Faculty Publications
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Item Clad developments through microwave hybrid heating technique processing and properties(CRC Press, 2022) Suresh, G.; Ramesh, M.R.; Hebbale, A.M.; Srinath, M.S.[No abstract available]Item Surface Engineered Titanium Alloys for Biomedical, Automotive, and Aerospace Applications(Springer Nature, 2023) Gudala, G.; Ramesh, M.R.; Srinath, M.S.This chapter provides an overview of surface modification of titanium alloy for applications in aerospace, automotive, and biomedical field. Current uses for titanium alloys are found in biomedical, automotive, aerospace, and other industrial applications. For aerospace uses, titanium alloys can be used for about 70% of the total, including engine components and airframe structures. Titanium alloys provide a notable advantage in several industrial applications, including heat exchangers, cooling systems in power stations, and chemical industries. In recent times, titanium alloys have been used in oil and gas drilling industries. It was observed that surface degradation of titanium alloy was observed in all the above applications after a certain amount of time or cycle. To enhance the surface properties of titanium alloy, surface engineering of titanium alloy with the appropriate surface modification technique is essential. The present trends predicted that industrial and commercial segments of titanium alloys could triple in the next five years. This chapter presents several case studies involving surface engineering techniques used for titanium alloys for potential automotive, biomedical, and aerospace applications. The demand for applications like the aerospace, biomedical, and automotive industry of titanium alloy boosts the ever-increasing demands for improving the surface modification of titanium alloys to meet the various needs. However, these alloys cannot possess all the desired attributes, especially important surface properties like wear and corrosion resistance. Therefore, surface modification techniques have to be used to enhance surface properties and satisfy the specific needs for various applications. This chapter discusses various surface modification methods used for titanium alloys to protect them from degradation. Titanium and titanium alloys can be extensively used in biomedical components and devices, especially in cardiac and cardiovascular applications, as hard tissue replacements. However, titanium alloys cannot meet all clinical requirements. Surface modification is often required to improve the biological, chemical, and mechanical properties. The present chapter also highlights the various surface modification techniques pertaining to titanium alloys, including thermal spraying, sol–gel, electrochemical treatment, and ion implantation from biomedical engineering. The present study focuses on improving the surface properties of titanium alloy for better wear resistance, corrosion resistance, and other biological properties using appropriate surface modification techniques while the desirable bulk attributes are retained. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Optimization of Parameters Influencing Tensile Strength of Inconel-625 Welded Joints Developed Through Microwave Hybrid Heating(Elsevier Ltd, 2018) Badiger, R.I.; Narendranath, S.; Srinath, M.S.Processing of bulk metals through microwave energy in recent years is finding widespread applications and is being prominently accepted by the manufacturing industries. Present work, investigates the effect of process parameters on the tensile strength of Inconel-625welded joints produced through microwave hybrid heating using design of experiments. Experiments were carried out by using Taguchi's L16 factorial design of experiment method. Input parameters chosen were separator type; susceptor type and filler powder size. The output response chosen was ultimate tensile strength. Optimization of the process parameters is done through Taguchi method and percentage influence of each process parameter on the strength of weld is determined using ANOVA method. Combination of parameters with graphite separator, SiCsusceptor and finer filler powder yields optimum result. © 2017 Elsevier Ltd.Item Joining of Inconel-625 alloy through microwave hybrid heating and its characterization(Elsevier Ltd, 2015) Badiger, R.I.; Narendranath, S.; Srinath, M.S.Joining of bulk metals using microwave energy is being explored as a new processing method in the era of high technology applications. The present work investigates the results of on-going project in which joining of Inconel-625 alloy has