Steel Ball Surface Research Articles

A study of the wear behavior of polymer–matrix composites containing discontinuous nanocrystalline alloy reinforcements

The tribological behavior of bakelite resin–matrix composites reinforced with nanocrystalline Al 6061 T6 particles produced by machining (grain size 70–500 nm) has been studied using block-on-ring and pin-on-disk tests. The polymer–matrix composite reinforced with nanostructured Al 6061 particles aged for 10 h [Al 6061 (3) 10 h] shows a wear reduction of around 60% with respect to the conventional microstructured reinforcement. Also it shows the lowest wear rates when compared with the nanostructured reinforcements aged for 5 h or 1 h, respectively. Friction coefficients and wear rates increased with increasing sliding speed and normal load. Under 10 N and 0.10 m s −1, Al 6061 (3) 10 h showed an initial friction and contact temperature increase and a very severe wear with material transfer to the steel ball surface. Increasing the steel–composite contact temperature to 100 °C (1 N; 0.05 m s −1) produced a one order of magnitude decrease both in friction and wear. Wear mechanisms for the polymer matrix and the aluminum reinforcement are discussed on the basis of SEM and EDS observations.

Friction-induced physical and chemical interactions among diamond-like carbon film, steel ball and water and/or oxygen molecules

Friction and wear behaviors of diamond-like carbon (DLC) film sliding against steel ball were investigated on a ball-on-disk test rig at different relative humidity (RH) in a nitrogen environment. The worn surface morphology of the steel ball was observed on a scanning electron microscope (SEM), while the chemical states of some typical elements on the worn surface of DLC film were investigated by means of X-ray photoelectron spectroscopy (XPS). The result showed that the DLC film recorded continuously increased friction coefficient and wear rate with increasing relative humidity from 5% to 100%. In dry nitrogen (RH < 5%), thick and compact transferred carbon-rich layer was observed covering on the worn surface of steel ball, while the chemical states of the original and worn film surface showed no obvious change. In humid nitrogen, distinct changes of the chemical states on the worn surface of DLC film took place, indicating that tribochemical reactions such as the oxidation of DLC film and the interactions between DLC film and steel ball were involved in the friction process. Therefore, it was proposed that the friction and wear behaviors of DLC film were dependent on the friction-induced physical and chemical interactions among DLC film, steel ball and water and/or oxygen molecules. The roles of environment in the friction and wear behaviors of DLC film were discussed in terms of the friction-induced physical and chemical interactions.

Experimental Study of Lubricant Film Thickness Behavior in the Vicinity of Real Asperities Passing through Lubricated Contact

This article presents an experimental study of the influence of real surface micro-geometry on the film thickness in a circular elastohydrodynamic (EHD) contact formed between a real, random, rough surface of steel ball and smooth glass disk. Phase shifting interferometry was used to measure in situ initial undeformed rough surface profiles, whereas thin film colorimetric interferometry provided accurate information about micro-EHD film thickness behavior over a wide range of rolling speeds. Two real roughness features were studied in detail—a 56-nm-high ridge and a 90-nm-deep groove, both transversely oriented to the direction of surface motion. It was shown that the ridge is heavily deformed in a loaded contact and its height increases with increasing rolling speed. The asperity tip film thickness behavior is quite similar to the contact average film thickness when the film thickness is higher than the undeformed ridge height. However, below this limit the film is thicker than what the EHD theory predicts. For the groove, a local reduction in film thickness at the leading edge was observed. When the groove is passing through the EHD conjunction, it maintains its undeformed shape. The behavior of both roughness features studied shows good agreement with previous experimental observations conducted using an artificially produced ridge and groove.

Determination of the Optimal Parameters for Freeform Surface Measurement and Data Processing in Reverse Engineering

One objective of this work is to determine the optimal combination of the probe diameter and grid distance for freeform surface measurement, and another is to determine the optimal parameters for the local Shepard interpolation. The optimal combination of the probe diameter and grid distance for freeform surface measurement was determined through a Taguchi matrix experiment. The smaller the probe diameter and grid distance, the better the accuracy of the surface normal based on the configured matrix experimental result. The optimal parameters, namely the exponent μ and the radius R, for the local Shepard interpolation were determined by using the minimisation method of the root-mean-square normalised error (RMSNE) between the measured data points and the theoretical data points on a standard steel ball surface. The optimal parameters determined were actually applied to the measurement of a freeform surface (mouse surface) on a coordinate measuring machine (CMM). The local Shepard interpolation method was used to interpolate 16 control points from 1054 measured data points. Bi-cubic Bezier- and B-spline surface CAD models were constructed through these interpolated control points.

