Ultrasonic Cavitation Erosion Research Articles

Influence of surface finishing by grinding on the cavitation erosion resistance of 316L and NiAl-bronze

Improving the mechanical properties of bulk and near-surface materials and alternating the dynamics of cavitating bubbles are two main methods to reduce cavitation erosion damage. Grinding and polishing, as two common surface finishing stages, can alter the cavitation erosion damage on metallic materials by affecting both the bubble dynamics and the mechanical properties of the surface. In this paper, the ultrasonic cavitation erosion resistance of 316L and NiAl-bronze alloys, each with two initial surface conditions of grinding and polishing is investigated, focussing on the material reaction. The mechanisms of material removal are discussed based on surface and subsurface observations to explain the effect of surface finishing on the cavitation erosion damage. After 8.5 h cavitation erosion testing time, a lower erosion mass loss was obtained for both alloys in the ground state as compared to the polished state suggesting that grinding can improve the cavitation erosion resistance of alloys. On the other hand, the polishing process improved the erosion resistance of NiAl-bronze at the early stages of cavitation. This is discussed in light of the two distinct surface characteristics of roughness and hardness, which, in turn, tend to increase and decrease cavitation erosion damage. Planar crystallographic boundaries and intermetallic-matrix interfaces were found to be the most susceptible sites to early erosion damage on the polished 316L and bronze, respectively.

Effect of 3.5 % NaCl solution with different Na2S concentrations on ultrasonic cavitation erosion behaviors of HVOF sprayed WC-Ni coatings

In this article, the WC-10Ni coatings were fabricated by HVOF spray, then the ultrasonic cavitation erosion performances of the coatings in distilled water and 3.5 wt% NaCl solution with various Na2S concentrations (0, 20 and 200 ppm) were investigated. The results of the cumulative volume loss of the coating in different mediums showed that the coating exhibited enhanced cavitation erosion resistance with the increase of Na2S concentrations in medium. The reason for the improvement on the cavitation erosion performance was the growth of corrosion product films containing sulphide. In comparison with the coating after cavitation erosion in medium without Na2S, no large craters and deep grooves were observed on the eroded coating surface in medium with Na2S. The ultrasonic cavitation damage of the coating manifests as the spall of the metal binder phase (Ni) and exposure of the hard phase (WC).

The influence of sulphide on the ultrasonic cavitation erosion-corrosion behaviors of HVOF-sprayed WC-Cr3C2-Ni coating

The present study emphasizes the role of sulphide on ultrasonic cavitation erosion-corrosion (UCE-C) behaviors of HVOF-sprayed WC-Cr3C2-Ni coating in 3.5 wt% NaCl solution with different sulphide concentrations. The results indicated that the ultrasonic cavitation erosion (UCE) resistance of the coating decreased significantly with increasing sulphide concentration. The coating reacted with oxygen and anion those transferred by UCE, and the cavitation impact force led to the lack of support for tungsten carbide particles, which resulted in the reduction in the mass of the coating. There were two main factors those affected the UCE-C mechanism, in which the passivation film helped to reduce the mass loss of the coating, while the impact force caused by cavitation destroyed the passivation film, led to the accelerated anion diffusion and ultimately accelerated the mass loss of the coating. Mechanical erosion dominated the UCE-C of the coating in all tested solutions.

Study on the influence mechanism of material damage on the cavitation erosion properties of hydraulic concrete

Flood releasing safety is one of the three major safety problems of high dams due to the high-water head and large discharge, and the safety problems caused by cavitation erosion are increasingly prominent, which has become one of the challenging problems for the safety of high dam flood discharge. Particularly, flood discharge and energy dissipation structures are susceptible to varying degrees of damage under external loading and material performance degradation. However, the action mechanism of damage-cavitation erosion for concrete remains unknown and unclear. In this paper, the cavitation erosion properties of concrete with different damage variables and the influence mechanism of damage-cavitation erosion are systematically studied. Based on the ultrasonic cavitation erosion tests of undamaged and damaged concrete, it is found that the mass loss, harshness, volume of pits, and depth of damaged concrete increased rapidly at first and then slowly, the maximum loss rate is almost dependent on the degree of damage, and its relationship with the damage degree can be described by a piecewise linear function. More importantly, a damage variable threshold for the step surge of concrete cavitation erosion is suggested. The cementitious material in damaged concrete is more prone to cavitation erosion due to the potential microcracks caused by the damage. Compared with the results of tests and simulations, the incentive mechanism of the surge of concrete cavitation erosion due to the concrete damage - microcrack initiation - strength and fatigue life reduction - microjet impact - water wedge excitation in cracks - development, expansion, and penetration of erosion pits is revealed. The influence mechanism revelation of damage-cavitation erosion for concrete will enrich the theory and technology of cavitation erosion risk assessment for hydraulic concrete structures.

