Browsing by Author "Prasad, C.D."

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An experimental study on material removal rate and surface roughness of Cu-Al-Mn ternary shape memory alloys using CNC end milling
(Institute of Physics, 2024) Praveen, N.; Siddeshkumar, N.G.; Prasad, C.D.; Kumar, M.; Kumar, S.; Hrishikesh, H.; Saravana Bavan, S.; Prabhu B, S.R.; Kumar, P.
This study investigates the impact of Computer Numerical Control (CNC) milling parameters on Cu-Al-Mn SMAs (Shape memory alloys) to evaluate the effects on Surface Roughness (SR) and Material Removal Rate (MRR). The primary variables examined comprise of cutting speed, feed rate, and depth of cut. Results indicate that the Shape Memory Effect (SME) is higher in Copper Aluminium Manganese (CAM 3) compared to CAM 1 and CAM 2, with SME improving from 3.5% to 5.5% as Manganese (Mn) content increases, reflecting an increase in dislocations within the metal’s crystal structure. Surface roughness increases with higher feed rates and depths of cut but decreases with increased cutting speed. MRR shows a positive correlation with feed rate, depth of cut, and cutting speed, though it decreases with higher Mn content. Notably, CAM 3 exhibits lower MRR compared to CAM 1 and CAM 2. Scanning Electron Microscopy (SEM) reveals that at lower feed rates (0.10 mm rev−1), the surface is smooth and free of ridges or feed marks, while at higher feed rates (0.18 mm rev−1), noticeable surface imperfections and plastic deformation occur. The addition of Mn improves surface smoothness and machinability, it also affects MRR. Further suggesting that Mn content and milling parameters significantly influence both the mechanical properties and machinability of Cu-Al-Mn SMAs respectively. © 2024 The Author(s). Published by IOP Publishing Ltd.
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.
Comparative investigation of HVOF and flame sprayed CoMoCrSi coating
(American Institute of Physics Inc. subs@aip.org, 2020) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.
Present studies deals with comparison of high velocity oxy fuel and flame spray coating process by developing CoMoCrSi (Tribaloy T400) coating on a titanium grade-15 substrate. Prior to coating, feedstock is processed to obtain higher fraction intermetallics through high energy ball milling technique under controlled atmosphere. Processed feedstock material is sprayed on a Ti-15 substrate through HVOF and Flame spray process. The coated specimens are subjected to metallurgical and mechanical characterization using optical microscope, scanning electron microscope, energy dispersive spectroscopy, x-ray diffraction, Vickers mico hardness tester and bond strength using pull off test method. HVOF sprayed coating exhibits superior properties compared to Flame sprayed coating in terms of surface roughness, porosity, micro hardness and adhesion strength. The detailed studies of two coating systems is discussed. Â© 2020 Author(s).
Comparison of Microstructural and Sliding Wear Resistance of HVOF Coated and Microwave Treated CoMoCrSi-WC + CrC + Ni and CoMoCrSi-WC + 12Co Composite Coatings Deposited on Titanium Substrate
(Springer Science and Business Media B.V. editorial@springerplus.com, 2020) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Srinath, M.S.; Channabasappa, B.H.
CoMoCrSi-WC + CrC + Ni and CoMoCrSi-WC + 12Co composite coatings are coated on titanium substrate by high velocity oxygen fuel method (HVOF). Prior to spraying, CoMoCrSi feedstock are processed through high energy ball milling (HEBM) in order improve the intermetallic laves phases and to reduce its particle size. The processed feedstock exhibits amorphous nature by improving laves phases and particle size of 60.12 ?m. Microwave heating energy is utilized as post heat treatment technique to improve the mechanical and metallurgical properties of as-sprayed coatings. Fused coatings reveals better properties in terms of surface roughness, porosity, microhardness and adhesion strength compared to as-sprayed coatings. Metallurgical bonding is observed in case of fused coatings due to diffusion of substrate elements. Frictional and wear behaviors have been investigated by a pin on disc apparatus at temperatures of 200 °C, 400 °C, and 600 °C under normal loads of 10 N and 20 N. Both wear trace and friction coefficients of the fused coatings are smaller than as-sprayed coatings and substrate at all test temperatures. The wear traces of fused coatings decreased with increasing the surface temperature due to the lubricant effect of cobalt oxides formed on the sliding surface. As a result, cobalt based cermet coatings are highly recommended as a durability improvement coating for the protection of sliding surface, such as high speed spindle. © 2020, Springer Nature B.V.
