Cavitation Erosion Research Articles

Enhanced cavitation erosion resistance of GX40CrNiSi25-20 cast stainless steels by surface TIG re-melting

This study aimed to reduce cavitation erosion effects by improving the surface properties of high-alloyed steel cast parts using the tungsten inert gas (TIG) surface physical modification technique. Local surface melting was performed at different linear energies (El = 4080–8880 J/cm) by varying the current between 100 and 200 A at a constant voltage of 10.2–11.1 V. Hardness increased from 210 to 390 HV5 when a TIG current of 150 A with a linear energy of El = 6630 J/cm was implemented.Using this technique, a surface layer with increased resistance to cavitation erosion was formed. This new surface absorbed large amounts of impact energy owing to a favourable combination of microstructural changes, leading to improved elastic and plastic properties, work hardening, cracking, and failure response. The cavitation erosion performance of the re-melted surface layer was analysed using a piezoceramic vibrating device according to the ASTM G32–2016 standard. Following TIG surface re-melting, the average penetration depth of erosion and the cavitation erosion rate increased by approxmately 6.8 times. Based on optical and electronic metallographic analyses, hardness measurements, and X-ray diffraction, it was shown that the morphology of the surface layer following cavitation erosion tests was affected. Microcraters tended to develop at locations where carbide particles from the alloying elements were previously present. At a current of 150 A, the depth of the microcraters reached values of approximately 15 μm; however, microcrater depth reached 10 μm in the austenite matrix. Based on these investigations, an understanding of the mechanisms that result in the improvement of the resistance to erosion by cavitation of cast high-alloy steels whose surfaces were re-melted using the TIG technique is developed.

Cavitation Erosion Prevention Using Laser Shock Peening: Development of a Predictive Evaluation System.

Marine flow-passing components are susceptible to cavitation erosion (CE), and researchers have worked to find ways to reduce its effects. Laser Shock Peening (LSP), a material strengthening method, has been widely used in aerospace and other cutting-edge fields. In recent years, LSP has been used in cavitation resistance research. However, the current LSP research does not realize a comprehensive predictive assessment of the material's CE resistance. This paper uses m stresses to develop a comprehensive set of strengthening effect prediction models from LSP to CE using finite element analysis (FEA). Results show that the LSP-1 sample (4 mm spot, 10 J energy) introduced a compressive residual stress value of 37.4 MPa, better than that of 16.6 MPa with the LSP-2 sample (6 mm spot, 10 J energy), which is generally consistent with the experimental findings; the model predicts a 16.35% improvement in the resistance of LSP-1 sample to water jet damage, which is comparable to the experimental result of 14.02%; additionally, interactions between micro-jets do not predominate the cavitation erosion process and the final CE effect of the material is mainly due to the accumulation of jet-material interaction.

Modelling and evaluating piston slap-induced cavitation of cylinder liners in heavy-duty diesel engines.

Cavitation erosion of cylinder liner seriously affects the operational reliability and service life of heavy-duty diesel engines. The accuracy of the modeling-based cavitation risk evaluation is limited by the unclear correspondence between cylinder liner vibration and coolant cavitation. This report is intended to investigate the correspondence between cylinder liner vibration and coolant pressure by combining vibration cavitation test, pressure gradient calculation, and visualization observation. The cavitation risk of the cylinder liner under piston slap is also quantitatively analyzed based on the nonlinear structural dynamics model. The results show that the occurrence of cavitation will cause a nonlinear relationship between the cylinder liner acceleration and the coolant pressure. The difference in cavitation risk for each cylinder is related to the structural modal characteristics of the crankcase. In addition, the effect of piston-liner clearance and piston pin offset on the cavitation risk is investigated based on the dynamics model.

The Effect of Diabetes Control Status on CT Findings in Pulmonary Tuberculosis: Emphasis on Bronchial Erosive Changes.

