Cavitation Erosion Performance Research Articles

A Nonaxial-Type Swirling Cavitating Nozzle for Exploiting Natural Gas Hydrate

Summary Natural gas hydrates (NGHs) have garnered widespread attention in the new energy sector, owing to their efficient and clean combustion properties. NGHs are ice-like substances formed by methane and water under high-pressure and low-temperature conditions, abundantly deposited in seabeds and frozen soil of highlands on Earth. However, the rock shelves of NGH reservoirs are mostly fragile and sparsely colloidal. Traditional mechanical mining methods can easily cause rock-shelf collapses, leading to mining accidents. Long-term indoor experiments and pilot mining projects have shown that cavitating nozzles can provide a feasible solution to the problem of efficient mining of NGHs. To further improve the efficiency of cavitating nozzle mining for NGHs, we have optimized and designed a nonaxial-type swirling cavitating nozzle (NASCN) based on traditional swirling cavitating nozzles (SCNs). Both numerical simulations and indoor experiments have verified the higher mining performance of this nozzle. In the numerical simulation experiments, we analyzed the cavitation performance, erosion performance, and energy consumption characteristics of different cavitating nozzles using the mixture multiphase flow model and the renormalization group (RNG) k-ε turbulence model. In the indoor experiments, we utilized a jet erosion experimental device for NGHs to analyze the erosion effects of different cavitating nozzles on hydrate samples. The results of these experiments indicate that the NASCN reduces energy consumption by 12% compared with traditional nozzles when there is little difference in cavitation performance and erosion performance. Moreover, under similar energy consumption, the NASCN improves erosion efficiency by 35.2% compared with traditional nozzles. These results demonstrate that the NASCN has good application value in the mining engineering of NGHs.

Microstructure and Cavitation Erosion Performance of Cold-Sprayed WC-12Co and WC-17Co Coatings on Hydraulic Turbine Steels

Microstructure and Cavitation Erosion Performance of Cold-Sprayed WC-12Co and WC-17Co Coatings on Hydraulic Turbine Steels

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.

Interfacial alloying between expanded austenite and Ti(AlCu)N coating for enhanced cavitation erosion resistance

Duplex surface treatments, combining nitriding and PVD coatings, have been considered as potential solutions to enhance material cavitation erosion resistance. This study investigates 316 L stainless steels after active screen plasma nitriding (ASPN), Ti(AlCu)N coating and duplex-treatment (Duplex) for enhanced cavitation erosion resistance. We elucidate a ‘denitriding - nitriding’ alloying behavior in association with high-energy ion sputtering for the interface between the nitrided case and the Ti(AlCu)N coating in the duplex-treated 316 L surface. Comparing the cavitation erosion performance among ASPN, Ti(AlCu)N and Duplex, the lowest weight loss of the duplex-treated surface is attributable to the enhanced load-bearing capacity from the multilayer system and the strong coating adhesion (HF1) after metallurgical evolution at the interfacial zone.

Effect of adaptive nanocrystalline behaviors on the cavitation erosion performance of Cu47.5Zr45.1Al7.4 bulk metallic glass

Amorphous alloys have attracted much attention in the field of cavitation erosion (CE) due to their good comprehensive properties. However, due to the special amorphous structures that are difficult to characterize, their micro-response behaviors and damage mechanisms during the CE process have not been well elucidated. In this paper, advanced techniques including focused ion beam (FIB) and transmission electron microscope (TEM) were used to comparatively study the microstructure evolution and volume loss rules of Cu47.5Zr45.1Al7.4 and Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glasses (BMG) under the action of cavitation load and cavitation heat to reveal their CE mechanisms. The results showed that the absence of small atoms in Cu47.5Zr45.1Al7.4 led to a large free volume, thereby compromising its hardness, modulus, and yield strength. However, this also made it more susceptible to shear banding, which in turn enhanced its energy absorption capabilities. Although Cu47.5Zr45.1Al7.4 had a higher glass transition temperature (Tg) and onset temperature of crystallization (Tx), as well as a wider supercooled liquid phase region (ΔTx), its exothermic peak was obviously pronounced and the transformation temperature range was significantly narrower. Therefore, it is more likely to adaptively form Cu-rich nanocrystals under the action of cavitation heat. Additionally, the larger free volume in the shear band was conducive to the diffusion of atoms and the occurrence of adaptive nanocrystallization behaviors in Cu47.5Zr45.1Al7.4. These nanocrystals were able to effectively force crack deflection, thereby dissipating impact energy and delaying the fatigue spallation of the material. Consequently, Cu47.5Zr45.1Al7.4 exhibited a far longer incubation period and a noticeably lower cumulative volume loss.

