Cavitation Resistance Research Articles

Effect of Main Arc Current on Microstructure and Cavitation Resistance of NiCrBSi-WC Alloy Coating Prepared by Plasma Transfer Arc Welding

Effect of Main Arc Current on Microstructure and Cavitation Resistance of NiCrBSi-WC Alloy Coating Prepared by Plasma Transfer Arc Welding

Research on the Cavitation Resistance Testing of Friction Stir Welded Joint of Cu99 Cooper

Research on the Cavitation Resistance Testing of Friction Stir Welded Joint of Cu99 Cooper

Eкспериментально-розрахункове визначення коефіцієнтів гідродинамічної моделі кавітуючих насосів рідинних ракетних двигунів

Cavitation phenomena in liquid-propellant rocket engine (LPRE) pumps not only affect the power performance characteristics of the pumps, but they also affect the pump dynamics and pogo vibrations. The theoretical characterization of cavitation phenomena in LPRE pumps is not a widely used practice because theoretical and experimental data are in unsatisfactory agreement. Because of this, use is made of approaches that employ experimental data. The goal of this work is to determine the coefficients of a hydrodynamic model of cavitating LPRE pumps throughout the cavity existence region based on the experimental frequencies of cavitation oscillations and cavitation self-oscillation boundaries. In determining the cavity elasticity and negative resistance, use was made of the experimental cavitation oscillation frequencies of 26 LPRE pumps differing in dimensions and capacity. In determining the cavitation resistance distribution coefficient and the cavity-due disturbance transfer time, the experimental cavitation self-oscillation boundaries of 14 more pumps were used. To extend the cavity elasticity determination region, the extrapolation dependence of the cavity elasticity in cavitation stall regimes was updated. To make the stratification of the cavity resistance dependence more uniform in the range of large discharge coefficients, incipient cavitation numbers were refined. Using he qualitative dependence of the cavitation resistance distribution coefficient obtained from theoretical transfer matrices of cavitating pumps and its lower estimate (at zero disturbance transfer time) and upper estimate (for a uniform stratification of pump transfer matrix determinants), its analytical dependence was found. Using it and the coefficients of a mathematical model of cavitation oscillations on the cavitation-self oscillation boundary, disturbance transfer times were found and approximated.

Research on the Cavitation Resistance Testing of Friction Stir Welded Joint of En Aw 1200 Aluminium Alloy

Aluminium alloys are being used more often as a result of industry demands for strong, lightweight materials. Because of its advantages over conventional fusion welding techniques, friction stir welding, or FSW, has become a promising technique for joining aluminium alloys. Nonetheless, there is still cause for concern regarding FSW joints' vulnerability to cavitation erosion, which is a major issue in applications exposed to harsh environments. The cavitation resistance of EN AW 1200 aluminium alloy joints made by the FSW process is the main objective of this study. By utilizing specialized equipment to conduct cavitation tests, the study uses a comprehensive methodology to assess the cavitation erosion behaviour of these joints. A number of variables are investigated in order to determine how they affect the cavitation resistance of the welded joints, including mechanical attributes, welding parameters, and microstructural features. The goal of the study is to shed light on how well FSW joints function and hold up in cavitation scenarios. This information will be useful in improving the dependability and suitability of EN AW 1200 aluminium alloy in sectors where the ability to withstand cavitation erosion is critical. The findings from this study are expected to contribute to the optimization of welding parameters and material selection, ultimately advancing the use of aluminium alloys in critical applications requiring resistance to cavitation-induced damage.

Experimental Analysis of Cavitation Erosion: Parameter Sensitivity and Testing Protocols