Bulk material influence on the aggressiveness of cavitation – Questioning the microjet impact influence and suggesting a possible way to erosion mitigation

In a study conducted over 10 years ago (Petkovsek and Dular, 2013) [1] we noticed that the thin metal sheet sustains less cavitation damage when it is attached to an acrylic glass (PMMA) than in the case when we attached it to quartz glass (SiO2). The reason for this was not explored at the time.In the present paper we present a systematic study of single cavitation bubble erosion of a thin aluminum foil, which was attached to either PMMA or SiO2 plate. We show that the damage sustained on the foil attached to PMMA plate is significantly smaller regardless of the bubble collapse distance from the boundary. The result is surprising since one would expect the weak foil to be severely damaged regardless of the material it is attached to.By femtosecond illumination and high-speed image acquisition we were able to capture the formation and progression of the shock waves, which are emitted at cavitation bubble collapse and observed that they are reflected on SiO2 boundary but that they traverse the PMMA bulk material. We offer an explanation that to achieve less damage the bulk material needs to have acoustic impedance similar to the one of the liquid medium in which cavitation occurs.Further on, we constructed a simple composite material where PMMA was attached to the SiO2 and showed that we can partially mitigate the damage. This was further confirmed by ultrasonic cavitation erosion tests.The results also imply that the cavitation damage originates solely from the shock wave, which is emitted at cavitation bubble collapse – consequently putting the idea of microjet impact mechanism under question. Finally, the study offers a new exciting approach to mitigate cavitation erosion by fine tuning the acoustic impedance of the coatings.

Factors affecting the procedure for testing cavitation erosion of GFRP composites using an ultrasonic transducer

In many marine applications, glass fibre reinforced polymer (GFRP) composites are exposed to adverse environmental effects including cavitation. Prolonged exposure to cavitation can damage GFRP composite surfaces that would eventually require repairing or replacing marine device components. This study initially investigates the deterioration of GFRP composite and its constituent materials (i.e., epoxy and glass) by cavitation erosion. The cavitation cloud is produced by an ultrasonic transducer, and cavitation erosion tests adhered to ASTM G32-16 standard. It is shown that the erosion process of GFRP composite has characteristics of both epoxy and glass. The second part of this study investigates the effect of several parameters associated with the experimental setup, testing procedure and material properties on ultrasonic cavitation erosion of GFRP composite. These parameters include gas content in testing liquid, type of specimen support, specimen water absorption, acoustic impedance, and tensile strength. It is reported that specimen edge treatment influenced water absorption, specimen preconditioning was important for accurate recording of erosion damage accumulation, acoustic impedance and tensile strength were directly correlated with erosion damage, while the cavitation erosion process of GFRP composite was mostly insensitive to gas content in testing liquid but was significantly affected by the type of specimen support.

Enhancing the cavitation erosion resistance of AISI 420-type stainless steel with quenching and partitioning

Stainless steels are commonly used in hydraulic components where they may be susceptible to cavitation erosion. In this study the cavitation erosion resistance of AISI 420-type stainless steel is examined after quenching and partitioning (Q&P) heat treatment. Q&P-samples were prepared with varying heat treatment parameters, and their initial properties were examined with X-ray diffraction and hardness measurements. Reference samples were also prepared with quenching and tempering and quenching without partitioning. The samples were eroded for 6 h with an ultrasonic cavitation erosion device, and their mass losses were measured. The eroded areas were examined with scanning electron microscopy, optical profilometry, and magnetic induction measurements. The results suggest that the cavitation erosion resistance of the examined stainless steel can be significantly enhanced with Q&P. This enhancement of cavitation erosion resistance results from high initial hardness and retained austenite fraction of the steel. During cavitation erosion the retained austenite can absorb cavitation bubble collapse energy by transforming into strain induced martensite, which increases the hardness of the steel and generates expansion of the lattice. This expansion additionally hinders crack propagation at grain boundaries, which reduces the formation of initial cavitation damage.