環境に優しい潤滑油 オリーブ油とオレイン酸メチル分子内官能基の潤滑性に及ぼす影響

The lubrication characteristics of the olive oils, which are used as biodegradable lubricants, on the steel ball were examined on the viewpoint of their growing area and quality of the olive oil. The discoloration of virgin olive oil and the friction face and/or the friction force of the steel ball were found to be dependent on their growing area as well as pure olive oil. Property of the constituent metal constituents of steel ball on the air oxidation of methyl ester of oleic acid, which is major constituent fatty acid of olive oil and the lubrication characteristics of the resulting oxidation products, were investigated. The autoxidation of methyl oleate under the existence of each acetylacetonatos of Cr, Mn, Fe, Ni, Cu, and V was carried out by blowing dry air at 80°C. All the metal salts except V facilitated the oxidation. The metals employed affect the yields and the types of the products, i.e., hydroperoxide, hydroxide and epoxide whom the functional group exists for the center location of molecular chain. Friction test for ball bearing was conducted by using each oxidation product and parent methyl oleate. The surface of the steel ball was the abrasive wear condition by hydroperoxide. The hydroxide gave excellent lubrication characteristics by hydroxy group adsorbed on the surface of steel ball. Epoxide increased the coefficient of friction. Methyl linoleate, having two double bonds, provided the flatted frictional surface at the ball bearing, but it is easy to be oxidized. To sum up the major characteristics of the autoxidation products which affect friction surface of steel ball, the function groups of center position in molecular chain of methyl oleate are of most significance. It was found that double bond and hydroxyl function of α-position of double bond are effective under the boundary lubrication.

A method for testing lubricants under conditions of scuffing. Part II. The anti‐seizure action of lubricating oils

AbstractThis paper describes an investigation of lubricating oils under extreme‐pressure (EP) conditions in a specially modified four‐ball tester. A new test method developed at the Tribology Department of ITeE described in Part I of this paper was used. In this, during a test run, the applied load is increased continuously and the friction torque is measured. A sudden increase in the friction torque indicates the collapse of the lubricating film — where scuffing is initiated. The load at this moment is called the scuffing load. If the load is increased further, it is possible to observe scuffing propagation until seizure occurs, i.e., a defined, maximum friction torque is reached. Thus, scuffing is considered as a process leading to seizure.Using the method, tribological experiments were performed employing various lubricating oils consisting of viscosity‐index improvers and antiwear (AW) and extreme‐pressure (EP) additives added to a base oil. Mineral and synthetic base oils of different kinematic viscosities were used. The aim was to investigate the influence of such lubricants on scuffing initiation and propagation with the present methodology.In Part I it was shown that scuffing initiation depends strongly on the kinematic viscosity of the lubricant; the higher the viscosity, the greater the scuffing load. The presence of AW and EP additives in the lubricant increases the scuffing load significantly. It was also shown that the kinematic viscosity of the lubricant oils has no effect on scuffing propagation. However, scuffing propagation is significantly mitigated by AW and, to a greater extent, by EP additives. The results of surface analyses show the decisive nature of the chemical reactions of AW and EP additives with the steel ball surface under scuffing conditions, as well as the possible diffusion of sulphur and phosphorus. Chemical reactions and diffusion lead to the creation of an inorganic surface layer (probably iron sulphide), the good anti‐seizure properties of which limit scuffing propagation.

Pitting mechanism on lubricated surface of babbitt alloy/bearing steel pair under ac electric field

The mechanism of electrical pitting on the lubricated surface of babbitt alloy/steel pair is investigated, and the threshold condition to avoid the occurrence of electrical pitting is also established by using a static electrical pitting tester with high precision under the influence of ac electric field. According to the SEM micro-graph and EDS analysis are, the mechanism of electrical pitting is significantly influenced by the interface power and the oil film thickness. At the smaller oil film thickness, the eroded surface of babbitt alloy exhibits a concave crater with a few micro-porosity in the vicinity of center region with a plateau on its surrounding, especially at high supply current. The polished track can be observed at the plateau. A large amount of tin element transfers to the steel ball surface because the molten tin contacts the ball. At the higher oil film thickness, only a little amount of metal element transfers to each other. The major pitting area of the babbitt alloy is caused at the initial stage of the arc discharge. With increasing arc discharge time, the pitting area increases slowly, and finally reaches a saturated value. When the electrical pitting occurs, correlation formula for the electrical pitting area in terms of interface power and melting point of material has been established. It is found that the higher interface power and the lower melting point of material, the higher electrical pitting area. Two electrical pitting regimes are found, namely, pitting and no-pitting regimes. The boundary between the pitting and no-pitting regimes is called the threshold voltage. Correlation formula for the threshold voltage in terms of oil film thickness and melting point of material is derived.

