Pattern Abrasion Research Articles

215 低燃費タイヤ用シリカ配合ゴムのパターン摩耗特性に及ぼすシリカ充てん量及びすべり率の影響(OS13-4 機械要素とトライボロジー)

215 低燃費タイヤ用シリカ配合ゴムのパターン摩耗特性に及ぼすシリカ充てん量及びすべり率の影響(OS13-4 機械要素とトライボロジー)

Wet Sliding Abrasion of Natural Rubber Composites Filled with Carbon Black at Different Applied Loads

The wet sliding abrasion and abrasion behavior of carbon black (CB)-filled natural rubber (NR) composites were investigated using a Deutsche Industrie Normen (DIN) abrader and compared to their dry abrasion resistance. The results showed that water tended to lubricate the contact between the rubber and the abrader and thus the abrasion loss was reduced. At different applied loads, the abrasion mechanism of the filled vulcanizates was different. When the applied load was below the turning point, the rubber abrasion was mainly fatigue abrasion and the main factor to influence the abrasion was the dynamic loss factor tanδ of the rubber. When the applied load was above the turning point, the rubber abrasion was mainly pattern abrasion and the main factors to influence the abrasion were the mechanical properties, in particular tensile and tear strength.

Pattern abrasion of ultra-high molecular weight polyethylene: Microstructure reconstruction of worn surface

Abstract The friction and wear behavior of ultra-high molecular weight polyethylene (UHMWPE) sliding against bearing steel (AISI 52100) in a ring-on-block contact mode under the lubrication of aqueous solution of 3.5% NaCl was evaluated. The worn polymer surfaces were analyzed by means of three dimensional profiling, atomic force microscopy, Polarized Raman microanalysis, field emission scanning electron microscopy, and nanoindentation testing. It was found that unusual wavelike abrasion patterns were formed on the worn surface of UHMWPE under properly selected sliding conditions. In the presence of plowing effect, the molecular chains of UHMWPE and short-rod like microcrystalline grains of abrasion pattern were both further oriented along the plowing direction and became tiny and dense owing to microstructure reconstruction. Resultant microstructurally reconstructed worn surface of UHMWPE had a higher nanoindentation hardness and modulus as well as increased wear resistance.

Friction and Wear Behavior of Ultra-High Molecular Weight Polyethylene Sliding Against GCr15 Steel and Electroless Ni–P Alloy Coating Under the Lubrication of Seawater

The friction and wear behavior of ultra-high molecular weight polyethylene (UHMWPE) sliding against GCr15 steel and electroless Ni-P alloy coating under the lubrication of seawater was investigated and compared with that under dry sliding and lubrication of pure water and 3.5 wt.% NaCl solution, respectively. It was found that under the lubrication of aqueous medium, the friction and wear behavior of UHMWPE mainly depended on the corrosion of counterface and the lubricating effect of the medium. Because of serious corrosion of counterface by the medium, the wear rates of UHMWPE sliding against GCr15 under the lubrication of seawater and NaCl solution were much larger than that under other conditions, and such a kind of wear closely related to the corrosion of counterface can be reckoned as indirect corrosive wear. However, when sliding against corrosion-resistant Ni–P alloy under the lubrication of seawater, the lowest coefficient of friction and wear rate of UHMWPE were obtained, owing to superior lubricating effect of seawater. Moreover, periodic ripple patterns were observed on the worn surfaces of UHMWPE sliding against GCr15 under the lubrication of seawater and NaCl solution, which were ascribed to the intelligent reconstruction of surface microstructure of UHMWPE upon large plowing effect of the counterface asperities. Based on scanning electron microscopic (SEM) and three-dimensional (3D) profile analyses of the worn surfaces of UHMWPE, a stick–slip dynamic mechanism was proposed to illustrate the pattern abrasion of UHMWPE.