Studies on the effect of diabetes mellitus (DM) on the radiologic findings of pulmonary tuberculosis (PTB) have reported inconsistent results. These findings may have been influenced by the glycemic control status of the patients studied. To our knowledge, no recent data have described the effect of the DM control status on CT findings in PTB in terms of medium-sized airway involvement that is visualized as bronchial erosion on CT. The aim of this present study was to determine whether the DM control status influenced radiological manifestations in patients with PTB, with an emphasis on bronchial erosive changes. We conducted a retrospective single-center study on patients who were newly diagnosed with PTB. A total of 426 consecutive patients with PTB who underwent CT scans at the time of diagnosis from 1 January 2017 to 31 March 2020 were included in this study. The included patients were categorized as having no DM (non-DM), controlled DM, or uncontrolled DM. The patient medical charts, microbiology study results, and pulmonary changes on the CT scans were analyzed. Among 426 patients with PTB who underwent CT scans at the time of diagnosis, 91 were excluded either due to undetermined hemoglobin A1C (HbA1C) levels (n = 25) or concomitant pulmonary diseases (n = 66) that would make the analysis of the pulmonary changes on CT scans difficult. Finally, 335 patients were included in this study (224 men and 111 women; mean age, 59 years; range, 16-95 years). Among the 335 patients, 82 (24.5%) had DM and 52 of those (63.4%) had an uncontrolled status. The frequency of cavitation (43% vs. 23% vs. 79%, p < 0.001) and bronchial erosion (44% vs. 30% vs. 73%, p < 0.001) was significantly different between the three groups. The uncontrolled DM group showed a high frequency of cavitation and bronchial erosion compared to the non-DM (cavitation, p < 0.001 and bronchial erosion, p < 0.001) and controlled DM groups (p < 0.001 and p < 0.001). However, the frequency of cavitation and bronchial erosion in the controlled DM group was not different compared to the non-DM group. The glycemic status (HbA1C ≥ 7.0), not the presence of DM, influenced the radiologic manifestations of PTB, especially in terms of medium-sized bronchial involvement, appearing as bronchial erosive changes and the feeding bronchus sign on chest CT scans. This difference in the uncontrolled DM group was likely to contribute to the higher frequency of cavitation.

Passivation effects on corrosion and cavitation erosion resistance of UNS S32205 duplex alloy in 3.5% NaCl

ABSTRACT The electrochemical and electronic properties of UNS S32205 duplex alloy passive film were studied with EIS and Mott–Schottky techniques, respectively. The role of Fe and Cr oxides in the passive film formation was checked using XPS. The cavitation behaviour was evaluated using an optical microscope OM. The studies were carried out in a 3.5% NaCl solution saturated with CO2 on various types of passive films: the air-formed (AF), the long-term aged (LTA), and the passivated (P1 and P2). The results showed that the electrochemical passivation treatment at passive region 1 improved the corrosion and cavitation behaviour compared to AF, while the long-term aging process made it worse. Passivation at passive region 2 was harmful and recorded the worst results under corrosion and cavitation erosion conditions. Thus, exposing the equipment made of this alloy to the passivation treatment at special conditions makes it more resistant to corrosion and cavitation erosion.

Numerical assessment of cavitation erosion risk on the Delft twisted hydrofoil using a hybrid Eulerian-Lagrangian strategy

Cavitation damage is a major threat to the life span of fluid machinery and has been a hot research issue in engineering for a long time. The current work aims to show the ability to assess cavitation erosion risk on the twisted hydrofoil using a hybrid Eulerian-Lagrangian solver. The volume of fluid method is used for the liquid-vapor interface of resolved vapor structures, while the discrete bubble model is utilized to track micro-scale unresolvable bubbles. A two-way coupling approach is introduced to enable the transition between resolved cavities and bubbles based on their volume, relative location, and shape. A Lagrangian erosion model considering the effect of asymmetric bubble collapse is proposed to predict cavitation erosion risk. Compared with the experimental result, the current model can accurately identify the high erosion risk regions on the hydrofoil surface. The distribution and intensity of the high impact pressures emitted from bubbles is quantitatively evaluated. In addition, the erosion sensitive zones at different stages of the one cloud cavitation cycle are determined and the hydrodynamic mechanisms of aggressive collapse events are analyzed in detail. The results reveal that the potential erosion risk is highest in areas where primary shedding occurs, which causes the macroscopic cavity to roll up. Bubbles with high impact pressures are mainly focused around the edges of the shedding cavity. The secondary shedding contributes to erosive structure in a limited middle angle of attack area, such that when the primary shedding U-shaped structure evolves and begins to collapse, it becomes less erosive, and only isolated points of erosion is found. Further investigation demonstrates that this is due to a transformation from U-shaped vortex to O-shaped vortex, moving the bubbles gradually away from the hydrofoil surface, thereby reducing the cavitation erosion risk.