The tribological behaviors of succinimide-modified lanthanum hydroxide nanoparticles blended with zinc dialkyldithiophosphate as additives in liquid paraffin

Lanthanum hydroxide nanoparticles modified with succinimide (coded as Succ-nano La) were prepared in laboratory. The tribological behavior of the synthesized nanoparticles blended with zinc dialkyldithiophosphate (ZDDP) as additives in liquid paraffin (LP) to a total concentration of 5 wt.% was investigated on a four-ball machine. The surface morphologies and elemental distributions of the worn steel ball surfaces were examined with scanning electron microscopy (SEM) and electron probe microanalysis (EPMA), respectively. The chemical states of some typical elements on the worn steel surfaces were analyzed with X-ray photoelectron spectroscopy (XPS). As a result, the best extreme pressure behavior was obtained at a weight fraction of 1:4 for Succ-nano La/ZDDP. The best antiwear ability was obtained at a weight fraction of 2:3 or 3:2 for Succ-nano La/ZDDP, which was accompanied by a parallel improvement in friction-reduction. Surface films consisting of La 2O 3, ZnO 2, sulfides, N-containing organic compounds and P-containing compounds were detected. The improvement in the friction-reduction and antiwear properties was attributed to these tribochemical products.

Lubricant Film Thickness in Rough Surface, Mixed Elastohydrodynamic Contact

A spacer layer imaging method has been employed to map lubricant film thickness in very thin film, rough surface, rolling elastohydrodynamic (EHD) contacts. A series of model roughnesses have been produced by depositing tiny ridges and bumps on a steel ball surface and the influence of these features on film thickness has been investigated at a range of rolling speeds. It has been shown that all the model surface features studied form speed-dependent, micro-EHD lubricating films, but the detailed shape and thickness of these films depends upon the geometry of the feature and the rolling speed. All model surface features also produce a net increase in mean film thickness, compared to the smooth surface, under operating conditions where the film thickness is less than the out-of-contact height of the surface feature studied. For a real, random, rough surface, however, mean film thickness is less than the smooth surface case. The film thickness mapping technique has also been used to measure the effective roughness of surfaces in lubricated contact. This shows that surfaces based on 2-D array of tiny circular bumps become rougher as the rolling speed and thus film thickness increases. However, real, rough surfaces appear to show a decrease of in-contact roughness with increasing rolling speed. [S0742-4787(00)01001-8]

Tribological performance and tribochemistry of nanocrystalline WC/amorphous diamond-like carbon composites

The tribological performance and tribochemistry of vacuum deposited nanocrystalline WC/amorphous diamond-like carbon (DLC) composite coatings were investigated. Coating chemistry was varied by regulation of carbon content between 30 and 90at.%. Deposition temperature was used to adjust the degree of β-WC crystallinity from near amorphous with 1–3nm sized grains to nanocrystalline with 5–10nm sized grains, which were embedded in unhydrogenated DLC matrix. The microstructure critically influenced both the hardness and tribological properties of WC/DLC composites. Coatings with poorly crystallized WC were softer (15GPa) and exhibited lower friction and higher wear rates in comparison to harder (26GPa) composites with larger WC nanocrystals. The hardness of WC/DLC composites was at least twice as high as the hardness of metal doped DLC coatings reported in the literature. Micro Raman and X-ray photoelectron analysis was performed on transfer films formed on the surface of steel balls in sliding against WC/DLC composites in humid air and dry nitrogen, which found both oxides and graphite carbon, providing self-lubrication. The high hardness and self-lubricating properties of WC composites resulted in low wear rates and friction coefficients of about 0.2. Relationships among coating chemistry, structure, hardness, friction, wear rates, as well as, tribofilm composition and structure are discussed.

Materials characterization and effect of purity and ion implantation on the friction and wear of sublimed fullerene films

