Browsing by Author "Ramesh, M.R."

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3D printing of functionally graded nanocomposites: An investigation of microstructural, rheological, and mechanical behavior
(John Wiley and Sons Inc, 2024) Kumar, S.; Rajath, S.; Shivakumar, N.D.; Ramesh, M.R.; Doddamani, M.
Manufacturing functionally graded material through 3D printing is challenging owing to the deposition of different materials with different thermal properties in each layer, leading to a higher thermal gradient between deposited and depositing layers, resulting in improper bonding between them and, hence, reduced mechanical properties. This study focuses on 3D printing of functionalized multi-walled carbon nanotubes (MWCNTs)/high-density polyethylene (HDPE)-based lightweight functionally graded nanocomposites (FGNCs) and their investigation for microstructural, rheological, physical, and mechanical properties. Functionalized MWCNTs (0.5% → 5%) are initially compounded with widely utilized HDPE to develop nanocomposites (H0.5→H5 pellets) for extruding filaments for 3D printing. 3D-printed FGNC samples are investigated through scanning electron microscopy (SEM), rheology, density, tensile, and flexural tests. SEM and rheology confirm the homogeneous dispersion of the filler in HDPE and the processing parameters suitability in blending, extrusion, and 3D printing. Complex viscosity (η*), loss modulus (E″), and storage modulus (E′) of FGNCs increase, while the damping decreases with the MWCNTs rise in the graded layers. Density results revealed the highest weight saving potential (~12%) of FGNC-2 (H1–H3–H5), showing great weight saving potential. Tensile and flexural properties rise when the MWCNTs content rises in the graded layer. The FGNC-2 showed the highest tensile strength and moduli, 37.12% and 90.41% higher than HDPE. Flexural strength and moduli are also found to be the highest for FGNC-2, 28.57%, and 26.83% higher than HDPE. The highest specific moduli and strength are found for FGNC-2, 46.16% and 44.14% higher than HDPE, respectively. Experimental findings are found to be strongly in agreement with numerical findings. 3D-printed FGNC-2 demonstrated the best flexural and tensile characteristics with the lowest weight and hence can be used to make practical parts and structures that need variable stiffness. Highlights: FGNCs functionally graded n anocomposites are concurrently 3D printed. FGNC-2 exhibited the highest weight saving potential of 12%. FGNC-2 showed 90.41% and 37.12% enhanced tensile modulus and strength. FGNC-2 displayed 28.57% and 26.83% improved flexural strength and modulus. FGNCs exhibited better mechanical performance than the homogeneous NCs. © 2024 Society of Plastics Engineers.
4D printing of heat-stimulated shape memory polymer composite for high-temperature smart structures/actuators applications
(John Wiley and Sons Inc, 2024) Kumar, S.; Ojha, N.; Ramesh, M.R.; Doddamani, M.
High temperature shape memory polymers (HT-SMPs) have great utilization in self-deployable hinges/morphing structures for space/aerospace, and high-temperature sensors/actuators for electronics. However, HT-SMPs have many drawbacks, such as low stiffness, strength, thermal stability, and dynamic mechanical properties. This work aims at improving these properties of highly utilized space grade HT-SMP, PEKK (polyether ketone ketone), by reinforcing it with low-cost carbon fibers (CFs), and developing its composite via additive manufacturing. The additively manufactured CF/PEKK composites are annealed at 200 °C (CF/PEKK-A200) and 250 °C (CF/PEKK-A250), and for the first time, investigated for shape memory effect (SME). The shape fixity and the shape recovery of the CF/PEKK-UNA (un-annealed), CF/PEKK-A200, and CF/PEKK-A250 are noted to be 95.97%, 88.95%, and 86.40%, and 88.70%, 92.70%, and 95.19%, respectively with a significant weight saving potential of ?21%. Dispersion of CFs in PEKK and suitability of processing parameters (blending, extrusion, and 3D printing) are confirmed through scanning electron microscopy (SEM). Thermal degradation temperature ((Formula presented.)) of the printed CF/PEKK composite (?568 °C) is found to be ?3.5% higher than PEKK (?549 °C). CF/PEKK-A250 exhibited the highest storage modulus (4438.23 MPa), ~158% higher than PEKK (1722.3 MPa), while CF/PEKK-A200 demonstrated the highest tensile modulus (10.9 GPa), which is 138.5% higher than PEKK (4.57 GPa) and 312.88% higher than CF/PEKK-UNA (2.64 GPa). Moreover, CF/PEKK-A200 exhibited 237.46%, 138.51%, 127.08%, 61.48%, 32.93%, and 50.35% higher tensile modulus than PEEK, PEKK, PEK, CF/PEK, CF/PEEK, and CF/PEKK composites, respectively, showing great potential to replace them. Highlights: Printed CF/PEKK composites are investigated for shape memory behavior. The printed composites exhibited outstanding shape memory properties. Printed-A200 exhibited 138.51% enhanced tensile modulus than pure PEKK. Also, the printed-A200 showed 313% enhanced modulus than printed-UNA. (Formula presented.) (568 °C) of the printed composites is found ?4% greater than pure PEKK. © 2024 Society of Plastics Engineers.
