Cavitation Wear Research Articles

Cavitation resistance of tungsten carbide applied on AISI 1020 steel by HVOF and remelted with CO2 laser

In engineering, there are major concerns about cavitation wear, as well as erosion, caused by the transport of abrasive sediments in hydraulic installations, like pumps and turbines, due to the damage these phenomena can cause in pumping stations and hydroelectric plants. Several studies are proposed to reduce this problem, like component design alteration and deposition of coatings with different materials that can be optimized for different wear issues. The objective of this work was to characterize and analyze the cavitation erosion of AISI 1020 steel samples coated with WC10Co4Cr deposited by high-velocity oxy fuel (HVOF) and laser-remelted with CO2 laser beam to evaluate the influence of this process in the cavitation erosion resistance of the coating. Microstructure, before and after laser treatment, was analyzed by means of optical and scanning electronical microscopy with SEM/EDS, indicated the metallurgical bonding between substrate and coating and a thickness reduction in the initial coating sprayed by HVOF of 100–35 µm after laser irradiation, with an enhanced coating hardness (20%) near the surface. The cavitation erosion resistance evaluated using vibratory ultrasonic equipment, according ASTM G32-92 standard, indicated a reduction of 40% after laser treatment. This performance could be attributed to the surface densification of the HVOF-sprayed coating.

Coolant boiling and cavitation wear – a new tool wear mechanism on WC tools in machining Alloy 718 with high-pressure coolant

In recent years, research interest in liquid coolant media applied to the tool–workpiece interface (the tertiary shear zone) has grown considerably. In particular, attention has increased for work where the media has been applied under high-pressure. This is most likely triggered by the positive results reported on similar applications, but with coolant media directed towards the rake face of the cutting tool (the secondary shear zone). The most typical applications have not surprisingly been related to the machining of Heat Resistant Super Alloys (HRSA) or other “difficult to machine” alloys where the main intention has been to extend tool life and improve surface finish through reduced shear zone temperatures.Concurrently, these achievements have revealed a knowledge gap and unlocked a new research area in understanding the effects and influences of coolant media applied on super-heated surfaces under high-pressure conditions. The aim of this study is to investigate the “coolant boiling and cavitation” phenomena that emerges during the application of coolant under high-pressure to the flank face of an uncoated WC tool while turning Alloy 718. The experimental campaign was conducted in three aspects: varying flank (coolant media) pressure; varying spiral cutting length (SCL); and varying cutting speed.The results revealed that the location and size of the coolant-boiling region correlated with flank wear, coolant pressure and vapour pressure of the coolant at the investigated pressure levels. Further, the results showed that coolant applied with a lower pressure than the vapour pressure of the coolant itself caused the “Leidenfrost” effect. This then acts as a coolant media barrier and effectively reduces the heat transport from the cutting zone.Further, erosion pits were observed on small areas of the cutting tool, resembling the typical signs of cavitation (usually found in much different applications such as pumps and propellers). The discovered wear mechanism denoted as “Cavitation Wear” was used as base for the discussion aimed to deepen the understanding of the conditions close to the sliding interface between the tool and the workpiece. Even though “Cavitation Wear” has been widely reported in hydraulic systems like pumps and water turbines, it is a new phenomenon to be seen on cutting tools while using high-pressure flank cooling.

Study of Cavitation Erosion-Corrosion Resistance of Thermally Sprayed Ni-Based Coatings Prepared by HVAF Process

In this study, two Ni-based coating materials, namely NiCrMoNb and NiCrBSi, have been applied using High Velocity Air Fuel (HVAF) thermal spraying process. The performance of the coated surface in resistance to cavitation erosion-corrosion of both coating materials, has been evaluated using an ultrasonic vibratory method. The cumulative material loss and erosion rate curves of the two coatings have been discussed. Surface topography, microhardness, macroscopic images, and scanning electron microscope (SEM) micrographs were used to characterize the coatings before and after the cavitation test. The cavitation results showed that the NiCrMoNb coating surface has exhibited better performance than the NiCrBSi coating surface under the same test conditions. The total cumulative weight loss of the NiCrMoNb coating was about 1/3 that of the NiCrBSi coating. SEM micrographs of the eroded surfaces showed that the surface layer of the NiCrBSi coating was more damaged, compared to layer of the NiCrMoNb coating. Overall, the NiCrMoNb coating can be effectively used against the cavitation wear, due to its superior performance.

