Slurry Erosion Tests Research Articles

Evaluation of Slurry-Eroded Rubber Surface Using Gloss Measurement

Slurry erosion testing is essential for evaluating the durability of materials under erosive conditions. This study examines the slurry erosion behaviours of chloroprene rubber (CR) under varying impact conditions to assess its durability. Traditional mass loss methods and qualitative techniques, including microscopy, SEM, and AFM, were employed to analyse eroded CR samples. Results indicate that cumulative material loss in CR increases linearly with sand impingement after approximately 60 kg of sand and correlates with an impact energy of about 30 kJ. The highest erosion rate was found at an impact angle of 15°. Erosion mechanisms vary with impact angle, affecting surface topography from cutting and ploughing at lower angles to deformation and crater formation at higher angles. Despite their efficacy, these methods are time-intensive and costly. This paper presents a novel approach utilising gloss measurement for continuous, non-destructive monitoring of eroded rubber surfaces. Gloss measurements are 24 times faster than traditional mass loss methods. Correlating gloss values with cumulative material loss, steady-state erosion, and impact energy offers significant time savings and an enhanced understanding of the erosion process. Experimental results demonstrate the effectiveness of gloss measurement as a reliable tool in slurry erosion testing of rubbers. The quantitative output from gloss measurements could support proactive maintenance strategies to extend service life and optimise operational efficiency in industrial applications, particularly in the mining industry.

Slurry Erosion Resistance, Morphology, and Machine Learning Modeling of Plasma-Sprayed Si3N4+TiC+VC and CrNi based Ceramic Coatings

This study presents a comprehensive analysis of the morphology, mechanical properties, erosion resistance, and machine learning modeling of Si3N4+TiC+VC and CrNi based ceramic coatings deposited via plasma spraying. The cross-sectional morphology analysis revealed good mechanical interlocking between the coatings and the substrate, with pores predominantly observed in the Si3N4+TiC+VC coating. The coating thicknesses were measured as follows: 260 μm for Si3N4+TiC+VC, 243 μm for Si3N4+TiC+VC blended with CrNi, and 232 μm for pure CrNi coating. Mechanical characterization showed that microhardness values ranged from 1933 HV for Si3N4+TiC+VC coating to 499 HV for pure CrNi coatings. Slurry erosion tests demonstrated that pure Si3N4+TiC+VC coating exhibited superior erosion resistance at 90º impingement angle compared to other coatings. Additionally, a rigorous evaluation of over 20 machine learning regression models revealed that Gaussian Process Regressors and Artificial Neural Network (ANN) with a layer size of 20, displayed satisfactory performance in modeling mass loss prediction. The erosion mechanisms observed in the coatings provided valuable insights into their response to slurry erosion, highlighting the influence of coating composition and impingement angles. The findings underscore the potential of Si3N4+TiC+VC ceramic coatings to enhance the erosion resistance of stainless steel, offering promising applications in various industries.

Effect of substrate’s surface roughness on corrosion and wear rate of Ni-GO nanocomposite coating

Corrosion is a natural process that occurs when refined metal is converted into a more stable form, such as oxide, hydroxide, or sulfide. Wear is the failure of a surface due to dynamic contact between two surfaces. In offshore operations and environments, corrosion and wear are major problems due to the presence of corrosive and abrasive elements. The coating is a common surface protection method that enhances corrosion resistance and prolongs lifespan. In this work, a Ni-Graphene nanocomposite coating was fabricated using the electrodeposition method. This work aimed to fabricate a Ni-GO nanocomposite coating on mild steel with different surface roughness, to characterize the physical, mechanical, and chemical properties of the coating, and to investigate its corrosion and wear rate. The fabrication process involved preparing substrates coated with Ni-GO nanocomposite through a 45-minute constant current electrodeposition process. The coated specimens were characterized using X-Ray Diffraction Machine (XRD), Scanning Electron Microscope (SEM), Alicona Infinite Focus, Vicker’s Hardness Test, Raman spectroscopy, and Adhesion test. The corrosion and wear rate of the coatings were investigated using a Slurry Erosion tester and Salt Water spray, respectively. The results showed that the Ni-Go nanocomposite coating on a smooth surface roughness substrate achieved the highest microhardness, wear resistance, and corrosion resistance, with values of 468.8 HV, 0.182% weight loss, and 0.03% weight gain, respectively. This indicates that the specimen coated with a smooth surface roughness substrate provided better coating performance than the rough and medium surface roughness substrates.

