A Study of Erosion Between Two Parallel Surfaces Oscillating at Close Proximity in Liquids

1967 ◽  
Vol 89 (3) ◽  
pp. 229-236 ◽  
Author(s):  
K. Endo ◽  
T. Okada ◽  
M. Nakashima
Keyword(s):  
Cavitation Erosion ◽  
Plane Surface ◽  
Surface Damage ◽  
Surface Layers ◽  
Fluid Films ◽  
Surface Shear ◽  
Close Proximity ◽  
Parallel Surfaces ◽  
Extent Of Damage ◽  
Bearing Alloy

A disk was vibrated in close proximity to a plane surface while submerged in either water or one of several oils. The specimens suffered surface damage either by subsurface fatigue or cavitation erosion. The type and extent of damage depends upon the thickness of the fluid films and the viscosity of the liquid. Specimens with bearing alloy surface layers showed cracks due to surface shear followed by flaking off of the bearing alloy.

The Effect of the EHD Pressure Spike on Rolling Bearing Fatigue

1987 ◽  
Vol 109 (3) ◽  
pp. 444-450 ◽  
Author(s):  
L. Houpert ◽  
E. Ioannides ◽  
J. C. Kuypers ◽  
J. Tripp
Keyword(s):  
Pressure Distribution ◽  
High Stress ◽  
Surface Damage ◽  
Rolling Bearing ◽  
Shear Stresses ◽  
Stress Concentrations ◽  
Surface Layers ◽  
Rolling Bearings ◽  
Life Model ◽  
Pressure Spike

A recently proposed fatigue life model for rolling bearings has been applied to the study of lifetime reduction under conditions conducive to microspalling. The presence of a spike in the EHD pressure distribution produces large shear stresses localized very close to the surface which may account for early failure. This paper describes a parametric study of the effect of such spikes. Accurate stress fields in the volume are calculated for simulated pressure spikes of different height, width and position relative to a Hertzian pressure distribution, as well as for different lubricant traction coefficients and film thicknesses. Despite the high stress concentrations in the surface layers, reductions in life predicted by the model are modest. Typically, the pressure spike may halve the life, with the implication that subsurface fatigue still dominates. In corroboration of this prediction, preliminary experimental work designed to reproduce microspalling conditions shows that microindents due to overrolling particles are a much more common form of surface damage than microspalling.

Analysis of Corrosion Resistance of Heat Exchanger Plates Made of AISI 316L Steel

2020 ◽  
Vol 405 ◽  
pp. 245-250
Author(s):  
Martin Juliš ◽  
Lenka Klakurková ◽  
Pavel Gejdoš
Keyword(s):  
Corrosion Resistance ◽  
Heat Exchanger ◽  
Chemical Composition ◽  
Surface Damage ◽  
Lower Amount ◽  
Aisi 316L ◽  
Velocity Flow ◽  
Close Proximity ◽  
316L Steel ◽  
Surface Damages

For the corrosion resistance analysis of the heat exchanger plates (made of AISI 316L steel) the samples with visible damage was delivered. The major part of the surface damages was located at the place of "close proximity" (or surface contact) of individual plates. Some of delivered samples showed an unequal layers of sediments, which indicating a different flow velocities of operating fluid through the plates. At locations of the upper part of the plates with no sedimentation (high velocity flow), the most surface damage was detected in "near contact" areas as well as outside. On the other hand, the area of the lower part of the plates, where the sediment deposition was massive (lowest velocity flow), was observed the smallest surface damage. The results of the chemical composition analyses showed a lower amount of molybdenum and a higher amount of phosphorus in case of all samples. The contents of the key elements necessary for the corrosion resistance (chromium and nickel) were only just above the lower limit of the prescribed chemical composition interval. For detailed study of surface damage, selected defects were observed and documented using scanning electron microscopy. Localized damage showed intercrystalline failure of material with typical surface morphology degraded as a result of cavitation damage under hydrodynamic stress.

scholarly journals INTENSIFICATION CAPACITY DEFENSIVE OF LAGENARIA SICERARIA (MOLINA) STANDLEY (CUCURBITACEAE) SENSITIVE ACCESSIONS TO INSECT PESTS BY THE PROVISION OF ORGANIC FERTILIZER