Cyclic Oxidation and Hot-Corrosion Behavior of HVOF-Sprayed NiCrAl Coating on Industrial Boiler Tube Steels
(Springer, 2024) Ramesh, M.R.; Medabalimi, S.; Rupanagudi, R.S.; Prasad, C.D.; Sollapur, S.B.
At high temperatures, coatings provide a protective scale development on surfaces to maintain long-term stability. In the current study, ASTM-SA210-Grade A1 (GrA1) and ASTM-SA213-T-11 (T11) boiler tube steels were coated with NiCrAl alloy with high-velocity oxy-fuel (HVOF) to prevent oxidation and hot corrosion. For hot corrosion and oxidation, 50 cycles at 900°C were taken into account. Additionally, tests of hot-corrosion behavior were conducted in an atmosphere containing molten salt (Na2SO4-60%V2O5), while tests of oxidation behavior were conducted in static air. The kinetics of oxidation were calculated using the thermogravimetric method. Using XRD, EPMA, and SEM/EDAX methods, the produced oxide scales were characterized. The oxidation rate of NiCrAl-coated steels was found to be lower than that of uncoated steels. The coated steels subjected to oxidation in air exhibit slow scale growth kinetics and oxides of α-Al2O3 and Cr2O3 on the outermost surface, while accelerated oxidation caused by the molten salt exhibits metastable Al2O3. Along the nickel-rich splat boundary, Cr and Al were formed a preferential oxidation, which prevents other oxygen from entering the coating via pores and voids, resulting in steady-state oxidation. © The Minerals, Metals & Materials Society 2024.
Development and Sliding Wear Behavior of Co-Mo-Cr-Si Cladding through Microwave Heating
(Springer editorial@springerplus.com, 2019) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Srinath, M.S.; Channabasappa, B.H.
The aim of the present study is to improve the sliding wear resistance of pure titanium grade-2 substrate by developing CoMoCrSi (Tribaloy T400) cladding on it by using microwave hybrid heating technique. The developed cladding is characterized by microstructural features, phase analysis, measurement of microhardness by employing a scanning electron microscope (SEM), X-ray diffraction (XRD) and Vickers microhardness. The cladding and substrate are subjected to sliding wear test against alumina counterpart at elevated temperatures under dry conditions using a pin on disc tribometer. The test is performed by varying normal load and temperatures, whereas sliding speed is maintained constant. The developed clad shown partial melting of CoMoCrSi powders and obtained sound metallurgical bonding with the substrate. The high specific energy of microwave diluted the substrate atoms into cladding region which forms Cr3C2, Co3Ti, and TiC, phases confirmed by phase analysis. The cladding obtained better porosity and microhardness are 1.5 ± 0.2% ?m and 760 ± 35 Hv respectively. The substrate exhibits low microhardness of 182 ± 25 Hv. The cladding exhibits 6 times of lower volume loss and 70.14% of less wear rate with respect to the substrate. The cladding experienced least coefficient of friction is 0.55 compared with the substrate. The worn surfaces of cladding and substrate are examined. The detailed mechanism of wear is discussed in this paper. © 2019, Springer Nature B.V.
EFFECT of LASER POST-TREATMENT on MICROSTRUCTURAL and SLIDING WEAR BEHAVIOR of HVOF-SPRAYED NiCrC and NiCrSi COATINGS
(World Scientific, 2022) Naik, T.; Mathapati, M.; Prasad, C.D.; Nithin, H.S.; Ramesh, M.R.