HVOF-sprayed surface coating with various compositions of Co-NiCrAlY-Al2O3 to minimize sediment erosion in hydraulic turbines

The components of hydropower plants are susceptible to sediment erosion caused by hard particles in the water. These hard particles cause substantial material loss and a reduction in the performance of the hydraulic turbines. The present study deals with the mitigation of sediment erosion in hydraulic turbines by developing a protective coating (CoNiCrAlY-Al2O3 metal-ceramic composite) using a high-velocity oxygen-fuel (HVOF) coating technique. Hardness measurement, surface wettability analysis, and surface roughness measurement were conducted to characterize the coatings, whereas scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS) were performed for metallurgical characterization. The slurry/sediment erosion behavior of bare and coated substrate was investigated using a slurry erosion tester. Experiments were performed for five coating compositions at different impact angles (30° ≤ ϴ ≤ 90°) and velocities (6 ≤ v ≤ 12 m/s). The maximum improvement in erosion performance (reduction in erosion rate compared to bare substrate ≈ 28.12 % at 30°, 9.29 % at 45°, and 11.69 % at 90° impact angle) was obtained for the coating having 12 wt% alumina doped into Co-NiCrAlY. The coating's performance was improved due to increased hardness, high shielding effect, and reduction in impact energy on Al2O3 by using CoNiCrAlY-Al2O3 deposition. The empirical correlation between erosion rate and velocity for both bare and coated substrates has also been proposed.

Slurry erosive wear behaviour of metal matrix composites – A review

Slurry erosion has become a problem in the components that handle particle-entrained slurry. The limitation of the metallic materials to inhibit the slurry erosive wear has led to the development of metal matrix composite (MMC) materials to suit applications in severe erosive environments. Compared to ductile and brittle materials, metal matrix composite materials behave differently when subjected to slurry erosion. However, due to the ductile matrix and hard reinforcement phases, the metal matrix composites exhibited semi-ductile and semi-brittle erosion behaviour under slurry erosion conditions. This work presents the material removal mechanisms of MMCs, erosion models, and types of equipment for slurry erosion testing. In addition, the various factors that influence slurry erosion, such as the properties of MMC, properties of flow, erodent particles, and slurry, have also been reviewed.

Performance of HVAF sprayed WC-10Co-4Cr coating onto cast 21-4N steel for slurry erosion: Characterization and erosion rate studies

In this study, 86WC-10Co-4Cr powder was thermally sprayed onto cast 21-4N steel using High Velocity Air-Fuel (HVAF) technology. The deposited coating exhibited a dense structure with minimal porosity (1.0 ± 0.3%) and excellent fracture toughness (5.1 ± 0.3 MPa m1/2). Slurry erosion tests had shown that the HVAF-coated steel had significantly improved erosion resistance compared to uncoated steel, attributed to its high hardness, fracture toughness, and dense microstructure. Statistical analysis revealed that slurry velocity and impact angle were the most influential parameters. Further, Field emission scanning electron microscope (FE-SEM) image analysis showed that the coated steel exhibited a brittle mode of material removal, while the bare steel displayed a ductile mode. Overall, the study highlights the effectiveness of HVAF-sprayed 86WC-10Co-4Cr coatings in enhancing erosion resistance, providing valuable insights into the coating’s microstructure and performance under different erosion conditions.