2020 ◽  
Vol 7 (3) ◽  
pp. 21-30
Author(s):  
K. G. ANZARA ◽  
B. B. N. GORE ◽  
B. N. D. Fouha ◽  
K. K. KOFFI ◽  
J-P BAUDOIN ◽  
...  
Keyword(s):  
Rural Women ◽  
Insect Pests ◽  
Organic Fertilizer ◽  
Insect Pest ◽  
Surface Damage ◽  
Organic Manure ◽  
Lagenaria Siceraria ◽  
Foliar Damage ◽  
The Difference ◽  
Extent Of Damage

Lagenaria siceraria (Molina) Standley is cultivated mainly for its oil-rich seeds and high nutrition value. It represents a potential source of additional income to rural women who are the main producers. However, production of L. siceraria is characterized by low yields, mainly due to beetle foliar damage. The evaluation of foliar damage on different accessions was based on Proportion of Damage Foliar (PDF) and Severity of Damage (SeDa). Of all accessions, only NI431 had were a proportion of leaves destroyed below 50%. Leaf surface damage for this accession was less than 25%. In contrast, NI227, NI219 and NI180 were characterized by more than 80% of the attacked leaves. In the following investigations, the effect of the organic manure based on beef droppings on the intensity of the foliar damage on NI431 and NI227 accessions was realized. The use of cattle droppings significantly reduced the number of leaves destroyed and the extent of damage in the NI227. Beef droppings also improved the yield of the plants of NI227. The difference in yield for NI227 between the two treatments (fertilized and unfertilized) was 33.53%. These results showed that it is possible to improve the productivity of NI227 through the use of organic manure. In contrast to NI227, Severity of the Damage was the same for both NI431 accession treatments (fertilized and unfertilized). This result showed that NI431 accession would be tolerant of insect pest and that this tolerance is related to genetic and non-nutritional factors of the soil.

scholarly journals CORROSION AND CAVITATION RESISTANCE IN SEAWATER OF CHROMIUM–NICKEL–MANGANESE HIGH-STRENGTH NITROGEN AUSTENITIC STEELS

2019 ◽  
Vol 62 (1) ◽  
pp. 49-56
Author(s):  
L. M. Kaputkina ◽  
A. G. Svyazhin ◽  
I. V. Smarygina ◽  
V. E. Kindop
Keyword(s):  
High Strength ◽  
Surface Damage ◽  
Ultrasonic Cavitation ◽  
Austenitic Steels ◽  
General Corrosion ◽  
Cavitation Resistance ◽  
Significant Damage ◽  
Stable Austenite ◽  
Extent Of Damage ◽  
Nickel Manganese

Corrosion and cavitation resistance in seawater of high-strength economically alloyed nitrogen chromium–nickel–manganese steels Cr19Mn10Ni6Mo2N and Cr19Mn10Ni6Mo2Cu2N is experimentally studied compared to chromium-nickel steels Cr18Ni9 and Cr18Ni9N. Tests for resistance to pitting corrosion were carried out according to the chemical method in the test solution 100 g/l FeCl3 ·6H2 O. Resistance to general corrosion was assessed by tests in synthetic seawater (3  %  NaCl). Test for cavitation resistance in seawater was performed using a research stand of high-intensity cavitation effects with the use of ultrasonic devices UIP 1000  hd Hielscher Ultrasonic in 3  %  NaCl solution in water at a frequency of 20 kHz, a power of 1000  W and amplitude of 25 microns for 8  –  36  hours. The extent of damage and change in the surface microhardness, change in the phase composition and mass of the samples were assessed after cavitation. It is shown that steels Cr19Mn10Ni6Mo2N and Cr19Mn10Ni6Mo2Cu2N are more susceptible to pitting in seawater and in solution of ferric chloride, and have the general corrosion rate lower than that of chromium-nickel steels type Cr18Ni9. It is shown that ultrasonic cavitation can not only lead to surface damage due to erosion, enhance local corrosion, but also to changes in their physico-mechanical properties by strain hardening and phase transformations. Steels Cr19Mn10Ni6Mo2N and Cr19Mn10Ni6Mo2Cu2N with thermally and mechanically stable austenite are more resistant to ultrasonic cavitation in the seawater in comparison with chromium-nickel steels, especially those with less strength and less resistant steel Cr18Ni9. So subjected to cavitation in the seawater for 36 hours, samples of chromium-nickel steels Cr18Ni9 and Cr18Ni9N had a significant change in their condition: significant damage (etching) and surface hardening, and there was formation of a small amount of martensite in steel Cr18Ni9. Samples of steels Cr19Mn10Ni6Mo2N and Cr19Mn10Ni6Mo2Cu2N had only minor changes in surface conditions and hardening of the surface layers.