A systematic study into the cavitation erosion test for marine propeller materials by cavitating jet technique

This paper presents an experimental investigation of cavitation erosion on widely used marine propeller materials by the cavitating jet technique as an alternative to cavitation tunnel tests, following the American Society for Testing and Materials (ASTM) standards. The cavitation erosion tests on aluminium samples were, initially, conducted to investigate the effect of stand-off distance and to compare the results with the available data in the literature. The comparative study confirmed that the erosion on the materials has practically the same pattern even if the nozzle diameter and sample size are different for the same cavitation number and at the optimum stand-off distance condition. Following this validation, the samples made of copper-based alloy marine propeller materials, specifically Cu1, Cu3, and Cu4, were tested for the first time in the literature to assess their erosion resistance at various cavitation numbers and test durations by considering various characteristics, such as erosion area, rate and intensity through comprehensive examinations. Among the materials examined, the Cu1, which has the lowest mechanical strength, was found to be the most susceptible to cavitation erosion. Interestingly, despite the Cu4 having the highest mechanical strength, the Cu3 demonstrated better erosion resistance, suggesting that the nickel and copper contents play a crucial role in the material's resistance to erosion. In order to evaluate and assess the cavitation effect more accurately the erosion damage on the material should be examined not only on the surface, but also in the depth. Based on the findings of this study, the cavitating jet technique may be a good alternative to investigate the cavitation erosion characteristics of propeller materials, if a relationship or scaling law between the water jet test technique and full-scale propeller loading, surface conditions, turbulence intensity, and bubble dynamics in operation can be established.

Influence of aging heat treatment at 180 °C on cavitation erosion for aluminum alloy type 5083 in cold rolled state

Aluminum-based alloys have wide applicability in the construction of aircraft, vehicles, and ships. Some of their components, during operation, such as the radiators and the rotors of the cooling pumps in the vehicles, and the propellers of fishing and pleasure boats are affected by the abrasive, chemical and cavitational corrosive action of the water. At certain hydrodynamic flow regimes, the most dangerous becomes the corrosion through cavitation. Operation in such regimes inevitably leads to damaging the structure, due to cyclic stresses of the micro-jets and shock waves generated by the implosion of cavitation bubbles. Although the chemical constitution and alloying with other chemical elements increase the mechanical properties, the service life is still limited when operating in high-intensity cavitation flows. Therefore, researchers are looking for solutions to improve this resistance through various treatments, such as bulk heat. Research heading the same direction, but, made on 5083 alloy, is presented in this paper. The results highlight the behavior of a modified structure compared to the semi-fabricated state (obtained by rolling), through three durations regimes (one hours, 12 hours and 24 hours) of aging heat treatment to 180 °C temperature, after hardening treatment at 450 °C. The cavitation tests were performed in the Laboratory of the Polytechnic University of Timisoara, on the standard vibrating device with piezoceramic crystals. The results were expressed by curves and parameters specific to the evaluation of cavitation resistance, and by macro and microscopic images, showing the unique aspects of the connection between the structure and the mechanical properties obtained through heat treatment regimes. Thus, comparison of the results, including with the delivery state (laminated product), shows that the highest resistance is provided by the treatment at 24 hours. At the same time, the erosion, of pitting and caverns type, and differs from one structure to another.

Cavitation behavior study of the aging heat treated aluminum alloy 7075

Aluminium-based alloy type 7075 is known for its good ductility, high mechanical strength, toughness and high fatigue strength, which is why it is mainly used in the construction of dynamically stressed parts in the structure of airplanes, vehicles and ships. Although it has these qualities, at present its behavior has not been studied at the hydrodynamic stresses that allow it to be used in parts that work in cavitation conditions, such as pump rotors and boat propeller blades. Therefore, the research in this paper highlights the behavior of laminated semi-finished structures and obtained by heat treatment of artificial aging at 180°C, with a maintenance time of one hour. Of the 7075 alloy at the demands generated by the vibrating cavity, created by the standard vibrating device with piezoceramic crystals (frequency of 20 kHz, amplitude of 50 µm and electrical power of 500 W). Analysis based on the curves MDE (t) and MDER (t), of the specific parameters of cavitation erosion MDEmax and MDERs as well as of the macro and microscopic images of the eroded structures of cavitation show that, compared to the delivered state (semi-finished), by the heat treatment applied the microstructure does not change cavitation

Pulsed TIG Cladding of a Highly Carbon-, Chromium-, Molybdenum-, Niobium-, Tungsten- and Vanadium-Alloyed Flux-Cored Wire Electrode on Duplex Stainless Steel X2CrNiMoN 22-5-3

