Abstract:Experiments of cavitation erosion are performed on a surface using the "stationary specimen method". A small diameter horn of 5 mm is selected instead of using the standard horn of 15.9 mm. The experiments are performed according to these parameters: an excitation frequency of the horn of 20 kHz, a gap between the horn and the specimen within the range from 0.05 to 0.5 mm and the displacement amplitude of the horn within a range of 15-50 μm. After examination of the samples, two erosion patterns can be clearly… Show more
“…Nevertheless, cavitating bubble clouds are essential for ultrasound material erosion in high intensity sonicated environments [38,39] As the numerical results show in Figure 6, high pressures induced by bubble collapse are not spread uniformly everywhere on the surface of specimen, but are concentrated at localized points. This agrees with [40] where severe cavitation was identified in specific areas across the specimen and not across the entire surface. The cavitation impacts start from the periphery of the sample and then, progress towards the center, which agrees well with the experimental findings in Figure 5.…”
Section: In-flight Particle Temperature and Velocitysupporting
Hydraulic components are coated by thermal spraying to protect them against cavitation erosion. These coatings are built up by successive deposition of single splats. The behavior of a single splat under mechanical loading is still very vaguely understood. Yttria-stabilized zirconia (YSZ) and stainless-steel splats were obtained by plasma spraying onto stainless steel substrates. The velocity and temperature of particles upon impact were measured and the samples were subsequently exposed to cavitation erosion tests. An acoustic cavitation simulation estimated the water jet velocity and hammer stresses exerted by bubble collapse on the surface of the specimen. Although the results suggested that high stress levels resulted from cavitation loading, it was clear that weak adhesion interfaces played a crucial role in the accelerated cavitation-induced degradation.
“…Nevertheless, cavitating bubble clouds are essential for ultrasound material erosion in high intensity sonicated environments [38,39] As the numerical results show in Figure 6, high pressures induced by bubble collapse are not spread uniformly everywhere on the surface of specimen, but are concentrated at localized points. This agrees with [40] where severe cavitation was identified in specific areas across the specimen and not across the entire surface. The cavitation impacts start from the periphery of the sample and then, progress towards the center, which agrees well with the experimental findings in Figure 5.…”
Section: In-flight Particle Temperature and Velocitysupporting
Hydraulic components are coated by thermal spraying to protect them against cavitation erosion. These coatings are built up by successive deposition of single splats. The behavior of a single splat under mechanical loading is still very vaguely understood. Yttria-stabilized zirconia (YSZ) and stainless-steel splats were obtained by plasma spraying onto stainless steel substrates. The velocity and temperature of particles upon impact were measured and the samples were subsequently exposed to cavitation erosion tests. An acoustic cavitation simulation estimated the water jet velocity and hammer stresses exerted by bubble collapse on the surface of the specimen. Although the results suggested that high stress levels resulted from cavitation loading, it was clear that weak adhesion interfaces played a crucial role in the accelerated cavitation-induced degradation.
“…The displacement of concrete in the three-dimensional space is approximately symmetrical via a radial distribution. This displacement implies the pressures induced by a bubble collapse are not spread uniformly everywhere on the surface of the specimen, which agrees with previous results [49] . Fig.…”
Cavitation damage is a micro, high-speed, multi-phase complex phenomenon caused by the near-wall bubble group collapse. The current numerical simulation method of cavitation mainly focuses on the collapse impact of a single cavitation bubble. The large-scale simulation of the cavitation bubble group collapse is difficult to perform and has not been studied, to the best of our knowledge. In this study, the equivalent model of impact loading of acoustic bubble collapse micro-jets is proposed to study the cavitation erosion damage of materials. Based on the theory of the micro-jet and the water hammer effect of the liquid–solid impact, an equivalent model of impact loading of a single acoustic bubble collapse micro-jet is established under the principle of deformation equivalence. Since the acoustic bubbles can be considered uniformly distributed in a small enough area, an equivalent model of impact loading of multiple acoustic bubble collapse micro-jets in a micro-segment can be derived based on the equivalent results of impact loading of a single acoustic bubble collapse micro-jet. In fact, the equivalent methods of cavitation damage loading for single and multiple near-wall acoustic bubble collapse micro-jets are formed. The verification results show the law of cavitation deformation of concrete using equivalent loading is consistent with that of a micro-jet simulation, and the average relative errors and the mean square errors are insignificant. The equivalent method of impact loading proposed in this paper has high accuracy and can greatly improve the calculation efficiency, which provides technical support for numerical simulation of concrete cavitation.