In this study, NiCrC and NiCrSi coatings are deposited on the MDN 310 steel using High-Velocity Oxy-Fuel (HVOF) process. Laser Surface Melting (LSM) post-heat treatment is carried out on as-sprayed coatings using Laser Engineered Net Shaping (LENSTM) with a power of 300W. The characteristics of both coatings in terms of mechanical and metallurgical properties have been investigated. The thicknesses of the as-sprayed NiCrC and NiCrSi coatings are in the range of 170-200μm. Laser-treated NiCrC and NiCrSi coatings exhibit a thickness range of 162-185μm, respectively. The microstructure of laser-treated NiCrC-300W coating clearly shows a dendrite-like structure, whereas the laser-treated NiCrSi coating exhibits hard layer and columnar homogeneity. Microhardness of as-sprayed NiCrC coating is 515±15 HV0.3 and that of NiCrSi coating is 645±25 HV0.3. Microhardness of laser-treated NiCrC coating is 720±30 HV0.3 and that of NiCrSi coating is 890±15 HV0.3. Dry sliding wear tests are conducted at room temperature (RT) and 400°C with 10-N and 20-N loads. The wear rates at 400°C temperature of laser-treated NiCrC and NiCrSi coatings produced are slightly below (1-2.2)×10-3mm3/m and (0.8-1.6)×10-3mm3/m, respectively. Laser-treated coatings produced better dry sliding wear behavior compared with as-sprayed coatings owing to dense microstructure. Formation of SiC phase in NiCrSi coating imparts high wear and frictional resistance compared to the NiCrC coating. © 2022 World Scientific Publishing Company.
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.
Effect of Mo- and SiC-Reinforced NiCr Microwave Cladding on Microstructure, Mechanical and Wear Properties
(Springer, 2023) Sharanabasava, H.; Prasad, C.D.; Ramesh, M.R.
A microwave hybrid heating technique was applied to produce the NiCr-Mo-SiC composite cladding on Titan-31. The developed claddings were tested for microstructural features, phase analysis, microhardness, and surface roughness parameters using scanning electron microscopy (SEM), X-ray diffraction (XRD), Vickers Microhardness, and 3D optical profilometers, respectively. Using a static alumina indenter on microwave clads, the linear reciprocator ball on plate wear test was performed. Both friction and wear track metrics have been studied. A dense microstructure without observable holes or fractures has been achieved, together with a homogeneous distribution of hard phases and strong metallurgical bonding. Cladding is typically three times tougher than the underlying metal. Due to the formation of hard carbide phases, which increased hardness and internal lubricity, cladding has a lower coefficient of friction than the substrate. © 2023, The Institution of Engineers (India).
Elevated temperature erosion performance of plasma sprayed NiCrAlY/TiO2coating on MDN 420 steel substrate
(Institute of Physics, 2022) Reddy G, M.S.; Prasad, C.D.; Patil, P.; Naresh, N.; Ramesh, M.R.
The current study deals with the erosion behaviour of a plasma-sprayed 70% NiCrAlY + 30% TiO2 coating on MDN 420 steel substrate at extreme temperatures. The coating was characterized by using an optical microscope, Scanning Electron Microscopy and X-ray diffraction methods. The coating's porosity, microhardness, surface roughness, and adhesion strength were all examined. The solid particle erosion experiments were carried out at temperatures of 300 °C, 500 °C, and 700 °C, with impact angles of 30° and 90°. The tests were conducted by using the alumina as an erodent in the hot air jet erosion testing machine. The erosion volume loss of coated and uncoated samples was measured using an optical profilometer. It is observed that erosion resistance of the coating was found to be more when compared to the substrate for the different test temperatures chosen. As the temperature increases, the erosion resistance of the coating also found increased from 300 °C to 700 °C at both impact angles of 30° and 90°. The morphology of the eroded coating surface reveals that the generalized behaviour of the coating is ductile in nature. © 2022 IOP Publishing Ltd.
Evaluation of microstructural and dry sliding wear resistance of iron-based SiC-reinforced composite coating by HVOF process wear resistance of Fe-based coatings
(CRC Press, 2021) Prasad, C.D.; Jerri, A.; Ramesh, M.R.
The current work describes the evaluation of microstructural and sliding wear resistance of iron-based composite coatings. The feedstock having (70%) Metco 41C and (30%) SiC were blended mechanically through ball milling process. Further, the prepared feedstock was sprayed by HVOF method on ASTM-SA213-T11 steel substrate. Fabricated coating samples and substrate were characterized on different metallurgical and mechanical methods. The coating and substrate were taken into sliding test using pin on disc tribometer by varying parameters of normal load 10 and 20 N at temperatures 200°C, 300°C as well as room conditions without applying lubrication. The tested samples were analyzed in terms of its microstructural and phase formation using SEM and XRD techniques, respectively. The wear properties such as friction coefficient, loss of material in terms of volume and wear rate of coating and substrate were estimated utilizing system-generated data. The hardness and wear resistance of coating improved due to the existence of hard carbide phases, such as SiC and Fe2C in coating area, were detected. © 2022 selection and editorial matter, Lalit Thakur, Hitesh Vasudev. All rights reserved.