SLURRY EROSION PERFORMANCE OF COLD SPRAYED WC-12Co COMPOSITE COATINGS

In the current investigation, a cold sprayed WC-12Co (WC- Tungsten Carbide, Co- Cobalt) composite coating was deposited on CA6NM steel. Further, microstructural analysis was carried out by using Scanning Electron Microscopy (SEM)/Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD) characterization techniques. Mechanical characterization was carried out to measure microhardness, bond strength and surface roughness. The value of coating hardness and surface roughness was measured to be 270 ± 15 Hv and 2.12 ± 0.5 [Formula: see text]m. Thereafter, slurry erosion test was performed under accelerated conditions and performance of coated samples was compared under different parameters such as erodent size, impact velocity, angle of impingement and slurry concentration. WC-12Co coatings show no phase transformation or de-carburization of the WC-Co particles as observed in other thermal spray techniques. The WC-12Co coatings was proved to have beneficial erosion reduction rate as compared to untreated CA6NM steel. The slurry erosion performance of coated samples was improved by 68%. SEM images of degraded coatings show the brittle characteristic of WC-12Co coatings.

Wear behavior of bare and coated 18Cr8Ni turbine steel exposed to sediment erosion: A comparative analysis

Hydropower plant components are exposed to sediment erosion due to the impact of hard particles flowing along with the water. As a consequence, significant material loss and substantial reduction in efficiency are encountered during plant operation. This work investigates the sediment erosion problem in hydraulic turbines using a slurry erosion tester. Experiments are performed on bare and coated 18Cr8Ni turbine steel at three impact velocities i.e. 6, 8, and 12 m/s, and two impact angles 30° and 90°. The size of impacting particles varies between 50 to 350 µm with a slurry concentration of 2500 ppm. The erosion rate is found to be maximum at 30° impact angle and minimum at 90° impact angle. With an aim to minimize the erosion of turbine steel, the test samples were coated with in-house formulated ceramic-based coating material using the high-velocity oxygen-fuel thermal spray technique. Vickers hardness test was performed to determine the hardness of the coatings. For metallurgical characterization, scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy techniques were used. A comparison of both bare and coated samples is carried out to observe the erosion-resistant aspects. A higher erosion resistance has been detected for the coated material as compared to the bare turbine material. The reduction in the erosion rate for coatings is 13.4% at 30° and 17.62% at 90° impingement angles. The obtained results are related to the tested materials’ microstructural, mechanical, and metallurgical aspects.

Enhanced erosion resistance of HVOF-deposited laser-textured TiC coating with PTFE

ABSTRACT This research explores the enhanced slurry erosion behaviour of a composite coating comprising Titanium Carbide (TiC) deposited via High Velocity Oxy-Fuel (HVOF) spraying process. The study integrates laser texturing and Polytetrafluoroethylene (PTFE) spraying techniques to improve the coating's performance. TiC coating is applied to SS316 substrates using HVOF, followed by laser surface texturing to create micro-scale circular patterns. A thin layer of PTFE is then sprayed onto the textured surface, enhancing static contact angle and anti-adhesive properties. Slurry erosion tests reveal significant improvements in the coating's resistance. The findings offer promising applications in slurry erosion-prone industries. Further investigations aim to study the erosive mechanism of the different samples and evaluate their long-term performance.

Mitigating slurry erosion in martensitic stainless steels through boronizing

In the present work, two grades of martensitic stainless steels (MSS) samples were boronized at 950 and 1000 °C for 6 h and then tempered at 600 °C for 2 h. These samples were subjected to a 36 h slurry erosion test, and their worn surfaces were characterized using optical profiling, SEM and XRD. Boronized samples exhibit significant enhancement in erosion resistance. SEM micrographs reveal minimal cracks and indentations while XRD shows presence of iron borides on eroded surface. Results suggest that boronizing temperature significantly enhances slurry erosion resistance of MSS used in hydro turbines, making them more efficient and sustainable.

