High Velocity Oxy-fuel Process Research Articles

A Comparative Study of the Life Cycle Inventory of Thermally Sprayed WC-12Co Coatings

In this research, a life cycle inventory (LCI) is developed for tungsten carbide–cobalt (WC-Co) coatings deposited via atmospheric plasma spray (APS), high-velocity oxy-fuel (HVOF), and cold gas spray (CGS) techniques. For the APS process, a mixture of Ar/H2 was used, while the HVOF process was fueled by H2. The carrier gas for CGS was N2. This study aims to determine and quantify the inputs (consumption of inputs and materials) and outputs (emissions to air, soil, water, and waste generation) that could be used in the life cycle analysis (LCA) of these processes. The dataset produced will allow users to estimate the environmental impacts of these processes using WC-Co feedstock powder. To obtain a complete and detailed LCI, measurements of electrical energy, gas, WC-CO powder, and alumina powder consumption were performed (the use of alumina was for sandblasting). Furthermore, emissions like carbon dioxide (CO2), carbon monoxide (CO), and noise were also measured. This practice allowed us to determine the input/output process quantities. For the first time, it was possible to obtain LCI data for the APS, HVOF, and CGS deposition processes using WC-12Co as a feedstock powder, allowing access to the LCI data to a broader audience. Comparisons were made between APS, HVOF, and CGS processes in terms of consumption and emissions. It was determined that the APS process consumes more electrical energy and that its deposition efficiency is higher than the other processes, while the HVOF process consumes a large amount of H2, which makes the process costlier. CGS has comparatively low electricity consumption, high N2 consumption, and low deposition efficiency. The APS, HVOF, and CGS processes analyzed in this study do not emit CO, and CO2 emissions are negligible.

Erosion Prediction Gaussian Process Regression Algorithm for Alumina and Chromia Reinforced Nickel-Based High-Velocity Oxy-Fuel Coatings

Background:: Machine learning (ML) methodologies have demonstrated efficacy in the determination of erosion rates and material removal. In this context, a novel Erosion Prediction Gaussian Process Regression Algorithm (EPGPRA) was developed to predict the volumetric erosion in thermal spray coatings. Aim:: In this patent, a novel EPGPRA based model was developed to predict the volumetric loss of 30Al2O3 and 20Cr2O3 reinforced Ni-based coatings deposited using a high-velocity oxy-fuel (HVOF) process. Objective:: The objective of this patent is to develop a GPR model for the prediction of Ni-30Al2O3 and Ni-20Cr2O3 coatings. Methods:: Spraying powders were applied to the SS316L steel substrate in order to develop coatings. An erosion tester was used in order to investigate the wear resistance of HVOF-coated steel. The gathered experimental dataset is put to use in the construction of a powerful GPR model. The outcomes from GPR model were then measured against the values obtained from the experiments. To demonstrate the accuracy of the GPR model, the produced model is evaluated against various cutting-edge machine learning methods. Results:: This innovation was successful in terms of developing a new GPR model for wear prediction. The discrepancy between the actual and expected values is the smallest for Matern 5/2 (M5/2) GPR in the validation set. It was also lesser as compared to Ensemble Boosted Trees, Support Vector Machine, Linear regression, and Fine Tree. In terms of MSE, MAE, RMSE, and R2 the accuracy performance of the M5/2 GPR model was determined to be 9.8565×10-5, 0.0048884, 0.009928, and 0.93 correspondingly. Ni-Chromia coating performed better than the Ni-Alumina. Conclusion:: As per this patent, a novel EPGPRA-based model was developed, which is the better machine learning technique for wear prediction of Ni-based HVOF coatings.

