Hydroxyapatite coating performance enhancement and characterization for Mg-Zn-Ca-Y alloys for biomedical application S. S. Gholap, R. R. Navthar, K. B. Kale, S. H. Gawande Discover Materials, 2026 Although magnesium (Mg)-based alloys have attracted considerable attention for use in temporary biomedical implants due to their biocompatibility and biodegradability, their clinical application has been limited by their inherently high degradation rate in physiological environments. To mitigate this limitation, hydroxyapatite (HAp) coatings were applied to Mg-4Zn-0.2Ca-(x)Y (yttrium) (x = 3, 6, 9, 12) % wt. alloys using a thermal coating technique aimed at enhancing corrosion resistance. Three different HAp coating thicknesses—50 μm, 100 μm, and 150 μm—were deposited onto the magnesium alloy substrates. Characterization via field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the formation of a dense, homogeneous, and compact HAp coating layer. The in vitro degradation tests revealed a substantial improvement in corrosion resistance, attributed to the protective nature of the HAp barrier. Furthermore, bioactivity assessments conducted in Hank’s balanced salt solution indicated the formation of a uniform and adherent layer of bone-like apatite on the coated surfaces, affirming the alloy’s potential for osteointegration. The application of HAp coating not only enhanced the corrosion resistance but also significantly improved the compressive and tensile strength of the magnesium alloy. Overall, the coated Mg-4Zn-0.2Ca-(x)Y alloys exhibit promising characteristics for use in temporary orthopedic and biodegradable implant applications, owing to their improved mechanical performance and superior resistance to physiological degradation.
Influence of Magnetic Abrasive Finishing Process Parameters on Surface Roughness of SAE 52100 Steel Using a Hemisphere Pole Geometry Electromagnet Rajendra E Kalhapure, Mayank Shekhar, Ravindra R. Navthar, Prashant N. Nagare Ssrg International Journal of Mechanical Engineering, 2025 Finishing is the last stage of the manufacturing of jobs that demand the utmost quality with regard to shape, precision, and surface integrity. Fine-finishing is a process that improves the surface of the workpiece, enhancing its functional and quality attributes. The automotive sector requires precise finishing to enhance the performance, appearance, and longevity of its components. 52100 bearing steel is widely utilized in the production of critical components for various bearings and other applications. However, conventional finishing methods can be difficult to apply when creating components of diverse shapes and sizes. To address this, advanced fine machining and finishing techniques are being employed. One such method is magnetic abrasive finishing (MAbF), a precision technique that produces outstanding quality components. This process utilizes a flexible magnetic abrasive brush (FMAB) guided by a magnetic field to achieve the desired finish. Typically, the magnetic abrasives used in MAbF consist of two key components: ferromagnetic materials and abrasives, which work in tandem. In this study, 52100 steel bars undergo fine polishing using an MAbF technique, with various process parameters being examined. Aluminum oxide (Al2O3) serves as the abrasive, while a hemisphere-shaped DC electromagnet is employed for the finishing process. Key variables can be adjusted to achieve optimal surface finishes, including magnetic flux density, component rotation speed, and the ratio of abrasive to ferrous powder in the mixer. The effectiveness of the process is influenced by factors such as the abrasive particle content in the mixing ratio, the speed of the workpiece, and the input DC power source that determines the magnetic flux density. The results indicate that increasing the rotation speed and DC voltage enhances the surface roughness of the 52100 bearing steel rods. Specifically, experiments reveal that improvements in rotation speed and DC voltage can lead to a 57% increase in the maximum enhancement of surface roughness.