A comprehensive characterization of 3D printable poly ether ketone ketone
(Elsevier Ltd, 2024) Ojha, N.; Kumar, S.; Ramesh, M.R.; Balan, A.A.S.; Doddamani, M.
The current work focuses on the comprehensive characterization of a 3D printable biomaterial, polyether ketone ketone (PEKK). The PEKK granules are first characterized and then utilized for extrusion of the PEKK filaments. The extruded PEKK filaments are characterized for crystallinity, quality, and printability, wherein they exhibit amorphous nature, good quality, and appropriate printability. Utilizing the filaments, the samples are printed with the appropriate printing parameters, which are further characterized for layer adhesion, voids, and crystallinity, wherein they showed seamless layer adhesion, improper beads consolidation, and the amorphous nature. The as printed samples are further annealed at different temperatures (200 and 250 °C). The scanning electron microscopy (SEM) of the annealed samples (A-200 and A-250) revealed better void consolidation, while the X-ray diffraction (XRD) revealed better crystallinity compared to the un-annealed sample. The printed samples are also investigated for dynamic mechanical analysis (DMA), shape memory, and tensile properties. The storage moduli of the annealed samples are observed to be better than the un-annealed sample. The annealed samples exhibited better shape memory properties: shape fixity and shape recovery ratio of A-200 and A-250 samples, 90.28 and 90.75%, and 99.16 and 94.73%, respectively, compared to the un-annealed samples. The highest shape fixity ratio and the shape recovery ratio are noted for A-250 (90.75%) and A-200 (∼ 100%). The A-200 and A-250 samples showed enhanced tensile modulus and strength, 4.16 and 49.67%, and 36.61 and 35.06%, respectively compared to the un-annealed sample. The highest modulus is noted for A-250, while the strength is comparable (36.61 and 35.06%) for A-200 and A-250. © 2023 Elsevier Ltd
A microstructural study and high-temperature oxidation behaviour of plasma sprayed NiCrAlY based composite coatings
(Elsevier B.V., 2025) Hebbale, A.M.; Ramesh, M.R.; Petr?, J.; Chandramouli, T.V.; Srinath, M.S.; Shetty, R.K.
In this study, the development and performance evaluation of plasma sprayed NiCrAlY based coatings, such as NiCrAlY, NiCrAlY + Al?O? and NiCrAlY + YSZ on T91 steel substrates for high temperature applications is carried out. Microstructural features, phase composition and oxidation resistance under cyclic oxidation at 800 °C of the coatings were characterized. Analysis of the XRD confirmed the formation of protective phases such as Cr?O?, Ni?Al and NiAl, and the improvement observed in the coating's performance was due to the addition of Al?O? and YSZ. Oxidation resistance was improved for the NiCrAlY + Al?O? coating through the formation of a dense Al?O? oxide layer, but the NiCrAlY + YSZ coating was superior in terms of thermal stability and spallation resistance, because YSZ has low thermal conductivity and high thermal shock resistance. Composite coatings showed improved cyclic oxidation behavior and microstructural analysis revealed reduced porosity and enhanced integrity. The results demonstrate that the addition of Al?O? and YSZ in the NiCrAlY coatings leads to capability of tailoring NiCrAlY–based coatings for high temperature industrial applications with improved durability and oxidation protection. © 2025 The Author(s)
Advanced machining of TiNiCo shape memory alloys for biomedical applications
(ICE Publishing, 2019) Soni, H.; Ramesh, M.R.; Narendranath, S.