Influences of flame remelting and WC-Co addition on microstructure, mechanical properties and corrosion behavior of NiCrBSi coatings manufactured via HVOF process

We investigated the microstructures, mechanical properties, and corrosion behavior of NiCrBSi coatings upon the addition of the WC-Co powder in various amounts (0, 5, 10, 15, and 20 wt%) using the high velocity oxy-fuel process on low-carbon steel. Additionally, flame remelting was performed at 1100 °C for 1 min following thermal spraying of the coatings. The microstructures of the coatings were examined using X-ray diffractometry and scanning electron microscopy, and the mechanical properties of the coatings were assessed via Vickers microhardness and ball-on-disk tests. The corrosion behavior of the coatings was evaluated using potentiodynamic polarization testing in a 20 vol.% sulfuric acid solution. The results demonstrated that an increase in the WC-Co amount enhanced the hardness and wear resistance of the coatings. For 10–20 wt% WC-Co addition, small cracks were observed in the as-sprayed coatings owing to the heat applied during thermal spraying and rapid cooling, respectively. The presence of porosity directly affects the corrosion behavior of the coatings. Flame remelting led to better cohesion and the distribution of the γ-Ni and WC phases, reducing microdefects, such as pores and cracks. The mechanical properties of the coatings improved as the WC-Co amount increased after flame remelting, resulting in the formation of intermetallic compounds (FeB, CoSi2, and Ni2Si) along with the WC phase. The flame-remelted NiCrBSi/ 10 wt% WC-Co coating demonstrated high hardness and low wear and corrosion rates (1072.26 HV, 4.8 × 10−6 mm3/m, and 0.560 mm/year, respectively). Therefore, WC-Co addition and the flame remelting process significantly enhanced the properties of NiCrBSi coatings. This study highlights the substantial contributions of WC-Co addition and the flame remelting process in enhancing the mechanical properties and corrosion resistance of NiCrBSi coatings. These findings offer valuable insights for optimizing the performance of commercially available coatings in various real-world applications in maintaining power plants and industrial components like high-pressure pump piston rods, acid-resistant pumps in oil refineries.

Characterisation and wear behaviour of SiC reinforced FeNiCrMo composite coating by HVOF process

ABSTRACT Analysis of the sliding wear and microstructural characteristics of iron based composite coatings are discussed. The feedstock, which consisted of 30% SiC and 70% FeNiCrMo, was mechanically combined using a ball milling process. A steel substrate made of ASTM-SA213-T11 was then sprayed with the prepared feedstock using the High Velocity Oxy Fuel (HVOF) process. The coating and substrate were put through a sliding test using a pin-on disc tribometer while being subjected to typical loads of 10 and 20 N at 200°C and 300°C as well as ambient conditions without lubrication. The samples were subjected to microstructures and phase studies using SEM and XRD techniques. Wear characteristics including friction coefficient, volumetric material loss, and wear rates of the coating and substrate were calculated using system-produced data. The hardness and wear resistance of the coated samples were improved owing to the coating region containing hard carbide phases such as SiC and Fe2C.

Microstructure and Wear Performance of CeO2-Modified Micro-Nano Structured WC-CoCr Coatings Sprayed with HVOF

Rare earth elements have been widely utilized in material manufacturing to enhance properties in various ways. In order to obtain the WC-10Co4Cr coating with uniform distribution of rare earths, CeO2-modified powder was prepared by mixing 1 wt.% nano-sized CeO2 during the initial ball-milling of the powder fabrication process. Bare and CeO2-modified WC-10Co4Cr coatings were deposited via high velocity oxygen fuel spraying to investigate the impact of CeO2 modification on the coating’s microstructure, mechanical properties and abrasive wear performance. The results show that the addition of CeO2 increased the interface energy, inhibiting the formation of the Co3W3C phase during the powder sintering process, as well as the W2C phase and CoCr alloy during the high-velocity oxy-fuel (HVOF) process. This led to a significantly decreased porosity and higher concentration of undissolved Cr-rich areas. The microhardness and fracture toughness of the CeO2-modified coating were 1230 HV0.3 and 5.77 MPam1/2, respectively. The abrasive wear resistance of the CeO2-modified coating was only 70.9% of that of the unmodified coating. Due to the weak cohesive strength between WC and Cr, Cr-rich areas were preferentially removed, resulting in an increased wear rate in the CeO2-modified coating.