トライボロジー関連研究の最近の進歩「ゴムの摩擦・摩耗」の発展

In this article the development of rubber friction and wear research is reviewed. Friction and wear of rubber are very important for the automobile tires, belts, seals and rolls. The brief history of rubber tribology is summarized in a table.The friction force of rubber consists of adhesion term and deformation term. Therefore the frictional behaviors mainly related to the viscoelastic properties of rubber. The influence of surface texture on rubber friction is also discussed. The friction of silica-filled SBRs, and the relationship between μ-v characteristics and friction vibration are explained. The rubber wear, pattern abrasion mechanism, the influence of mechanical properties on the wear, the environmental effect of rubber wear, and the wear of silica-filled SBR are discussed.

Study on the formation of periodic ridges on the rubber surface by friction and wear monitoring

A rubber wheel was rubbed against a steel cylinder in order to investigate ridge formation in the course of pattern abrasion. Distribution maps of the coefficient of friction and worn surface profile along the circumference of the rubber wheel were made throughout the experiment by monitoring friction and wear during sliding. The coefficient of friction had a stripe-like variation with stripes translating parallel to each other in the contrary direction of rubber sliding. The worn surface profile, measured using a laser profile meter, had a stripe-like variation with stripes combining each other. The movement rate of ridges was calculated from the gradient of each stripe-like variation in the maps. The ridges remained until the steady state moved faster than the combined ridges before reaching the steady state. The difference between ridge movement rates was the source of the ridge combination phenomenon.

ゴムのパターン摩耗時のアブレージョンパターン成長機構に関する研究(OS9-2 摩擦・摩耗)

ゴムのパターン摩耗時のアブレージョンパターン成長機構に関する研究(OS9-2 摩擦・摩耗)

111 ゴムのパターン摩耗における摩擦面のモニタリング

111 ゴムのパターン摩耗における摩擦面のモニタリング

F-0204 ゴムのパターン摩耗における摩擦・摩耗モニタリング(S34-1 トライボロジー現象のその場観察)(S34 トライボロジー現象の新しい計測・観察法)

F-0204 ゴムのパターン摩耗における摩擦・摩耗モニタリング(S34-1 トライボロジー現象のその場観察)(S34 トライボロジー現象の新しい計測・観察法)

The Strain Generated on a Rubber Surface in the Course of Pattern Abrasion

Abstract The surface strain on a rubbing rubber surface was examined in the course of pattern abrasion. Rubbing experiments between the outermost surface of a rotating isoprene rubber wheel and a cylindrical lens were conducted. Observations of the contact area were made through the lens. Markers were put on the rubbing rubber surface to measure strain. The maximum strains at the inclined rubber surface between the ridges were from around 40% to 100%. In order to measure the strain at the crack-propagating area, a marker was put on the lower front part of the ridge. It was found that the strain necessary for crack propagation underneath the ridge was 750%, which was almost equivalent to its breaking strain, irrespective of the applied load. At that moment, newly generated crack surface was confirmed. However, no visible crack was observed through an optical microscope when the strain was measure at 200% to 400%.

Effect of Sliding Speeds on the Friction and Wear of Pattern Abrasion of Rubber

To investigate the effect of sliding speeds on the friction and wear of pattern abrasion of rubber, rubber wheel was rubbed against a plano-convex cylindrical lens at various sliding speeds from 1 to 1000mm/s. At low speeds less than 10mm/s the linear rate of wear and coefficient of friction increased with sliding speed. They were remained almost constant between sliding speeds of 10 and 100mm/s. Beyond sliding speeds of 100mm/s, the linear rate of wear decreased rapidly by a factor of 100. The same tendencies appeared with the coefficient of friction. At that time the rubber surface was covered with a sticky material.The variations in the spacing of patterns and the spacing of striations with the sliding speeds were also studied. The spacing of patterns and the spacing of striations increased with sliding speeds at low speeds less than 10mm/s. They were almost constant between sliding speeds of 10mm/s and 100mm/s. At sliding speeds higher than 100mm/s, the spacing of patterns rapidly decreased. At that time the striations were not observed since the sticky material covered the abraded rubber surface.The linear rate of wear, though discontinuous, was proportional to the third power of the pattern spacing at sliding speeds from 1 to 1000mm/s.

