A high-pressure abrasive jet erosion testing system for determining the wear resistance of metallic substrates coated with Colomonoy-88 and Stellite-6

Abstract

A high-pressure mud jet erosion test system for determining the wear resistance of metallic substrates coated with Colomonoy-88 and Stellite-6, consisting of: a pressurized mixing vessel for receiving water and abrasive material, wherein the mixing vessel is sealed at the top with a watertight cap and a pressure relief valve is functionally connected at the top to regulate the internal pressure; an erosion motor connected to the bottom of the mixing container for controlling the speed of the erosion particle feed; a water supply line attached to the top of the mixing funnel to supply fresh water to maintain an optimal sludge concentration, the water supply line being connected at its other end to a water tank and a high-pressure water pump being integrated into the water supply line to transfer water from the water tank to the mixing funnel while passing through a filter in the water tank; a mixing chamber which is functionally connected to the pressurized mixing funnel as a homogeneous suspension flow channel; a test chamber unit connected to the mixing chamber, wherein the test chamber unit includes a pressure nozzle and a sample holder as an integrated assembly, the pressure nozzle being positioned to generate a high-speed suspension jet, and the sample holder being configured to fix a test specimen at a fixed distance and adjustable angle with respect to the nozzle outlet; a sludge container arranged below the test chamber for collecting the sludge consumed after sample impact, wherein a high-pressure sludge recirculation pump is connected to the sludge container via a pipeline to draw in the consumed sludge and return it to the pressurized mixing vessel, thus creating a closed circuit; and a control unit configured to allow control of the sludge jet velocity, the angle of impact on the sample, the speed of the erosion motor, the speed of the high-pressure sludge recirculation pump, the speed of the high-pressure water supply pump, and the duration of the test procedure.

Description

AREA OF INVENTION

[0001] The present disclosure relates to a high-pressure mud jet erosion test system for determining the wear resistance of metallic substrates coated with Colmonoy-88 and Stellite-6. In particular, the invention relates to a system for determining the wear resistance of an SS316 substrate coated with Colmonoy-88 (C-88) and Stellite-6 (S-6) by means of high-speed flame spraying. BACKGROUND OF THE INVENTION

[0002] Erosion caused by the impact of solid particles presents a significant engineering challenge in various industrial applications, including pipelines, water turbine components, gas valves, aerospace components, and fluid impellers. In hydroelectric power plants, hard materials such as clay, garnet, biotite, feldspar, and quartz are carried by the flowing water and collide with turbine components at high speed. This leads to surface erosion and, consequently, component damage. This problem is exacerbated during the monsoon season, particularly for hydroelectric power plants in the Himalayan regions, and often necessitates plant shutdowns.

[0003] Surface wear during sludge erosion is influenced by numerous parameters, including particle size, shape, hardness, velocity, and concentration of the erosive agent, as well as material properties such as microstructure, tensile strength, yield strength, fatigue strength, and toughness. Analyzing sludge erosion under real operating conditions is challenging due to the difficulty of controlling these numerous parameters in realistic working environments.

[0004] Existing approaches to improving erosion resistance include increasing surface hardness through thermal spray coating processes. High-velocity oxygen fuel spraying (HVOF) has established itself as a simple and cost-effective solution, enabling the deposition of coatings with exceptional mechanical properties. Compared to other flame spraying processes, HVOF offers superior adhesion between the coating and the substrate, as well as high cohesive strength between the deposited particles. This is due to the lower temperatures combined with significantly higher kinetic energies.

[0005] Previous research has investigated various coating materials, including NiCrBSi with nano-Al2O3, WC-Cr3C2-Ni, WC-Ni, WC-10Co-4Cr, and NiCrSiB / Al2O3 composites. However, despite the application of different thermal spraying processes and coating materials, no definitive recommendations for the optimal selection of coatings and testing methods could be developed.