The effect of WC-CoCr content on hardness and tribological properties of NiCrBSi coatings fabricated by the HVOF process

Although Ni-based alloy composites are commonly used as coatings for the enhancement of tribological properties of structural materials. The achievement of a dense and well-distributed microstructure with high content of reinforcing materials is still a challenge. Herein, we aimed to prepare NiCrBSi/WC-CoCr composite materials with different amounts of WC-CoCr (0–45 wt%) using V-mixer and high-velocity oxy-fuel (HVOF) coatings techniques and evaluated the hardness and tribological properties of the coatings at 500 °C. Particularly, we optimized the distribution of WC-CoCr in NiCrBSi matrix using a set of optimized parameters for mixing and coating processes. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to characterize the microstructures of the coatings. It was observed that an appropriate balance of hard phase (WC-CoCr splats: 30 wt%) and soft phases (Ni-base alloy: 70 wt%) can lead to a uniform, dense, and well-bonded microstructure resulting in the achievement of high hardness, low wear rate, and friction coefficient. Higher contents of WC-CoCr splat (45 wt%) led to a loosening of the interphase bonding on one hand (due to weak wetting between WC-CoCr splats and uncomplete melting of WC-CoCr splats during coating process), and enhanced oxide formation in the coating owing to alumina insertion (from wearing of alumina balls) on the other hand. Overall, the comparison of the harnesses and friction coefficients obtained in the present work shows how an optimized process could lead to the accomplishment of properties superior to those reported in the works.

Investigations on the Microstructure and Corrosion Performance of Different WC-Based Cermet Coatings Deposited by High Velocity Oxy Fuel Process onto Magnesium Alloy Substrate

Investigations on the Microstructure and Corrosion Performance of Different WC-Based Cermet Coatings Deposited by High Velocity Oxy Fuel Process onto Magnesium Alloy Substrate

SUPPORT VECTOR MACHINE LEARNING ON SLURRY EROSION CHARACTERISTICS ANALYSIS OF Ni- AND Co-ALLOY COATINGS

In this paper, a novel support vector machine (SVM) learning approach has been used to predict the silt erosion of coatings sprayed by the high-velocity oxy-fuel (HVOF) process. The silt erosion resistance of HVOF-coated Co- and Ni-alloys is studied using an erosion tester. Both of these spraying powders were deposited on the 18Cr-12Ni-2Mo austenitic steel substrate. For the erosion experiments, the fixtures were developed to test the erosion characteristics at different impingement conditions (i.e. [Formula: see text], [Formula: see text], and [Formula: see text]). The image processing technique enables an understanding of the erosion mechanisms of coatings. The support vector regression is more effective than the traditional regression models. The proposed model employs support vector regression with parameter tuning. The ideal parameters are selected with the help of the grid search method. The model is trained by supplying 70% data and validated with 15% data. Afterward, the remaining 15% is given to the prepared model as testing data. The dataset obtained is employed for building an effective support vector regression model. The predicted results are compared against the original experimental values. The developed model is also compared with other state-of-the-art machine learning techniques for showing the preciseness of the proposed model. The Ni-based HVOF coating showed superior performance ([Formula: see text]) better than the Co-based HVOF coating under similar experimental conditions. An SVM model was successfully developed to predict the erosion of coated and uncoated 18Cr-12Ni-2Mo austenitic steel. The precision performance of the SVM model was calculated in terms of [Formula: see text], RMSE, [Formula: see text], and MAE as 0.99, [Formula: see text], 0.99, and [Formula: see text], respectively.

HVAF vs oxygenated HVAF spraying: Fundamental understanding to optimize Cr3C2-NiCr coatings for elevated temperature erosion resistant applications

High velocity sprayed Cr3C2-NiCr coatings are a viable solution to improve the life of power plant components and are often influenced by the choice of processing conditions. The new generation convertible high-velocity air-fuel (HVAF) process offers higher versatility to spray wide ranging particle sizes including the standard high-velocity oxy-fuel (HVOF) grade. However, the use of such oxygenated spraying termed as ‘HVAF(O)’ mode necessitates better understanding for reliable and repeatable coating. Single particle splat morphology and fracture mechanisms of HVAF and HVAF(O) sprayed Cr3C2-NiCr coatings were correlated with the microstructural features, mechanical properties and erosion performance with two different particle sizes. Among the coatings studied, HVAF(O) sprayed coarse Cr3C2-NiCr and HVAF sprayed fine Cr3C2-NiCr provided the least thermal degradation, and better mechanical properties which collectively ensured enhanced erosion performance. The overall coating performance can be attributed to the appropriate choice of process conditions and suitable particle size. In comparison with conventional HVOF process that generally induces a certain degree of thermal degradation within the hard carbides, oxygenated HVAF(O) sprayed Cr3C2-NiCr coating still retained most of the starting carbide phase with minimal thermal degradation, which resulted in superior erosion performance.