The hardfacing process aims to increase the life span of structural components in the petrochemical, mining, nuclear and automotive industries. During operation, these components are subject to demands of abrasion wear, cavitation erosion and corrosion. Duplex stainless steels are characterized by high mechanical characteristics and corrosion resistance, but poor behavior to abrasive wear and cavitation erosion. The improvement in wear resistance is possible by selecting and depositing a special alloy on the surface using a joining technique that ensures a metallurgical bonding between the layer and the substrate. The experimental investigations carried out in this work demonstrate the ability of the TIG pulsed welding process to produce layers with good functional properties for engineering surfaces. The “Corodur 65” alloy was deposited on a duplex-stainless-steel substrate, X2CrNiMoN22-5-3, using a series of process parameters that allowed for the control of the cooling rate and heat input. The properties of the deposited layers are influenced not only by the chemical composition, but also by the dilution degree value. Since the deposition of layers through the welding operation can be considered as a process with several inputs and outputs, the control of the input parameters in the process aims at finishing the granulation and the structure in the fusion zone as well as limiting the segregation phenomena. The aim of this work is to investigate the microstructural characteristics of the iron-based alloy layer, Corodur 65, deposited via pulsed current TIG welding on duplex X2CrNiMoN22-5-3 stainless-steel substrates.

Investigation of cavitation properties of a mobile pumping unit

BACKGROUND: In the introduction to the article, a review of publications on cavitation, vibration and noise in centrifugal pumps, including the issues of cavitation erosion of impellers, is carried out. AIMS: Comparison of cavitation properties of a centrifugal pump of a mobile pumping unit with and without a pre-engineered screw by computational fluid dynamic (CFD) modeling. METHODS: The calculation of the flow part of a pre-injected impeller stage is described and the CFD model of its hydrodynamic simulation is described. In the CFD model, Navier-Stokes equations averaged over the Reynolds number and the working fluid continuity equation were used. A two-phase fluid model was used to simulate cavitation. RESULTS: The final results of the calculations carried out in the above models are presented. Calculations were obtained for a pump with impeller with and without an upstream stage (screw). For the impeller without a screw, the cavitation margin of 4.7 m was obtained, which is critical for such a pump. For a pump with an impeller with an upstream auger the cavitation margin is 1,7 m, that is much better and allows to show efficiency of such solution. CONCLUSIONS: The requirement of hydrodynamic modeling for selection of optimal flow part of centrifugal pump to improve its cavitation characteristics is formulated.

Effects of cavitation erosion-induced surface damage on the corrosion behaviour of TA31 Ti alloy

This study used electrochemical noise technology to analyse the effects of surface damage induced by cavitation erosion (CE) on the pitting and passivation behaviours of TA31 Ti alloy. According to the results, TA31 Ti alloy exhibited high corrosion resistance in NaCl solutions. However, the residual tensile stress layer generated during grinding and polishing reduced its passivation ability. Subsequently, the residual tensile stress layer was eliminated after CE for 1 h, improving the passivation ability of the material. Thereafter, pitting corrosion was initiated on the material surface. Increasing the CE time from 1 h to 2 h gradually decreased the passivation ability of the alloy. A large number of CE holes promoted the transition from pitting initiation to metastable pitting growth. which gradually dominated the surface of TA31 Ti alloy. The damage mechanism of uniform thinning increased the passivation ability and stability of the alloy with the increase in CE time from 2 h to 6 h. Therefore, the surface of TA31 Ti alloy was dominated by the initiation of pitting corrosion.

Assessment of the residual life of turbine runners with operational defectiveness

