Abrasion Phenomena Research Articles

遊星ミル内媒体運動のＤＥＭシミュレーションによる摩耗粉発生の解析

In order to investigate the abrasion phenomena in a planetary ball mill, we conducted the grinding operation without a powder and sought a correlation between the ball abrasion and the ball impact energy estimated by a Discrete Elemental Method (DEM) simulation. Experimental results showed that the mass of abraded balls increased in proportion to the grinding time in the early stage of grinding up to 75min. The abrasion rate increases quadratically with the mill rotation speed. It decreases with an increase in ball diameter up to 12.7mm and then slightly increases when the diameter is 15.8mm. It also increases with an increase in the ball filling ratio of the mill up to 50%. Similar tendencies are found in the impact energy calculated from the balls motion simulated by DEM. Therefore, it is said that the abrasion rate has a strong correlation to the impact energy of balls under any milling conditions.

Abrasion phenomena in twill tencel fabric

AbstractThe abrasion characteristics of Tencel fabrics were evaluated by Martindale abrasion and laundering, and the breakdown mechanism of fibers was surveyed by scanning electron microscopy. The fabric was subjected to pad‐dry‐cure treatment with two different types of modified dimethyloldihydroxyethylene urea resins (Reaktant DH and Reaktant FC). Although the degree of dry abrasion varied with different resins, the damage exhibited by individual fibers differed little from untreated to resin‐treated; the major mechanism of abrasion was through friction, and the mechanism of fiber failure was multiple splitting and transverse cracking. In untreated Tencel, the characteristic feature of wet abrasion was massive fibrillation, and in crosslinked fabrics, the wet abrasion mechanism was through fiber slippage and slicing action, although in the Reaktant FC‐treated fabric, the wet abrasion mechanism was more through slicing than through fiber splitting. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1391–1398, 2006

Obtenção e caracterização de blendas de asfalto CAP 20, modificado com poliestireno reciclado, resíduos de pneu e lignina organossolve

O presente trabalho trata da obtenção e caracterização de blendas envolvendo matrizes asfálticas (CAP 20), em misturas com poliestireno reciclável (PS), pó de pneu (PPN) e lignina organossolve (LIG). Quando se adicionam polímeros à matriz asfáltica, pretende-se, principalmente, aumentar a impermeabilidade, impedindo a deterioração pela água, diminuir a fragilidade a baixas temperaturas e diminuir o desgaste por abrasão. As propriedades físicas, incluindo índice de penetração, ponto de amolecimento e índice de susceptibilidade térmica do CAP 20 modificado, foram analisadas e comparadas com o CAP 20 não modificado. Os resultados obtidos mostram que a adição de PPN, PS e LIG afeta as propriedades mecânicas das blendas formadas com o CAP 20, diminuindo os índices de penetração e aumentando os pontos de amolecimento de uma maneira geral.

Modified Taber apparatus and new test geometry to evaluate the reduction of organic coatings corrosion protective properties induced by abrasive particles

Organic coatings are one of the most common methods used in the protection from corrosion of industrial components. In many applications, the protective properties against corrosion are associated with several other properties, including resistance to abrasion and particle impacts. This is particularly important for the automotive and naval industry, and those applications that involve abrasive phenomena, such as presence of dust, sand or grains of hard material. The Taber test is among the most common tests to evaluate the abrasion resistance of coatings. In a previous work it was shown that electrochemical tests, after Taber Abraser standard test, allowed the evaluation of the decrease of corrosion protection properties. Nevertheless, assessment of the damage was carried out step by step, removing the samples from the abrading apparatus. The aim of this study is the evaluation of the possibility to measure in continuous, using electrochemical tests, the decrease of protection properties of an organic coating, caused by abrasion of artificial sand. A modification in the design of the standard Taber Abraser apparatus allowed the electrical contact between the substrate of the sample and the electrochemical equipment. Following the newly designed set-up, it is possible to evaluate the electrochemical properties of the system without removing the sample from the abrading system. A change of the geometry of the coated sample was also necessary, in order to build the cell. The latter contained the slurry made of a corrosion limited aggressive solution and the abrading sand. The impedance measurements were carried out without removing the coated samples from the Taber apparatus and using the abrading slurry as electrolyte. Useful information about the damage induced on the coated samples were recorded.