The scientific goal of this study was to investigate the effects of various parameters on cavitation-induced erosion, with the aim to enhance the understanding and assessment of cavitation resistance in hydraulic systems. Cavitation erosion poses significant challenges to the durability and efficiency of hydraulic components, such as those found in hydropower plants and pumping stations. Prompted by the need to improve the reliability of cavitation testing and material assessment, this research conducted a comprehensive sensitivity analysis of a cavitation jet apparatus (CJA). This study employed an experimental platform that consisted of a vertical cylindrical test tank, a submerged nozzle, and an aluminum sample. By examining a range of orifice diameters, this research identified that smaller diameters led to increased erosion intensity, with the most pronounced effects observed at a diameter of 2 mm. Furthermore, various standoff distances (SoDs) were tested, which revealed that shorter distances resulted in greater erosion, with the highest impact noted at an SoD of 5 cm. This study also evaluated different nozzle geometries, where it was found that a 132° conical sharped edges nozzle, combined with an orifice diameter of 2 mm and an SoD of 5 cm, produced the most severe erosion. Conversely, chamfered edges nozzles and a commercial nozzle (MEG2510) with an SoD of 10 cm or greater showed reduced erosion. These results highlight that by standardizing the testing duration to 1200 s, the CJA could reliably assess the cavitation resistance of materials. This study established a clear relationship between increased pressure and higher impact forces, which led to more severe erosion. The findings underscore the effectiveness of the CJA in evaluating material resistance under various cavitation conditions, thus addressing a critical need for reliable cavitation testing tools.

Role of wall roughness on the energy performance for a mixed flow pump with tip clearance

Abstract This study delves into the intricate influence of wall roughness on the mixed flow pump energy performance, particularly focusing on the simultaneous presence of tip clearance. Utilizing a well-performing mixed flow pump with a tip clearance of 0.8 mm as the subject of investigation, the research employs numerical simulation at different roughness to comprehensively analyse the effects of wall roughness on pump head, efficiency, and cavitation performance. The numerical simulation employs the SST k-ω model and the equivalent sand-gain roughness model to simulate the turbulent flow account for wall roughness. The findings discerned that both head and efficiency are inversely related to wall roughness, with decrements amplified at elevated flow rates. Notably, the ‘hump’ in head performance near 60% of the design flow rate is significantly influenced by roughness beyond 31.6μm. Additionally, efficiency exhibits a minor uptick at 0.56μm roughness before a subsequent decline. The study also highlights the multifaceted impact of roughness on the internal flow structures, including vortex and cavitation patterns. These insights emphasize the importance of balancing roughness levels to enhance energy efficiency and cavitation resistance, crucial for the practical application and long-term reliability of such machinery.

Research on Rapid Detection Method of Cavitation State of Water jet Propulsion Pump Based on Multi-source and Multi-feature of Acoustic Emission Signal and Bayesian Network

Abstract Cavitation prevents the conversion of internal dynamic and pressure energy in a water jet propulsion pump and causes erosion of flow passage components. Acoustic emission is a non-destructive test method for instability signals. Based on the incipient mechanism and development process of cavitation, three acoustic emission signal feature parameters (ring counting rate, energy release rate, Hurst index) are proposed to define the cavitation state utilizing the waveform pattern and signal self-similarity. The multi-source and multi-feature cavitation identification model of acoustic emission signals is established through cavitation simulation, multi-monitoring point acoustic emission signal testing, and feature parameter extraction, and a large number of probabilistic trainings are carried out using Bayesian network, resulting in a fast cavitation state identification method based on acoustic emission signals. The research results have important practical engineering application significance for the prediction of cavitation resistance, real-time dynamic monitoring of cavitation phenomenon and prevention of cavitation damage.

Effect of ZrO2 Particles on the Microstructure and Ultrasonic Cavitation Properties of CoCrFeMnNi High-Entropy Alloy Composite Coatings

CoCrFeMnNi-XZrO2 (X is a mass percentage, X = 1, 3, 5, and 10) high-entropy alloy composite coatings were successfully prepared on 0Cr13Ni5Mo martensitic stainless steel substrates using laser cladding technology. The phase composition, microstructure, mechanical properties, and cavitation erosion behavior of the composite coatings under different contents of ZrO2 were studied. The mechanism of ZrO2 particle-reinforced cavitation corrosion resistance was studied using ABAQUS2023 finite element software. The results show that the phase structure of the composite coating organization is composed of FCC phase reinforced by ZrO2 phase. The addition of ZrO2 causes lattice distortion. The coatings have typical branch crystals and an equiaxed crystal microstructure. With the increase in ZrO2 content, the microhardness of the composite coatings gradually increases. When X = 10%, the coating’s microhardness reached 348 HV, which was 95.53% higher than the high-entropy alloys without ZrO2 added. Adding ZrO2 can prolong the incubation period of high-entropy alloys; the high-entropy alloy composite coating with 5 wt.% ZrO2 exhibited the best cavitation resistance, with a cumulative volume loss rate of only 15.74% of the substrate after 10 h of ultrasonic cavitation erosion. The simulation results indicate that ZrO2 can withstand higher stress and deformation in cavitation erosion, reduce the degree of substrate damage, and generate higher compressive stress on the coating surface to cope with cavitation erosion.