“…The experimental methodology used for the cavitation-erosion testing is explained in 7,10,16,17 . With respect to the used equipment, the diameter of the horn was 10 mm and the distance between the horn and a sample was 1 mm.…”
Section: Cavitation-erosion Testingmentioning
confidence: 99%
“…Research results concerning the applications of different classes of materials, including ceramics and composite materials for a similar use, were published in the last decade. [1][2][3][4][5][6][7][8][9][10] Different types of ceramics based on silicon nitride and zirconia, as well as alumina-based ceramic materials were investigated in the conditions of cavitation erosion. 2,[4][5][6][7][8][9] In numerous papers [1][2][3][4][5][6][7][8][9][10][11][12] related to the investigations of the erosion rate of these materials, attempts were made to investigate the type of cracking as well as the influence of the grain sizes and the contents of different compounds and phases on the resistance of the materials to the erosive wear.…”
A cordierite/SiC composite was created in situ with reactive sintering at 1250°C and 1300°C. The cordierite precursor was made from commercially available spinel, alumina and quartz and was mixed with the comercial SiC powder to obtain composite materials during the sintering. It was found that cordierite particles bind efficiently with the SiC powder during sintering and that reactive sintering is an effective way to produce ceramics at a relativly low temperature. The goal of this investigation was to check the possibilities of using the silicon carbide-cordierite composite as a material resistant to the erosive wear. The fluid dynamic system of the experimental methodology was used here to produce ultrasonic erosive wear. Two kinds of SiC/cordierite samples were investigated, KS 50 and KS 30, with different mass contents of cordierite (w = 50 % and w = 30 % of cordierite). The mass loss and the level of surface degradation were measured before and during the experiment. The level of surface degradation of the samples was monitored using the Image-Pro Plus program for the image analysis. It was found that after 150 min the mass loss was below 1.3 mg and the surface degradation was below 7 %. The obtained results indicated that both samples exhibited an excellent erosion resistance during the cavitation experiment. Keywords: ceramic-matrix composites (CMCs), damage tolerance, non-destructive testing, cavitation-erosion diameter and area Kompozit kordierit-SiC je bil izdelan in-situ z reakcijskim sintranjem pri 1250°C in 1300°C. Kordieritna predoblika, izdelana iz komercialno dostopnega {pinela, aluminijevega oksida in kremena, je bila zme{ana s prahom komercialnega SiC, da bi dobili s sintranjem kompozitni material. Ugotovljeno je, da delci kordierita u~inkovito ve`ejo SiC-prah med sintranjem in da je reakcijsko sintranje u~inkovita metoda za izdelavo keramike pri relativno nizki temperaturi. Cilj te raziskave je preveriti mo`nost uporabe SiC-kordieritnega materiala, odpornega proti obrabi z erozijo. Za ultrazvo~no erozijsko obrabo je bila uporabljena eksperimentalna metoda fluidnega dinami~nega sistema. Preiskovani sta bili dve vrsti vzorcev SiC-kordierit, KS 50 in KS 30, z razli~nima masnima vsebnostima kordierita (w = 50 % in w = 30 % kordierita). Masni dele`obrabe povr{ine je bil izmerjen pred preizkusom in po njem. Stopnja degradacije povr{ine vzorcev je bila ugotovljena s programom za analizo slik Image Pro Plus. Ugotovljeno je bilo, da je bila izgube mase po 150 min manj{a od 1,3 mg in degradacija povr{ine manj{a od 7 %. Dobljeni rezultati ka`ejo, da imata med preizkusom kavitacije oba vzorca odli~no odpornost proti eroziji. Klju~ne besede: kompozit s kerami~no osnovo (CMCs), toleranca po{kodb, neporu{ne preiskave, premer in povr{ina erozije pri kavitaciji
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