Effect of nano yttria-stabilized zirconia on properties of Ni-20Cr composite coatings

In the present work, 5 wt.% and 10 wt.% yttria-stabilized zirconia (YSZ) nanoparticles were reinforced in Ni-20Cr powder and deposited on boiler tube steel using a high-velocity oxy-fuel spraying process. The effect of YSZ reinforcement on microhardness, surface roughness and porosity was investigated. The hardness was the highest for nanocomposite coating reinforced with 10 wt.% YSZ and hardness was found to increase with a decrease in porosity. The coating microstructure and elements were characterized using field emission scanning electron microscopy (FE-SEM) with an energy dispersive spectroscope (EDS). The constituents of the coating were identified using X-ray diffractometer. It was found that the composite coating with 10 wt.% YSZ reinforced nanocomposite coating has the highest microhardness, in the range of 1008-1055 hv. During the coating process, nano YSZ particles were dispersed in the gaps between the micrometric Ni-20Cr particles, providing a better coating matrix than conventional Ni-20Cr. The Ni-20Cr with 10 wt.% of YSZ nanoparticles showed better results in terms of mechanical and microstructural properties during the investigation.

Resistance to slurry erosion by WC-10Co-4Cr and Cr3C2 − 25(Ni20Cr) coatings deposited by HVOF stainless steel F6NM

Hydroelectric turbine machinery experience extreme wear and tear due to slurry erosion and is one of the leading causes for the unplanned shutdown of hydro power plants. The coatings produced by High-velocity oxy-fuel (HVOF) thermal spray process on different hydro-turbine parts is known for improving wear resistance. In the present study, WC-10Co-4Cr and Cr3C2 − 25(Ni20Cr) coatings were sprayed by HVOF process on F6NM stainless steel of Dul-Hasti hydro-power plant turbine material. The slurry erosive wear studies of developed coatings was performed using high speed slurry erosive wear tester. Sediments collected from Dul-Hasti power plant dam site was taken as erodent material. The effect of four parameters specifically rotational speed (500–1250 rpm), slurry concentration (25–40 wt%), sand particle size (125–425 μm), and test duration (450–900 min) on slurry erosion of coated materials was studied. It was observed that among all the developed three coatings, the WC-10Co-4Cr coated samples has shown superior erosion resistance compared to Cr3C2 − 25(Ni20Cr) coated samples due to its improved micro-hardness. Both the developed coatings were observed to be useful in enhancing the erosion resistance of F6NM steel significantly. Erosion mechanism were studied in detail using SEM. The properties such as hardness and porosity were also examined.

Optimisation of HVOF Spray Process Parameters to Achieve Minimum Porosity and Maximum Hardness in WC-10Ni-5Cr Coatings

High-velocity oxy-fuel (HVOF) spray coating plays a major role in many surface treatment methods, which tend to improve erosion and corrosion resistance properties. HVOF is well known for its dense and high-quality coating ability. This is due to the less in-flight exposure time, which tends to have less oxide content because of its high-velocity properties. Among the number of process parameters, porosity and hardness are predominant factors while considering wear rate and corrosion behaviour analysis. The current study aims to optimise HVOF process parameters to obtain low levels of porosity and high hardness values in the WC-10Ni-5Cr coating sprayed on 35 Mo Cr steel. The flow rates of oxygen, LPG, coating powder feed rate and spray distance are selected in this study as these have a superior influence on the final condition of the coating. Statistical tools such as the design of experiments (DoE), analysis of variants and response surface methodology (RSM) were used to achieve the desired results. As per the result analysis, the oxygen flow rate has a higher effect on the porosity value and microhardness value of the coating.

Influence of Spray Parameters on the Metallurgical and Functional Properties of HVOF WC Based Cermets Deposited onto Low Alloy Steel

Abstract: Tungsten carbide based spray coatings are widely used in industry for application requiring abrasion, sliding, fretting and erosion corrosion resistance. High velocity oxy-fuel (HVOF) flame spraying was used for producing high quality carbide composite coatings. In this study, a WC-CoCr and WC-CoCrNi powders were thermal sprayed using a HVOF process. The spray parameters were varied in order to investigate their influence on microstructure and mechanical properties of coatings. It is possible to produce homogeneous coating by controlling the flame temperature, the velocity of the gun transverse, the powder feed rate and the nature of the powders. The mechanical properties and the porosity rate could be optimized in order to improve the functional properties.