scholarly journals Investigation on Ultrasonic Cavitation Erosion Behaviors of Al and Al-5Ti Alloys in the Distilled Water

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1631
Author(s):  
Jingtao Zhao ◽  
Zongming Jiang ◽  
Jingwen Zhu ◽  
Junjia Zhang ◽  
Yinglong Li
Keyword(s):  
Cavitation Erosion ◽  
Erosion Resistance ◽  
Surface Damage ◽  
Damage Mechanism ◽  
Ultrasonic Cavitation ◽  
Dislocation Slip ◽  
Distilled Water ◽  
New Device ◽  
Cavitation Erosion Resistance ◽  
Ultrasonic Cavitation Erosion

Al and Al-5Ti alloys were manufactured by an ultrasonic casting method with a new device, and their ultrasonic cavitation erosion behaviors of Al and Al-5Ti alloys in the distilled water were clarified. The damage mechanism was analyzed by macro photograph, scanning electronic micrograph and three-dimensional morphology, and the results demonstrate that Al-5Ti alloys have better cavitation erosion resistance than Al in terms of the mass loss and the surface damage. The deformation mechanism of Al and Al-5Ti alloys under cavitation erosion is mainly dislocation slip, and the Al3Ti phase enhances the cavitation erosion resistance of Al-5Ti alloys. In addition, the maximum depth of cavitation pits in the Al-5Ti sample is less than that in the Al sample for 31.3%.

Importance of harvesting system and variety for storage losses of sugar beet

2018 ◽  
pp. 474-484 ◽  
Author(s):  
Christa Hoffmann ◽  
Meik Engelhardt ◽  
Michael Gallmeier ◽  
Michael Gruber ◽  
Bernward Märländer
Keyword(s):  
Sugar Beet ◽  
Surface Damage ◽  
Invert Sugar ◽  
Root Tip ◽  
Storage Losses ◽  
Harvesting Systems ◽  
Optimal Setting ◽  
Considerable Impact ◽  
Extent Of Damage ◽  
The Impact

Damage resulting from harvest operations increases the storage losses of sugar beet. Because of different equipment, the kind and extent of damage may differ between harvesting systems. The objective of the study was to analyze (I) the impact of different harvesting systems and cleaning intensities on damages of sugar beet, and furthermore, (II) the effect of these damages on storage losses. In 2015 and 2016 at four sites, two sugar beet varieties were harvested with two six-row harvesters (axial rollers versus turbines for cleaning) using three cleaning intensities with three replicates in tracks of 200m length. Roots were stored in a climate container at 9°C for 5 and 12 weeks. The results show that the diameter of root tip breakage and surface damage increased with cleaning intensity. Marked differences occurred among varieties and sites. The factor analysis indicates that the extent of damage (root tip breakage, surface damage) had a considerable impact on the infestation with mold and rots, the accumulation of invert sugar and sugar losses after storage. However, the higher root tip breakage of beets harvested by harvester2 was accompanied by lower sugar losses than in harvester1 after 12weeks storage, in particular with the aggressive cleaning intensity. The marked impact of the cleaning intensity emphasizes the importance of the operator and of the optimal setting of the harvester for a good harvest quality and thus storability of sugar beet.

scholarly journals Effect of Thermal Treatment and Erosion Aggressiveness on Resistance of S235JR Steel to Cavitation and Slurry