Cavitation Erosion-Corrosion Resistance of Deposited Austenitic Stainless Steel/E308L-17 Electrode

The ultrasonic vibratory test was carried out to evaluate the cavitation erosion/corrosion resistance of welded-deposited austenitic stainless steel/E308L-17. Three layers of the E308L-17 electrode were deposited onto AISI 1040 substrate utilizing Shielded Metal Arc Welding (SMAW) process. The eroded surfaces of the E308L welded deposit/coating and AISI 1040 substrate steel have been analyzed by evaluating surface topography, as well as scanning electron microscope (SEM) micrographs. In addition, the cumulative weight loss and erosion rate curves were attained to evaluate the cavitation resistance of the tested materials. The cavitation results showed that the E308L-17 deposited stainless steel has lost about 15 mg as a cumulative weight, while the loss of AISI 1040 substrate was about 123 mg. This is equal to 0.12% and 1.0% of the original test specimen weight for the E308L-17 and AISI 1040, respectively. Consequently, E308L-17 austenitic stainless steel can be effectively used as a protective material for surfaces exposed to cavitation wear, since the AISI 1040 substrate has been enhanced by 8 times using E308L stainless steel.

ВЛИЯНИЕ КОРРОЗИОННОГО ФАКТОРА НА КАВИТАЦИОННУЮ ИЗНОСОСТОЙКОСТЬ СПЛАВОВ ДЛЯ ГРЕБНЫХ ВИНТОВ

The resistance of the stainless steel 08H14NDL, the bronze BrA8Mts11Zh3N2L and the brass LTs40Mts3Zh to cavitation erosion was investigated in fresh water and artificial sea water. The tests were carried out on an ultrasonic vibratory apparatus. The horn of the vibratory device resonated at approximately 22 kHz, a peak-to-peak amplitude being changed from 24 to 54 μm. The distance between the horn butt-end and the specimen surface equaled 0.5 mm. It was shown, that the increase in the amplitude of vibration leads to the decrease in the difference between the cavitation wear in fresh water and the sea water. It was demonstrated that under the cavitation attack of high intensity the wear of the brass in the sea water can be essentially lower than the one obtained in the fresh water. The demonstrated paradox may be attributed to the peculiarities of the cavitation impact on the ultrasonic vibratory apparatus combined with the plasticizing action of the aggressive liquid. The ultrasonic frequency of the shock waves action on the surface increases dislocations mobility, whereas the stripping the surface layers with sea water alleviates the discharge of the dislocations on the surface: the chemomechanical effect takes place.

Calculations of research reactor thermal hydraulics based on VVER-440 fuel assamblies

