of iron and other minor impurities. The obtained TiC powder after leaching was characterized by X-ray diffraction (XRD), Raman spectroscopy, electron probe micro analysis (EPMA), field emission scanning electron microscopy (FESEM) and particle size analysis (PSA). XRD, Raman spectroscopy results confirmed the formation of TiC. EPMA, EDS results indicated the synthesized product obtained after leaching to be free from iron and other minor impurities. Particle size analysis result revealed the average particle size of TiC powder to be 2.54��m. � 2016
Coarsening Kinetics of Semi-solid A356�5wt%TiB2 in situ Composite
(2015) Deepak Kumar S.; Acharya M.; Mandal A.; Chakraborty M.
An attempt has been made to investigate the coarsening behaviour of semisolid A356�5wt%TiB2 in situ composite produced by Cooling slope casting. It was found that the average grain size of ?-Al in the gravity-cast alloy got reduced from 98 to 48��m in the semi-solid A356�5TiB2 composite. The primary ?-Al in the composite were found to undergo substantial spheroidisation after 5�min at a reheating temperature of 585��C (fs�=�0.5). Further, increase in holding time from 5 to 15�min resulted in grain growth of ?-Al in both the alloy and the composites. The coarsening rate constant, K, for A356�5wt%TiB2 composite was found to be 339.73�?m3/s which is 32�% lower than that of semi-solid A356 alloy, thus proving the effectiveness of TiB2 particles towards grain coarsening. � 2015, The Indian Institute of Metals - IIM.
Deformation behavior of semi-solid forged A356�5TiB2 nano-in situ composites
(2019) Deepak Kumar S.; Chatttee A.; Jha S.K.; Singh N.K.; Mandal A.
The research work investigates the application of semi-solid metal processing (SSMP) to predict the deformation behavior of semi-solid A356�5TiB2 nano-in situ composites. The semi-solid forging of A356�5TiB2 in situ composites was carried out in three steps. In the first step, cooling slope (CS) casting setup was developed to generate the non-dendritic feedstock of the composites for subsequent thixoforging. In the second step, differential thermal analysis was used to estimate the semi-solid temperature range in order to achieve partial remelting temperatures and solid fraction profiles of the composites. In the final step, the non-dendritic feedstock of the composites was thixoforged with different % reductions ranging from 30 to 50%. It is noted that the semi-solid A356�5TiB2 nano-in situ composites with 40% deformation attained the ultimate tensile strength (UTS) of 318 MPa, in peak aged condition which is about 110.6% compared to gravity-cast alloy. This is attributed due to the presence of nano-TiB2 particles in the semi-solid forged A356�5TiB2 in situ composite, which clearly indicates the influence of semi-solid forging on the deformation behavior and tensile properties of composites. � Springer Nature Singapore Pte Ltd. 2019.
Design and implementation of a 2-DOF PID compensation for magnetic levitation systems
(2014) Ghosh A.; Rakesh Krishnan T.; Tejaswy P.; Mandal A.; Pradhan J.K.; Ranasingh S.
This paper employs a 2-DOF (degree of freedom) PID controller for compensating a physical magnetic levitation system. It is shown that because of having a feedforward gain in the proposed 2-DOF PID control, the transient performance of the compensated system can be changed in a desired manner unlike the conventional 1-DOF PID control. It is also shown that for a choice of PID parameters, although the theoretical loop robustness is the same for both the compensated systems, in real-time, 2-DOF PID control may provide superior robustness if a suitable choice of the feedforward parameter is made. The results are verified through simulations and experiments. � 2014 ISA.
Effect of Cooling Slope Angle on Microstructure of Al-7Si Alloy
(2015) Acharya M.; Deepak Kumar S.; Mandal A.
Attempts were made to obtain non-dendritic microstructure in Al-7Si alloy by pouring the melt on mild steel cooling slope. The melt was poured into the slope at different angles�15�, 30�, 45� and 60�. The pouring temperatures chosen were 630 �C, 640 �C and 650��C corresponding to melt superheat of 15 �C, 25 �C and 35��C. The results indicate that a lowest slope angle of 15o along with superheat of 15��C leads to microstructure with minimum grain size of 33�?m and shape factor of 0.81. The findings showed that lower slope angles would yield minimum grain size, are in contradiction to earlier studies, which could be related only to the lowest possible superheats used in the present study. � 2015, The Indian Institute of Metals - IIM.