Ultrasonic Cavitation Erosion Behavior of CoCrxFeMnNi High-Entropy Alloy Coatings Prepared by Plasma Cladding

CoCrxFeMnNi (x represents the atomic percentage of Cr element, x = 20, 25, 30, and 35, denoted as Cr20, Cr25, Cr30, and Cr35 alloys) high-entropy alloy (HEA) coatings were cladded by plasma arc on the surface of 0Cr13Ni5Mo steel. The effects of Cr elements on the cavitation erosion mechanisms were studied by comparing the differences of microstructure, microhardness, cavitation erosion volume loss (CVL), cavitation erosion volume loss rate (CER), and eroded surface morphologies between the coatings. As the Cr content increased, the microhardness of the coatings increased continuously, and the microstructure transformed into fine dendrites. The microhardnesses of Cr20, Cr25, Cr30, and Cr35 were 223.9 HV, 250.5 HV, 265.2 HV, and 333.7 HV, respectively. With structural change, the slip pattern shifted from uniform distribution to distribution along the grain boundary, increasing slip resistance. Additionally, strain hardening capacity increased with reduced stacking fault energy (SFE). The resistance to cavitation erosion (CR) of the HEA increased with the increase in Cr content. The CVL of 20 h cavitation erosion of Cr35 coating was only 26.84% of that of 0Cr13Ni5Mo steel, and the peak CER was only 28.75% of that of 0Cr13Ni5Mo steel. The fracture damage mechanisms of the four HEA coatings were an obvious lamellar structure and fibrous fracture.

Effect of Toughness and Ductility on the Cavitation Erosion of Martensitic Stainless Steel

Martensitic stainless steel containing 13% Cr–4% Ni suffers cavitation erosion (CE) as the common material of hydro turbine impellers. Two 13% Cr–4% Ni stainless steel samples were obtained by different melting and heating processes. One was of relatively low toughness but high ductility (LTHD), and the other was of relatively high toughness but low ductility (HTLD). This paper is to clarify the relationship between the mechanical properties and the CE resistance of the experimental steel samples. The CE of the two materials was studied using an ultrasonic vibration cavitation erosion rig. Mass loss, morphological observation, nanoindentation characterization, and tensile tests were employed to clarify the erosion mechanism. The results showed that LTHD stainless steel had slightly higher ductility, but lower toughness than HTLD material. The mass loss method verified that the CE resistance of LTHD material was higher than that for the HTLD material. In addition, both materials had an incubation stage of 2 h in the distilled water. The SEM revealed that material removal was preferentially initiated from the grain boundaries and slip zone after the incubation period. The ductility could delay the fracture of the material, which contributed more to cavitation erosion resistance than the toughness of the materials. The hardness test showed few relationships with the CE resistance.

Cavitation erosion resistance enhancement of the surface modified 2024T351 Al alloy by ultrasonic shot peening

In this study, a novel surface strengthening method for improving cavitation erosion resistance by ultrasonic shot peening (USP) was proposed. Modified 2024T351 aluminium alloy surface layer with the characteristics of refined grains size, increased microhardness and residual compressive stress was prepared by USP treatment. Then the ultrasonic cavitation erosion (UCE) behaviour of the processed 2024T351 Al alloy was investigated. Results indicated that under the combined action of surface hardening and residual compressive stress, the cavitation weight loss of the USP-ed sample was significantly reduced. For the USP-ed 2024T351 Al alloy with an intensity of 0.101mmA, the weight loss after 3 hours' UCE treatment was reduced by 54.2 % compared to the untreated sample. This study also found that the increased surface roughness during shot peening could reduce the cavitation resistance properties. However, the weakening can be avoided by surface finishing. Results indicate that USP is a potential physical strengthening method that can significantly improve the cavitation erosion resistance of metals.

Microstructure and cavitation erosion resistance of arc ion plating NiCrAlY coating on the 304L stainless steel

To improve the ultrasonic cavitation erosion resistance of the 304L stainless steel, the NiCrAlY coating on the 304L substrate was fabricated by the arc ion plating (AIP) with three different parameters. The three types of coatings exhibited superior cavitation erosion resistance compared to the common cavitation erosion protective coating systems and 304L. Some micro-pores within the coating obtained by lower bias will be acted as the source of crack formation, but enhance the elastic recovery ability. Higher bias during coating fabrication hardens the coatings while does not significantly decrease the elastic recovery, thus maximally improves the performance. The cavitation erosion mechanism of the coatings will be discussed in terms of their microstructure and mechanical properties.