Enhanced slurry erosion resistance of low friction and highly hydrophobic halloysite-fluoro-polysilsesquioxane coatings

Multifunctional coatings were obtained by a sol-gel co-condensation of a fluorinated silane and tetraethoxysilane over activated Halloysite nanotubes (hHNT). They were applied onto epoxy based substrates (neat epoxy or hHNT loaded) with different curing conditions. The coatings characterization showed low friction and high hydrophobicity. The coefficient of friction against stainless steel was 0.1, according to the nanoscratch test and the advancing contact angles reached values in the range 135–145°. The materials were subjected to a slurry erosion test under high speed flow condition and wettability was used to characterize the surface integrity over erosion-cumulative time periods. Fluorine containing coatings exhibited an outstanding resistance to the high speed slurry erosion (HSSE). After 1 h of HSSE test, average advancing contact angles of 145° were measured for the fluorinated samples. The high hydrophobicity of the coatings showed a correlation with the erosion resistance, while the substrate showed no effect. An explanation of the cushioning effect of hydrophobicity upon erosion wear is given, based on wall-detached eddies on the boundary layer.

Corrosion studies on low-cost solid lubricant coated stainless steel specimen

AISI 304 stainless steel is widely used in industries owing to its many desirable qualities like excellent formability, drawability and resistance to corrosion. However, AISI 304 stainless steel corrodes when exposed to halide environment such as chloride and fluoride. This study is primarily focused to assess the anti-corrosion properties of AISI 304 steel when coated with CaF2 solid lubricant. CaF2 solid lubricant was synthesized from the discarded egg-shells by ion exchange method by treating the egg-shell powder with hydrogen fluoride solution. Thermal spray coating method was used to coat the synthesized CaF2 solid lubricant on the AISI 304 stainless steel specimen. Slurry erosion test and electrochemical impedance spectroscopy test were conducted on the coated and uncoated specimen to assess the corrosion resistance. From the experimental results, the corrosion rate of the coated specimen was found to be very effective compared to the uncoated specimen.

Study on wear behaviour of aluminium-based piston alloy using different coatings

The wear rate of a piston in an engine determines how long it can run and how much power it can produce. The wear rate of lightweight piston materials used in medium cars was examined. The piston itself was used to cut the plates after it had been formed in an aluminium alloy. It was then successfully prepared for coating with hard anodizing and tin coating after being trimmed to a diameter of 90 mm. There are a number of wear tests, including the pin on the disc test, slurry abrasion test, scratch test, and erosion test to analyse the wear rate. The coating's substance and intended applications determine which wear test is used. Slurry erosion and corrosion tests for the coating are favoured for usage on automobiles. But the pin on disc and scratch tests are frequently carried out in cases where the coating is applied dry. In the current investigation, only one variable load (30 N, 40 N, and 50 N) and sliding speed (500 rpm) was chosen for the wear test. Sliding distance (1200 m) was treated as a constant. Under dry conditions, a pin-on-disc machine was used to test the wear of the coatings and soft materials. SEM analysis was used to examine the surface morphology of the coating's worn surfaces. It was discovered that as the load grew, the coating's wear rate also did. It was discovered that as the load was raised, the coating's co-efficient of friction decreased. With the aid of an optical telescope, the microstructure of the coating's worn surfaces was also inspected, although no evidence of a change in the microstructure owing to frictional heat was discovered. It was discovered that the coating's micro hardness decreased away from the wear track at the coating's cross section. Using a SEM, adhesion, deformation, and microcutting were the main wear mechanisms seen.

Investigations on erosion performance of carbon fiber–epoxy-based composite adhesion on 16Cr5Ni steel

This work presents a novel insight into slurry erosion behavior of thin layer of carbon fiber–epoxy-based composite adhered on 16Cr5Ni steel (adhesive coating) to evaluate its viability as a feasible candidate for slurry erosion applications. Experiments were conducted on a laboratory-developed slurry erosion test rig under accelerated conditions to study the effect erosion parameters namely slurry concentration, impact angle, and impact velocity. Under all the experimental conditions, adhesive coating showed better slurry erosion resistance in comparison with bare 16Cr5Ni steel specimens. Scanning electron microscopy analysis revealed that in the case of bare 16Cr5Ni steel; ploughing, micro-cutting, crater, plastic deformation, and lip formation were identified as main mechanism responsible for slurry erosion, whereas in the case of adhesive coating; pitting, cracking, fracturing, and shearing-off were found to be mainly responsible for material loss. It implies that adhesive coating showed a brittle mode of failure under slurry erosion conditions, whereas 16Cr5Ni steel exhibited a ductile mode of erosion.