Effect of high magnesium content on microstructure of Al-7Si alloy
(2014) Mandal A.; Chippa N.; Jayasankar K.; Mukherjee P.S.
A new class of ternary Al-7Si-xMg alloys was developed with improved microstructure consisting of fine spheroidal Mg2Si and eutectic Si particles dispersed in ?-Al. The studies show that Mg and Sr have a modification effect on eutectic Si and Mg2Si particles respectively. In alloys with high Mg, a combination of Sr addition followed by T6 treatment resulted in a fine and spheroidal eutectic mixture of Si and Mg2Si. It was concluded that 2 wt% Mg is optimum to obtain a minimum amount of coarse Mg2Si particles in the Al-7Si-xMg system as well as modify the eutectic Si particles. Furthermore, the hardness of Al-7Si-xMg alloys with and without Sr addition is comparable with those of in-situ Al-7Si-TiB2 composites indicating that they can be used as an alternative for the composites for wear resistant applications.�2013 Published by Elsevier B.V.
Effect of semi-solid forging on microstructure and mechanical properties of in-situ cast Al-Cu-TiB2 composites
(2017) Mathew J.; Mandal A.; Kumar S.D.; Bajpai S.; Chakraborty M.; West G.D.; Srirangam P.
The present work deals with the effect of semisolid processing on microstructure and mechanical properties of Al-4.5% Cu � 5% TiB2 in-situ cast composites. The composite was prepared by flux assisted synthesis in which TiB2 particles were formed in-situ through an exothermic reaction between K2TiF6 and KBF4 halide salts. Al-4.5�wt% Cu alloy and Al-4.5% Cu-5% TiB2 composite samples were forged in semisolid state with 0.3�vol fraction of liquid. Semisolid forging was carried out for two forge reductions (30% and 50% forge reductions). Microstructure studies show that the semi-solid forging results in uniform distribution of TiB2 particles and Al2Cu particles in the composite. Further, TiB2 particles play a dual role as grain refiners as well as reinforcements of composites. EBSD and nano indentation studies shows that semisolid forging results in dynamic recrystallization of grains in the composite with significant grain refinement which leads to a marked increase in hardness and elastic modulus of the alloy as well as the composite. � 2017 Elsevier B.V.
Effect of Semi-Solid Heat Treatment on the Microstructure and Dry Sliding Wear Behavior of Al�20Si Alloy at Optimized Parametric Conditions
(2019) Acharya M.; Mandal A.
Abstract: Hypereutectic Al�20Si alloy needs optimization of different process parameters in order to obtain maximum wear resistance for tribological applications aerospace and automobile industries. The present study attempts to find the best possible combination of the process parameters for the semi-solid heat treatment of the alloy in Taguchi Method. The effects of three different control variables i.e. sliding velocity, sliding distance, and load on the wear characteristics were investigated. The optimal values of control factors were determined on the basis of �smaller-is-better� approach from Taguchi optimization technique. The optimized conditions for wear tests were then applied to the isothermally heat-treated samples (10�30�min) at 600��C. The quantitative analysis shows the significant change in the size, morphology, and distribution of primary Si and eutectic Si with heat treatment. Moreover, the worn surfaces were analyzed from the microstructures obtained in Field Emission Scanning Electron Microscopy (FESEM). The improved wear resistance observed in the case of 20�min of holding time can be attributed to the combined effect of refinement of primary Si, modification of eutectic Si and equiaxed ?-Al during semi-solid heat treatment. Graphic Abstract: [Figure not available: see fulltext.]. � 2019, The Korean Institute of Metals and Materials.
Effect of Strontium and Misch Metal on Al�14Si�3Mg Alloy
(2015) Mandal A.; Acharya M.