[0006] Therefore, there is a need for a comprehensive system that can systematically evaluate the erosion wear behavior of various coating combinations applied using HVOF spraying, controlling and varying several test parameters to simulate real-world operating conditions. Such a system would enable a comparative analysis of coating performance and the identification of optimal coating materials for specific erosion environments. SUMMARY OF THE INVENTION

[0007] The present disclosure relates to a high-pressure mud jet erosion test system for determining the wear resistance of metallic substrates coated with Colmonoy-88 and Stellite-6. In particular, the invention provides a comprehensive system for testing surface damage and degradation of HVOF-sprayed coatings under controlled mud jet erosion conditions, thus enabling the systematic evaluation of coating materials, including Colmonoy-88 and Stellite-6, on substrate materials.

[0008] The present disclosure relates to a high-pressure mud jet erosion test system for determining the wear resistance of metallic substrates coated with Colomonoy-88 and Stellite-6. The system comprises: a pressure mixing vessel for receiving water and erosion material, which is sealed at the top with a watertight lid and has a pressure relief valve for regulating the internal pressure; an erosion motor, which is mounted at the bottom of the mixing vessel and controls the feed rate of the erosion particles;A water supply line is connected to the top of the mixing vessel to supply fresh water for maintaining an optimal sludge concentration. This water supply line is connected at its other end to a water tank. A high-pressure water pump is integrated into the water supply line to pump water from the water tank to the mixing vessel, with the water passing through a filter in the water tank. A mixing chamber is connected to the pressure mixing vessel as a homogeneous suspension flow channel. A test chamber unit is attached to the mixing chamber and includes a pressure nozzle and a sample holder as an integrated unit. The pressure nozzle is positioned to generate a high-velocity suspension jet, and the sample holder is configured to fix a test sample at a fixed distance and adjustable angle to the nozzle outlet.a suspension tank located below the test chamber unit to collect the suspension consumed after sample impact, wherein a high-pressure suspension recirculation pump is connected to the suspension tank via a pipeline to draw in the consumed suspension and return it to the pressure mixing vessel, thus creating a closed circuit; and a control unit configured to allow regulation of the slurry jet velocity, the angle of impact on the sample, the speed of the erosion motor, the speed of the high-pressure slurry recirculation pump, the speed of the high-pressure water supply pump, and the duration of the test procedure.

[0009] One objective of the present disclosure is to provide a high-pressure mud jet erosion testing system for determining the wear resistance of metallic substrates coated with Colomonoy-88 and Stellite-6.

[0010] Another objective of the present disclosure is the application and testing of HVOF-sprayed coatings under variable mud erosion parameters, including jet velocity, erosive flow rate, impact angle and particle size range.

[0011] Another objective of the present disclosure is the characterization of surface failure mechanisms and the elemental composition of eroded coated surfaces using integrated analytical instruments.

[0012] However, another objective of the present disclosure is to carry out a comparative evaluation of the erosion resistance between different coating materials and uncoated substrates under simulated operating conditions.

[0013] To further clarify the advantages and features of the present disclosure, the invention is described in more detail with reference to specific embodiments illustrated in the accompanying drawings. It is understood that these drawings merely show typical embodiments of the invention and are therefore not to be understood as limiting its scope of protection. The invention is described and explained in more detail and with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE IMAGES

[0014] These and other features, aspects and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which identical symbols represent identical parts, wherein: Fig. Figure 1 shows a block diagram of a high-pressure mud jet erosion test system for determining the wear resistance of metallic substrates coated with Colomonoy-88 and Stellite-6 according to an embodiment of the present disclosure; and Fig. Figure 2 shows a diagram of the mud jet erosion test system according to an embodiment of the present disclosure.

[0015] Furthermore, those skilled in the art will recognize that the elements in the drawings are simplified and not necessarily drawn to scale. For example, the flowcharts illustrate the process by highlighting the main steps to facilitate understanding of this disclosure. With regard to the construction of the device, one or more components may be represented in the drawings by conventional symbols. The drawings may show only those specific details relevant to understanding the embodiments of this disclosure, so as not to clutter the drawings with details that are already apparent to those skilled in the art from the description contained herein. DETAILED DESCRIPTION:

[0016] To facilitate understanding of the principles of the invention, reference is made below to the embodiment illustrated in the drawings, which is described using specific terms. It is understood, however, that this does not limit the scope of protection of the invention. Rather, modifications and further developments of the illustrated system, as well as further applications of the inventive principles depicted therein, are conceivable, insofar as they would typically occur to a person skilled in the art in the field of the invention.