Having thoroughly analyzed the design features of VVER-type pressurized water reactors and VVR-type research reactors, the authors propose a design of a research reactor with low-enriched fuel based on deeply updated VVER-440 fuel assemblies. The research reactor is intended to solve a wide range of applied problems in nuclear physics, radiation chemistry, materials science, biology, and medicine. The calculated thermal hydraulics confirms the correctness of the fundamental approaches laid down in the reactor design. An equivalent reactor core model in the form of a thick-walled cylinder was considered, and the radial power density distribution was obtained. According to the heat power level, five groups of FAs were identified. For each group, the coolant mass flow rate was calculated, which ensures alignment with the outlet coolant temperature. The coolant flow regime was also estimated. It turned out that for the first row of FAs, the flow regime is in the transition region, while for the other rows the flow regime is laminar. A test by the Gr.Pr≥1.105 criterion showed its conformity (the calculated value was 1.96.106), indicating the transition to a viscous-gravitational regime. The FE surface overheating was calculated relative to the mixed coolant average temperature. The axial coolant flow temperature distribution is the same in all the FAs, the change in power is compensated by the corresponding change in the coolant flow. The maximum coolant overheating on the FE wall relative to the flow core is observed in the central FAs, reaching 31 °C, the boiling margin is about 15 °C. The estimates showed a significant dynamic pressure margin during natural thermal-convective circulation. By calculation, the values of the FE surface overheating during the reactor normal operation were obtained. An approximately 15-degree surface overheating margin relative to the saturation curve is shown, which guarantees the absence of cavitation wear of the FE claddings. In general, the performed calculations confirmed the correctness of the approaches laid down in the reactor design and made it possible to specify the core thermal hydraulics necessary for further developing the concept.

Effect of Nano Alumina on the Properties of Fluorinated Polyurethane

This article selects studies on the preparation of fluorinated polyurethane-nano-alumina composite coating materials, and analyzes the anti-wear, water resistantance, and surface microstructure. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) shows that the polyurethane synthesized in this study does not contain hydrophilic –CH2OH groups. The cavitation wear test depicts that the actual cavitation amount C of the Al2O3-FPU (4) (fluorinated polyurethane) coating is 0.9035 × 10−3 kg, and the anti-wear ability increases by 61.9% compared with FPU-0.5. The water-resistant test shows that the contact angle of water droplets on the surface of the coating increase from 95.3° of FPU-0.5 to 123.1° of Al2O3-FPU (4), and the water absorption decreases from 2.52% to 1.04%. Scanning electron microscopy (SEM) observation confirms that alumina particles can protrude on the coating surface and resist strong wear, while the C-F chain with high bond energy at the near-surface exhibits high strength and water resistance, which prevents wear from spreading deep into the coating. Differential scanning calorimetry (DSC) results show that the Tg(HS) value of the hard segment phase decreases with higher external force. Notably, when the coating is subjected to erosion, which enhances the crystallinity of the hard segment phase, the tensile strength of the hard segment phase of the coating surface is improved, which supports the wear resistance. Herein, we show that the addition of nano-alumina to fluorinated polyurethanes can control high water and abrasion resistance.

Использование результатов измерения шероховатости поверхности для прогнозирования долговечности материалов гребных винтов при кавитационном изнашивании

Использование результатов измерения шероховатости поверхности для прогнозирования долговечности материалов гребных винтов при кавитационном изнашивании

Tribological study of piston–cylinder interface of radial piston pump in high-pressure common rail system considering surface topography effect

Based on the theory of thermal fluid dynamic lubrication, the Reynolds equation and energy equation of the average flow of a piston–cylinder interface of a radial piston pump in a high-pressure common rail system are established, considering the surface topography effect. The tribological properties of the piston–cylinder interface are calculated by solving the Reynolds equation and energy equation. A surface wear model is established and the wear distribution and trend of the piston–cylinder interface are studied. The wear characteristics of the piston–cylinder interface are verified through experiment, and the wear lubrication of the piston–cylinder interface is discussed. The surface topography effect has a considerable influence on the characteristics of the piston–cylinder interface film. Different surface morphologies change the film characteristics of the piston–cylinder interface, yielding different wear behaviors on the mating surface. The wear of the piston–cylinder interface first decreases along the film outlet to the inlet and then rises. The cylinder surface mainly exhibits abrasive, cavitation, and micro-convex scratch wear, whereas the piston surface mainly shows cavitation wear. The results obtained in this study are of considerable significance as they reveal the tribological properties of the piston–cylinder interface under the surface topography effect.