Microstructure and properties of Ta-reinforced cobalt based composite coatings processed by direct laser deposition

Circulating water pump is an important component in coastal nuclear power plant, and is prone to suffering erosion and corrosion from the sea water. In the present study, Ta-reinforced cobalt-based composite coatings were prepared on the surface of a martensitic stainless steel by direct laser deposition technology. The effect of Ta on the phase composition, microstructure, micro-hardness, residual stress, corrosion resistance and erosion performance of the cobalt-based composite coatings was systematically investigated. The results indicated that the addition of Ta can lead to the formation of dispersed TaC ceramic particles in the coatings. In the meantime, TaC particles with flaky shape greatly changed the morphology of reticular eutectic carbides and residual stress distribution in the coatings. The potentiodynamic polarization testing and electrochemical impedance spectroscopy (EIS) measurements showed that the addition of Ta had no prominent influence on the corrosion resistance of cobalt-based coatings. Generally speaking, the coating with 30 wt% Ta addition exhibited the best comprehensive performance considering micro-hardness measurement, residual stress value, potentiodynamic polarization testing, and slurry erosion testing under two erosion angles. In situ synthesized TaC phases could effectively alleviate the impact of solid particles in the erosion process, and improve the erosion resistance of the cobalt-based composite coating.

Impact of HVOF sprayed Vanadium Carbide (VC) based novel coatings on slurry erosion behaviour of hydro-machinery SS316 steel

In this research work, different compositions of VC (Vanadium Carbide) +CuNi-Cr (Cupronickel-Chromium) ranging from 0% to 100% were deposited over hydro-machinery steel (SS316) with the help of HVOF spraying system. The slurry erosion for different composition of coatings and bare SS316 steel have been evaluated with the help of slurry erosion testing machine. From the experiments, it was concluded that amongst all the developed coatings, 100% VC based coating has shown exceptionally good resistance to slurry erosion as compared to other composition of coatings owing to extra microhardness attained by VC granules. Brittle mode of erosion mode was observed for coating with VC as major constituent, which was reported to be converted to ductile mode with the increase in CuNi-Cr addition percentage.

Image Processing Approach for Estimating the Degree of Surface Eroded by Slurry at Different Impact Velocities

Abstract In this research, we utilize image processing to analyze surfaces acquired from slurry-erosion tests carried out on AISI 5117 steel at various velocities and impact angles of 30 deg and 90 deg. The fractal and wavelet decomposition transform are two analysis tools that are particularly promising in this regard. These can be used to extract metrics that characterize slurry erosion in the same way that erosion rate is characterized. The study found that for a higher velocity of 15 m/s and a 30-deg impact angle, the fractal value was larger, irrespective of magnification. The fractal value is also in a positive linear regression with magnification. The extracted features of wavelet analysis were not distinctive for slurry-erosion behavior. The role of impact velocity in creating erosion damage is related to the variety of erosion mechanisms that are dependent on the particles’ kinetic energy. Microscopic examinations of damaged surfaces revealed that extruded lips indentation was the major mechanism of erosion, which occurred at 5 m/s speed and 30-deg impingement angle. Ploughing was proved that it was the predominant erosion mechanism at high velocity. Hence, the impact velocity determines the length of the wear tracks created by the ploughing mechanism.