Effect of Y2O3 doping content on phase composition, mechanical properties and cavitation erosion performance of ZrO2 ceramics

Y2O3 stabilized ZrO2 (YSZ) is considered to be promising in resisting force-heat coupling damage caused by cavitation erosion (CE). However, the impact of doping Y2O3 on the microstructure and properties of ZrO2 is extremely complex, and there is still a lack of understanding about it, let alone the mechanism of these factors on the CE performance. In light of this, the present study investigated the effects of Y2O3 doping content (3 mol%, 7 mol% and 17 mol%) on the phase composition, grain size, microstructure, density, mechanical properties and CE performance of YSZ, and deeply analyzed the CE mechanism. The results indicated that the Y3+ entering the zirconia lattice effectively stabilized the high-temperature phases (t, t′ and c) and suppressed the formation of m-phase. With the increase of Y3+ concentration, the content of t continuously decreased while that of c continuously increased, so that only t + t′ phases were contained in the 3YSZ and only t′+c phases were contained in the 17YSZ. Meanwhile, the grain sizes and pores were constantly increasing, which obviously deteriorated the hardness, toughness and CE resistance. The t→m transformation under the action of cavitation load effectively absorbed impact energy and suppressed the propagation of fatigue cracks, thereby significantly delaying the fatigue spallation of materials. The 3YSZ with the densest microstructure, the best mechanical properties, the smallest grain size and the highest content of t-phase exhibited the best CE resistance. However, the continuous accumulation of m-phase at the grain edge, especially the amorphous structure formed by hydrolysis promoted by cavitation heat, provided a preferential channel for the propagation of fatigue cracks, and thus ultimately led to the exfoliation of the grains.

Differences in ultrasonic cavitation damage between new and used engine coolants with varying time in operation

This study investigates the cavitation erosion performance of heavy-duty engine coolants before and after operation in trucks using an ultrasonic test rig based on ASTM G32. Fresh coolants with 35% and 50% v/v glycol were compared with used coolants. One coolant was obtained from a gasoline-fueled vehicle with a mileage of 27000 km, and two from diesel-fueled vehicles with mileages of 16000 and 180 000 km, respectively. Surface tension and boiling point at atmospheric pressure were measured, a chemical analysis was carried out, and suspended particles were quantified by dynamic image analysis. The results showed that the used coolants caused a lower mass loss in ultrasonic cavitation testing than the fresh ones, and that they had higher boiling points, lower pH and a higher number of suspended particles, especially of those smaller than 30μm. Surface tension was higher for the used coolants from Diesel engines.The lower mass loss caused by all three used coolants can be attributed mainly to their high boiling point and high particle count. The presence of particles is believed to promote the heterogeneous nucleation of smaller, more stable bubbles, which may protect the exposed surface by shockwave absorption and microjet deflection. Some dissolved ions in the used coolants may help reduce their aggressivity by inhibiting bubble coalescence, reducing bubble collapse energy, despite increasing surface tension. Surface tension has complex interactions with the solutes, particles and bubble formation and cannot, in isolation, explain the differences in performance of the coolants.

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).

Effect of pre-corrosion on the cavitation erosion performance of two aluminum bronzes in 3.5% NaCl solution

The cavitation erosion (CE) behaviors of two aluminum bronzes after pre-corrosion in 3.5% NaCl solution were studied. Results indicated that the CE rate was increased by a factor of 82% for the nickel aluminum bronze (NAB) and 26.73% for the manganese aluminum bronze (MAB) after 30 days’ pre-immersion, compared with the results of the corresponding fresh sample without pre-corrosion. Mechanical impact was dominantly responsible for the CE damage of the pre-corroded samples. Pre-corrosion increased the E/T (the contribution of pure erosion to the CE-corrosion damage) value from 42.66% to 65.20% for the NAB and from 72.46% to 80.13% for the MAB. After pre-immersion, pits appeared at the eutectoid microstructure in the NAB and the network-shaped β phases in the MAB because of selective phase corrosion. This increased the surface roughness and weakened the surface mechanical property. Therefore, large and deep cavities and remarkable material loss were created due to the collapse of eutectoid microstructure in the NAB and the detachment of κ phases and brittle fracture of β phases in the MAB. The grievous CE damage of the MAB samples was highly attributed to the inferior mechanical property. In contrast, pre-corrosion had a much greater influence on the CE behavior of the NAB, because the CE resistance was remarkably deteriorated as a result of the corrosion damage at the eutectoid microstructure.