Microstructural, Mechanical and Wear Behavior of HVOF and Cold-Sprayed High-Entropy Alloys (HEAs) Coatings

HEAs powders, unlike standard alloys which contain one or two base elements, are new alloys that contain multiple elements in the same quantity. These materials have outstanding physical and mechanical properties and for this reason, are of great interest in the material science community for their application in advanced industrial sectors. In this investigation, cold spray (CS) and high-velocity oxy fuel (HVOF) processes were used to deposit Cantor alloy (FeCoCrNiMn) coatings. Starting feedstock powders were thoroughly characterized in terms of size, shape, phase and elastic modulus. For CS process, the coating deposition efficiency and porosity could be optimized by varying gas pressure, gas temperature and stand-off distance. In the case of HVOF process, stand-off distance influenced the thickness of the coatings. Besides, on the optimized CS and HVOF coatings, corrosion tests in 3.5% NaCl solution, as well as rubber wheel, ball on disk and jet erosion tests were carried out to evaluate their wear behavior. Also, to benchmark the corrosion and wear behavior of optimized coatings, the results were compared to 316L and C-Steel bulks. The tribological study shows that Cantor alloy coatings deposited via CS and HVOF are promising to protect parts and components in a harsh environment.

Wear resistance study on HVOF based SiC and TiB2 ceramic coating for AH36 steel for marine based thermal applications

ASTM AH36 steel has been a primary material used for marine-based construction and applications. It is also a primary material employed in boilers and thermal-based equipment. The material is known for versatility and reliability in marine environments. However, the steel has an inherent limitation for wear resistance when subjected to adverse conditions during operation by the marine ecology as well as abrasive materials when being in thermal operation. This has been a major reason for services and these problems can be mitigated by improving the hardness, chemical inertness and adhesion to the substrate. Silicon Carbide (SiC) and Titanium Diboride (TiB2) are noted for their hardness and ecologically inert behaviour. The steel surface has been coated with these ceramic materials to improve the wear resistance. The coating is provided by the High-Velocity Oxy-Fuel (HVOF) technique. A microstructural, mechanical and wear analysis is performed on SiC, TiB2 and Mixture of 80 %SiC-20 %TiB2 coated specimens to analyze the surface modifications. Based on the pin on disc test results it can be observed that the application of Silicon Carbide and Titanium Diboride coatings has shown an improvement in wear resistance by reducing a wear loss by 1/8th, 1/6th and 1/10th respectively against the uncoated specimen. This increase in wear resistance is attributed to the improvement in the hardness of the surface by formation of harder compounds and additional phases during HVOF process. This indicates that inert material-based surface modifications can be an ecofriendly and effective way to improve the wear resistance in marine steels.

Development of FeV-WC Ni Cr B Si coating on Stainless steel using HVOF process

In the present investigations, 50% Fe V + 50% (WC Ni Cr B Si) Coating is developed on SS304 Substrate with High-Velocity Oxy-Fuel (HVOF) thermal spray process. SS304 substrate is commonly used for the plant machinery process vessels which are affected by moderate corrosion and wear applications. This investigation aims to study the performance of the developed coating. The Feedstock powders are characterized by various characterization methods such as SEM, EDS, and XRD, while the as-sprayed coating is characterized by SEM and XRD. The vicker hardness testing technique is used to identify the hardness of the coating. Present research work represents that developed coating improvises average microhardness of substrate from 185 to 205 HV0.1 to 340–680 HV0.1 and thus improves the wear resistance.