The individual and combined effect of Strontium and Misch metal on microstructure and properties of Al�14Si�3Mg alloy was investigated. Addition of 3 wt%�Mg to Al�14Si alloy resulted in microstructure comprising of ?-Al and ternary eutectic (?-Al, Si and Mg2Si). It was found that Strontium and Misch metal behaved differently when added to Al�14Si�3Mg alloy resulting in significantly different microstructure. While addition of only strontium did not show formation of any new phase having any deleterious effect on microstructure and hardness, the addition of only misch metal though, led to the appearance of rare earth rich phases with branched morphology resulting in decrease in hardness. Also, it was concluded that misch metal in conjunction with strontium yielded best results in terms of microstructure and hardness. The microhardness measurements showed that ternary eutectic region was 1.4�1.7 times harder than the binary eutectic region. Furthermore, the T6 treated Al�14Si�3Mg alloy containing Strontium and Misch metal led to a substantial increase in hardness which was superior to some commercially available Al�Si alloys. Also, differential scanning calorimetry studies were carried out to determine the freezing range of the alloys and assess their feasibility for semisolid processing. � 2015, The Indian Institute of Metals - IIM.
Effect of Thixoforming on the Microstructure and Tensile Properties of A356 Alloy and A356-5TiB2 In-situ Composite
(2015) Deepak Kumar S.; Mandal A.; Chakraborty M.
In the present work, A356 alloy and in situ A356-5TiB2 composite feedstock was produced by employing Cooling slope casting technique. The technique resulted in near spherical morphology of primary ?-Al phase in the feedstock of both the alloy and composite. A fine distribution of eutectic Si phase within the matrix was observed in the composite feedstock. The rheocast billets of both the alloy and composite were then thixoformed successfully at 50�% solid fraction temperatures of 580 and 585��C respectively. Further, tensile properties of thixoformed alloy and composite were measured and compared with those of gravity-cast samples. It was observed that the % increase in yield strength and tensile strength of thixoformed alloy increased by 43 and 36�% respectively with respect to the gravity-cast alloy. The thixoformed composite attained the highest ultimate tensile strength of 211�MPa which is about 40�% higher as compared to gravity-cast alloy. Interestingly, the ductility of the composites is comparable to that of alloy after thixoforming. � 2015, The Indian Institute of Metals - IIM.
Erosion behavior of glass-epoxy composites filled with SiC from bamboo leaf
(2011) Mantry S.; Mohapatra S.; Mohapatra S.; Singh S.K.; Mandal A.; Satapathy A.
The present article reports the processing, mechanical characterization and solid particle erosion response of a new class of multi phase composites consisting of epoxy resin reinforced with E-glass fiber and SiC particulates. The SiC powder synthesized from bamboo leaf employing DC extended thermal plasma technique has been used as the filler in this glass-epoxy composite. It is observed that with increasing percentage of filler particles, there is a decline in tensile and flexural strength, but there is significant improvement in hardness and erosion wear performance. It is also observed that, among all the factors, impact velocity is the most significant factor followed by filler percentage and impingement angle, while erodent size has the least significance on erosion of the hybrid composite. Taguchi's orthogonal arrays have been used to identify the controlling factors influencing the erosion wear rate. � Carl Hanser Verlag GmbH & Co. KG.
Erosion Response of Thixoformed A356-5TiB2in situ Composite Using Taguchi's Experimental Design
(2017) Kumar S.D.; Vundavilli P.R.; Mandal A.; Mantry S.; Chakraborty M.
The present article describes the application of Taguchi's experimental design methodology to investigate the erosion wear behavior of in situ-formed A356-5TiB2composite subjected to thixoforming. The effects of process parameters�such as impact velocity, erodent temperature, erodent size, standoff distance, and impingement angle�on the erosion rate have been analyzed. The results indicated that impact velocity is the most significant factor and accounts for 42.31% of the total effect on the erosion rate of the thixoformed A356-5TiB2composite. It is found that material loss during erosive wear is primarily due to microploughing (i.e., abrasive type) and microfracture (i.e., impact type). The erosion rate of thixoformed A356-5TiB2in situ composite was found to be 48.82�mg/kg, which is nearly 44% lower than that of as-cast alloy. � 2016 Society of Tribologists and Lubrication Engineers.