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.

Effect of Heat Treatment on the Cavitation Erosion Behavior of Nanocrystalline Surface Layer of 304 Stainless Steel

In this study, a nanocrystalline layer composed primarily of martensite phase was prepared on the surface of 304 stainless steel. Furthermore, the martensite phase content in the nanocrystalline layer was adjusted by heat treatment at 500 °C and 550 °C, respectively, and the cavitation erosion resistance of the nanocrystalline layer before and after heat treatment was investigated. The results showed that the nanocrystalline layer before and after heat treatment exhibited excellent erosion resistance, with cumulative mass loss of approximately 1/7, 1/5, and 1/3 that of the traditional 304 stainless steel, respectively. The nanocrystalline layer could significantly inhibit the growth of cavitation pits due to the high density of grain boundaries. However, due to the decrease in hardness of the nanocrystalline layer after heat treatment, the propagation speed of cavitation cracks was accelerated, and the cavitation erosion performance of the nanocrystalline layer showed a downward trend.

Effect of Initial Surface Scratches on the Cavitation Erosion Behavior of 316L Stainless Steel Substrates and 316L Stainless Steel Coatings

Rough surfaces have been widely considered as negative factors affecting cavitation erosion resistance. However, this study presented the opposite result. Here, 316L stainless steel substrates and the arc-sprayed 316L stainless steel coatings were subjected to a specific grinding process that introduced scratches on the surfaces. The surface hardness values of these ground specimens were measured to evaluate the influence of the grinding-induced strain hardening. The cavitation erosion performance of the specimens was evaluated. The results showed that rough surfaces with scratches could enhance the cavitation erosion resistance, particularly at the early stage of cavitation erosion. The scratches had a greater effect on the cavitation erosion resistance of the coatings than on the substrates. Moreover, rough surfaces with initial surface scratches could extend the incubation period of the 316L stainless steel substrates due to the inhibition of the plastic deformation. The SEM observation showed that the scratch structure of the coating surface inhibited the growth of cracks and the propagation of cavitation pits. This study could also serve as a reference for investigating the cavitation erosion behaviors of materials with a particular surface feature.

The effect of microstructure and mechanical properties on sliding wear and cavitation erosion of plasma coatings sprayed from Al2O3 + 40 wt% TiO2 agglomerated powders

This paper discusses the influence of 40 wt% TiO2 addition to Al2O3 and the selection of plasma spray parameters on the morphology, microstructure, microhardness and adhesion of coatings. Mainly, the tribological behavior and cavitation erosion performance of produced coatings were evaluated. First, the two-factorial design of the experiment, with the stand-off distance and torch scan speed as variables, was used to plan coating deposition by means of atmospheric plasma spraying (APS). Then, a process response using a multiple regression method was used to investigate the influence of factors variation on coatings functional properties. Although these properties were already investigated in alumina-titania coatings, there are still some knowledge gaps. Particular attention was given to the composition of Al2O3 + 40 wt% TiO2, because, so far, it is the most rarely discussed in the literature in terms of, e.g., cavitation or wear resistance. Increasing the torch scan speed and decreasing the spraying distance densifies the microstructure and increases coating's mechanical properties. A dense and low porosity structure facilitates cavitation erosion resistance and minimizes friction coefficient. Cavitation erosion damage relies on brittle cracking initiated at coatings porosity. Therefore, coatings with decreasing porosity show layer-like removal contrary to uniform material removal stated for porous coatings. The sliding wear mechanism has been dominated by abrasive wear and fatigue cracking. Accumulated wear debris undergoes adhesive smearing and removal.