Wire electro discharge machining (WEDM) is one of the most productive non-traditional machining processes. Complex shapes can be cut through the WEDM process. In the present study, attempts have been made to study the effects of various process parameters of WEDM such as pulse on time (Ton), pulse off time (Toff), servo voltage (SV), wire speed (WS) and servo feed (SF) on the material removal rate (MRR) and surface roughness (SR) for machining of TiNiCo shape memory alloys, traditionally used as bone staple material. Grey-relational-analysis-based entropy measurement methods were used for formulating a hybrid combination of optimisation methods, in order to investigate the input parameters of WEDM on the comprehensive performance of a bone staple material’s SR and MRR. Experiments were carried out by using response surface design (L-33), and the input parameters were ranked based on the grey relational grade. An experimental run was conducted using the optimal combination of input parameters of WEDM, which was obtained from the analysis. Ton of 125 µs, Toff of 42 µs, SV of 40 V, SF of 2180 machine units and WS of 4 m/min were obtained as the best combination of input process parameters for TiNiCo alloy. © 2019 ICE Publishing. All rights reserved.
An experimental study of influence of wire electro discharge machining parameters on surface integrity of TiNiCo shape memory alloy
(Cambridge University Press, 2017) Soni, H.; SannaYellappa, N.; Ramesh, M.R.
Shape memory alloys (SMAs) are unique class of smart materials with excellent physical, mechanical and biomedical properties, which have wide applications in several fields such as aerospace, robotics, biomedical, and dental etc. These alloys are well known for exhibiting shape memory effect (SME) and pseudoelasticity (PE), it is a well-established fact that they are required to be processed into functioning parts. The conventional machining affects the internal properties of shape memory alloys and hence, it is reported that nonconventional machining techniques are more suitable. Wire electro discharge machining (WEDM) is one of the nonconventional machining processes for machining complicated shapes without hampering the internal properties of such type of materials. In the present experimental investigation, wire electro discharge machining of Ti50Ni40Co10 shape memory alloy (SMA) has been carried out and machining performances such as surface roughness (SR), and material removal rate (MRR) have been evaluated. Experimental results exposed that pulse on time, pulse off time and servo voltages are most influential process parameters on the responses. The machined surface has been characterised with respect to microstructure, microhardness, and phases formed. © Materials Research Society 2017.
An investigation on high temperature erosion behaviour of plasma sprayed CoCrALY/Al2O3/YSZ on fe and ni based alloys
(Universiti Putra Malaysia Press Tower 2, UPM-MDTC Technology Centre Serdang, Selangor 43400, 2017) Nithin, H.S.; Desai, V.; Ramesh, M.R.
Parts of aircraft and gas turbines used for power production are subjected to severe erosion damage since aircrafts frequently operate in sandy environment. Low cost fuel such as poor quality coal is used in gas turbines which produce suspended hard particle in the exhaust. In the past, researchers have worked on minimising the erosion by using certain coatings. Development of new coatings is necessary in order to explore further in improving resistance against erosion process under high operating temperature of gas turbine, aero engines and other components. In the present work, the investigation of elevated temperature erosion behaviour of CoCrAlY/Al2O3/YSZ coatings synthesised by plasma spraying on two different base metals, namely, Hastelloy X (Superni 76) and AISI 321 (MDN 321) was carried out. The coated samples were subjected to erosion test at 600ºC with the impact angles of 30º and 90º under steady state condition. Alumina powder was used as erodent material of uneven angular shape of 50 ?m particle size. The morphology and phase formed on eroded surface are characterised using SEM and X-ray diffraction to determine the erosion mechanism. The rate of erosion is determined by weight loss method and the CoCrAlY/Al2O3/YSZ coating showed up to about 25% lower erosion rate than the substrate alloy. It was observed that the erosion resistance of CoCrAlY/Al2O3/YSZ coating on both MDN 321 and Superni 76 gave almost similar erosion resistance which shows that the erosion behaviour of coating is not influenced by substrate unless spray parameter and substrate roughness is changed. © 2017 Universiti Putra Malaysia Press.