Experimental Analysis for the Surface Roughness Improvement of Bearing Steel SAE 52100 Using Magnetic Abrasive Finishing Process Rajendra E. Kalhapure, Gaurav Kumar Gugliani, Ravindra R. Navthar, Prashant N. Nagare Ssrg International Journal of Mechanical Engineering, 2025 52100 bearing steel is mainly used in various applications, including seal rings, sleeves, bearings, balls, bearing races, rollers, guide bars, and knives, among others. Traditional finishing processes might be difficult to perform when making diverse components in varied forms and sizes. This aims to employ advanced fine machining and finishing procedures. Magnetic abrasive finishing is one of the precision fine-finishing approaches that yield exceptionally high-quality components. This process employs a flexible magnetic abrasive brush that is guided by a DC magnetized field to achieve desired results. The magnetized abrasives utilized in this fine-finishing process generally consist of two components: ferromagnetic material and abrasive particles, which must be interconnected. In this study, 52100 steel bars are fine-finished on a Magnetic abrasive finishing setup using multiple process variables. For this investigation, an Aluminum oxide (Al2O3) is used as an abrasive for this micro-finishing process. Variables such as magnetic density, workpiece rotating speed, and abrasive mixer can be easily varied to research greater surface finishes. The success of the process is determined by elements such as abrasive particle contents in mixing ratio, workpiece speed, and the input DC power source for magnetic flux density. The testing results reveal that the surface roughness of 52100 bearing steel rods improved with a high voltage of 36V and a rotational speed of 1026 rpm. Experiments demonstrate that raising the voltage and rotating speed improves surface roughness by a greater percentage.
Experimental Heat Transfer Analysis of Helical Coiled Tubes on the Basis of Variation in Curvature Ratio and Geometry Susheel Madhavrao Magar, Gaurav Kumar Gugliani, Ravindra Rambhau Navthar Journal of Heat and Mass Transfer Research, 2024 The influence of curvature ratio (CR) within helical tubes on secondary flows and subsequent enhancement of heat transfer is well-established. Furthermore, the interaction between the shell fluid and the helical tube is recognized as pivotal in this regard. In this paper, the impact of varying CR and coil geometry on the performance of heat exchangers (HEs) through experimental heat transfer analysis conducted on five distinct coils viz., straight helical (ϴ= 90°), conical (ϴ= 70°,50°,30°), and spiral (ϴ= 0°) configurations have been studied. Moreover, correlations for modified effectiveness are proposed for all HEs. The Reynolds number range chosen for the analysis spans from 3700 to 20000, encompassing laminar and turbulent flow regimes of the coil hot water. The optimal HE is identified based on thermal and hydrodynamic parameters, including hot water temperature difference, effectiveness, modified effectiveness, rate of heat transfer, pressure drops of the coil, shell fluids, and pumping power. Observations reveal that helical cone coil heat exchangers (HCCHEs) demonstrate superior thermal and hydrodynamic characteristics when the fluid flow aligns with increasing CR. Notably, for both laminar and turbulent flows, the highest hot water temperature difference, effectiveness, and rate of heat transfer are observed for ϴ= 30° HCCHE, while the lowest values are attributed to ϴ= 90° HE. Tube side Nusselt numbers, pressure drops, and friction factors show agreement with the predictions of researchers. The analysis reveals that the coil fluid pressure drop is maximal for ϴ =0° HE, whereas the maximum shell fluid pressure drop is encountered for ϴ =90° HE. Furthermore, the highest pumping power per unit heat transfer area for coil and shell fluids are noted for ϴ= 0° HE and ϴ= 90°HE, respectively, while ϴ= 30° HCCHE exhibits comparable performance to the remaining HEs within the specified parameter range, establishing its optimality.
Suggestion of Correlations to Obtain Shell and Tube Side Nusselt Numbers in Coiled Heat Exchangers Magar Susheel Madhavrao, Gugliani Gaurav Kumar, Navthar Ravindra Rambhau Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, 2024 In coiled tube heat exchangers increase in curvature ratio and effective contact of shell fluid with coil surface led to better thermal characteristics. This work addresses study of thermal performance, shell and tube heat transfer coefficients (ho and hi). Also, mathematical correlations are predicted to obtain shell and tube Nusselt numbers (Nuo and Nui). In the designing of compact coiled heat exchangers consisting of straight helical coil (SHC), conical coil (CC) and spiral coil knowledge of Nuo and Nui is necessary whereas mathematical correlation to calculate Nuo considering variations in shell geometry is not found. Five heat exchangers consisting of three cone coils (angle, ϴ = 30°, 50° and 70°), spiral coil (ϴ = 0°) and SHC (ϴ = 90°) are tested. Using Wilson plot method ho and hi are obtained for wide range of tube side Reynolds numbers (Rei = 3700 - 21000). It is observed that, highest ho is obtained for ϴ = 30°CC with better thermal performance. Lowest ho is obtained for ϴ = 90°SHC. Ratio of height of shell, Hs and diameter of shell, Dso is considered in prediction of single correlation as: Nuo = 16.55.Reo0.55.Pro0.4 *(Hs/Dso)0.096. Comparison with experimental findings shows variation of 0-14%. Similarly two correlations are proposed as: Nui = 0.0512.Rei0.80.Pri0.4.CRave0.18 and Nui = 0.0365.Dei0.815.Pri0.4.CRave-0.3. A fair agreement is found with existing researchers.