In previous studies, sublimed C60-rich fullerene films on silicon, when slid against a 52100 steel ball under dry conditions, have exhibited low coefficient of friction (∼0.12). Films with different purities can be produced by sublimation at different substrate temperatures. In this paper, effects of purity of fullerene films and ion implantation of the films with Ar ions on the friction and wear properties of sublimed fullerene films are reported. C60-rich films (called here films with high purity) exhibit low macroscale friction. An increased amount of C70 and impurities in the fullerene film determined using Raman and Fourier transform infrared (FTIR), increases its coefficient of friction. Microscale friction measurements using friction force microscopy also exhibited similar trends. Low coefficient of friction of sublimed C60-rich films on silicon is probably due to the formation of a tenacious transfer film of C60 molecules on the mating 52100 steel ball surface. Based on scanning tunneling microscopy (STM), transmission electron microscopy (TEM), and high resolution TEM (HRTEM), we found that fullerene films primarily consisted of C60 molecules in a fcc lattice structure. Nanoindenter was used to measure hardness and elastic modulus of the as-deposited films. Ion-implantation with 1 × 1016 Ar+ cm−2 reduced macroscale friction down to about 0.10 from 0.12 with an increase in wear life by a factor of 4; however, doses of 5 × 1016 ions cm−2 gave three times higher friction and poorer wear life; higher doses disintegrated the C60 molecules. Based on STM, TEM, Raman, FTIR, and laser desorption Fourier-transform ion cyclotron resonance mass spectrometer (LD/FT/ICR) studies, we found that the ion implantation with a dose of 1 × 1016 Ar+ cm−2 resulted in smoothening of the fullerene film surface probably by compacting clusters, but without disintegrating the C60 molecules. However, a high dose of 5 × 1016 Ar+ cm−2 damaged the C60 molecules, converting it to an amorphous carbon. Nanoindentation studies show that ion implantation with a dose of 1 × 1016 Ar+ cm−2 resulted in an increase in the hardness from about 1.2 to 4.0 GPa and in elastic modulus from about 70 to 75 GPa and modified the elastic-plastic deformation behavior.

Effect of Surface Roughness on Contact Pressure of Static Seals : Effect of Tangential Force on Conical Inside-Seal Surface

The sealing characteristics between a turned surface of soft material such as copper and a smooth seal surface of a rigid steel ball in static contact were investigated. This seal surface received not only a normal force but also a tangential force. The following results were obtained from calculations using a model that considered surface roughness on a turned seal surface as a wedge-shaped asperity, and gas leakage tests. ( 1 ) The linear sealing load Pc/l decreased with a decrease in the conical half-angle θ of the conical inside-seal surface. In the case of a surface roughness of 8 μm, the value of Pc/l at θ=15° was about 0.4 times that at θ=60°. ( 2 )The recommended values of θ were in the range of 5° to 35°, and the Pc/l values corresponding to this range were predicted.

Fretting of polymer. (2nd report Direct observation of fretting phenomena)

Fretting damaged surfaces of PMMA (polymethyl methacrylate) and steel balls in contact are directly and microscopically observed by optical microscope for various level of normal load, amplitudes of steel balls and fretting frequencies. It is found that corrugation occurs on the surface of PMMA during fretting and it is closely related with the wear of steel balls. After the initiation of corrugation, two types of wear are observed in our experiments : (a) the steel ball continues to slide on PMMA and the wear debris of the steel ball is enveloped in the softened PMMA ; and (b) the steel ball adheres to the corrugation and the wear debris accumulates at the boundary of adhered area. To study the cause of corrugation, the distribution of temperature of the fretting surface is numerically analyzed by the nonlinear transient heat conduction equation with the heat generated by the dissipation of energy during fretting. As a result, the increase of temperature by the dissipation of energy is very little, and it may be attributed to the viscoelastic property of PMMA.

Thin Residual Films Between Steel-Mercury Surfaces

Several models for adsorbed films on metal surfaces have been proposed, such as monolayers and multilayers. For these films, the effect of solvent molecule is not sufficiently taken into consideration. In this study, a steel ball and mercury surfaces were used as electrodes, and the oil-film thickness between the electrodes was estimated by measuring the capacitance of the film. n-Hexane and n-hexadecane were used as solvents. The adsorbed film is a stearic acid n-hexane solution having a concentration of less than 10 mol·m−3 showed a thickness of three molecular layers of stearic acid. On the contrary, n-hexadecane solution gave about 2 × 10−7 m of thickness. Chain-matching effects were observed with n-hexadecane solutions of acids and alcohols. The acid and alcohol having a chain-length of C16 showed the highest thickness of adsorbed Film. The difference between carboxylic and hydroxy groups was also observed in their degree of chain-matching effects. Presented as an American Society of Lubrication Engi...

Study on the Scoring Resistance of Lubricating Oil in Four Ball Test : 2nd Report, Maximum Temperature on the Contact Surface

In this paper, first if was clarified how to evaluate the effect of heat transfer to ball-fixtures through steel ball surfaces on bulk temperature rises of steel balls in operation and then using the result an equation to calculate maximum contact surface temperature considering bulk temperature rises in operation was given. After the examination of experimental results obtained by a Shell type Four Ball Machine and calculated results, the following conclusions are deduced. The larger the contact surface area is, the greater the effect of bulk temperature rises of steel balls on maximum contact surface temperature becomes. Quantities of heat transferred to ball-fixtures amounted to 40 percent of supplied heat quantity in the case of stationary steel ball and as much as 70 percent in the case of rotating steel ball, and so in calculation of bulk temperature rise of steel ball in operation they cannot be ignored.