Features of cavitation wear of chrome electrolytic coatings

Cavitation wear is a pervasive phenomenon on water transport. The parts of ship propulsion system as well as the water-cooled surface of cylinder liners of high-speed ship diesels are subjected to cavitation attack. Bright chromium deposits are used to protect the water-cooled surface of liners. Nevertheless, the effect of cracks appearing in the electrolytic chrome coating upon depositing on the cavitation resistance of coating is still an open relevant problem. The goal of the study is to analyze the kinetics and mechanism of the destruction of the bright chrome electrolytic deposit under cavitation attack. The cavitation resistance of chrome electrolytic coatings after grinding and after polishing was studied. The chrome electrolytic coatings were obtained on the plates (90 × 30 × 7 mm in size) made of cast iron SCh21. The chrome was deposited on one side (90 × 30 mm) of the plate placed vertically by flow anodic jet chrome plating in standard electrolyte (kg/m3): chrome anhydride — 250; sulfuric acid — 2.5; trivalent chrome — no more than 5; trivalent iron ions — no more than 10. The electrolyte was prepared using distilled water of a single distillation. The parameters of depositing: electrolyte temperature is 50°C; the current density amounts to 60 A/dm2. Four samples cut from the same plate were used. The coatings on the first two samples were ground using the abrasive paper number 320. The coatings on the second pair of samples were first ground successively on the abrasive paper of different grit: 320, 500, 800, 1000, and 1200, and then polished on the cloth with GOI paste. The cavitation wear tests were carried out on a magnetostrictive vibratory rig in fresh water, the frequency and amplitude of the rig horn vibration was equal to 22 kHz and 28 μm, respectively. The spacing between the chrome-plated sample surface and the horn butt was 0.5 mm. The wear of the samples was evaluated by periodical weighing during testing. The wear of the ground samples turned to be significantly higher, than that of polished samples. The photographs of the surface after different duration of the cavitation attack show that the initial cracks formed on the coating during chrome plating are the centers of cavitation destruction. To reduce the negative impact of initial cracks on the cavitation resistance of the bright chrome electrolytic coatings deposited on the water-cooled surface of the cylinder liners of diesels it is shown expedient to include polishing in the technological process of depositing chrome coatings.

Impact of Double-Suction Pump Eye Diameter Variation on Cavitation Phenomena

Cavitation phenomena in pumps are major determinants of the lifespan of both the impeller and the pump itself, causing significant vibration and noise, which are critical concerns for pump designers. This study focuses on the influence of various geometric factors of the impeller, including the shape of the blade leading edge, blade inlet angle, number and thickness of blades, surface roughness, wrap angle, impeller outlet width, inlet hub diameter, and tip clearance. The pump analyzed in this study, which exhibited issues of vibration and noise in actual industrial settings, was evaluated by varying only the shroud diameter based on Gulich’s theory, while keeping other parameters constant, to assess the effects on cavitation phenomena across five different impellers. Single-phase analysis was initially conducted to evaluate the performance of each pump model, with the reliability of the numerical analysis methods validated by comparison with experimental data. Furthermore, to analyze cavitation phenomena, a multiphase flow analysis was performed using the Rayleigh–Plesset model within a computational fluid dynamics framework. Quantitative analysis of cavitation occurrence, NPSH3% head-drop performance, and bubble volume was conducted. The results confirmed that the M1 model, featuring a shroud diameter of 560 mm, exhibited superior cavitation resistance. Variations in cavitation occurrence observed under three different flow conditions demonstrated a nonlinear trend, but overall, improvements were noted within a specific diameter range. This study offers valuable insights and data for pump design applicable in real-world industrial settings.