been effectively carried out through microwave hybrid heating. Characterization of the microwave developed joints is done through SEM, XRD, UTM and Vicker's microhardness tester. The microstructural analysis through scanning electron microscope exhibits a fully fused weld interface free from interfacial cracks. XRD study reveals the formation of carbides of Ni, Cr and Mo in the joint interface. The average Vicker's microhardness in the joint region observed was 360 ± 20 Hv. Assessment of tensile strength shows an ultimate tensile strength of 328 MPa with 9.04% elongation. Further the fractured joints are subjected to fractography study which possibly reveals a mixed mode fracture. © 2015 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.Item Influence of microwave hybrid heating on the sliding wear behaviour of HVOF sprayed CoMoCrSi coating(Institute of Physics Publishing helen.craven@iop.org, 2018) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Srinath, M.S.; Channabasappa, B.H.CoMoCrSi superalloy powder (Tribaloy-T400) consists of intermetallic laves phase and primary eutectic phase of Co-rich solid solution. Processing of Tribaloy-T400 powder is carried out through high-energy ball milling (HEBM) technique to obtain a higher volume fraction of intermetallic laves phases. The feedstock is sprayed using high-velocity-oxy-fuel (HVOF) process on titanium grade-15 substrate. The coating microstructure is homogenized by microwave hybrid heating technique. Characterization of feedstock, as-sprayed and microwave fused coatings is done by using Scanning Electron Microscopy (SEM), Energy dispersive spectroscopy (EDS) and x-ray Diffraction (XRD). Porosity, surface roughness, microhardness, and bond strength are measured. Adhesive wear behavior of the coatings under the dry sliding condition is evaluated at an applied load of l0 and 20 N and temperature of 200, 400 and 600 °C Fused coating exhibit higher wear resistance than the as-sprayed coatings and substrate. The hard intermetallic laves phases which are amorphous (bulk metallic glass) in nature strengthen the coating at high temperatures. © 2018 IOP Publishing Ltd.Item Microstructure and mechanical properties of Inconel-625 welded joint developed through microwave hybrid heating(SAGE Publications Ltd info@sagepub.co.uk, 2018) Badiger, R.I.; Narendranath, S.; Srinath, M.S.Application of microwave energy for processing of bulk metals is effectively utilized to join Inconel-625 plates through hybrid heating technique using Inconel-625 powder as an interface filler material. Post welding characterization of microwave developed joints through X-ray diffraction shows the development of carbides of niobium and chromium as well as intermetallic phases along with the primary ?-phase face-centered cubic matrix. Microstructural examination reveals the formation of Laves phase along the grain boundaries in the fusion zone. Microwave-induced joints exhibit average microhardness of 245 ± 20 HV and 0.7% porosity in the fusion zone. Average ultimate tensile strength and flexural strength of the developed joints were estimated at 375 and 377 MPa respectively. Average impact toughness of microwave-induced joints is observed to be 18 J. © IMechE 2017.Item Microstructure and tribological behavior of flame sprayed and microwave fused CoMoCrSi/CoMoCrSi-Cr3C2 coatings(Institute of Physics Publishing helen.craven@iop.org, 2019) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Srinath, M.S.; Channabasappa, B.H.This present work deals with the investigation of dry sliding wear behavior of CoMoCrSi and CoMoCrSi-Cr3C2 depositing on titanium substrate through Flame spray process, subsequently fused by the microwave hybrid heating process. Prior to the deposition of the coating, CoMoCrSi powder is milled by using high energy ball milling (HEBM) process and later 30% of Cr3C2 powder is added. Microstructural features and phase analysis of milled powders, as-coated and microwave fused coatings are inspected by using SEM with EDS and XRD process respectively. The coatings before and after fusing are tested for microhardness and bond strength by using a Vickers microhardness and universal tensile machines respectively. Dry sliding wear behavior of coatings before and after fusing is conducted against alumina counter face at ambient and elevated temperatures, also normal load is varied. The wear mechanism of both coatings is examined by employing XRD, SEM-EDS techniques. The fused coatings exhibit lower friction and better wear resistance compared with as-deposited coatings. The detailed results of each test of their coatings are discussed in