On the Anomaly of Cumulative Erosion and Abrasion-Time Curves

Abstract Erosion and abrasion-time curves of laboratory tests are of various forms. Most of these curves have a typical form, and are considered to be representative of erosion and abrasion phenomena. Other curves are considered anomalous; however, no definite explanations are offered for these irregularities. Analysis of the anomalous curves enables detection of the causes for these anomalies. The main causes detected for curve shape variation are: faulty test equipment, improper test procedure, variation in test specimen structure and properties, and wrong evaluation of test results.

Wear of Rice in an Abrasive Milling Operation, Part II: Prediction of Bulk Temperature Rise

The phenomenon of abrasion of rice grains during milling operations was analysed in Part I. This part includes modelling of the temperature rise and energy utilisation in an abrasion milling operation and its effect on milling quality of grain. Medium grain brown rice was milled in an abrasive polisher. The rise in the bulk temperature was modelled by energy balance, on the basis of abrasion wear theory. The head rice yield was correlated with the final temperature of the grain and was found to decrease steadily with increase in the bulk temperature of the grain. The developed model accurately predicted well the bulk temperature rise in the rice grains with milling time. Energy utilised for milling was found to be about 33%, whereas, about 10% of the energy was utilised to raise the temperature of the grains, and 55–60% of the total energy was utilised in running the machine in idle conditions.

A Study on Tactile Friction and Wear - Frictional Wears Characteristics of Human Fingers on Various Soft Materials

The tactile wear ("tezure" in Japanese) is an abrasion phenomenon caused by the contact of humans hand with the surfaces of materials over a long period of time. Though this phenomenon has been the focus of various articles, an extensive study with regard to the wear characteristics is of profound importance. To date, we have several remarkable examples such as the statue of Pindola Bharadvaja (Buddhist) and the St. Peter statue (Christian). Followers of the respective religions who are deeply attached and rooted have been touching the statues as part of their rituals for many generations over centuries. In this study, an attempt is done to verify the friction and wear characteristics of the human finger with various soft materials and woods.

A Study on Tactile Friction and Wear (2nd Report Frictional Wears Characteristics of Various Soft Metals by Contact of Human Fingers)

The tactile wear (“tezure” in Japanese) is an abrasion phenomenon of material surfaces caused by the contact of human hand over a long period of time. Though this phenomenon has been the focus of various articles, an extensive study with regard to the wear characteristics is of a profound importance. To date, we have several remarkable examples such as the statue of Pindola Bharadvaja (Buddhist) and the St. Peter statue (Christian). Followers of the respective religions who are deeply attached and rooted have been touching the statues as part of their rituals for many generations over centuries. In this study, an attempt is done to verify the friction and wear characteristics of various soft metals with contact of human finger. The results of our experiments show that the friction coefficient upon the contact of the human finger and pure copper are very high and thus proving tactile wear of soft metals can be generated easily.

Electron-beam excited plasma etching reactor with polyimide interface film

An electron-beam excited plasma reactor was developed, where an electron-beam was transmitted into the reactor through an interface film from the source. The interface film of polyimide was abraded during the electron-beam transmission and the interface material was deposited on a substrate in the reactor. The abrasion phenomena were studied experimentally by using Monte Carlo simulation of electron-beam transmission in the film. At the condition of minimized abrasion, stable etching of the Si wafer in CF 4 was realized under a negative bias condition.