Fracture toughness and cavitation erosion behavior of Fe-based amorphous composite coatings with Ni-coated Al2O3 addition

Fe-based amorphous composite coatings were prepared on 304 stainless steel substrates using atmosphere plasma spraying (APS), aiming to investigate the effect of Ni-coated Al2O3 particles addition on fracture toughness and cavitation erosion behavior of Fe-based composite coatings. The microstructure, phase composition, elastic modulus, microhardness and fracture toughness of the coating were characterized using scanning electron microscopy with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), microhardness tester and nanoindentation. The cavitation erosion behavior of Fe-based coatings was investigated by ultrasonic vibration cavitation method. Fe-based amorphous composite coatings exhibit a characteristic lamellar microstructure and reveal the presence of amorphous phases along with α-(Fe, Cr), NiO, Ni and Al2O3 crystalline phases. When the content of Ni-coated Al2O3 in coating increases from 0 wt% to 3 wt%, there is slight deterioration in porosity from 3.64 % to 4.75 % and fracture toughness from 2.579 MPa·m1/2 to 2.392 MPa·m1/2, yet an increase in microhardness from 925.4 HV0.5 to 1090.3 HV0.5. The composite coating with 3 wt% Ni-coated Al2O3 demonstrates the peak cavitation resistance and its cumulative mass loss is significantly reduced by 36.4 % compared to the pure Fe-based coating. The cavitation erosion failure of Fe-based amorphous composite coatings is predominantly characterized by the brittle fracture mechanism. The fundamental process driving cavitation erosion damage involves the material peeling and coating delamination instigated by intense micro-jet impact and shock wave propagation. The proposed Fe-based amorphous composite coatings can be applied to improve the anti-cavitation performance of components in contact with high-speed fluids, such as ship propellers and centrifugal pump blades.

Comparing the Cavitation and Slurry Erosion Wear Resistance of 16Cr-5Ni Stainless Steel with 13Cr-4Ni CA6NM Stainless Steel

Comparing the Cavitation and Slurry Erosion Wear Resistance of 16Cr-5Ni Stainless Steel with 13Cr-4Ni CA6NM Stainless Steel

Cavitation erosion performance and phase transformation strengthening behavior of laser clad iron-based shape memory alloy coatings

In order to avoid cavitation damage on the surface of overcurrent components after long-term service, the surface is reinforced with a coating to improve its cavitation resistance, thus prolonging service life. The present study employed analytical techniques, such as X-ray diffractometry (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM), to investigate the cavitation erosion performance of laser clad Fe-Mn-Si-Cr-Ni shape memory alloy (SMA) coatings with focus on the enhancing mechanism of their martensitic phase transformation. The results indicated that laser cladding could produce high-quality SMA coatings, free of defects such as pores and cracks, resulting in a significant improvement in the cavitation erosion performance. After 5 h of the cavitation, the coated samples remained in the cavitation erosion incubation stage, demonstrating an accumulated mass loss rate of approximately 0.12 mg/h, merely 13 % of that observed in the matrix samples. Extensive microstructural delamination occurred in the matrix samples after 5 h of the cavitation, whereas the coated samples exhibited only "shear bands" formed by plastic deformation on the surface. The martensitic phase transformation from γ-austenite to ε-martensite served to dissipate the stress induced by cavitation bubble collapse on one hand, and, on the other hand, the robust nature of martensite produced a hardening effect, significantly enhancing the cavitation resistance of the coating.

Improving the cavitation corrosion resistance of 6061 aluminum alloy by anodizing

Anodic oxidation is a common surface strengthening method to improve the comprehensive properties of aluminium alloys (AAs), such as wear and corrosion resistance, but its application on cavitation erosion is rarely touched. In this paper, the effect of sealing treatment on the properties of anodized AA6061 was investigated by using scanning electron microscopy (SEM), friction and wear experiment, cavitation experiment, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The experiment results showed that the oxide film under hydrothermal sealing had a superior cavitation and corrosion resistance, due to the high hardness and less defects in the film. Compared to distilled water conditions, corrosion mitigated the cavitation erosion of anodized AA6061 in simulated seawater, and the weight loss under simulated seawater after sealing was reduced up to a maximum of 30%.