Improvement of the design of hydraulic transport devices for the transport of hydroabrasive media in the enrichment industry

Hydrotransport equipment of mining and processing plants has low operational reliability, insufficient service life due to intense hydroabrasive wear of the working surfaces of pipelines and pumping equipment, design flaws of some ground pump units and their operation. Significant hydroabrasive wear of the main structural element of the ground pump – impeller, causes additional disturbing dynamic forces, which leads to increased vibration of the unit and, therefore, to its premature failure. To date, insufficient attention has been paid to the impact of hydroabrasive wear of the impeller of ground pumps on the service life of their plants.The analysis of manifestation of cavitation wear of parts of the ground pump flow part is carried out, measures to reduce cavitation due to favorable conditions for the liquid flow into the pump and to reduce the vacuum gauge suction lift are outlined. A number of technological and constructive solutions are also proposed to reduce the harmful effects of cavitation.Materials for manufacturing parts of a centrifugal ground pump with high performance and service life are selected and analyzed. These alloys showed high corrosion resistance due to high chromium content.The ways of improving the design of centrifugal ground pump parts are outlined, which allows increasing the service life, creating an automated system for diagnosing the state of the structure as a whole

Influence of Applied CrN+WC/C and WC/C Coatings on the Cavitation Wear Processes of Constructional Elements

When designing the individual subassemblies of machines or entire devices one has to draw special attention to the resistance of the elements working there, to tribological damages (mechanical, fatigue, adhesion, abrasion, hydrogen and other damages) as well as to non-tribological damages (corrosion, diffusion, cavitation, erosion, ablation and others). The main purpose of this publication was to examine the influence of the applied CrN+WC/C and WC/C protective coating deposited by PVD (Physical Vapour Deposition) method on the cavitation wear processes of construction elements working in difficult cavitation environment. Two steels were selected for detailed examinations in the conditions of cavitation wear. The first one is P265GH steel commonly used for pressure devices working at elevated temperatures, with a ferritic – pearlitic structure, and the other derives from a group of stainless steels, i.e. chromium – nickel X2CrNi18-9 (304L) steel with an austenitic structure. The tests results obtained allow to conclude that the application of special low – friction protective coatings allows to reduce costs associated with selection of engineering materials for a substrate of constructional elements working in a cavitation wear environment. P265GH steel is 4.5 times cheaper than austenitic chromium – nickel X2CrNi18-9 (304L) steel, and if a CrN+WC/C and WC/C coating is deposited in this case, this considerably extends the working time of such elements in a cavitation environment.

Predicting the Cavitational Wear Resistance of Electrolytic Chromium Coatings

Test results are presented for the cavitational wear resistance of electrolytic chromium coatings and alloys used in the manufacture of cylinder blocks and bushing for diesel engines. A method is proposed for predicting the wear resistance by measuring the worn surface profile.

Mechanical and Functional Properties of Cavitation Generators with PVD Functional Coatings Intended for Use in the Cavitation Environment

The main purpose of this publication was to describe in details the correlation between microhardness and scratch test results of the tested coatings deposited by PVD (Physical Vapour Deposition) method on the cavitation generators working in cavitation environment. First coating in the form of composite layer CrN+WC/C and second WC/C plate coating were deposited on two selected steels which already are used or can be use on constructional elements working in a cavitation wear environment. Steel P265GH is commonly used for pressure devices working at elevated temperatures, with a ferritic – pearlitic structure, and the other tested steel from a group of stainless steels, i.e. chromium – nickel X2CrNi18-9 (304L) steel with an austenitic structure due to its corrosion resistance, it can also be used in these conditions. The tests results obtained allow to conclude composite CrN+WC/C coating exhibit better adhesion than WC/C plate coatings deposited on the both tested constructional steels. A critical load value for the CrN+WC/C coating spans between 29 and 34N and is 35-40% higher than for the plate WC/C coating.

Cavitation Wear of Basalt-Based Glass Ceramic.