Experimental investigations and multi-response optimisation of wire electric discharge machining of hypereutectic Al-Si alloys
(2016) Babu D.M.; Kiran S.V.; Vundavilli P.R.; Mandal A.
Wire electrical discharge machining (WEDM) is a non-traditional machining process, which is used for machining of difficult to machine materials, like composites and inter metallic materials. In the present paper, an attempt is made to machine hypereutectic Al-Si alloys using WEDM as these materials are widely used in automotive, aerospace and electronic fields because of its attractive properties. In the study, the WEDM machining parameters, such as pulse on time, pulse off time, wire feed rate and variation of percentage of silicon are taken as controlling factors for experimentation. In the present manuscript, an attempt is made to study the influence of percentage of silicon in the alloy system on the performance measures, such as material removal rate (MRR) and surface roughness (SR) of machining. Further, the influence of various input process parameters on the responses has also been studied. In order to optimise the said performance characteristics, two multi-objective optimisation methodologies namely grey relational analysis (GRA) and principal component analysis (PCA) are implemented. It has been observed that principal component analysis is found to perform better than grey relational analysis. Copyright � 2016 Inderscience Enterprises Ltd.
Fatigue analysis of A356-TiB2 (5wt%) in-situ nano composites
(2019) Deepak Kumar S.; Jha S.K.; Karthik D.; Mandal A.
In the present work, Low-cycle fatigue (LCF) tests were performed on A356 Aluminium alloy and A356-TiB2(5wt%) in-situ nano-composites to estimate their fatigue performance. The tests were performed by strain controlled with a strain ratio of Re = -1. The cyclic stress-strain curves were determined for each imposed strain levels. The LCF and their characterization in the cyclic plastic response of both the alloy and composites were analysed. It is interesting to note that the type of cyclic deformation behaviour in Al-Mg-Si alloys seems to be influenced by the dispersed phases and TiB2 particles. The LCF values for the A356-TiB2(5wt%) composites were found to be higher than those of the A356 alloy. The separation fatigue life's of the A356-TiB2(5wt%) in-situ nano-composite and A356 alloy was found to be 15652 and 12350 cycles respectively. This is attributed due to the presence of minute TiB2 particles which obviously affected the microstructure, hardness, tensile strength and fatigue life of the composites compared to the base alloy. It is further noted that the LCF values of the present composites were found to be higher than those of the alloys reported in the literature. � 2019 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Nanotechnology: Ideas, Innovations & Initiatives-2017 (ICN:3i-2017).
Hot Deformation Behavior of AA2024 with and without In Situ Titanium Diboride Dispersoids
(2019) Panda R.; Gupta R.K.; Mandal A.; Chakravarthy P.
AA2024 is known for its good combination of mechanical properties and is widely used in aircraft fuselage and other aerospace applications. However, because of its relatively lower yield strength, it has limited application in high-stress regions. In alloy AA2024, when titanium diboride particulates are embedded uniformly, it is expected to improve the strength of alloy by working as particulate dispersed composite. However, deformation of such metal matrix composite (MMC) is likely to be difficult and different from the base alloy. In this work, the deformation behavior of AA2024 alloy and its composite with titanium diboride particles developed in situ through salt-metal reaction have been studied. Hot deformation behavior was studied through hot isothermal compression tests over a temperature range of 300�C-450�C and strain rate from 0.01-10 s-1. The results show that there is an increase in flow stress with an increase in strain rate and a decrease in flow stress with an increase in temperature. Processing maps were generated based on the dynamic material model to identify the stable and unstable regions for hot working. The strain rate sensitivity of the composite has been compared to base alloy AA2024. Deformation parameters were calculated from the stress-strain data, and constitutive equations have been generated. Softening in alloy and in MMC is found to be caused by dynamic recrystallization. Microstructural modifications that are caused by titanium diboride reinforcement and its impact during hot deformation are reported. The safe zones for the hot working of both base alloy and MMC were found to be in the range of 380�C to 450�C in a strain rate of 0.001-10 s-1 � 2019 by ASTM International.