Microstructure, mechanical properties, and cavitation erosion performances of cold sprayed CuZn35 coatings

CuZn alloy (as known as brass) is widely used in ship components due to its combination of high hardness and fatigue strength, and therefore good cavitation erosion performance. In this study, CuZn35 powder was for the first-time cold spray deposited on pure aluminum substrates for potential application as cavitation protection of hull pipelines. Parametric studies were carried out and the respective deposition characteristics were analyzed, and cavitation erosion performances of different CuZn35 coatings were characterized in deionized water using ultrasonic vibration experiments. The results showed that with the increase of gas temperature, cold sprayed CuZn35 coatings generally showed better cold sprayability and coating performance on aluminum substrates. The cold sprayed CuZn35 coatings exhibited a dense structure (porosity ~0.43 %), fine grain (~0.549 μm), a relatively high microhardness (~226 HV), and a relatively high bonding strength (54 MPa). The cavitation resistance of cold sprayed CuZn35 coatings showed a lowest volume loss rate of 0.22 mm3/h in deionized water, which was lower than that of as-cast CuZn35 (0.39 mm3/h). After 120 min cavitation, various features such as undulation deformation, pit and crack propagation, and material peeling appeared on cold sprayed CuZn35 coatings. It was noted that cold sprayed CuZn35 coatings, different from the as-cast CuZn35, exhibited the main cavitation mechanism of delamination caused by interlayer crack propagation.

Behavior of the hard phases of copper alloys subjected to cavitation erosion investigated by SEM observation

This work investigated the cavitation erosion performance of two copper alloys in deionized water (DW) and artificial seawater (ASW) for 10 h. Specifically, scanning electron microscopy observation was performed on the alloys exposed to cavitation erosion for different periods (within 3 h) at the same sites to study the microstructural evolution. The results tested in DW showed that the accumulation of the stress at phase boundaries caused crack generation in the α phase and severe deformation of the hard phases (κ & Fe(Al,Cu)), resulting in the exfoliation of the hard phases. However, the deformation of the hard phase was not observed from the samples tested in ASW due to stress corrosion cracking and material dissolution at the phase boundaries.

Numerical Simulation of the Straight-Swirling Integrated Jet and Its Application in Natural Gas Hydrate Drilling

Summary Natural gas hydrate (NGH) is a potential clean energy source and is buried abundantly in seafloor sediments. Waterjet is a key technology involved in both the marine NGH solid fluidization exploitation method and the integrated radial jet drilling and completion method. To improve the efficiency of breaking and extracting NGH through a waterjet, a straight-swirling integrated jet (SSIJ) nozzle is designed based on the convergent-divergent geometry and impeller in this study. With a computational fluid dynamics method, the 3D model of SSIJ is constructed, and the characteristics of velocity field, pressure field, cavitation cloud distribution, and turbulence kinetic energy are analyzed, the results of which are compared with conical jet (CJ), convergent-divergent jet (CDJ), and swirling jet (SJ). Laboratory experiments of gas hydrate-bearing sediments (GHBS) erosion by the four kinds of jets mentioned above are conducted to evaluate the jet erosion performance based on the in-house experimental apparatus for NGH generation and cavitating jet erosion. Results indicate that the SSIJ can significantly enhance the breaking volume and efficiency of waterjet erosion on GHBS compared with the other three methods. The most important driving force for improved efficiency is the 3D velocity, which can induce axial impact stress, radial tensile stress, and circumferential shear stress on the impinged GHBS. Additionally, the insertion of an impeller with the center hole greatly improves the cavitation erosion performance of SSIJ. This paper illustrates the erosion performance of four kinds of waterjets in breaking GHBS and provides preliminary insights into the potential field applications in NGH exploitation.

Effect of Microstructure and Hardness on Cavitation Erosion and Dry Sliding Wear of HVOF Deposited CoNiCrAlY, NiCoCrAlY and NiCrMoNbTa Coatings.