Failure mechanisms of physically vapour deposited coated hardmetal cutting inserts in turning

Thin hard physical vapour deposition (PVD) coatings attribute excellent cutting performance to cemented carbide inserts, allowing a beneficial exploitation of modern CNC machine tools. Based on the continuous chip formation, coatings experience distinct failure mechanisms in turning. To clarify the influencing parameters on coating wear resistance release, turning experiments with TiAlN derived coatings, deposited on cemented carbide inserts have been carried out. At a variety of cutting speeds, the experimental results are explained through analytical ones obtained by means of finite elements method (FEM) calculations indicating a coating static decohesion at low cutting speeds, owing to its overstressing. On the other hand, at higher cutting speeds tribomechanical abrasive phenomena are dominant. Nevertheless, the cutting accomplishment of coated tools is impressive, in as much as even after the local initiation of coating failures the tool still exhibits adequate cutting reserves, continuing its severe service up to the end of its operational life due to abrasive flank wear. As the overall cutting length increases theoretical and experimental results show that a progressive local coating decomposition occurs while the cutting forces remain practically stable. Herewith chip formation alterations such as a gradual increase of the chip compression ratio and a consequent reduction of the tool contact stresses are induced.

Wear resistance of laser-clad Ni–Cr–B–Si alloy on aluminium alloy

Using a 5 kW CO 2 laser, two kinds of plasma-sprayed coatings, Ni–Cr–B–Si and Ni–Cr–B–Si+WC alloys, were remelted on aluminium alloy. The wear resistance of both laser-treated samples and plasma-sprayed samples were investigated using a pin-on-disc sliding friction wear tester. A scanning electron microscope (SEM) was used to analyse the abrasion phenomena of the samples and a transmission electron microscope (TEM) was used to study the microstructure of the laser-clad zone. Experimental results showed that the laser-clad samples had double the wear resistance of the plasma-sprayed samples, and that the laser-clad Ni–Cr–B–Si sample exhibited the highest wear resistance. The results of wear surface analysis showed that the microstructure of the alloyed layer of the laser-clad samples was quite compact and the surfaces were also very smooth, and there was less peeling phenomenon of the granules. The microstrucutre of the plasma-sprayed sample was rather loose and there were a lot of granular peelings left on the worn surface. A study of the microstructure showed extensive amorphous and ultra-crystalline structures in the laser-clad zone, to which the increase in hardness and wear resistance may be attributed.

Les traitements de surfaces appliqués aux moules et outils : une évolution permanente des performances

Moulding technology facilitates the production of components with complex designs. In France the turnover of the moulding industry doubles each ten years and the main sector of activity of this industry is polymer moulding, which accounts for 58 % of the total turnover. Because of fast tool wear caused by the severe conditions experienced during injection processes increased tool performance is needed. Methodical investigations show tool life limitations. Complementary industrial points of view indicate that tool life is often limited by surface wear phenomena (see annexes I and 2). Abrasion, corrosion and sticking phenomena can cause tool surface damage whilst mechanical stresses can induce fatigue and plastic deformations, Tool performance must be adapted to different solicitations on it's core volume and surface. Surface engineering sciences, numeric simulations and surface analyses are necessary to establish correct diagnostics which will allow for developments enabling a significant increase in tool life. Core material improvement and better surfaces treatments are also needed. New designs and new metallurgical choices could be industrialised to produce short series or prototypes. Surface phenomena should also be examined using a microscopic approach. A surface may be seen as the limit between solid and gas (see annexe 3). With careful observation of the surface from the outer limit to the inner undamaged metal structure one can identify several layers such as adsorption layers, oxide layers and brittle metal layers. An oxide layer whose growth rate and stability are dependent on thermodynamic conditions covers most metallic surfaces. Topographic analysis is a complementary approach to understanding surface phenomena such as sticking or seizure. Reflectivity and colour measurements can provide very efficient though indirect quantification of surface morphology and roughness (see annexe 4). Tribological tests confirm the relation between the coefficient of friction a surface and it's reflectivity. Numeric simulations can make tool design optimisation easier. New composite materials covered with metallic layers can be used to make moulds for the production of prototypes. The HIP (Hot Isostatic Pressure) technology is competitive for the production of moulds with complex designs. Aluminium moulds covered by protective layers are attractive for medium series. Specific developments of PVD processes are necessary to keep good adhesion at low temperature (150 °C). Recent progress in steel metallurgy offers improvements on machining, welding and mechanical resistance. Powder metallurgy, laser and plasma technologies are efficient means for restoring tools. Super alloys can solve glass moulding problems. In the case where several types of solicitations are present, coating properties complement core material properties. Thermal treatments and thermo-chemical treatments can improve resistance to thermal and mechanical fatigue. Thick metallic layers can offer efficient protection against corrosion. PVD coatings produce a large quantity of materials, which can offer good resistance to abrasion and oxidation or offer a low friction coefficient (see annexe 5). Multilayers can combine several of these properties. Specific surface finishing and recent process progress allow this technology to be carried out successfully. Multi-technological coatings are industrially used in the case of severe corrosion + abrasion or fatigue + abrasion.