ゴムのパターン摩耗過程における摩擦力と接触面積の変化

In this study variation in the frictional force of rubber was examined at the initial stage of pattern abrasion. The abrasion patterns′ lengths on the contact surface were also investigated to deduce the frictional force per unit length of abrasion patterns.In the experiments, a rubber specimen was rubbed against a mating flat glass and the contact surface was observed through the mating glass. As a result, the contact area observed at the initial stage was decreased to reach a constant value after repeated sliding. At the initial stage many small abrasion patterns were observed. At the steady state of rubbing the size of individual abrasion pattern became larger and the number of abrasion patterns was reduced. The frictional force per unit length of abrasion patterns gradually increased with the prolonged sliding and then attained to a constant value. In the experiments examined the frictional forces were ranging from 0.3N/mm to 0.5N/mm. Therefore it is found that the cracks underneath the abrasion patterns are propagated by the frictional force.

Chemical Aspects Concerning the Friction and Abrasion of Rubber

Abstract The frictional force (fF) is proportional to the normal force; for rubber it is corrected by a factor involving the pressure and elasticity due to a change of the contact surface. During friction induced by a slider, fF fluctuates, which is conventionally explained by a stick-slip mechanics. However, the effect of the temperature and velocity on fF as well as the frequencies of vibration and pattern abrasion producing worn products of various size, are not studied using mechanical model. On the contrary, the author discusses here the chemical mechanism of stick-peeling based on a model involving pseudo crosslinks of multi-sizes. The frictional force (fF) is taken to be equal to the peeling force (fP), For adhesives, fP is proportional to the adhesion force (fA) affected by such rheological factors as the peeling velocity (v), the thickness (h), and the relaxation time (τ); fP = fA(τvh)0.5. Here, fA is proportional to the fraction of the pseudo link (ν) and the wetting energy (W) divided by the peeling distance, which is almost equal to the bond length (l) and fA is expressed as fA = (ν/N)2/3(W/l). ν is the number of links formed on the surface of the rubber, and is varied with the sizes of the links 4 (link A) and 16 (link B) and their relaxation times of 10−3.4 s (τA) and 10−1 s (τB). Also, for the frictional force (fF) the same equation is obtained when v and h are taken to be the velocity of the slider and the thickness of the rubber layer deformed by the slider, respectively. Friction produces two kinds of vibrations by the dissociation of links A and B; their frequencies are given by the reciprocal of τA and τB, respectively. Abrasion is caused by the scission of rubber chains connected with links A and B in the peeling process. The former abrasion yields powdery wear products by crazing, whereas in the latter the scission of chemical bonds of the energy (D) develops to give crest-shape tearing i.e. so-called pattern abrasion. The sizes of wear products are proportional to the relaxation distances corresponding to τA and τB. The resistance to abrasion of rubber is expressed by a ratio of the force at a break (fB) to fF, fB/fF = (ν/N)1/3(D/Wl2)(vτh)−0.5. Carbon black improves the abrasion resistance due to its reinforcing ability, and the resistance is enhanced by increasing the content, specific surface area and adhesion ability of carbon black. Their optimum values were also estimated theoretically.

Effect of ageing on strength and wear of tank track pad compounds

The effect of ageing on the strength and wear of natural rubber (NR), styrene-butadiene rubber (SBR), NR-SBR blends and hydrogenated nitrile rubber (HNBR) based tank track pad compounds has been investigated over a range of ageing temperatures and times. HNBR compounds show a stable ageing resistance at all the ageing temperatures (75–125 °C); the other compounds lose about 60%–90% of their original strength, indicating their unserviceability above 75 °C. The HNBR compound shows excellent abrasion resistance even after ageing at 125 °C for 72 h, and its abrasion resistance is about six to seven times higher than that of the other compounds. The results are explained on the basis of relative thermo-oxidative degradation resistance. Microscopic investigation of the abraded surface of HNBR shows only scratch marks, indicating abrasive wear as the principal mechanism of wear, while the other compounds undergo wear by a pattern abrasion mechanism. Abradability is related to the reciprocal of breaking energy.