[0017] It will be clear to those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not to be understood as a limitation thereof.

[0018] References to “an aspect”, “another aspect”, or similar phrases in this description mean that a particular feature, structure, or property described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, phrases such as “in one embodiment”, “in another embodiment”, and similar expressions in this description may, but do not necessarily, all refer to the same embodiment.

[0019] The terms "includes," "comprehensive," or similar expressions denote non-exclusive inclusion. Thus, a procedure or method containing a list of steps does not only include those steps but may also include further steps not explicitly listed or inherent in the procedure or method. Likewise, the statement "includes..." for one or more devices, subsystems, elements, structures, or components, without further limitations, does not preclude the existence of other devices, subsystems, elements, structures, or components.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meanings generally known to those skilled in the art in the field to which this invention belongs. The systems, methods, and examples described herein serve only for illustration and are not to be understood as limiting.

[0021] Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0022] Fig. Figure 1 shows a block diagram of a high-pressure slurry jet erosion test system for determining the wear resistance of metallic substrates coated with Colomonoy-88 and Stellite-6 according to an embodiment of the present disclosure.

[0023] According to Fig. 1 The system comprises: a pressurized mixing vessel (102) for receiving water and cleaning agent, wherein the mixing vessel (102) is sealed at the top by a watertight cap (104) and a pressure relief valve (106) for regulating the internal pressure is fitted at the top of the mixing vessel (102); a cleaning agent motor (108) fitted at the bottom of the mixing vessel (102) to control the feed rate of the cleaning agent particles; a water supply line (110) fitted at the top of the mixing vessel (102) to supply fresh water to maintain an optimal sludge concentration, wherein the water supply line (110) is connected at its other end to a water tank (112) and wherein a high-pressure water pump (114) is integrated into the water supply line (110) to convey water from the water tank (112) to the mixing vessel (102) as it passes through a filter (112a) in the water tank (112);a mixing chamber (116) functionally connected to the pressurized mixing vessel (102) as a homogeneous sludge flow channel; a test chamber unit (118) connected to the mixing chamber (116), the test chamber unit (118) comprising a pressure nozzle (118a) and a sample holder (118b) as an integrated unit, the pressure nozzle (118a) being positioned to generate a high-speed sludge jet, and the sample holder (118b) being configured to fix a test sample at a fixed distance and adjustable angle to the nozzle outlet; a sludge container (120) arranged below the test chamber unit (118) to collect the sludge consumed after the sample impact, wherein a high-pressure sludge circulation pump (122) is connected to the sludge container (120) via a pipeline to draw in the consumed sludge and return it to the pressure mixing vessel (102), thereby creating a closed circuit;and a control unit (124) configured to allow control of the slurry jet velocity, the angle of impact on the sample, the speed of the erosion motor (108), the speed of the high-pressure slurry circulation pump (122), the speed of the high-pressure water supply pump (114) and the duration of the test procedure.

[0024] In one embodiment, the high-pressure suspension circulation pump (122) draws the used suspension directly from the suspension container and conveys it into the pressurized mixing funnel (102). This enables a closed circuit and avoids the need for continuous refilling with fresh suspension.

[0025] In one embodiment, the high-pressure water supply pump (114) independently pumps fresh water via the water supply line (110) into the pressurized mixing tank (102) to compensate for water loss during testing and to maintain optimal viscosity of the suspension, particle concentration and suspension properties.

[0026] In one embodiment, the erosion motor (108) controls the speed of the erosion particle feed, wherein the rotational speed of the erosion motor (108) is adjustable via the control unit (124) and thus enables an adaptation of the test intensity and the erosion conditions to the test requirements.

[0027] In one embodiment, the pressure jet nozzle (118a) converts the pressurized suspension stream from the mixing chamber (116) into a concentrated high-speed jet that is directed at the sample and generates a controlled impact velocity and kinetic energy independent of gravitational effects.