Silt erosion performance of high velocity oxy fuel- (HVOF) sprayed Al2O3–Cr2O3 composite coatings on turbine steel

PurposeThe purpose of this paper is to investigate the erosion performance of high velocity oxy fuel- (HVOF) sprayed Al2O3–Cr2O3 composite coatings under silt slurry conditions.Design/methodology/approachThe requisite HVOF composite coatings has been deposited on the stainless steel substrate (SS-304). The slurry erosion pot tester of make Ducom was used for conducting the silt slurry erosion tests on the required substrates. The comprehensive experiments were conducted at different particle size of silt in the range 212–250, 150–212, 53–106 µm, and the concentration of the silt ranged from 10%–40% by weight. The rotational speed of the pot tester has been varied between 500 and 1,500 revolutions per minute, and the test duration has been kept to 4 h.FindingsThe erosion wear resistance of the uncoated SS-304 has been greatly enhanced by the application of HVOF-sprayed Al2O3–Cr2O3 composite coatings. The addition of CeO2 has a significant impact in reducing the erosive wear caused by silt slurry. The composite coating powder composition of 65%Cr2O3 + 34.5%Al2O3 + 0.5%CeO2 has shown the highest erosion resistance.Practical implicationsThe developed coatings have the potential to be used for hydro turbines as subjected to silt slurry conditions.Originality/valueThe erosion wear experiments are conducted comprehensively for coated and uncoated samples and the scanning electron micrographs supports the findings.

Effects of WC addition on the erosion behavior of high-velocity oxygen fuel sprayed AlCoCrFeNi high-entropy alloy coatings

In this study, AlCoCrFeNi (H1), AlCoCrFeNi+25 wt%WC-10Co (H2), and AlCoCrFeNi+50 wt%WC-10Co (H3) high-entropy alloy (HEA)/tungsten carbide (WC) composite coatings were deposited onto 316 stainless steel substrates by applying the high-velocity oxygen fuel spraying technology. The phase, layered microstructure, microhardness, and erosion behavior of the coatings were analyzed by performing X-ray diffractometry, scanning electron microscope/energy dispersive spectrometry, Vickers microhardness testing, and slurry erosion testing. The effects of WC addition on the erosion behavior and mechanism of the coatings at different flow velocities were investigated. The deposited coatings were compacted and adhered well to the substrate. The AlCoCrFeNi coating was composed of BCC and FCC phases. The porosity of the H1, H2 and H3 coatings were 0.24%, 0.33% and 0.45%, respectively, and were less than 1%. The microhardness of the HEA/WC composite coatings was positively correlated with WC content. The volume loss and rate of volume loss of the coatings decreased with the addition of WC. The erosion mechanism of the AlCoCrFeNi coating was typical ductile wear, with a small amount of interlayer peeling. Furrows, cuttings, and plastic deformation caused by low grazing angles contributed to the failure of the AlCoCrFeNi coating. In the HEA/WC composite coatings, WC protected the HEA from more severe plastic deformation by second-phase strengthening, and the main erosion mechanism of WC was gradual brittle detachment caused by high-grazing-angle erosion in which craters, cracks, and massive spalling were responsible for the erosion process.

Experimental and numerical approach to predict slurry erosion in jet erosion test rig

Surface degradation due to slurry erosion is the common phenomenon encountered in fluid handling and material processing industries. Slurry erosion research initiated at the latter half of the twentieth century. Huge economic losses incurred through slurry erosion, to such an extent that components can't be repaired. Erosion is a complex process, because it operates with many factors and these factors contribute individually and in combined form, they affect severely. To evaluate materials' behavior under erosion environment, slurry erosion test rigs are developed. Numerous jet erosion test rigs are developed, yet standardization of the test method is unattainable due to its intricacy. Jet type slurry erosion test rigs are the preferable choice, as they offer flexibility with the test parameters and it could provide impact characteristics. Erodents' introduction is a tedious task, as particles have to be introduced into the flowing fluid. In the present article, a novel device named modified Venturi device is developed. Performance of the test rig is evaluated by varying the operating test parameters and by evaluating Cast Iron sample as the candidate material. From the results, it is noticed that developed test rig can be successfully employed to evaluate the erosion behavior. Erosion depends on the kinetic energy and the drag force on the particle. Numerical approach through CFD has been adopted and found that the experimental results are in good correlation with Finnie erosion model. SEM Micrographs reveal the material removal mechanism in the test rig.