Impression creep behaviour of TiB2 particles reinforced steel matrix composites
(2018) Sahoo S.; Jha B.B.; Mahata T.S.; Sharma J.; Murthy T.S.R.C.; Mandal A.
Impression creep behaviour of the powder metallurgy processed steel matrix composites was investigated under constant stress at different temperatures in the range of 873�973 K. By using the power-law relationship, the estimated activation energy for unreinforced steel was found to be 149 kJ mol?1 and steel reinforced with 2 and 4 vol.-% TiB2 was found to be 298 and 338 kJ mol?1, respectively indicating better creep resistance of the reinforced steel matrix composites. Dislocation creep is the dominant creep mechanism based on the calculated values of stress exponent and activation energy. Hence, this method can be used to assess the potential of steel matrix composites for use as structural materials for high-temperature application. � 2018, � 2018 Institute of Materials, Minerals and Mining.
Influence of in-flight particle state diagnostics on properties of plasma sprayed YSZ-CeO2 nanocomposite coatings
(2014) Mantry S.; Jha B.B.; Mandal A.; Mishra D.K.; Mishra B.K.; Chakraborty M.
This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia (YSZ) coatings. This article depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on particle temperature, velocity and size of the splat prior to impact on the metallic substrate. Particle temperature measurement is based on two-color pyrometry and particle velocities are measured from the length of the particle traces during known exposure times. The microstructure and adhesion strength of as-sprayed nano-YSZ coatings were studied. Field emission scanning electron microscopy results revealed that morphology of coating exhibits bimodal microstructure consisting of nano-zones reinforced in the matrix of fully melted particles. The coating adhesion strength is noticed to be greatly affected by the melting state of agglomerates. Maximum adhesion strength of 42.39 MPa has been experimentally found out by selecting optimum levels of particle temperature and velocity. The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nano-zones. � 2014 The Author(s).
Influence of reinforcement and processing on steel-based composites: Microstructure and mechanical response
(2018) Sahoo S.; Jha B.B.; Sahoo T.K.; Mandal A.
Steel matrix composite reinforced with 2�4 vol.% titanium diboride particles was fabricated successfully by powder metallurgy route through hot pressing method. Influence of sintering parameters on densification was investigated by measurement of density of resultant composites. Microstructural analysis of hot-pressed materials was performed. Hardness and deformation behavior under constant load were evaluated by conducting microhardness and nanoindentation tests. The addition of titanium diboride proved to be effective for enhancement of hardness and strength. Composite with 4 vol.% titanium diboride sintered at 1100�C resulted in improved hardness and elastic modulus which could be related to Orowan strengthening resulting from homogeneous distribution of fine titanium diboride particles in steel matrix. The results indicate that proposed method is economically feasible to process steel matrix composites with improved properties. A comparatively lower temperature and pressure offers better control of interface kinetics and microstructure. � 2017 Taylor & Francis.
Mechanical alloying and properties of immiscible Cu-20 wt.% Mo alloy
(2015) Kumar A.; Jayasankar K.; Debata M.; Mandal A.
Abstract In the present article, an attempt has been made to synthesize binary Cu-20 wt.% Mo immiscible alloy by mechanical alloying of pure elemental Cu and Mo powders. The aforesaid alloy was prepared by commercial planetary ball mill (PBM) and indigenous dual drive planetary ball mill (DDPBM). Both the milling techniques resulted in homogenous distribution of fine and hard Mo particles in soft copper matrix. The crystallite size of the alloy milled in DDPBM exhibited a minimum value of 12 nm after 40 h of milling which was confirmed using XRD and TEM. Further, the mechanically alloyed powders were cold pressed and sintered at different temperatures between 900 and 1050 �C for 1 h. The sintered Cu-20wt.%Mo alloy showed a good combination of coefficient of thermal expansion, electrical conductivity and hardness in spite of having a density 93%. � 2015 Published by Elsevier B.V.