Ultrasonic Cavitation Erosion Behavior of Cocrxfemnni High-Entropy Alloy Coatings Prepared by Plasma Cladding

Ultrasonic Cavitation Erosion Behavior of Cocrxfemnni High-Entropy Alloy Coatings Prepared by Plasma Cladding

Synergetic Effect of Corrosion and Ultrasonic Cavitation Erosion on Leaded Brass

Synergetic Effect of Corrosion and Ultrasonic Cavitation Erosion on Leaded Brass

Investigation on Ultrasonic Cavitation Erosion of Aluminum–Titanium Alloys in Sodium Chloride Solution

Two kinds of Ti-alloys, i.e., Al–5Ti and Al–10Ti alloys, were manufactured in this study, and their ultrasonic cavitation erosion behaviors in 3.5 wt.% NaCl solution were evaluated by the cumulative mass loss, scanning electronic micrograph, and three-dimensional morphology. The results show that mass loss and surface damage of the Al, Al–5Ti, and Al–10Ti alloys obviously increased with the increasing cavitation erosion time. Compared with the pure Al, the cavitation resistance of the Al–5Ti and Al–10Ti alloys was improved because of the presence of the TiAl3 phase. In addition, the synergistic effect between cavitation and corrosion of the Al–Ti alloy in 3.5 wt.% NaCl solution was studied according to the polarization curve of the moving electrode. The mass loss caused by the synergistic effect between cavitation erosion and corrosion accounted for a large percentage, 23.59%, indicating that corrosion has a critical impact on the cavitation erosion of the Al–Ti alloys. Compared with corrosion promoted by cavitation erosion, the cavitation erosion promoted by corrosion had a larger promoting effect.

Erosion characteristics and failure mechanism of reservoir rocks under the synergistic effect of ultrasonic cavitation and micro-abrasives

Ultrasonic cavitation erosion of reservoir rocks in distilled water with and without SiO2 micro-abrasives (mean diameter 0.5 μm, mass concentration 1–7 wt%) are conducted. The erosion characteristics of eroded rocks are measured and analyzed. Both the area of cavitation damage zones and the surface roughness are increased when rocks are eroded in water-abrasive mixture. Compared with distilled water, the mass loss in 3 wt% water-abrasive mixture has improved by 69.66–104.23% (average 81.41%) for sandstone, 495.05–665.15% (average 557.38%) for shale, and 158.49–211.92% (average 188.16%) for granite during an erosion time of 5 ∼ 60 min. The promoted erosion can be explained by the synergistic effect of cavitation and micro-abrasives. The failure mechanisms are elucidated for different types of rocks. The erosion of reservoir rocks results from the peeling-off of mineral grains and the breakdown of large mineral crystals. Numerous micro-fractures and pores are produced in the surface of the eroded rocks, creating additional permeable channels for fluid flow. The results demonstrate that the presence of micro-abrasives can increase the ultrasonic cavitation erosion of reservoir rocks, indicating that the addition of micro-abrasives is feasible to enhance the performance of ultrasonic treatment for oil wells in petroleum industry.

The role of crystal orientation and grain boundaries in the cavitation resistance of EN 1.4301 austenitic stainless steel: An EBSD study

Characterization of crystal orientation and grain boundaries is of great interest in the understanding of the mechanisms taking place during the degradation process originated by the exposure of materials to erosive media. In the present study, an austenitic stainless steel previously analyzed by electron backscatter diffraction was exposed to ultrasonic cavitation erosion. Several parameters such as crystal orientation, misorientation, coincidence site lattice, Schmid factor and twin orientation were examined in order to determine their influence on the local susceptibility to early damage induced by cavitation. Crystallographic orientation was found to play a significant role in the deformation mechanisms occurring inside grains. Furthermore, high misorientation between adjacent grains was recognized as a determining factor leading to early damage observed at random grain boundaries, while the difference in Schmid factor was identified to have a significant effect on the cavitation resistance of twin boundaries. Moreover, the effect of the deviation from the ideal orientation predicted for coherent twins was analyzed in connection with cavitation resistance.