Interpretation of PVD Coated Inserts Wear Phenomena in Turning

PVD coatings attribute excellent cutting performance to cemented carbide inserts. Based on the continuous chip formation, coatings experience distinct failure mechanisms in turning. To clarify the influencing parameters on coating wear resistance release, turning experiments with a TiAIN derived coating, deposited on cemented carbide inserts, have been carried out. The experimental results are explained through analytical ones obtained by means of FEM calculations, indicating a coating static decohesion at low cutting speeds, owing to its overstressing. At higher cutting speeds, a coating adhesion improvement was found out, whereas a further cutting speed increasing reveals the dominant influence of tribomechanical abrasive phenomena and adhesion release on the coating wear behavior. As the overall cutting length increases, a progressive local coating decomposition occurs. Herewith chip formation alterations are induced, such as a gradual increase of the chip compression ratio and a consequent reduction of the tool contact stresses.

Metrology conditions for thin layer activation in wear and corrosion studies

Thin Layer Activation (TLA) is an ion beam technique. This method consists of an accelerated ion bombardment of the surface of interest of a machine part subjected to wear. Radioactive tracers are created by nuclear reactions in a well defined volume of material. Loss of material owing to wear, corrosion or abrasion phenomena is characterized by monitoring the resulting changes in radioactivity. For the industrial application of this method, special attention has been paid during irradiation to the range of activated thickness, yields and activation homogeneity and to on-line radioactivity measurements. There are two basic methods for measuring the material loss by TLA technique. One of them is based on remanant radioactivity measurements using a previously obtained calibration curve. The second is based on measuring the increasing radioactivity in the lubricant due to suspended wear particles. In this paper, we have chosen to present some calibration curves for both proton and deuteron irradiation of Fe, Cr, Cu, Ti and Ni samples. Thickness ranges are indicated and intrinsic error checking and calculational procedures are also presented. The article ends with a review of some typical experiments involving running-in programme optimization and lubricants certifying procedures.

Fullerene C60 destruction under shear deformation and high pressure action

Fullerene C60 was subjected to shear deformation and high pressure (3.3 GPa) action. The products obtained can be divided into unchanged C60 and a black substance insoluble in benzene. The latter part increases with severity of shear deformation applied. The IR and Raman spectra of the transformed material lacked significant signals, giving evidence of the destruction of the C60 buckyball structure and formation of a phase closer to the amorphous system of sp2 and sp3 hybridized carbon atoms. Scratching and abrasion phenomena observed under SDHP action, must be attributed to the newly formed carbon phase and not to the initial C60 nature.

Microstructure and tribological properties of ZrO 2 ceramics

The effect of sliding velocity on the tribological properties of zirconia-based ceramics, two yttria partially stabilized zirconia and a zirconia-alurnina composite, slid against a high-purity, high-density alumina, were investigated using a pin-on-disc tribometer. The materials were tested at three different sliding velocities (0.3, 0.7 and 1.0 m s −1) with a normal load of 33.47 N and a distance travelled of 3000 m. Under the test conditions all the couples showed rather low values of the coefficient of friction. At 0.3 and 0.7 m s −1, the zirconia discs showed greater wear than the zirconia-alumina composite discs. Worn surface analysis, using a scanning electron microscope equipped with an energy dispersive X-ray attachment, showed that the wear mechanism is a complex process involving abrasive phenomena, brittle fracture, plastic deformation and zirconia transferred on to high-density alumina pins.