Characterization of RF-Sputtered ZnO Thin Film Coatings on Aluminum (Al6061): Microstructure, Wettability, Cavitation, and Corrosion Analysis

The study focuses on the characterization of Aluminum (Al-6061) coated with RF-sputtered Zinc Oxide (ZnO) thin film, aiming to understand the complex interactions between microstructure, wettability, cavitation resistance, and corrosion performance. The study involves the use of various analytical techniques such as Field Emission Scanning Electron Microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and water contact angle (WCA) measurements. The cavitation erosion testing has been conducted under various factors namely jet velocity (m/s), impingement angle (°), and stand-off distance (cm), respectively, and that too at various levels. Further, with the use of RSM, the study also contributes to the interplay in between factors and acquiring optimized results. Moreover, the findings of the study provide valuable insights into the effectiveness of the ZnO coating in enhancing corrosion resistance and reducing mass loss due to cavitation erosion. The study’s results offer significant implications for the engineering and design of protective coatings for Aluminum surfaces, with the potential to enhance durability and performance in various industrial applications.

Xylem cell size regulation is a key adaptive response to water deficit in Eucalyptus grandis.

Future climatic scenarios forecast increasingly frequent droughts that will pose substantial consequences on tree mortality. In light of this, drought-tolerant eucalypts have been propagated; however, the severity of these conditions will invoke adaptive responses, impacting the commercially valuable wood properties. To determine what mechanisms govern the wood anatomical adaptive response, highly controlled drought experiments were conducted in Eucalyptus grandis W. Hill ex Maiden, with the tree physiology and transcriptome closely monitored. In response to water deficit, E. grandis displays an isohydric stomatal response to conserve water and enable stem growth to continue, albeit at a reduced rate. Maintaining gaseous exchange is likely a critical short-term response that drives the formation of hydraulically safer xylem. For instance, the development of significantly smaller fibers and vessels was found to increase cellular density, thereby promoting drought tolerance through improved functional redundancy, as well as implosion and cavitation resistance. The transcriptome was explored to identify the molecular mechanisms responsible for controlling xylem cell size during prolonged water deficit. Downregulation of genes associated with cell wall remodeling and the biosynthesis of cellulose, hemicellulose and pectin appeared to coincide with a reduction in cellular enlargement during drought. Furthermore, transcript levels of NAC and MYB transcription factors, vital for cell wall component biosynthesis, were reduced, while those linked to lignification increased. The upregulation of EgCAD and various peroxidases under water deficit did not correlate with an increased lignin composition. However, with the elevated cellular density, a higher lignin content per xylem cross-sectional area was observed, potentially enhancing hydraulic safety. These results support the requirement for higher density, drought-adapted wood as a long-term adaptive response in E. grandis, which is largely influenced by the isohydric stomatal response coupled with cellular expansion-related molecular processes.

Influence of TiO2dopingand spraying power on the microstructure, mechanical properties and cavitation erosion resistance of YSZ coatings

Yttria-stabilized zirconia (YSZ) and TiO2- doped YSZ (TiYSZ) coatings were prepared using Atmospheric Plasma Spraying (APS) at different power levels to protect of flow passage components from cavitation erosion. We analyzed, the effects of TiO2 doping and spraying power on the coatings' phase structure, microstructure and mechanical properties using XRD, Raman spectroscopy, SEM, Vickers hardness and nano-indentation. We tested the cavitation erosion behavior of TiYSZ coatings and YSZ coatings (as a reference) in a laboratory setting employing vibration-induced cavitation in accordance with ASTM standard G32-16. The results showed that the YSZ coating contained 50% c-phase and 50% t-phase, while the TiYSZ coating contained approximately 78 % c-phase. Spraying power hadlittle effect on the phase structure of either coating. However, higher spraying power increased the density of the coating, leading to greater microhardness. TiYSZ coatings were denser than YSZ at any power level and did not exhibit a distinct microcolumnar grain structure, unlike YSZ. Additionally, TiYSZ coatings displayed better mechanical properties, including higher hardness, elastic modulus, toughness, and fracture strength compared to YSZ. As a result, the cavitation resistance of TiYSZ coatings improved by about 50% compared to YSZ. Furhermore, we found that chemical degradation of YSZ-based ceramics under cavitation erosion conditions plays a role in cavitation erosion. We also observed that cavitation-induced amorphization is a key mechanism contributing to this degradation.