High temperature erosion performance of NiCrAlY/Cr2O3/YSZ plasma spray coatings
(Taylor and Francis Ltd., 2023) Reddy, G.M.S.; Prasad, C.D.; Patil, P.; Shetty, G.; Naresh, N.; Ramesh, M.R.
The current investigation's objective was to assess the air jet erosion tester's ability to measure the erosive behaviour of plasma sprayed coatings on titanium-15 alloy. 65% NiCrAlY, 30% Cr2O3, and 5% YSZ make up the coating's chemical composition. A study of microstructure and phases was carried out. Microhardness and adhesive strength have both been measured in this work. With impact angles of 30° and 90° at 300°C, 500°C, and 700°C, Al2O3 erodent was utilised in a solid particle erosion test. An optical profilometer was used to calculate the erosion volume loss. The coating erosion resistance was found to be higher than the substrate sample for the test temperature that was employed, and this was more obvious at higher impact angles and higher temperatures The ductile character of the coating is seen in the contour of the deteriorated coating surface. © 2023 Institute of Materials Finishing Published by Taylor & Francis on behalf of the Institute.
High temperature gradient cobalt based clad developed using microwave hybrid heating
(2018) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Sarkar, A.
The development of cobalt based cladding on a titanium substrate using microwave cladding technique is benchmark in coating area. The developed cladding would serve the function of a corrosion resistant coating under high temperatures. Clads of thickness 500 ?m have been developed by microwave hybrid heating. A microwave furnace of 2.45GHz frequency was used at a 900W power level for processing. Impact of processing time on melting and adhesion of clad has been discussed. The study also extended to static thermal analysis of simple parts with cladding using commercial Finite Element analysis (FEA) software. A comparative study is explored between four variants of the clad being developed. The analysis has been conducted using a square sample. Similar temperature gradient is also shown for a proposed multi-layer coating, which includes a thermal barrier coating yttria stabilized zirconia (YSZ) on top of the corrosion resistant clad. The YSZ coating would protect the corrosion resistant cladding and substrate from high temperatures. � 2018 Author(s).
High temperature gradient cobalt based clad developed using microwave hybrid heating
(American Institute of Physics Inc. subs@aip.org, 2018) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Sarkar, A.
The development of cobalt based cladding on a titanium substrate using microwave cladding technique is benchmark in coating area. The developed cladding would serve the function of a corrosion resistant coating under high temperatures. Clads of thickness 500 Î¼m have been developed by microwave hybrid heating. A microwave furnace of 2.45GHz frequency was used at a 900W power level for processing. Impact of processing time on melting and adhesion of clad has been discussed. The study also extended to static thermal analysis of simple parts with cladding using commercial Finite Element analysis (FEA) software. A comparative study is explored between four variants of the clad being developed. The analysis has been conducted using a square sample. Similar temperature gradient is also shown for a proposed multi-layer coating, which includes a thermal barrier coating yttria stabilized zirconia (YSZ) on top of the corrosion resistant clad. The YSZ coating would protect the corrosion resistant cladding and substrate from high temperatures. Â© 2018 Author(s).
High-temperature oxidation behavior of plasma-sprayed NiCrAlY/TiO2 and NiCrAlY/Cr2O3/YSZ coatings on titanium alloy
(Springer Science and Business Media Deutschland GmbH, 2022) Reddy, G.M.S.; Prasad, C.D.; Shetty, G.; Ramesh, M.R.; Rao, T.N.; Patil, P.
The 70% NiCrAlY + 30% TiO2 and 70% NiCrAlY + 25% Cr2O3 + 5% YSZ metallic coatings are sprayed on titanium-15 alloy of ASTM B338, Grade 2, by using the plasma spray coating technology. Cyclic oxidation studies are conducted on the uncoated and coated alloys at 700 °C under static air environment. The kinetics of oxidation is studied by using the thermo-gravimetric method. Phase, microstructural, and chemical analysis tests are performed on as-sprayed and oxidized coatings. The coated alloys are found to be more resistant when compared to the uncoated alloys. The NiCrAlY + Cr2O3 + YSZ coating is found to be more protective when compared to NiCrAlY + TiO2 coating. It is concluded that the formation of Cr2O3, NiCr2O4, and Al2O3 is attributed to the development of oxidation resistance in the coatings. © 2022, International Institute of Welding.