[0028] In one embodiment, the sample holder (118b) has adjustable clamping and angular positioning mechanisms that make it possible to align the test sample at a desired angle of impact relative to the trajectory of the mud jet, the angle of impact being adjustable and controllable via the control unit.

[0029] In one embodiment, the water tank (112) is equipped with a filter (112a) that removes impurities and deposits from the fresh water before it is directed via the water supply line and the high-pressure water pump (114) into the pressurized mixing tank (102).

[0030] In one embodiment, the control unit (124) allows independent and simultaneous adjustment of the test duration, the rotational speed of the erosion motor, the rotational speed of the high-pressure suspension circulating pump, and the rotational speed of the high-pressure water supply pump. This enables precise control and variation of the erosion test parameters during system operation. The control unit is configured to vary the jet velocity from 15 to 60 m / s, the erosion flow rate from 550 to 1150 1 / s, the impact angles from 30 to 90 degrees, and the test duration from 15 to 60 minutes.

[0031] In one embodiment, a metallic substrate coated with Colomonoy-88 and Stellite-6 is produced and used as a square specimen to determine its wear resistance, wherein an HVOF thermal spraying system with a sandblasting mechanism is configured to facilitate the coating of Colomonoy-88 and Stellite-6 onto the metallic substrate.

[0032] The present invention relates to a high-pressure mud jet erosion testing system for determining the wear resistance of coated metallic substrates, in particular Colomonoy-88 and Stellite-6 coatings. The system utilizes a closed, dual-pump architecture that enables continuous recirculation of the spent sludge under controlled erosion conditions. The key innovation is the integration of a high-pressure sludge recirculation pump, which recovers the spent sludge from the collection tank and returns it to the pressure mixing vessel. This prevents material losses and improves material efficiency. The system allows for precise control of the erosion test through independent control of jet velocity, impact angle, erosion motor speed, and pump speed.A pressure jet nozzle creates a gravity-independent, high-speed mud impact, thus ensuring reproducible and aggressive erosion conditions suitable for evaluating the durability of coated materials.

[0033] In one embodiment, a mud jet erosion test system forms an integral part of the system. It comprises a conical hopper, an erosion motor, a water motor, a mixing chamber, a nozzle, a rectangular sample holder, a pressure regulating valve, and a water tank. The mixing chamber ensures a homogeneous mud flow through the nozzle. The mud jet erosion test device is configured to allow for variation of various test parameters, including the jet velocity (15 to 60 m / s), the erosion flow rate (550 to 1150 1 / s), the impact angle (30 to 90 degrees), and the test duration (15 to 60 minutes). The system enables testing with sand as the erosion material in various grain size ranges.

[0034] The system also includes a characterization unit for analyzing surface failure mechanisms and the elemental composition of the samples under investigation. This unit comprises a scanning electron microscope for analyzing surface morphology and failure mechanisms such as microcutting, cratering, and ploughing, as well as an energy-dispersive X-ray spectrometer for analyzing the elemental composition of eroded surfaces.

[0035] The system enables a systematic comparative evaluation of erosion resistance between different coating materials and uncoated substrates, thus facilitating the identification of optimal coating solutions for specific erosion environments.

[0036] In this embodiment, stainless steel 316 is used as the substrate material, which is commonly used as a pump material due to its ductility and corrosion resistance. The chemical composition of the substrate material is analyzed using optical spectrometry. For erosion tests, square samples with dimensions of 25 × 25 × 25 mm are punched from the substrate material, which is supplied as sheet metal, using wire EDM.

[0037] In one embodiment, the system is configured to apply Colmonoy-88 and Stellite-6 powders with a particle size of 20–53 µm to the SS316 substrate material. The system includes a coating unit that uses a thermal spraying process to coat the substrate material. Prior to coating, the surface of the substrate material is roughened to a depth of 8–10 µm by sandblasting. For the thermal spray coating, the system uses a spray gun to achieve a coating thickness of approximately 175–330 µm. The workpieces are then cooled with compressed air after thermal spraying.

[0038] Fig. Figure 2 shows a diagram of the mud jet erosion test system according to an embodiment of the present disclosure.