An integral augmented sliding mode controller: the experimental application to level control plant Ajit Rambhau Laware, Bhagsen Jaggnath Parvat, Ravindra Rambhau Navthar International Journal of Automation and Control, 2024 It is well-known that servo and regulatory problems in industrial applications requires zero steady-state error. In the absence of an integral-action, uncontrolled systems give steady-state error to some extent or degraded performance under parametric uncertainties and bounded disturbances. Hence, real-time experimentation with integral augmented sliding mode control (IASMC) is adopted to enhance the closed-loop performance of level control plant. Lyapunov candidate function ensures the stability of a system. The practicability of IASMC is guaranteed with laboratory level control model. Experimental results obtained are compared with conventional sliding mode control (SMC) strategies reported by earlier researchers, and proportional-integral-derivative (PID) controller. An evaluation of experimental results with the assumption that nominal plant dynamics are known reveals that the proposed control design method provides a better set-point tracking performance, and fast and smooth level regulation in the presence of external bounded disturbances. It shows better time-domain specifications and error-based performance indices. The study shows that IASMC is applicable to industrial control systems and an alternate control strategy to prevalent design methods.
Effect of the pin temperature and SiC reinforcement on dry sliding tribological behavior of aluminium based silicon carbide metal matrix composite (Al-SiC) using Taguchi approach Milind S. Mhaske, R.R. Navthar, U.M. Shirsat Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology, 2023 This paper deals with the replacement of existing brake pad material based on its highest strength and stiffness-to-weight ratio. To overcome this problem, we have investigated the input process parameters: silicon carbide weight percentage, normal pressure, sliding speed or distance, and temperature, all of which affect tribological properties. The tribological behavior of an aluminum-based silicon carbide metal matrix (Al-SiC) is investigated at elevated temperatures in this study. The metal matrix composite brake pad material has been introduced recently due to its cost-effectiveness, stable coefficient of friction, lower wear rate, and constant contact pressure at high temperatures. In this investigation, an LM25-SiC composite was fabricated using the stir casting technique, in which SiC particles were reinforced at 5%, 10%, and 15% by weight in the base alloy LM25. The investigation was carried out for friction and wear studies on a pin on a disc tester at elevated temperatures for different loads and sliding distances. The investigation using the design of experimentation highlighted by the Taguchi technique highlights the effectiveness of replacing existing brake pad material. The experimental results show improved mechanical properties due to the addition of SiC, and it is also observed that a 15% SiC addition to base metal gives optimal sliding wear.