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1456
Author(s):  
Alicja K. Krella ◽  
Dominika E. Zakrzewska ◽  
Marta H. Buszko ◽  
Artur Marchewicz
Keyword(s):  
Thermal Treatment ◽  
Mass Loss ◽  
Cavitation Erosion ◽  
Surface Damage ◽  
Strong Increase ◽  
Slurry Erosion ◽  
Erosion Processes ◽  
Significant Damage ◽  
Cavitation Tunnel ◽  
Deep Pits

S235JR steel is used in many applications, but its resistance to the erosion processes has been poorly studied. To investigate this resistance, cavitation, and slurry erosion tests were conducted. These tests were carried out at different erosion intensities, i.e., different flow rates in the cavitation tunnel with a system of barricades and different rotational speeds in the slurry pot. The steel was tested as-received and after thermal treatment at 930 °C, which lowered the hardness of the steel. To better understand the degradation processes, in addition to mass loss measurements, surface roughness and hardness were measured. Along with increasing erosion intensity, the mass loss increased as well. However, the nature of the increase in mass loss, as well as the effect of steel hardness on this mass loss, was different for each of the erosion processes. In the cavitation erosion tests, the mass loss increased linearly with the increase in flow velocity, while in the slurry tests this relationship was polynomial, indicating a strong increase in mass losses with an increase in rotational speed. Cavitation erosion resulted in stronger and deeper strain hardening than slurry. Surface damage from cavitation erosion tests was mainly deep pits, voids, and cracks during the slurry tests, while flaking was the most significant damage.

A Proposed Model of Boundary Lubrication by Synovial Fluid: Structuring of Boundary Water

1979 ◽  
Vol 101 (3) ◽  
pp. 185-192 ◽  
Author(s):  
W. H. Davis ◽  
S. L. Lee ◽  
L. Sokoloff
Keyword(s):  
Synovial Fluid ◽  
Boundary Lubrication ◽  
Hydration Shell ◽  
Check Valve ◽  
Surface Layers ◽  
Surface Shear ◽  
Hydration Shells ◽  
Proposed Model ◽  
Artificial Surfaces

On the basis of data obtained from in-vitro friction tests using both cartilage and widely differing artificial surfaces, a general model for boundary lubrication of joint cartilage by synovial fluid is presented. It postulates that one portion of the synovial lubricating glycoprotein (LGP) is adsorbed to the surface. Reduction in surface shear is accomplished by formation of hydration shells about the polar portions of the adsorbed LGP creating a thin layer of viscous structured water at the surface. Mutual electrostatic repulsion between charged polysaccharide moieties aids in separation of the adsorbed surface layers. The hydration shell also serves as a check valve to control the movement of water out of and into the cartilage matrix during motion.

Cavitation Erosion Resistance of Sputter-Deposited Cr3Si Film on Stainless Steel

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Shuyun Jiang ◽  
Hongqin Ding ◽  
Jiang Xu
Keyword(s):  
Electron Microscopy ◽  
Stainless Steel ◽  
Cavitation Erosion ◽  
Erosion Resistance ◽  
Surface Damage ◽  
304 Stainless Steel ◽  
Glow Discharge Plasma ◽  
Damage Degree ◽  
Average Grain Size ◽  
Cavitation Erosion Resistance

In this technical brief, a Cr3Si nanocrystalline film was deposited on 304 stainless steel (SS) substrate using a double glow discharge plasma technique. The film was characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy, nanohardness tester, and scratch tester. The as-deposited film with a thickness of 5 μm consisted of A15 structured Cr3Si phase with an average grain size of 8 nm. The hardness values of the film were determined to be 26 GPa, which was ten times greater than 304 SS. A self-designed ultrasonic vibration cavitation erosion apparatus was employed to evaluate the cavitation erosion resistance of the Cr3Si film. The results showed that after cavitation tests of 30 hrs, the erosion mass loss of the film was only 60% of that for 304 SS substrate. SEM observation of the erosion surfaces indicated that the surface damage degree of the Cr3Si film is significantly less than that of 304 SS.

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