[0039] In one embodiment, the coated substrate is subjected to an erosion wear test using a mud jet erosion tester, with sand serving as the erosion material. The sand surface was examined using scanning electron microscopy (SEM). The SEM images show the spherical and granular structure of the sand surface. For sieve analysis, sand samples with grain sizes of 75 µm, 75–150 µm, 150–250 µm, and 250–355 µm were prepared using British standard sieves.

[0040] As in Fig.As shown in Figure 2, the sludge jet erosion test rig consists of two main parts: a test section and a control unit. The test section comprises a conical hopper (capacity: 60 liters), an erosion motor, a water motor, a mixing chamber, a nozzle, a rectangular sample holder, a water pressure regulating valve, a sludge container, and a water tank. The system also includes a high-pressure water pump and a high-pressure sludge line with a pump. Test duration, erosion motor speed, and water motor speed can be varied via a control unit. A mixing chamber at the hopper outlet ensures a uniform flow of homogeneous sludge through the nozzle. Tests were conducted with the sludge jet erosion test rig using varying sludge jet velocity, erosion agent quantity, test duration, and impact angle.The jet velocity varied between 15 and 60 m / s, and the amount of erosion agent between 550 and 1150 l / s. The tests were also conducted for particle size ranges of 75, 75–150, 150–250, and 250–355 µm. The test duration varied between 15 and 60 minutes, and the impact angles were changed from 30° to 90°. The weight loss of the material in grams was used to investigate erosion wear.

[0041] Energy-dispersive X-ray spectroscopy (EDS) determined the elemental composition of the coating powders. The Colmonoy-88 coating contained B, C, Al, Si, Cr, Co, Ni, and W at proportions of 3.01%, 1.35%, 0.12%, 1.89%, 17.14%, 2.27%, 73.64%, and 0.57%, respectively. The Stellite-6 coating contained C, Si, Cr, Co, Ni, and W at proportions of 2.08%, 0.75%, 33.83%, 6.69%, and 3.37%, respectively. Scanning electron microscopy of the cross-section showed an average coating thickness of 185 to 315 µm. The coating proved to be uniform and defect-free, exhibiting a nearly homogeneous surface microstructure of interconnected particles. The interface was flawless, with the deposited coating and the base material in continuous interaction. Numerous tiny, unmelted particles were found embedded in molten splashes. The coating surface also exhibited several microcracks.

[0042] The microhardness of SS-316 ranged from 192 to 144 HV, with a mean of 236 HV. The microhardness of the Colmonoy-88 coating ranged from 334 to 450 HV, with a mean of 784 HV. The microhardness of the Stellite-6 coating ranged from 252 to 316 HV, with a mean of 568 HV. The porosity of the Colmonoy-88 coating was calculated to be 1.7% and that of the Stellite-6 coating 2.3%. These values ​​are consistent with the porosity values ​​reported in the literature for HVOF coatings. The surface roughness of the coated samples was higher than that of the uncoated steel.

[0043] X-ray diffraction analysis of the Colmonoy-88 coating revealed the presence of a nickel phase as well as peaks of WC, Cr 23 C6, Ni3B and Ni3Si. XRD analysis of the Stellite-6 coating revealed the presence of Fe3C, c o and Cr 23C6. XRD analysis of both coatings after erosion revealed that they contained the same elements as before erosion. The retention of the same compounds in the coatings after the mud jet erosion test can be attributed to their high hardness, chemical stability, and resistance to phase transformations under mechanical wear. The strong metallurgical bonding of the phases, combined with the protective oxide layers formed by chromium, ensures the preservation of the coating composition.

[0044] Tests with the mud jet erosion tester showed that maximum erosion occurred on uncoated 316 stainless steel. The operating parameters significantly influenced the erosion wear behavior of both coated and uncoated samples.