The residual life of the runners of hydraulic turbines in the presence of operational defects is estimated. The main problems of the operation of hydraulic turbines associated with technological defects and exhaustion of the standard resource are described. The main requirements for initial data to be used in estimation of the residual resource and the requirements for predicting the residual resource of runners based on the results of surveys and analysis of their technical condition are specified. We have classified and briefly described the applied approaches and techniques used in estimation of the residual resource. The main damaging factors affecting the residual life of the runners are revealed: deformation aging of the metal, cavitation, corrosion and fatigue damage to the elements of runners. The most characteristic defects are divided into three groups: zones of cavitation erosion; corrosion-fatigue cracks; and weld defects. Particular attention is paid to corrosion-fatigue cracks identified using flaw detection. The mechanism of crack formation and the most probable location of the cracks in the runner are shown. Statistical data on the number of cracks at the onset of the runner operation and at the time of shutdown maintenance are presented. The main statistical parameters of the sample and the parameters of crack size distributions including the distribution law are determined. The distribution law is exponential for the crack length parameter; whereas for the crack opening width it is log-normal. The revealed multidirectional cracks are located at the surface, subsurface or inner layer of the metal. They arise from operational defects (ulcers, craters, undercuts or delamination) and grow during operation of the turbine units. We also present the design schemes of elements with cracks used for quantification of resources according to the criteria of fracture mechanics. The results of calculations for static and dynamic crack resistance are presented as the dependence of stress intensity factors on the crack size. The levels of the total accumulated damage to the runners, the values of the residual life at the stage of crack nucleation and development were determined for 11 hydraulic units in the «start-stop» and «working» cycles. The main conclusion is that the total operating time of the hydraulic turbine runners significantly exceeds the standard operating life, while the residual resource is insufficient for a further period of long-term operation.

The coupling effect of cavitation-erosion and corrosion for HVOF sprayed Cu-based medium-entropy alloy coating in 3.5 wt.% NaCl solution

Ship propellers suffered from serious coupling damage of cavitation-erosion (CE) and corrosion when operated with high-speed in the marine environment. To improve the CE-corrosion resistance of the Ni–Al bronze (NAB) propeller alloy, a novel Cu-based medium-entropy alloy coating (Cu55Al20Ni12Ti8Si5, at.%) was prepared by high-velocity oxygen-fuel spraying technology in this study. The characteristics and CE behavior of coating and NAB were comparatively investigated, then the CE damage mechanism was discussed by analyzing CE damage morphologies. The influence of CE on corrosion behavior and the coupling effect between CE and corrosion were further elucidated by electrochemical corrosion experiments. The results indicated that the as-sprayed coating mainly comprised of BCC solid solution phase and NiTi-rich precipitates, which possessed higher hardness (6.73 ± 1.23 GPa) and superior resilience (27.0%) than the NAB. The cumulative mass loss rate for the coating after 18 h CE in distilled water and 3.5 wt.% NaCl solution was only 38.7% and 80.6% that for the NAB, revealing the better anti-CE performance of the coating. The preferential CE of the BCC matrix around the NiTi-rich precipitates, fatigue fracture and lamellar spalling were summarized as the main CE damage mechanism for the coating in 3.5 wt.% NaCl solution. CE had a significant influence on corrosion behavior of coating and NAB, which resulted in corrosion performance degradation of both two materials. The CE-corrosion coupling effect led to the remarkable mass loss, and mechanical effect rather than corrosion effect was ascribed to be the dominated factor for the damage of coating and NAB.

Study on the Dynamic Characteristics of the Impact Loads in a Near-Wall Double-Cavitation Bubble Collapse

Cavitation and cavitation erosion are complex hydrodynamic behaviors that significantly influence the stability and reliability of pumping units in aerospace and navigation power systems, hydraulic engineering, and other fields. Studies on cavitation have primarily and heavily focused on the collapse of multiple cavitation bubbles; understanding the movement of multiple cavitation bubbles is important for cavitation research. In this study, the collapse process of near-wall double-cavitation bubbles was numerically simulated and experimentally verified, and the evolution of the near-wall double-cavitation bubble collapse was investigated. Two different distances were altered in the study. The distance between the double-cavitation bubble and the distance between the cavitation bubbles and the wall, the effects of dimensionless parameters, such as the near-wall coefficient and the cavitation bubble spacing coefficient, the collapse time, jet angle, and impact load on the wall can be determined. It was found that the collapse time of the double-cavitation bubbles decreased in a negative exponential distribution with an increase in the cavitation bubble spacing coefficient, along with decreases in a negative exponential distribution with an increase in the near-wall coefficient. The jet angle increased in a negative exponential distribution with an increase in the cavitation bubble spacing coefficient and decreased in a negative exponential distribution with an increase in the near-wall coefficient. The impact load on the wall initially increased and then decreased in the form of a quadratic function, with an increase observed in the cavitation bubble spacing coefficient. With an increase in the near-wall coefficient, the impact load on the wall first decreased, then increased, and finally decreased in the form of a cubic function.