Effect of heat treatment on microstructure and cavitation resistance of multi-dimensional WC-10Co4Cr coating

The multi-dimensional WC-10Co4Cr coating was prepared on 316 stainless steel by using HVOF spraying, and the impact of heat treatment temperature on the microstructure, cavitation resistance, and mechanical properties of the multi-dimensional WC-10Co4Cr coating was studied. Heat treatment at higher temperatures leads to lower porosity and upper hardness of the coating. Meanwhile, oxidation products such as CoWO4 and Cr2O3 were produced at 500°C. The coating has the best anti-cavitation performance after heat treatment at 300°C.

Resistance of HVOF-Sprayed Cr3C2-25NiCr and WC-10CO-4Cr coatings to cavitation and erosion by mud jetting

This study investigates chromium carbide-based coating material’s cavitation and erosion resistance with 25% nickel-chromium. (Cr3C2-25NiCr) and Tungsten carbide coating with 10% cobalt and 4% chromium (WC-10CO-4Cr) coatings deposited by high-velocity oxygen fuel (HVOF) thermal spraying. The coatings were characterized by microstructure, porosity, hardness, and fracture toughness. Cavitation tests were performed in distilled water and water-sand mixtures to assess the synergistic effect of erosion and cavitation. Erosion tests were conducted using a mud jet at different impact angles (30°, 60°, 90°). The Cr3C2-25NiCr coating exhibited higher cavitation resistance due to its higher fracture toughness and lower porosity. However, the WC-10CO-4Cr coating showed superior erosion resistance, attributed to its finer and more homogeneously distributed carbides. The dominant wear mechanisms were micro grooving, carbide detachment, and cracking. The impact angle significantly influenced the erosion rates, with ductile materials like CA6NM steel being more susceptible at lower angles, while brittle coatings showed the opposite behavior. The findings highlight the importance of coating properties and test conditions on the wear performance, providing valuable insights for selecting suitable coatings for hydropower applications.

Визначення коефіцієнтов гідродинамічної моделі кавітуючих насосів рідин-них ракетних двигунів за їх теоретичними передатними матрицями

The characterization of cavitating pumps of liquid-propellant rocket engines (LPRE) is an important problem because of the need to provide the pogo stability of liquid-propellant launch vehicles and the stability of liquid-propellant propulsion systems for cavitation oscillations. The development of a reliable mathematical model of LPRE cavitating pumps allows this problem to be resolved. The goal of this work is to determine the cavitation number and operating parameter dependences of the coefficients of a lumped-parameter hydrodynamic model of LPRE cavitating pumps from their theoretical transfer matrices obtained by a distributed-parameter model. The following coefficients are found as a function of operating parameters: the cavitation elasticity, the cavitation resistance, the cavity-caused disturbance transfer delay time, and the cavitation resistance distribution coefficient. The last two coefficients are new in the hydrodynamic model of cavitating pumps, and they were introduced when verifying the model using experimental and theoretical pump transfer matrices. Analyzing the cavitation resistance distribution coefficient as a function of operating parameters shows that it markedly decreases with increasing cavitation number. This testifies to that the location of the lumped cavity compliance is shifted from the mid position towards the pump inlet. Therefore, the assumption that the lumped cavity compliance is located in the middle of the attached cavity regardless of the cavitation number is not justified. The fact that the distribution coefficient as a function of cavitation number intersects the abscissa axis near a cavitation number of 0.25 may indicate the boundary of existence of attached cavities and thus the applicability boundary of the theoretical model. The disturbance transfer delay time as a function of cavitation number sharply increases at cavitation numbers of about 0.05. At cavitation numbers of about 0.25, it is close to a constant.