An investigation on tribological performance in HVOF sprayed of Amdry1371 and Amdry 1371/WC-Co coatings on Ti6Al4V
(Elsevier B.V., 2024) Behera, N.; Srihari, M.; Sharma, Y.K.; Ramesh, M.R.
This study investigates the effect of 30 wt% WC addition into Mo-based coating on the microstructure and dry sliding wear performance at elevated temperatures. A ball-on disk tribometer assessed coating wear and friction behavior at room temperature (RT), 300, and 600 °C with loads of 10 and 20 N. The wear rate and mechanism were assessed using SEM-EDX and an optical profilometer. The coating characteristics included density, porosity, surface roughness, microstructure, and microhardness. The bond strength of Amdry1371 and Amdry1371/30%WC-Co coatings is analyzed using the scratch test. During the scratch test, both coatings show cohesive failure at 30-50 N and cohesive along with adhesive failure at 70 N loads. Compared to Amdry1371 coating, Amdry1371/30%WC-Co coating has greater microhardness and bond strength. The wear rate and friction coefficients of Amdry1371 and Amdry1371/30%WC-Co coatings increase with temperatures up to 300 °C and decrease at 600 °C. Wear debris is generated when contact surfaces fracture under the applied load, acting as a third body in the sliding process. This phenomenon, observable from room temperature to 300 °C, increases wear rate and friction coefficients. Protective oxide phases formed on worn surfaces like MoO3, NiMO4, CoWO4, Cr3O8, and WO3 film at 600 °C. This glaze layer is present on worn surfaces, significantly reducing friction coefficients and the wear rate of coatings. Amdry1371/30%WC-Co coating exhibits superior wear resistance and lower friction coefficients than Amdry1371 coating due to MoO3 and WO3. At RT, the dominant abrasive wear mechanism shifts to oxidative wear at 600 °C for both coatings. © 2024 Elsevier B.V.
ANN and RSM modeling methods for predicting material removal rate and surface roughness during WEDM of Ti50Ni40Co10 shape memory alloy
(AMSE Press 16 Avenue Grauge Blanche Tassin-la-Demi-Lune 69160, 2017) Soni, H.; Narendranath, S.; Ramesh, M.R.
Present study exhibits the comparison between experimental and predicted values. Where response surface method (RSM) and artificial neural network (ANN) were used as predictor for the prediction of wire electro discharge machining (WEDM) responses such as the material removal rate (MRR) and surface roughness (SR) during the machining of Ti50Ni40Co10 shape memory alloy. It has been noticed from the literature survey that pulse on time and servo voltage are most important process parameters for the machining of TiNiCo shape memory alloy, hence there are five levels of these process parameters were chosen for the present study. For the present study selected alloy has been developed through vacuum arc melting and L-25 orthogonal array has been created by using Taguchi design of experiment (DOE) for experimental plan. During the present study ANN predicted values have been found to very close to experimental values compare to RSM predicted values, hence it can be say that ANN predictor gives more accurate values compare to RSM predicted values. © 2017 AMSE Press. All rights reserved.
Buckling and dynamic responses of 3D printed nanocomposites and their graded variants
(Elsevier Ltd, 2023) Kumar, S.; Ramesh, M.R.; Jeyaraj, P.; Doddamani, M.