Cavitation dynamics and flow aggressiveness in ultrasonic cavitation erosion

The mechanisms of cavitation erosion have been the subject of numerous studies, but the cavitation dynamics and flow aggressiveness thereby produced are less known. We develop a new numerical model to capture the cavity evolution and pressure pulsation, which are related to cavitation erosion. The source term in the interphase mass transfer model is obtained from Rayleigh–Plesset equation under the acoustic field. Mathematical closure is achieved by the temperature-dependent Tait equations of state to apply to the cavitation. The comparison with the measurement results of ultrasonic cavitation shows that the model has a good predictive ability in cavity evolution, cavity volume and pressure pulsation. The surface erosion pattern is attributed to concentrated pressure. Given the shielding effect of the central bubble, the pressure is concentrated on the edge, resulting in an annular region with the greatest depth. The cavity characteristics are gap-dependent. When the gap height is 1.0 mm, cavitation erosion is the most serious. The size of the erosion area is determined by the maximum bubble number density on the sample surface.

Ultrasonic cavitation erosion behaviors of high-velocity oxygen-fuel (HVOF) sprayed AlCoCrFeNi high-entropy alloy coating in different solutions

In this study, an AlCoCrFeNi high-entropy alloy (HEA) coating was fabricated by HVOF spraying process. The HEA coating was consisted of the BCC phase (Al-rich phase) and FCC phase (Al-poor phase). The BCC phase was main phase. The mechanical performances and corrosion resistances of the coating and 06Cr13Ni5Mo martensitic stainless steel were analyzed in detail. The cavitation erosion behaviors and mechanisms of the HEA coating and 06Cr13Ni5Mo steel were investigated in distilled water and 3.5 wt% NaCl solution. The effects of microstructures, mechanical properties and corrosion properties on cavitation erosion mechanisms were discussed through the observation of eroded surface morphologies. The results showed that the cavitation erosion resistance of the AlCoCrFeNi coating was about 3.5 times that of the 06Cr13Ni5Mo steel in both solutions. In the 3.5 wt% NaCl solution, corrosion damage aggravated cavitation erosion damage, although the enhancement effect of corrosion on cavitation was limited. The corrosion environment did not change the cavitation erosion mechanisms of the two materials. The cavitation erosion mechanism of the HEA coating was lamellar spalling caused by the extension of the interlaminar cracks. Due to the lower plastic deformation resistance, the cavitation erosion mechanism of the 06Cr13Ni5Mo steel was material spalling caused by plastic deformation and fatigue fracture.

Cavitation erosion behavior of high‑nitrogen austenitic stainless steel: Effect and design of grain-boundary characteristics

An understanding of the cavitation erosion behavior and mechanisms of high‑nitrogen austenitic stainless steel is of interest for scientific and economic reasons. The original microstructure of 18Mn18Cr0.6 N steel was examined using electron backscatter diffraction analysis. Specimens were eroded using an ultrasonic cavitation erosion facility. The damaged surfaces were observed using scanning electron microscopy. Coherent Σ3 boundaries had the worst cavitation erosion resistance; the cavitation damage was located primarily at the same sides of the twins with a low Taylor factor. The cavitation erosion resistance decreased in the order: random high-angle grain boundaries and Σ27 boundaries; incoherent Σ3 boundaries; Σ9 boundaries; and coherent Σ3 boundaries. The Taylor factor was important in the analyses of metal material cavitation erosion. A large difference between the two grains or twins in the Taylor factor yielded a higher cracking risk of the boundary between them. Grain rotation led to a step formation at a boundary and the cavitation damage was accelerated. Three types of cavitation erosion were identified. A cavitation mechanism model for coherent Σ3 boundaries was proposed. Finally, the design of grain-boundary characteristics to improve the cavitation erosion resistance was discussed.

Cavitation erosion behavior of nickel foam/polyurethane co-continuous composite

The cavitation erosion behavior of Ni foam/polyurethane (PU) co-continuous composites under different experimental conditions was investigated using an ultrasonic vibration cavitation erosion device. Experimental results showed that the Ni foam metal skeleton structure had severe effects on the cavitation resistance of the composites. The composites with thick metal arris and large pore size exhibited good resistance to cavitation erosion. Stress waves had greater influence on the cavitation erosion behavior of composites than micro-jets. In a synergistic way of buffering stress wave in the resin phase and absorbing stress waves in the metal phase, the composites could exhibit better cavitation resistance than pure PU.