Impact of Variable Process Parameters of Magnetic Abrasive Finishing on Surface finish of mild Steel Using a DC current for Electromagnets RE Kalhapure, SM Magar, SK Sheikh, RR Navthar Journal Publication of International Research for Engineering and Management … , 2026 2026
Hydroxyapatite coating performance enhancement and characterization for Mg-Zn-Ca-Y alloys for biomedical application SS Gholap, RR Navthar, KB Kale, SH Gawande Discover Materials , 2026 2026 Citations: 1
Experimental Analysis for the Surface Roughness Improvement of Bearing Steel SAE 52100 Using Magnetic Abrasive Finishing Process DRN Rajendra Kalhapure SSRG International Journal of Mechanical Engineering 12 (1), 43-48 , 2025 2025 Citations: 1
A comprehensive review on laser bending of advanced materials V Aher, RR Navthar Lasers in Manufacturing and Materials Processing 11 (3), 814-852 , 2024 2024 Citations: 12
Experimental Heat Transfer Analysis of Helical Coiled Tubes on the Basis of Variation in Curvature Ratio and Geometry SM Magar, GK Gugliani, RR Navthar Journal of Heat and Mass Transfer Research 11 (1), 89-108 , 2024 2024 Citations: 5
Multi-objective optimization and experimental investigation of quarter car suspension system: M. Nagarkar et al. M Nagarkar, Y Bhalerao, S Sashikumar, V Hase, R Navthar, R Zaware, ... International Journal of Dynamics and Control 12 (5), 1222-1238 , 2024 2024 Citations: 17
Suggestion of correlations to obtain shell and tube side Nusselt numbers in coiled heat exchangers MS Madhavrao, GG Kumar, NR Rambhau J. Adv. Res. Fluid Mech. Therm. Sci. 116 (1), 201-222 , 2024 2024 Citations: 2
An integral augmented sliding mode controller: the experimental application to level control plant AR Laware, BJ Parvat, RR Navthar International Journal of Automation and Control 18 (4), 385-407 , 2024 2024 Citations: 3
Effect of the pin temperature and SiC reinforcement on dry sliding tribological behavior of aluminium based silicon carbide metal matrix composite (Al-SiC) using Taguchi approach MS Mhaske, RR Navthar, UM Shirsat Proceedings of the Institution of Mechanical Engineers, Part J: Journal of … , 2023 2023 Citations: 5
Review on the types of solar stills M Shinde, R Navthar, SM Shinde International Journal of Ambient Energy 43 (1), 1420-1428 , 2022 2022 Citations: 18
Keywords: Proportional plus Integral plus Derivative controller Second-order sliding-mode controller The Jaya algorithm Artificial bee colony Real-time experimentation AR Laware, RR Navthar, VS Bandal, DB Talange ISA TRANSACTIONS 126, 498-512 , 2022 2022
Global optimization of second-order sliding mode controller parameters using a new sliding surface: An experimental verification to process control system AR Laware, RR Navthar, VS Bandal, DB Talange ISA transactions 126, 498-512 , 2022 2022 Citations: 9
Topology Optimization of Arms and Hinges of a Combat Vehicle Using FEA. DS Ugalmugale, NR Patel, RR Navthar IUP Journal of Mechanical Engineering 13 , 2020 2020
Wear Particle Analysis Using Ferrography. DNRR Patil, Yogita N IUP Journal of Mechanical Engineering 13 , 2020 2020
Experimental Investigation of Pool Boiling Heat Transfer Enhancement using Natural Surfactant PA Kekan, RR Navthar, SD Kathwate International Journal ofAdvanced Research in Science & Technology (IJARST) 7 … , 2020 2020
Experimental Investigation on Heat Transfer Enhancement in Hydraulic System by Finned Tube Heat Exchanger PB Kale, RR Navthar, SD Kathwate International Journal ofAdvanced Research in Science & Technology (IJARST) 7 … , 2020 2020
Experimental Investigation of Heat Transfer Performance of Rectangular and Triangular Fin Heat Sink R Nagargoje, RR Dr Navthar, SD Kathwate International Engineering Research Journal (IERJ) 7 (3) , 2020 2020 Citations: 2
Performance analysis of single slope solar still with improved design M Shinde, DN Ravindra, S Shinde, V Bhojwani International Journal of Ambient Energy, • https://doi.org/10.1080/01430750 … , 2020 2020 Citations: 1
Effect of vibration on Heat Transfer Enhancement in dimpled Surfaces TS Khamkar, RR Navthar, SK Kardile Journal of Information and Computational Science 9 (8), 196-201 , 2019 2019
Wear Particle Analysis Using Ferrography PDRRN Yogita N. Patil International Engineering Research Journal (IERJ) 3 (3), 1-4 , 2019 2019