The experimental and numerical investigations are carried out for buckling and vibration of 3D printed functionalized MWCNTs/HDPE based nanocomposite (NC) and their functionally graded nanocomposite (FGNC) variants. Pcr(critical buckling load) is computed through MBC (modified budiansky criteria) and DTM (double tangent method) techniques. It is observed that Pcr of the 3D printed NCs and FGNCs increases with the functionalized MWCNTs content. The Pcr values for the NCs (H0.5-H5) computed using DTM and MBC increased in the range of 16–79%, while for FGNC-1 (H0.5-H1-H3) and FGNC-2 (H1-H3-H5), the Pcr increased from 54 to 91% compared to HDPE. Further, it is observed that the natural frequency of the NCs and FGNCs increases with the functionalized MWCNTs loading while decreases with rise in compression. The natural frequency of the NCs (H0.5-H5) and FGNCs increased up to 41% than HDPE. The highest Pcr and the natural frequency is noted for H5 and FGNC-2 prints. The experimental and numerical results showed good agreement. © 2023 Elsevier Ltd
Buckling behavior of non-uniformly heated 3D printed plain and functionally graded nanocomposites
(John Wiley and Sons Inc, 2023) Kumar, S.; Ramesh, M.R.; Jeyaraj, J.; Powar, S.; Doddamani, M.
The functionalized multi-walled carbon nanotubes (MWCNTs) (0.5–5 wt.%) are compounded with high density polyethylene (HDPE), and, subsequently, used for extruding nanocomposite filaments to fabricate nanocomposites (NCs) and functionally graded nanocomposites (FGNCs) through 3D printing. The 3D printed NCs are investigated for coefficient of thermal expansion (CTE), and buckling under different non-uniform temperature distributions (case-1: left edge heating, case-2: centre heating, and case-3: left and right edge heating). A significant reduction in CTE is observed with MWCNT addition and gradation. The highest reduction in CTE is observed for H5 (5 wt.% of MWCNT in HDPE) NC and H1 ⟶ H3 ⟶ H5 (FGNC-2) among the NCs and the FGNCs. It is noted that Tcr (critical buckling temperature) is highest for case-3 and lowest for case-2. The highest deflection is noticed in case-2, while no significant difference is observed in case-1 and case-3 heating conditions. It is also observed that Tcr increases with gradation and MWCNTs addition. The H5 NC and FGNC-2 exhibited the highest Tcr among the NCs and FGNCs, respectively. The maximum deflection is noticed for HDPE, whereas the minimum deflection is noticed for FGNC-2 and H-5 NC among the tested samples. The results also revealed that Tcr is very sensitive to type of heating. © 2023 Society of Plastics Engineers.
Characterisation and performance evaluation of TiSiN &tiAlSiN coatings by RF magnetron sputtering deposition during end milling of maraging steel
(Institute of Physics Publishing helen.craven@iop.org, 2019) Varghese, V.; Ramesh, M.R.; Dupadu, D.; Shaik, H.
Monolayer nanostructured thin films of TiSiN & TiAlSiN were deposited on WC-Co milling inserts using RF magnetron sputtering for metal cutting. The alloy targets of TiSi (80/20 at%) & TiAlSi (34/56/10 at%) were used for the deposition in an Ar + N atmosphere. The deposition time and parameters are optimized to develop a uniform and homogenous coating. The mechanical and metallurgical properties are characterized to analyze the wear resistance of the coating. The machinability studies on MDN 250 maraging steel is carried out using TiSiN and TiAlSiN coated WC-Co inserts under dry and wet environment. The machining responses such as surface roughness, cutting force, tool wear and tool life are analyzed by varying spindle speed. The results showed that TiAlSiN coating had a higher wear resistance and machining performance compared to the TiSiN coating owing to the high hardness and plasticity index of the coating. © 2020 IOP Publishing Ltd.
Characterization and evaluation of carbide-based composite coatings for high-temperature wear resistance on Titanium substrate
(SAGE Publications Ltd, 2025) Behera, N.; Ramesh, M.R.
Titanium alloys are used in the automotive and aerospace industries, but perform poorly at high temperatures due to inadequate wear and friction properties. This study investigates Cr3C2-25%CoNiCrAlY and WC-CoCr coatings applied via High-velocity oxygen Fuel on a titanium-31 substrate. Coatings were evaluated from 200–800?°C under 20?N and 30?N using a ball-on-disc tribometer. Characterization techniques included scanning electron microscope, X-ray diffraction, microhardness, porosity, and bond strength. WC-CoCr coating showed higher hardness and bond strength than Cr3C2-25%CoNiCrAlY. Both coatings exhibited reduced wear rates until 600?°C, after which the wear rates increased at 800?°C due to enhanced oxidation. The coefficient of Friction decreased with increasing temperature. At 600?°C, oxide phases helped reduce wear and friction. WC-CoCr coating shows better wear resistance than Cr3C2-25%CoNiCrAlY coating and the substrate. Wear mechanisms changed from abrasive and fatigue at 200?°C to oxidative and adhesive at 800?°C. Volumetric ball loss was higher for WC-CoCr due to its greater hardness. © The Author(s) 2025
Characterization and sliding wear behavior of CoMoCrSi+Flyash composite cladding processed by microwave irradiation
(Elsevier Ltd, 2021) Prasad, C.; Shashank Lingappa, M.; Joladarashi, S.; Ramesh, M.R.; Sachin, B.