This paper examines the possibility of using basalt-based glass ceramics for construction of structural parts of equipment in metallurgy and mining. An ultrasonic vibration method with a stationary sample pursuant to the ASTM G32 standard was used to evaluate the possibility of the glass ceramic samples application in such operating conditions. As the starting material for synthesis of samples, olivine–pyroxene basalt from the locality Vrelo–Kopaonik Mountain (Serbia) was used. In order to obtain pre-determined structure and properties of basalt-based glass ceramics, raw material preparation methods through the sample crushing, grinding, and mechanical activation processes have been examined together with sample synthesis by means of melting, casting, and thermal treatment applied for the samples concerned. The mass loss of samples in function of the cavitation time was monitored. Sample surface degradation level was quantified using the image analysis. During the test, changes in sample morphology were monitored by means of the scanning electronic microscopy method. The results showed that basalt-based glass ceramics are highly resistant to cavitation wear and can be used in similar exploitation conditions as a substitute for other metal materials.

Кавітаційно-ерозійна зносостійкість вуглецевих конструкційних сталей

In the paper, based on the analysis of literary sources and own researches of authors, the results of cavitation and erosion wear resistance of structural steels are systematized depending on their thermal processing (structure) and type of environment.The structural structure of steels is based on the analysis of wear resistance during cavitation and erosion fracture of surfaces, and the mechanisms of cavitation fracture of dodectoid, zavectotoid and perlite steels are considered.Destruction of dodectoid steels begins with ferrite, and then extends to perlite grains. The wear resistance of the pearlite grains of the plate-shaped form is higher than that of perlite of the granular form. Cavitation wear resistance of zeutectoid steels is determined mainly by the properties of perlite. The mechanical properties of which depend on the dispersion and shape of the particles of cementite.In perlite steels, reducing the size of its grain increases their erosion resistance, especially in the presence of cementite in the structure of the grid, and not ferrite grids.Using different types of thermal and thermocyclic heat treatment, it is possible to form appropriate structures and, accordingly, increase the cavitation and erosion wear resistance.

Powder plasma deposition as a method to increase the wear resistance and service life of steel machine parts

ABSTRACT The article considers one of the options for protecting the products surface from cavitation wear and hydroabrasive erosion using a modern high-tech method of high-energy plasma surfacing. Metallographic, X-ray analysis and mechanical tests were performed. Also, comparative tests of cavitation resistance of plasma-surfaced samples with powders of ПР-65Х25Г13Н3 and ПР Н77Х15С3Р2 grades were carried out. Analysis of the results showed that the surfacing material of the brand ПР-65Х25Г13Н3 has higher strength and plastic characteristics than the material of the brand ПР-Н77Х15С3Р2. Compared with the surfacing material of the brand ПР-65Х25П13Н3 (Кr = 1,17), this powder has a high coefficient of wear resistance (Кr = 2,77), which indicates an increased resistance of the material to abrasive wear (2,4 times). The welding is formed from these powders increases the cavitation resistance of the surface of the steel 10Х18Н12М3Л 1,2 and 3,4 times. Application of plasma powder surfacing methods in mechanical engineering allows to protect critical steel parts from cavitation and erosion wear and to extend their service life.

On the cavitation resistance of deep rolled surfaces of austenitic stainless steels

In the present work, two austenitic stainless steels (AISI 304 and AISI 316) were evaluated in cavitation tests with deep rolling treatments (DRT) on their surfaces. The results show that both steels exhibited better behaviour after the deformation process than in untreated conditions; however, the wear rate did not stabilize for the deformed surfaces due to the gradient of properties, attributed mainly to hardness profile of the material after DRT. A correlation between the cavitation erosion resistance and the fatigue strength is presented, with the cavitation wear rate and incubation time showing a good correlation with the fatigue strength coefficient in the case of high-cycle fatigue. In the case of low-cycle fatigue, a good correlation was established for the cavitation wear rate considering the Manson-Coffin theory of strain fatigue, assuming that the cavitation wear rate is inversely proportional to the fatigue life and using a fracture strain equal to the fatigue-ductility coefficient. In this case, a proportional constant around of 103 was found to establish the correlation for both steels. On the other hand, a linear correlation between the cumulative mass loss and surface roughness was separately established for steels under DRT conditions and untreated conditions. In addition, it was demonstrated that DRT is a great possible method for reducing the cost by wear.