[0045] Tests with various blasting velocities of 15, 30, 45, and 60 m / s over a duration of 60 minutes, an abrasive flow rate of 1150 g / min, a particle size of 250–355 µm, and an impact angle of 90° showed that both uncoated and coated 316 stainless steel exhibited increasing mass loss with increasing blasting velocity. This indicates that blasting velocity significantly influences erosion wear. The reason for this is the increasing kinetic energy of the sand particles with increasing blasting velocity. At high blasting velocities, the rebounding particles cannot interact with newly impacting particles, as is possible at low blasting velocities. Coated materials showed significantly less erosion wear compared to uncoated 316 stainless steel.The influence of the beam velocity on the mass loss was greatest for uncoated surfaces, followed by surfaces coated with Stellite-6 and finally surfaces coated with Colmonoy-88.

[0046] Tests with different erosion flow rates of 550, 750, 950, and 1150 g / min over a period of 60 minutes, at a jet velocity of 60 m / s, a particle size of 250–355 µm, and an impact angle of 90° showed that erosion wear increases non-linearly with the erosion flow rate. This increased wear is due to the larger quantity of impacting erosion particles. A high flow rate allows a greater number of erosion particles to impact the sample surface, resulting in a higher mass loss. The influence of the erosion flow rate on erosion wear was greatest for uncoated SS-316 samples, followed by Stellite-6 coated surfaces and finally Colmonoy-88 coated surfaces.

[0047] Experiments with four different particle size ranges (75, 75–150, 150–250, and 250–355 µm) at a jet velocity of 60 m / s, an erosion agent flow rate of 1150 g / min, an impact angle of 90°, and a test duration of 60 minutes showed that erosion wear increased with increasing particle size. Larger particles possess more kinetic energy, resulting in a greater impact force on the sample surface and thus significant erosion wear. The influence of particle size on erosion wear was greatest for uncoated surfaces, followed by surfaces coated with Stellite-6 and Colmonoy-88.

[0048] Tests conducted with four different durations (15, 30, 45, and 60 minutes) at a jet velocity of 60 m / s, an abrasive flow rate of 1150 g / min, an impact angle of 90°, and a particle size of 250–355 µm showed that the test duration directly influences the erosion wear of both coated and uncoated sample surfaces. This is due to the continuous impact of the abrasive particles on both surfaces. The uncoated surface showed the greatest influence of the test duration on the erosion wear, followed by the surfaces coated with Stellite-6 and Colmonoy-88.

[0049] Experiments conducted at four different impact angles of 30°, 45°, 60°, and 90°, a jet velocity of 60 m / s, a particle size of 350–500 µm, an abrasive flow rate of 1150 g / min, and a test duration of 60 minutes showed that the erosion wear of uncoated 316 stainless steel decreased with increasing impact angle. For uncoated 316 stainless steel, maximum erosion occurred at 30° and minimum at 90°. At 30°, both the tangential and normal velocity components were present, while at 90° only the normal velocity component was present. For the surface coated with Colmonoy-88, the erosion wear increased with the impact angle, reaching a maximum at 45° and then decreasing again to a minimum at 90°. The maximum erosion on the Stellite-6 coated surface occurred at an impact angle of 60°.The formation of craters and oxides could be the cause of this behavior.

[0050] Scanning electron microscopy (ESM) analyses revealed the erosion wear mechanisms of coated surfaces under various test conditions. Uncoated stainless steel SS-316 showed significant damage upon exposure to a suspension with a particle size of 250–355 µm, with increased cratering and depressions. EDS analysis of uncoated SS-316 yielded the following mineral content: C 0.72%, N 0.56%, Si 0.91%, Mo 0.04%, Cr 11.51%, Mn 1.50%, Fe 84.34%, Ni 0.36%, and Cu 0.06%.

[0051] The eroded surface of the Colmonoy-88 coating exhibited narrow craters due to the presence of borides and carbides at shallower impact angles. At higher impact angles, the damaged surface showed fractures, intact areas, and carbide outcrops, as the hard phase opened at these angles. EDS analysis revealed the following mineral content: 2.38% B, 0.88% C, 0.10% Al, 3.79% Si, 16.66% Cr, 5.35% Fe, 0.54% Co, 69.66% Ni, and 0.65% W.