The present work deals with the development of CoMoCrSi+Flyash composite cladding on AISI 410 steel substrate using a domestic microwave oven with cladding process parameters of frequency 2.45GHz, with the power of 900W and processing time is 1800s. The developed clad is characterized by metallographic and mechanical properties. Further, the substrate and cladding samples are tested for high-temperature sliding wear behaviour using a pin on disc apparatus. The clad specimen exhibits partial melting of particles and observed uniformity in thickness. X-Ray Diffraction analysis shows the presence of Cr3C2, Co3Ti, TiC, SiC, and Mo3Si hard phases that are formed during the cladding process, while excellent metallurgical bonding can be observed which provides improved hardness. The addition of flyash into the cobalt-base matrix enhanced high-temperature strength results in better wear resistance due to the formation of oxide layers. Â© 2021 Elsevier Ltd. All rights reserved.
Characterization and Sliding Wear Behavior of Iron-Based Metallic Coating Deposited by HVOF Process on Low-Carbon Steel Substrate
(Springer, 2020) Prasad, C.D.; Jerri, A.; Ramesh, M.R.
The main aim of this work is to improve the sliding wear resistance of boiler steel material. The iron-based or Metco 41C metallic feedstock was deposited over the ASTM-SA213-T11 steel substrate using high-velocity oxy-fuel spraying process. The resultant deposits were subsequently characterized for microstructure, density, hardness, porosity and surface roughness. These characterizations were carried out with the help of XRD, SEM and Vickers’s microhardness tester. The sliding wear performance of the substrate and coatings were investigated by varying normal loads of 10 N and 20 N at temperatures of 200 °C, 300 °C as well as room conditions by employing pin-on-disk tribometer. The friction coefficient, volume of wear loss and wear rate were being found out. The wear results were compared among the substrate and coating. The formation of additional carbide phases such as Fe2C and SiC in Metco 41C coating led to higher hardness results in better wear resistance compared with the substrate. © 2020, Springer Nature Switzerland AG.
Characterization and Wear Behavior of NiCrMoSiC Microwave Cladding
(Springer, 2024) Sharanabasava, H.; Prasad, C.D.; Ramesh, M.R.
A microwave hybrid heating technique has been employed to develop NiCr-Mo-SiC composite cladding on titanium alloy (Grade-5/Ti-6Al-4 V/Titan-31). The developed claddings have been characterized for microstructural features, phase analysis, microhardness measurements, and 3D optical profile parameters by employing scanning electron microscopy, x-ray diffraction, Vickers microhardness tester, and 3D optical profilometer, respectively. Microwave clads have been subjected to linear reciprocator ball on plate wear test with static alumina indenter. Wear track parameters and friction coefficients have been studied. A dense microstructure with uniform distribution of hard phases and good metallurgical bonding with no visible pores and cracks has been obtained. Cladding exhibits nearly 2 times higher hardness than the base alloy. Coefficient of friction studies revealed that higher molybdenum content enhances internal lubricity. © 2023, ASM International.
Charactersation & hot corrosion studies on plasma sprayed (WC-CO) / (CR3C2-NICR) Coating on titanium & special steel alloys
(IAEME Publication, 2018) Reddy, M.S.G.; Ramesh, M.R.; Nageswara Rao, N.T.; Jegadeeswaran, N.