Combined wear of slurry erosion, cavitation erosion, and corrosion on the simulated ship surface

The surface material of marine ship hulls suffers degradation by slurry erosion because of the impact of sands or solid particles in seawater. When the ship’s moving speed increases, pressure is changed suddenly and cavitation erosion will occur. Therefore, in the ocean, the corrosion of the surface material of the ship hulls is a combined damage in a slurry erosion and cavitation erosion states. An experimental device, for the combined wear, capable of simulating the above working conditions is designed and manufactured. A combined wear test of various materials (Q235, DH32, and NM360 steels) is conducted. The results show that cutting furrows of the slurry erosion, pinholes of the cavitation erosion, holes of electrochemical corrosion, and their combined effect increase the material wear rates and areas. Ductile materials of high strength have less slurry and cavitation damage, and more corrosion damage. For ductile materials of low strength, slurry and cavitation wear play an important role. When the slurry impact speed is increased, the wear degree of materials is also increased. This experimental setup for the combined wear provides a strong support for the development of wear-resistant materials for ship hulls and the structural optimization of ship hulls.

Outstanding cavitation erosion resistance of hydrophobic polydimethylsiloxane‐based polyurethane coatings

ABSTRACTCavitation erosion will create shock waves and water jets in turbulent flows. These impact pressures will affect the surface, which will lead to crack propagation and severe material degradation. In this study, we have developed hydrophobic polydimethylsiloxane‐based polyurethanes (Si‐PUx) with hydroxypropyl polydimethylsiloxane (H‐PDMS) and polytetramethylene glycol (PTMG) as mixed soft segments and 2,4‐tolylene diisocyanate, 1,4‐butanediol, triethanolamine as hard segments via a polycondensation reaction and studied its properties. The cavitation wear experiment showed that the cavitation erosion resistance of Si‐PUx coating continuously improved with the increase of H‐PDMS content, while the adhesion force of Si‐PUs reduced with the increasing of H‐PDMS content. The surface of Si‐PUx coating after cavitation test was observed using an optical microscope and three‐dimensional profiler. The cumulative mass loss of Si‐PUx with 12.5 wt % H‐PDMS was only 2.96 mg and the surface showed no obvious holes and cracks after 80 h cavitation. The results showed that cavitation resistance had a correlation with degree of water resistance, hardness, adhesion strength, and dynamic mechanical properties of coating. It seemed that the Si‐PUx coating could withstand a longer period cavitation erosion resistance compared to high strength epoxy, which could be used as protective coating for flow components under water. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 47668.

Problems of water lifting machine systems control in the republic of Uzbekistan with new innovation technology

The article presents the results of the study of the main categories of losses for the elements of irrigation systems, shows the experience of using pumping equipment on irrigation systems, discussed methods for increasing the volumetric efficiency, improving the hydraulic conditions for supplying flow to the impeller and reducing cavitation. The purpose of the research is the scientific substantiation of the usage of samples of modern pumps, in modern water-lifting systems in the context of import substitution programs with innovation technology. The results of the study of the main categories by irrigation system elements are presented, the experience of pumping equipment use on irrigation systems is described, the methods for increasing the volumetric efficiency, for improving the hydraulic conditions for supplying the flow to the impeller and reducing the cavitation wear are examined in the article. The complex solution of such problems as the increasing the efficiency of the pumping equipment was proposed, which allowed to increase the actual performance factor of the given pump from 83 to 88 %, compared to the factory data.