Browsing by Author "Jha B.B."

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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.
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 and Wear Behaviour of Hot-Pressed 304 stainless Steel Matrix Composites Containing TiB 2 Particles
(2019) Sahoo S.; Jha B.B.; Mahata T.; Sharma J.; Murthy T.S.R.C.; Mandal A.
In the present article, mechanical and wear behaviour of hot-pressed 304 stainless steel matrix composites containing 2 and 4�vol% TiB 2 particles was investigated. A density of over 92% was achieved at optimum hot-pressing temperature and TiB 2 particles� content. Microhardness and yield strength of the composites were found to be improved remarkably as compared to their unreinforced counterpart. The enhancement of mechanical properties of the composites was discussed in light of their microstructural aspects and different possible strengthening mechanism models. Taylor strengthening was found to be dominant strengthening mechanism as compared to Orowan strengthening and load-bearing effect. Dry sliding wear behaviour was also investigated under load of 35�N at sliding speed 0.3�m/s. The wear resistance of the composites was found to be improved owing to uniform distribution of hard TiB 2 particles. Based on our findings, it was concluded that processing parameters and amount of TiB 2 have significant influence on mechanical and wear behaviour of steel matrix composites. � 2019, The Indian Institute of Metals - IIM.
Microstructure and Thermal Characterization of Plasma-Sprayed Nanostructured La2Ce2O7-Doped YSZ Coatings
(2014) Mantry S.; Mandal A.; Mishra D.K.; Jha B.B.; Mishra B.K.; Chakraborty M.
Nanostructured La2Ce2O7-doped YSZ coatings were developed using atmospheric plasma-spraying technique by optimizing various process parameters. To ensure the retention of nanostructure, the molten state of nanoagglomerates was monitored using plasma and particle diagnostic tools. It was observed that the morphology of the coating exhibits a bimodal microstructure consisting of nanozones reinforced in a matrix of fully-molten particles. The thermal diffusivity of nano-LaCeYSZ coatings is lower than that of nano and bulk YSZ. The reason for this change in thermal diffusivity may be attributed to scattering of phonons at grain boundaries, point defect scattering and higher inter-splat porosity. Also, the thermal conductivity of the nanocomposite coatings was lower than those of nanostructured and bulk YSZ coatings. XRD results show cubic zirconia with a small amount of tetragonal zirconia. The average grain size of the as-sprayed La2Ce2O7-YSZ nanocomposite coatings is ~150-200�nm. The improved thermal behavior is mainly due to a dense, packed, and more compact structure of the coatings. � 2014, ASM International.
Tribo-performance of plasma-sprayed nanostructured yttria-stabilized zirconia coatings using Taguchi's experimental design
(2014) Mantry S.; Sahoo R.; Jha B.B.; Mishra B.K.; Chakraborty M.
Plasma-sprayed thermal barrier coatings are frequently subjected to impacts by solid particles, which induce surface erosion. This article depicts the solid particle erosion response of plasma sprayed nanostructured yttria-stabilized zirconia (YSZ) coatings on Inconel 718 substrates. The influence of five operating parameters i.e. impact velocity, erodent size, erodent temperature, impingement angle, and stand-off distance with four different level each, on performance output (i.e. erosion rate) are studied using Taguchi's L16 orthogonal array design. Out of the five parameters, impact velocity has been found to be most significant factor followed by erodent temperature and impingement angle influencing erosion. Maximum erosion takes place at an impingement angle of ?60� showing the semi-ductile response of the coating to solid particle erosion. The morphology of the eroded surface also showed micro-cutting and small crater formation in the binder matrix caused by the repetitive impacts of erodent particles. It was observed that coating with nano-YSZ grains exhibited higher erosion resistance compared to conventional YSZ coating. � IMechE 2014.