[0052] The Stellite-6 coating sprayed onto SS-316 exhibited ductile properties. The damaged surface showed plow and micro-cutting wear. EDS analysis of the eroded surface revealed a content of 1.34% C, 29.34% Co, 1.14% Ni, 3.31% Si, 2.45% W, and 62.46% Cr.

[0053] Compared to the Stellite-6 coating, the Colmonoy-88 coating exhibited higher erosion resistance. Its higher hardness of 784 HV compared to 568 HV for the Stellite-6 coating was the reason for this greater erosion resistance. Furthermore, the substrate of the Colmonoy-88 coating was reinforced by sufficiently robust secondary phases such as Cr7C3, Ni3C, and Cr. 23 C6 is protected from the impact of sand particles. The presence of carbides and borides in the Colmonoy-88 coating, as well as the inclusion of tungsten / chromium carbides, improved the erosion resistance compared to the Stellite-6 coating.

[0054] The coated substrate material serves for the comparative analysis of Colomonoy-88 and Stellite-6 coatings, which were successfully applied to SS316, a material commonly used as a pump material, using HVOF technology. The following observations can be derived from the results and investigations: ▪ The coating of Colmonoy-88 and Stellite-6 was effectively applied to SS316 using an HVOF spraying process. The layer thickness ranged between 185 and 315 µm. ▪ Due to the high hardness value of the Colmonoy-88 coating (784 HV), it has better erosion resistance than Stellite-6, and the Stellite-6 coating (568 HV) also has better erosion resistance than SS 316 (236 HV). The Colmonoy-88 coating is more resistant to mud erosion than the Stellite-6 coating due to the presence of carbide sand borides and chromium. This is because the chromium and tungsten carbide particles strengthen the bond between the coating powder particles. ▪ The erosion resistance results from the following order: Colmonoy -88 has the highest wear resistance, followed by Stellite-6 and then SS-316. ▪ Colmonoy-88 exhibits ductile behavior, while Stellite-6 shows brittle behavior in mud erosion tests. Factors such as jet velocity, exposure time, abrasive flow rate, and abrasive particle size significantly influence wear behavior, with erosive wear increasing as these factors increase. However, compared to uncoated surfaces, the erosive wear of coated surfaces is generally lower. ▪ Ploughing and cratering were the most important erosion wear mechanisms observed on the coated 316 stainless steel. These patterns demonstrate how well the coating reduces erosion wear due to its high wear resistance.

[0055] The results show that the coatings applied using HVOF improve the service life and performance of the 316 stainless steel substrate material during sludge handling. This development reduces erosion-related wear on sludge pumps, thus increasing their service life and operational efficiency.

[0056] The drawings and the preceding description illustrate embodiments. Those skilled in the art will recognize that one or more of the described elements can be combined to form a single functional element. Alternatively, certain elements can be divided into several functional elements. Elements of one embodiment can be added to another. For example, the process flows described here can be modified and are not limited to the manner described herein. Furthermore, the actions of a flowchart need not be performed in the sequence shown; nor do all actions necessarily need to be carried out. Actions that do not depend on other actions can be performed in parallel with the other actions. The scope of protection of the embodiments is in no way limited by these specific examples. Numerous variations, whether explicitly stated in the description or not, such as...Differences in structure, dimensions, and materials are possible. The scope of protection of the embodiments is at least as comprehensive as described by the following claims.

[0057] The advantages, other benefits, and problem solutions have been described above with reference to specific embodiments. However, the advantages, benefits, problem solutions, and any components that can effect or enhance an advantage, benefit, or solution are not to be construed as critical, necessary, or essential features or components of the claims. REFERENCES 100 A high-pressure grinding jet erosion test system for determining the wear resistance of metallic substrates coated with Colomonoy-88 and Stellite-6. 102 pressure mixing tanks 104 Waterproof Lid 106 Pressure relief valve 108 Erosion engine 110 Water supply line 112 Water tank 112a Filter 114 High-pressure water supply pump 116 Mixing chamber 118 Test chamber unit 118a Pressure nozzle 118b Sample holder 120 slurry tanks 122 High-pressure suspension circulating pump 124 Control unit 202 Pressure relief valve 204 Waterproof closure 206 High-pressure suspension supply 208 High-pressure water supply 210 funnels 212 Water + eroding 214 Erodent Motor 216 Mixing Chamber 218 nozzle 220 Sample Holder 222 Sample 224 Pump 226 Sludge tank 228 filters 230 water tank