MOST CITED SCHOLAR PUBLICATIONS
Stability analysis of hydrodynamic journal bearing using stiffness coefficients RR Navthar, NV Halegowda International Journal of Engineering Science and Technology 2 (2), 87-93 , 2010 2010 Citations: 23
Review on the types of solar stills M Shinde, R Navthar, SM Shinde International Journal of Ambient Energy 43 (1), 1420-1428 , 2022 2022 Citations: 18
Multi-objective optimization and experimental investigation of quarter car suspension system: M. Nagarkar et al. M Nagarkar, Y Bhalerao, S Sashikumar, V Hase, R Navthar, R Zaware, ... International Journal of Dynamics and Control 12 (5), 1222-1238 , 2024 2024 Citations: 17
Experimental Investigation of Tribological Properties Using Nanoparticles as Modifiers in Lubricating Oil MAB Najan, RR Navthar, MMJ Gitay International Research Journal of Engineering and Technology (IRJET) 4 (9 … , 2017 2017 Citations: 14
Digital image correlation technique for strain measurement of aluminium plate SS Gadhe, RR Navthar International Journal of Engineering Trends and Technology (IJETT) 39 (6 … , 2016 2016 Citations: 14
CFD analysis of Francis turbine RR Navthar, J TejasPrasad, D Saurabh, D Nitish, A Anand International Journal of Engineering Science and Technology 4 (7), 3194-3199 , 2012 2012 Citations: 13
A comprehensive review on laser bending of advanced materials V Aher, RR Navthar Lasers in Manufacturing and Materials Processing 11 (3), 814-852 , 2024 2024 Citations: 12
Performance Optimization of Tie rod using FEA S Mungi, R Navthar IJERD, International Journal of Engineering Research and Development 11 (03 … , 2015 2015 Citations: 11
Global optimization of second-order sliding mode controller parameters using a new sliding surface: An experimental verification to process control system AR Laware, RR Navthar, VS Bandal, DB Talange ISA transactions 126, 498-512 , 2022 2022 Citations: 9
Vibration Analysis and Fault Diagnosis of Induction Motor Bearing Using Artificial Neural Network (ANN) K Vaibhav A, DN R R International Journal of Engineering and Techniques - 2 (5), 52-59 , 2016 2016 Citations: 9
Vibration Analysis and Fault Diagnosis of Induction Motor Bearing Using Artificial Neural Network (ANN) K Vaibhav A, RR Navthar International Journal of Engineering and Techniques 2 (5), 52-59 , 2016 2016 Citations: 9
Optimization of Disc Brake Rotor with Modified Shape RS Kajabe, RR Navthar vol 3, 52-60 , 2015 2015 Citations: 9
Tribological Investigation and Development of Tin Based Babbitt Composite Material RS Gujar, RR Navthar International Research Journal of Engineering and Technology 4, 3190-3196 , 2017 2017 Citations: 8
Experimental investigation of oil film thickness for hydrodynamic journal bearings RR Navthar, NV Halegowda Applied Mechanics and Materials 110, 2377-2382 , 2012 2012 Citations: 8
Design and analysis of Cylinder and Cylinder head of 4-stroke SI Engine for weight reduction RR Navthar, PA Narwade International Journal of Engineering Science and Technology 4 (03), 847-853 , 2012 2012 Citations: 7
Analysis of oil film thickness in Hydrodynamic Journal Bearing using Artificial Neural Networks N Ravindra R, NV Halegowda Ciit International Journal of Artificial Intelligent System & Machine … , 2011 2011 Citations: 7
Pressure distribution analysis of hydrodynamic journal bearing using artificial neural network RR Navthar, NV Halegowda, S Deshpande International Conference on computer & automation Eng. 4th (ICCAE2012) , 2012 2012 Citations: 6
Experimental Heat Transfer Analysis of Helical Coiled Tubes on the Basis of Variation in Curvature Ratio and Geometry SM Magar, GK Gugliani, RR Navthar Journal of Heat and Mass Transfer Research 11 (1), 89-108 , 2024 2024 Citations: 5
Effect of the pin temperature and SiC reinforcement on dry sliding tribological behavior of aluminium based silicon carbide metal matrix composite (Al-SiC) using Taguchi approach MS Mhaske, RR Navthar, UM Shirsat Proceedings of the Institution of Mechanical Engineers, Part J: Journal of … , 2023 2023 Citations: 5
Controlling CO2 Emissions from Power Plants: A Environmental View SG Kotakar, RR Navthar Applied Mechanics and Materials 110, 2049-2053 , 2012 2012 Citations: 5