Metallic coatings based on cobalt and nickel are promising for elongating the life span of machine components operated in harsh environments. However, reports regarding the ambient temperature tribological performance and cavitation erosion resistance of popular MCrAlY (where M = Co, Ni or Co/Ni) and NiCrMoNbTa coatings are scant. This study comparatively investigates the effects of microstructure and hardness of HVOF deposited CoNiCrAlY, NiCoCrAlY and NiCrMoNbTa coatings on tribological and cavitation erosion performance. The cavitation erosion test was conducted using the vibratory method following the ASTM G32 standard. The tribological examination was done using a ball-on-disc tribometer. Analysis of the chemical composition, microstructure, phase composition and hardness reveal the dry sliding wear and cavitation erosion mechanisms. Coatings present increasing resistance to both sliding wear and cavitation erosion in the following order: NiCoCrAlY < CoNiCrAlY < NiCrMoNbTa. The tribological behaviour of coatings relies on abrasive grooving and oxidation of the wear products. In the case of NiCrMoNbTa coatings, abrasion is followed by the severe adhesive smearing of oxidised wear products which end in the lowest coefficient of friction and wear rate. Cavitation erosion is initiated at microstructure discontinuities and ends with severe surface pitting. CoNiCrAlY and NiCoCrAlY coatings present semi brittle behavior, whereas NiCrMoNbTa presents ductile mode and lesser surface pitting, which improves its anti-cavitation performance. The differences in microstructure of investigated coatings affect the wear and cavitation erosion performance more than the hardness itself.

Microwave cladding of NiCrSiC-5Al2O3 on austenitic stainless steel to improve cavitation erosion resistance

The current investigation aimed to study the cavitation erosion performance of the microwave synthesized NiCrSiC-5Al2O3 composite clad with a 900 W power multimode domestic microwave applicator of 2.45 GHz frequency. The clads were deposited on the austenitic grade stainless steel, namely AISI-316. The as-deposited composite clad’s microstructure, crystal structure, porosity, microhardness, and flexural strength were examined. Cavitation erosion study was done using the vibratory cavitation method at varying standoff distance (SOD)-(0.5 mm, 1 mm, 1.5 mm) and vibration amplitude (AMP)-(40 μm, 50 μm, 60 μm), keeping other parameters constant. The results had shown that the deposited NiCrSiC-5Al2O3 composite clad exhibited 1.20% porosity, 489.16 ± 47.95 HV0.3 microhardness, 264.91 ± 4.5 MPa flexural strength, and performed 3.5 times much better than the AISI-316 in terms of cavitation resistance. The least weight loss occurred at 1.5 mm SOD and 40 μm AMP, where the highest weight loss was observed at 0.5 mm SOD and 60 μm AMP. The erosion mechanism of the NiCrSiC-5Al2O3 composite clad surface was observed as plastic deformation followed by surface fatigue; the clad surface was eroded in the form of pits, craters, impingement marks, secondary cracks, and plastically deformed lips.

Influence of 13 wt% TiO2 content in alumina-titania powders on microstructure, sliding wear and cavitation erosion resistance of APS sprayed coatings

Abstract This paper discusses the influence of using 13 wt% of TiO2 addition to Al2O3 powder and selection of plasma spray parameters on morphology, microstructure, phase composition, mechanical properties, and, particularly, tribological behaviour and cavitation erosion performance of produced coatings. Two types of powders were used to spray the coatings by means of atmospheric plasma spraying (APS): Al2O3 (AT0) and Al2O3 + 13 wt% TiO2 (AT13). The stand-off distance and torch scan speed were two spray parameters considered in this work. The aim of the study was to investigate how the addition of titania to alumina in agglomerated and sintered nanostructured powders could improve the coating microstructure and functional properties. The results demonstrated that addition of TiO2 in the powder provides denser microstructure of the coating, improves the contact between splats, prevents the coating from severe fragmentation and spallation during wear, and prolongs the cavitation lifetime. In general, AT0 coatings exhibit slightly better wear resistance than AT13 equivalents. On the other hand, it was found that AT13 coatings present superior cavitation erosion resistance when compared with AT0.

Cavitation erosion resistance of high-entropy FeCoCrNiMoXB0.2 coatings cladded by laser

ABSTRACT The cavitation erosion resistance of high-entropy FeCoCrNiMoXB0.2(X = 0, 0.5, 1), coatings cladded by laser was studied. The test was processed by a magnetostrictive cavitation method in both distilled water and 3.5 wt-% NaCl solution. It was observed that the mass-loss rate of the coatings rarely increased or even decreased in the first few hours. This study verified that the formation of cavitation pits and extend of cracks due to the mechanical shock were the dominant factors causing cavitation of the coatings. The additional Cl– exhibited a deteriorative effect on the cavitation erosion performance of this high-entropy alloy coating, which leads to an increase of the mass-loss in NaCl solution than that in distilled water. Moreover, the hardness and stability of the high-entropy coatings were enhanced owing to the increase of Mo content, thus improving the cavitation erosion resistance.