Influence of annealing on microstructure and cavitation erosion resistance of iron-based metallic glass coatings synthesized by HVOF thermal spraying

This study aimed to deposit a novel iron-based metallic glass coating onto 316L stainless steel and analyze the microstructures, phases, mechanical properties, and cavitation erosion resistances of the as-sprayed and annealed coatings. The coatings were annealed at temperatures of 540, 640, and 740 °C, resulting in varying crystal contents. As the annealing temperature increased, the amorphous content of the iron-based coatings decreased from 90% to 62%, 35%, and 29%, respectively, while the microhardness increased from 849 HV0.2 to 944, 970, and 860 HV0.2, respectively. The coating annealed at 640 °C exhibited the best resistance to cavitation erosion, whereas the coating annealed at 740 °C had the poorest resistance. Cavitation erosion always initiated from defects in the amorphous/nanocrystal coatings, such as pores, microcracks, or phase interfaces, and then propagated along these defects, eventually causing the stripping of particles. During cavitation erosion, the well-bound particles fragmented under repeated shocks, and the amorphous phase crystallized into nanocrystals, leading to detachment of particles in small sizes.

Study on cavitation erosion resistance of bimodal grain copper alloy fabricated by laser shock peening

The surface of marine fluid operating machinery is commonly damaged by cavitation, and the protection of its surface is one of the key technologies in contemporary marine industry. Bimodal grain weaving is an important means to enhance the cavitation erosion (CE) resistance of materials. Traditional bimodal grain fabrication methods are based on the grain refinement-recrystallization principle or on the mixed powder sintering principle, which are too tedious. In this paper, laser shock peening (LSP), a convenient technique, is innovatively utilized to fabricate bimodal grain weaving on the surface of nickel-aluminum bronze (NAB), a material with excellent cavitation erosion resistance, by using the principle of inhomogeneity Gaussian beam laser shock peening. The mechanism of its cavitation erosion resistance is also investigated. The results show that the depth of the affected layer induced by laser shock peening can reach 460 μm. At a laser power density of 5.37∗107 J/cm2, a bimodal grain weave with a large number of micron-sized grains interwoven with ultrafine grains is formed on the NAB surface. The results of ultrasonic cavitation experiments show that the cavitation erosion resistance of bimodal grain surface fabricated by laser shock peening is improved by approximately 2.18 times than that of matrix. The synergy of strength and toughness of bimodal grains is one of the important reasons for the improved cavitation erosion resistance of NAB. This research is expected to further promote the application of bimodal grain weaving in the marine high-speed flow-passing components.

Cavitation erosion of the CoCrFeNi high entropy alloy having elemental segregation

The cavitation-erosion (CE) damage features and a microstructural peculiarity of the CoCrFeNi high entropy alloy (HEA) are presented in this paper. While this HEA is theoretically predicted and often experimentally demonstrated to be a single-phase solid solution, noticeable elemental segregation has been observed in both the interdendritic regions and dendrite interiors in this study. This segregation causes a subtle reduction of lattice parameter, and the interdendritic segregated regions are frequently CE damage initiation sites. In the dendrite interiors, oxygen-rich particles with elemental segregation as their wrappings and the small speckles of elemental segregated regions show different CE damage features. In the dendrite interiors, CE-induced martensite formation is negligibly, and slip lines and their intersections are CE damage initiation sites. While a few CoCrFeNi-based HEAs have been shown to be CE-resistant in the literature, the CE resistance of the CoCrFeNi base itself is not high.

Investigation on the failure mechanism of graphite-like carbon coatings under cavitation erosion in distilled water

In this study, the use of graphite-like carbon (GLC) coatings deposited via magnetron sputtering to enhance the cavitation erosion (CE) resistance of 316L stainless steel is presented. The cross-sectional analysis and Rockwell testing show that the GLC coating exhibits the dense structure and good adhesion. The hardness and elastic modulus of the coating measured by nanoindentation reached 17.3 GPa and 197.3 GPa, respectively. Furthermore, the GLC coating exhibits excellent corrosion resistance upon electrochemical measurements. With the analysis of surface topography, chemical composition and carbon bonds, a model describing the CE failure mechanism of the GLC coatings is presented. The CE failure of the GLC can be divided into four primary stages: an initial generation of striated bulges with the release of internal stress accompanied with graphitization, followed by the generation of micro-cracks, the coating spallation with the interlinked micro-cracks and the final coating delamination.

Cavitation Erosion Modelling – Comparison of Different Driving Pressure Approaches

Cavitation Erosion Modelling – Comparison of Different Driving Pressure Approaches