Claims

[1] A high-pressure mud jet erosion test system for determining the wear resistance of metallic substrates coated with Colomonoy-88 and Stellite-6, consisting of: a pressurized mixing vessel for receiving water and abrasive material, wherein the mixing vessel is sealed at the top with a watertight cap and a pressure relief valve is functionally connected at the top to regulate the internal pressure; an erosion motor connected to the bottom of the mixing container for controlling the speed of the erosion particle feed; a water supply line attached to the top of the mixing funnel to supply fresh water to maintain an optimal sludge concentration, the water supply line being connected at its other end to a water tank and a high-pressure water pump being integrated into the water supply line to transfer water from the water tank to the mixing funnel while passing through a filter in the water tank; a mixing chamber which is functionally connected to the pressurized mixing funnel as a homogeneous suspension flow channel; a test chamber unit connected to the mixing chamber, wherein the test chamber unit includes a pressure nozzle and a sample holder as an integrated assembly, the pressure nozzle being positioned to generate a high-speed suspension jet, and the sample holder being configured to fix a test specimen at a fixed distance and adjustable angle with respect to the nozzle outlet; a sludge container arranged below the test chamber for collecting the sludge consumed after sample impact, wherein a high-pressure sludge recirculation pump is connected to the sludge container via a pipeline to draw in the consumed sludge and return it to the pressurized mixing vessel, thus creating a closed circuit; and a control unit configured to allow control of the sludge jet velocity, the angle of impact on the sample, the speed of the erosion motor, the speed of the high-pressure sludge recirculation pump, the speed of the high-pressure water supply pump, and the duration of the test procedure. [2] System according to claim 1, wherein the high-pressure suspension circulation pump draws the used suspension directly from the suspension container and transfers it to the pressurized mixing funnel, thereby enabling closed-circulation operation and avoiding continuous refilling with fresh suspension. [3] System according to claim 1, wherein the high-pressure water supply pump independently delivers fresh water via the water supply line into the pressurized mixing vessel to compensate for water loss during the test and to maintain optimal viscosity of the suspension, particle concentration and suspension properties. [4] System according to claim 1, wherein the erosion motor operationally controls the speed of the erosion particle supply and the speed of the erosion motor is adjustable via the control unit, thereby enabling the test intensity and erosion conditions to be adapted to the test requirements. [5] System according to claim 1, wherein the pressure jet nozzle converts the pressurized suspension stream from the mixing chamber into a concentrated high-speed jet directed at the sample, generating a controlled impact velocity and kinetic energy independent of gravitational effects. [6] System according to claim 1, wherein the sample holder has adjustable clamping and angular positioning mechanisms that make it possible to align the test sample at a desired angle of impact relative to the trajectory of the mud jet, wherein the angle of impact is adjustable and controllable via the control unit. [7] System according to claim 1, wherein the water tank is equipped with a filter for removing impurities and deposits from the fresh water before it is directed via the water supply line and the high-pressure water pump into the pressurized mixing tank. [8] System according to claim 1, wherein the control unit enables independent and simultaneous adjustment of the test duration, the speed of the erosion motor, the speed of the high-pressure suspension circulating pump and the speed of the high-pressure water supply pump, thus allowing precise control and variation of the erosion test parameters during system operation, wherein the control unit is configured to vary the jet velocity from 15 to 60 m / s, the erosion flow from 550 to 1150 l / s, the impact angles from 30 to 90 degrees and the time duration from 15 to 60 minutes. [9] System according to claim 1, wherein a metallic substrate coated with Colomonoy-88 and Stellite-6 is produced and used as a square specimen to determine its wear resistance, wherein an HVOF thermal spraying system with a sandblasting mechanism is configured to facilitate the coating of the metallic substrate with Colomonoy-88 and Stellite-6.

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