High-Temperature Oxidation Studies of Plasma-Sprayed NiCrAlY/TiO2 and NiCrAlY/Cr2O3/YSZ Cermet Composite Coatings on MDN-420 Special Steel Alloy
(Springer, 2021) Madhu Sudana Reddy, G.; Prasad, C.D.; Shetty, G.; Ramesh, M.R.; Rao, T.N.; Patil, P.
The plasma spray process was used to form 70%NiCrAlY + 30%TiO2 and 70%NiCrAlY + 25%Cr2O3 + 5%YSZ cermet coatings on MDN-420 special steel alloy. Cyclic oxidation testing was conducted on coated and uncoated specimens at 700°C under a static air environment. Thermogravimetric analysis was applied to establish the oxidation kinetics. X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy-dispersive x-ray spectroscopy (EDS), and electron probe microanalysis (EPMA) techniques were used to analyze the oxidized products. The NiCrAlY + Cr2O3 + YSZ coating was found to be most resistive when compared with the NiCrAlY + TiO2 coating in the aggressive oxidation environment. Net weight loss was observed for bare MDN-420 alloy due to sputtering. The oxidation resistance of the coatings was due to formation of Cr2O3, NiCr2O4, NiO, and Al2O3 phases. © 2021, ASM International.
High-Temperature Tribological Studies on Hot-Forged Al6061–TiB2 In Situ Composites
(Springer Science and Business Media Deutschland GmbH, 2022) Venkategowda, C.; Hanumanthappa, H.; Prasad, C.D.; Shanmugam, B.K.; Sreenivasa, T.N.; Kumar, M.S.R.
The present investigation deals with the tribological behavior of high-temperature hot-forged Al6061–TiB2 in situ composites. Three samples of Al6061–TiB2 in situ composites were prepared with the variation in the in situ TiB2 particles. An in situ technique forms TiB2 particles by facilitating a reaction between Al–3%B and Al–10%Ti parent metals in the Al6061 melt at 800 °C. Further, approximately 5 wt% and 10 wt% TiB2 particles were created in the Al6061 composite using suitable quantities of parent alloys. At 500 °C, the Al6061 and its in situ composites were subjected to hot forging, and about 50% reduction is employed. The scanning electron microscope (SEM) and optical microscopy analysis were conducted to check the TiB2 particle dispersion and worn surfaces in the in situ composites. The TiB2 particle dispersion is found to be fairly uniform throughout the Al6061 matrix with minimal clustering. The results indicate that the friction coefficient increases initially when the temperature increases and then declines due to the oxides in the debris released from the top surfaces of the samples. The results show that the increase in the TiB2 content in the Al6061–TiB2 composites increases the composite wear rate. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
Hot corrosion behavior of plasma-sprayed NiCrAlY/TiO2 and NiCrAlY/Cr2O3/YSZ cermets coatings on alloy steel
(Elsevier B.V., 2021) Reddy, M.; Prasad, C.D.; Patil, P.; Ramesh, M.R.; Nageswara Rao, N.
The objective of the Present research work is to evaluate the hot corrosion resistance of plasma-sprayed 70% NiCrAlY+ 30% TiO2 and 70% NiCrAlY+ 25% Cr2O3+5% YSZ coatings on MDN 420 alloy. Hot corrosion tests are carried out under molten salt environment of Na2SO4+60 % V2O5 salt mixture at 700°C for 50 cycles. Each cycle consisting of 1 hour heating in a silicon carbide tubular furnace followed by 20 min of cooling. The thermogravimetric technique was used to determine the kinetics of corrosion. The scanning electron microscopy (SEM), energy dispersive analysis (EDAX), electron probe microanalyser (EPMA) and X-ray diffracton (XRD) techniques were used to evaluate the characterization of coatings with regard to coating bondstrength, thickness, microhardness and porosity. The parabolic rate constants of coated steels are lower when compared to the uncoated substrate. The NiCrAlY+ Cr2O3+YSZ coating is found to be more protective when compared to NiCrAlY+ TiO2 coating. The oxides of Al2O3, NiCr2O4, and Cr2O3 are formed on the outermost layer of the coatings which gives the resistance the coatings to high-temperature corrosion. © 2020
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.