A present study is an attempt to evaluate the hot corrosion resistance of plasma sprayed 35%(WC-Co)+65 %(Cr3C2-NiCr) coatings on Titanium-15 & MDN 420 alloys in molten salt environment of Na2SO4+60 %V2O5 salt mixture at 700oC under cyclic conditions. The hot corrosion tests are carried out for 50 cycles, for 1 hour each cycle of heating followed by 20 minutes of cooling in open air environment. The tests are conducted in silicon carbide tubular furnace. Thermogravimetric studies are made to establish the kinetics of corrosion for the uncoated and coated samples. The SEM/EDS, XRD & X-ray elemental mapping techniques are made to analyze the parameters like element concentration, morphology, & phase composition & of the hot corrosion products. The parabolic rate constants are evaluated for understanding the corrosion behavior of coatings. It is observed that (WC-Co) + (Cr3C2-NiCr) coated MDN-420 is more resistant than coated (WC-Co) + (Cr3C2-NiCr) coated titanium-15. From the present study it is concluded that the hot corrosion resistance of both the coatings has been attributed to the formation of Ni3V208, NiCr2O4, NiWO4, and COCr2O4 & Cr3C2. © IAEME Publication.
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]
Combating corrosion degradation of turbine materials using HVOF sprayed 25% (Cr3C2-25(Ni20Cr)) + NiCrAlY coating
(2013) Jegadeeswaran, N.; Ramesh, M.R.; Bhat, K.
High velocity oxy fuel process (HVOF) is an advanced coating process for thermal spraying of coatings on to components used in turbines. HVOF process is a thermal spray coating method and is widely used to apply wear, erosion, and corrosion protective coatings to the components used in industrial turbines. 25% (Cr3C2-25(Ni20Cr)) + NiCrAlY based coatings have been sprayed on to three turbine materials, namely, Ti-31, Superco-605, and MDN-121. Coated and uncoated substrates were subjected to hot corrosion study under cyclic conditions. Each cycle consisted of 1 hour heating at 800°C followed by 20 minutes air cooling. Gravimetric measurements were done after each cycle and a plot of weight gain as a function of number of cycles is drawn. Parabolic rate constants were estimated for the understanding of corrosion behaviour. It was observed that coated Ti-31 and MDN-121 were more resistant compared to the uncoated ones. Uncoated superco-605 was undergoing sputtering during corrosion study and hence comparison between coated and uncoated superco-605 was difficult. The cross-sectional analysis of the corroded, coated samples indicated the presence of a thin layer of chromium oxide scale on the top of the coating and it imparted better corrosion resistance. Parabolic rate constants also indicated that coating is more beneficial to Ti-31 than to MDN-121. © 2013 N. Jegadeeswaran et al.
Comparative investigation of coating and friction stir processing on Mg-Zn-Dy alloy for improving antibacterial, bioactive and corrosion behaviour
(Elsevier B.V., 2021) Rokkala, U.; Jana, A.; Bontha, S.; Ramesh, M.R.; Balla, V.K.
Magnesium based alloys are well-known materials for temporary implant applications. However, failures due to early degradation and bacterial infection are limiting their applications. To overcome these problems, in the present work a Mg-Zn-Dy alloy based composite surface was prepared using coating and friction stir processing (FSP) techniques. Herein, hydroxyapatite (HA) and silver (Ag) particles were deposited on Mg-Zn-Dy alloy to obtain HA and Ag coated surface (C-HAg). Later, FSP was carried out on the C-HAg surface to develop a Mg-Zn-Dy alloy based composite surface (F-HAg). Field emission scanning electron microscope (FESEM) and energy dispersive X-ray analysis (EDS) confirm the mixing of HA and Ag particles with the Mg-Zn-Dy substrate. Antibacterial studies reveal that both C-HAg and F-HAg samples inhibit Escherichia coli and Staphylococcus aureus bacteria. In vitro cytotoxicity study indicates that the both samples are non-toxic in nature. Results of in vitro corrosion study reveal a significant reduction (72%) in corrosion rate of F-HAg sample when compared to C-HAg sample. The F-HAg samples showed simultaneous improvement in corrosion resistance and antibacterial properties with good biocompatibility. The results of this study indicate that the developed composite surface is a promising material for antibacterial and biodegradable implant applications. © 2021 Elsevier B.V.