On the Material and the Tribology of Alumina-Alumina Couplings for Hip Joint Prostheses

The yearly sphericity deviation ranged from 0.03 mu to 3.7 mm in 48 retrieved implants with alumina--alumina bearing balls and cups. Excessive amounts of wear are predominantly design dependent or caused by malalignment. But the abrasion phenomena occurring in the cup centers and in the corresponding ball areas are related to unfavorable function zones. The influence of the lubricating gap geometry as studied in laboratory tests shows the form of sphericity deviations to be of decisive importance for wear and friction, if extended over small angles. Then, the contact stresses attributable to the actual effective curvatures of the bearing exceed the resistance to abrasion of the material under boundary lubrication conditions. There are remarkable differences between the early and actual material quality. Based on the state of knowledge of material aspects of wear criteria for the optimization of material and design, promising tolerable wear rates may be achieved.

Some solutions for the kinetics of combined fracture and abrasion breakage

A phenomenological description of autogenous breakage of ores is accomplished by considering the simultaneous occurrence of fracture- and abrasion-like processes. A general differential equation is derived and solved for the batch abrasion phenomenon with and without fracture breakage of lumps within a screen size interval. For short grinding times, that is, for less than 50% of breakage, pure abrasion produces an almost first-order disappearance of the top size class material. A strong increase in the kinetic of disappearance occurs when the larger lumps reduce to the lower sieve size of the interval. Approximate solutions for the complete batch and continuous steady-state equations are developed by using a first-order fracture and the limiting first-order abrasion kinetics. In accordance with experimental findings, non-normalized B values with regard to particle size and bimodal distributions of progeny fragments are predicted by the model.

Sclerometric characterization of nearly brittle materials

The abrasion of nearly brittle materials can be considered as a multipoint scratching and indenting process. Knowledge of flow morphologies around the abrasive protuberances, the determination of the energy dissipated during single-contact scratching experiments and the estimation of the forces acting on the abrasive particles are therefore essential for a better understanding of the wear and finishing processes based on abrasion phenomena. Experiments using linear and pendular sclerometers were conducted on various materials such as glass, ceramics, metals and polymers. The results described in the present paper show the effects of the geometry, the speed and the rheology on the abrasive process. The forces induced and the morphologies of the scratches are studied. The behaviour of the abrasive contact is in particular very nicely described by a critical transition from ductile to brittle abrasion which is analysed in detail for soda-lime glass. This transition is itself correlated with the dynamic hardness and the dynamic toughness of the tested materials. The results have a bearing on the prediction of the behaviour of nearly brittle materials when used as bulk materials or surface coatings in tribological applications dealing with abrasive wear.

地中内部ひずみ計測定結果の判定について

In case of landslide investigations, a confirmation of existing depth of slide surface is one of the most essential investigation. For the purpose of pipe-strain gauges are usually used in the most landslide areas in Japan. On the basis of these observational results, the existing depth of slide surface is definited and these data are presented for planning and designing landslide preventive works. However, recently we have been able to see many column diagrams of strain variation which have some unreasonable measured results of those pipe-strain gauges.Thereupon, on the basis of these observational examples, we carried out comparison between the measured results of these pipe-strain gauges and geological column, and measured results by inserting-type-strain meter, examination of the insulation resistance of the circuit including pipe-strain gauges and lead wires, and measurement of the resistance of each strain gauge. Further, we considered causes why such unseasonable column diagrams of strain variation were obtained.As a result of these examinations, the main causes of such unreasonable columns are as follows:1) Scratch or disconnection of lead wires and treatment parts of waterproof and dampproofing of strain gauges when inserting a pipe-strain gauge into a borehole or when pulling out a casing pipe from a borehole.2) Deteriorative phenomena of insulation resistance of lead wires and treatment parts of gauges for a long time.3) Abrasion phenomena of strain gauges from vinyl chloride pipe for long time.