Ni-based coating protection of 316L stainless steel at dry, elevated temperature and wet sliding condition

The NiCrSiB coatings are used extensively for wear and oxidation resistance in numerous applications like hot forming industries, power generation plants, petroleum refining, and nuclear power plants. In this paper, NiCrSiB powder deposited by APS (atmospheric plasma spray) and HVOF (high velocity oxy-fuel) process on stainless steel 316L substrate was investigated for the friction and wear at RT (room temperature), 700 °C, at the lubricating condition with clean and contaminated oil with nano alumina particles. The sliding wear tests were carried out on standard tribometer against silicon nitride (1580 HV0.3) counter material following ASTM G99 standard. The coatings characterization was performed using porosity analysis, nano-indentation, 3D non-contact analysis, EDX (energy-dispersive X-ray), SEM (scanning electron microscope) and LRS (Laser Raman Spectrum). The wear, friction and the wear mechanisms were investigated for both coatings at tested conditions. Although the coating wear was substantially affected by the temperature, the specific wear rate of the APS and HVOF coatings lies in the range 10-4 to 10-5 mm3/N.m and hence serviceable up to 700 °C. The coating's wear mechanisms at elevated temperature were a combination of adhesive and tribo-oxidative wear. At the dry, wet, and high-temperature condition, the HVOF coating retains higher wear resistance than APS coating, due to the high dense structure, low porosity, low inflight oxidation and high nano hardness. The nano alumina particles in the contaminated oil reduces the COF significantly for HVOF coating whereas, negligible change in COF has been observed for APS coating.

Effect of carbon nanotubes on microhardness and adhesion strength of high-velocity oxy-fuel sprayed NiCr–Cr3C2 coatings

NiCr–Cr3C2 coatings are widely used for high temperature and tribological applications due to their high hardness, oxidation, and wear resistance properties. In the present investigation, an attempt is made to further enhance the hardness and adhesion strength of NiCr–Cr3C2 coatings by reinforcing them with multi-walled carbon nanotubes. The carbon nanotubes (3–7 wt%) with varying weight percentages were mixed with NiCr–Cr3C2 using a planetary ball rolling mill and sprayed on SA213 T12 (T12 alloy steel tube) using a high-velocity oxy-fuel spraying process. The microstructures of mixed powder, coating cross-section, and fractured coating surface were characterized using a scanning electron microscope while X-ray diffraction was used for phase identification in the fractured coating surface. The coated samples were subjected to microhardness and adhesion strength tests according to ASTM E384 and ASTM D4541-09 standards. Out of all coatings, NiCr–Cr3C2/7% carbon nanotube composite coating showed the lowest porosity of 1.17%, highest microhardness, and adhesion strength of 563.8 HV and 55.8 MPa, respectively. A fracture analysis after a pull-off adhesion test revealed adhesion failure for NiCr–Cr3C2 coating and combined adhesion/cohesion failure for NiCr–Cr3C2/7% carbon nanotube composite coating.

EFFECT OF LASER POST-TREATMENT ON MICROSTRUCTURAL AND SLIDING WEAR BEHAVIOR OF HVOF-SPRAYED NiCrC AND NiCrSi COATINGS

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 300[Formula: see text]W. 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 170–200[Formula: see text][Formula: see text]m. Laser-treated NiCrC and NiCrSi coatings exhibit a thickness range of 162–185[Formula: see text][Formula: see text]m, 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 [Formula: see text] [Formula: see text] and that of NiCrSi coating is [Formula: see text] HV[Formula: see text]. Microhardness of laser-treated NiCrC coating is [Formula: see text] HV[Formula: see text] and that of NiCrSi coating is [Formula: see text] HV[Formula: see text]. 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 [Formula: see text][Formula: see text]mm3/m and [Formula: see text][Formula: see text]mm3/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.

A REVIEW ON THE INFLUENCE OF PROCESS PARAMETERS AND HEAT TREATMENT ON THE CORROSION PERFORMANCE OF NI-BASED THERMAL SPRAY COATINGS

Various typical engineering components fail from surface under aggressive conditions like oxidation and hot corrosion. This paper is focused on the responsible failure mechanism of oxidation and hot corrosion. The surface properties like corrosion resistance can be enhanced by introducing a layer of Ni-based materials by using thermal coating techniques. The coatings developed by using processes like high velocity oxy-fuel, plasma spray and cold spray exhibits some surface defects like porosity, surface roughness and un-melted particles. Such defects can be further minimized by using optimization of process parameters and various heat treatment processes. The current study is restricted to the analysis of Ni-based coatings developed using high velocity oxy-fuel, plasma spray and cold spray process. In this paper, the optimization of various process parameters along with heat treatments has been discussed in regard to the tailoring of microstructure and the mechanical properties of the developed coatings.