this paper. © 2018 IOP Publishing Ltd.Item Optimization of Process Parameters by Taguchi Grey Relational Analysis in Joining Inconel-625 Through Microwave Hybrid Heating(Springer New York LLC barbara.b.bertram@gsk.com, 2019) Badiger, R.I.; Narendranath, S.; Srinath, M.S.The quality of welded joints developed using microwave hybrid heating (MHH) technique is largely influenced by properties of the constituents employed in the process. This article investigates the influence of process parameters on tensile strength and flexural strength of Inconel-625 plates welded through MHH. Experiments were planned according to Taguchi L 16 orthogonal array by considering three factors: separator, susceptor and filler powder particle size. Ultimate tensile strength and flexural strength of the specimens welded at 600 and 900 W were chosen as response characteristics. Application of Taguchi-based GRA has been effectively used to optimize multi-performance characteristics of the process. ANOVA results indicate that size of interface filler powder is the most significant factor in determining the joint strength followed by separator and susceptor. Further to corroborate the optimal parameter setting for maximum strength values, metallurgical characterization of the specimens is carried out through XRD and SEM. Specimens processed at 600 W exhibited superior properties compared to their counterparts developed at 900 W. © 2018, Springer Science+Business Media, LLC, part of Springer Nature and ASM International.Item Effect of Power Input on Metallurgical and Mechanical Characteristics of Inconel-625 Welded Joints Processed Through Microwave Hybrid Heating(Springer, 2019) Badiger, R.I.; Narendranath, S.; Srinath, M.S.; Hebbale, A.M.In the present study, welding of Inconel-625 through the use of microwave hybrid heating (MHH) has been achieved at two power levels 600 W and 900 W in a low-cost home microwave oven. Nickel-based powder EWAC was used as filler interface between faying surfaces. Effect of power variation on the metallurgical and mechanical characteristics of the microwave welded joints has been investigated. Developed joints were characterized through XRD, optical microscope, SEM, universal testing machine and Vickers microhardness tester. XRD study of the weld zone indicated the formation of various carbides and intermetallics. Joint microstructures witnessed a completely fused weld interface without any interfacial cracks. EDS analysis of the joint microstructure revealed lesser amount of segregation of niobium and molybdenum with the specimens developed at 600 W which could be attributed to the lower heat input associated with 600 W power that also resulted in fine grain structure. Further, the specimens processed at 600 W exhibited better tensile and flexural properties when compared to their counterparts produced at 900 W power. Fractography study of the specimens revealed a combined ductile and brittle fracture. © 2019, The Indian Institute of Metals - IIM.Item Effect of microwave heating on microstructure and elevated temperature adhesive wear behavior of HVOF deposited CoMoCrSi-Cr3C2 coating(Elsevier B.V., 2019) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Srinath, M.S.; Channabasappa, B.H.This research reports the improvement of high-temperature sliding wear resistance of a grade 15 titanium alloy protected by an HVOF sprayed CoMoCrSi-Cr3C2 coating. The coatings have been tested in as-sprayed condition and after a post-deposition microwave heating step. The powder feedstock has been manufactured by high energy ball milling. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) equipped with the Energy Dispersive Spectroscopy (EDS) methods were used for coatings characterization. Surface roughness, microhardness, adhesion strength, and porosity of coatings were also measured. The wear test was conducted at an applied load of l0 N and 20 N with varying temperatures of 200 °C, 400 °C, and 600 °C under dry sliding conditions. Co3Mo2Si, Co7Mo6, Mo3Si, Co3Mo, and Co2Mo3 were the intermetallic laves phases generated in the CoMoCrSi feedstock during HEBM process. The microwave-fused coating exhibited metallurgical bonding, homogeneous structure, less porosity, and greater hardness as compared to as-sprayed coating. Microwave-treated coating revealed better wear property than an as-sprayed coating. This was mainly due to the intermetallic formation and metallurgical bonding in coatings. The fused coatings exhibit tribo-oxide layers during sliding action which was the main phenomenon of improving the wear resistance of the fused composite coatings. © 2019 Elsevier B.V.