Friction and wear of short-fibre-reinforced rubber composites under various sliding speeds and loads

Friction and wear properties of short-fibre-reinforced chloroprene rubber composites were examined in the longitudinal (L), transverse (T) and normal (N) directions of the oriented polyamide fibres. The experiments were conducted for various sliding speeds of rubbing against abrasive papers. The rubbing experiments were also conducted under various loads, using both metal gauze and abrasive paper. When rubbed against abrasive paper and metal gauze, the wear rates of the short-fibre-reinforced rubber (SFRR) composites were lower than those of the unreinforced chloroprene rubber. A marked difference in the wear rates for these two specimens was observed when each was rubbed against metal gauze. A considerable difference was also observed when each was rubbed against abrasive paper. The minimum wear rates were obtained for rubbing in the N direction of the SFRR under the conditions examined. The maximum wear rates were observed for rubbing in the T direction. The wear rate for rubbing in the L direction exhibited medium values. The load dependence of the wear rates was greater for the SFRR than for the unreinforced rubber when rubbed against metal gauze. However, the load dependence of the wear rates for the SFRR was similar to that for the unreinforced rubber when rubbed against coarse abrasive paper. With decreasing load, the wear states of the unreinforced rubber rubbed against metal gauze changed from pattern abrasion to milder wear that arose from the hardening of the rubber surface. The speed dependence of the wear rate and frictional coefficient was very small for rubbing against coarse abrasive paper. When rubbed against fine abrasive paper, the variation of the friction with sliding speed was observed to be peak-shaped for the SFRR rubbed in both the N and L directions. The peak of friction was manifested by the transfer of rubber to the mated abrasive paper. Following the transfer of rubber, the wear rate decreased. Abrasion patterns were observed only for the unreinforced rubber rubbed against fine abrasive paper. The spacing of the patterns became wider with decreasing sliding speeds.

Pattern abrasion mechanism of rubber

To investigate the mechanisms of the pattern abrasion of rubber, the wear processes of an isoprene rubber were examined. After repeated rubbing, small ridges initially appeared on the surface of the rubber. They increased in size as the cracks lengthened at the lower front of the ridges. Propagating crack marks, i.e. striations, were observed on the rubber surface. Initially, the crack propagated downwards at the bottom of the ridge to form a low slope about 14° downwards into the rubber surface. As the tongue grew, the crack tended to direct itself upwards to form a loose wear particle. Thus growth and detachment of the tongue occurred repeatedly. Therefore the whole propagating distance to make a wear particle was more than twice that of the low slope, because the upward-propagating distance seemed to be longer than the distance of the low slope. It was found that the wear rate of rubber was affected not only by the crack propagation rate along the low slope but also by the crack propagation rate which occurred as it moved upwards.

Pattern Abrasion and Other Mechanisms of Wear of Tank Track Pads

Abstract Wear of tank track pads has been studied under different conditions. With T142 pads tested on an M-60 tank, the mode of failure was found to depend on the test conditions. Among eighteen experimental compounds tested, improved wear (vs. the standard compound) under one test condition was generally at the expense of poorer wear under one or both of the other test conditions. However, in agreement with previous results, an HNBR/Zn-methacrylate/peroxide compound gave improved wear rate under all three test conditions. Wear of the T142 pads on a hilly cross-country course and on a combination course was generally by massive chunking. On a paved road course, most compounds wore by pattern abrasion. A few compounds worn on this course formed deep pockets parallel to the surface, resulting in the eventual loss of the large flaps between the pocket and the surface. Pattern abrasion was also found on T156 pads of four different compounds, tested on an M-1 tank on the paved road course. The abrasion patterns of both types of pads had a shingled appearance, with the ridges pitched so as to bite into the road surface. The abrasion patterns were characterized quantitatively by profilometry, using standard parameters calculated for surface roughness of metals and other materials. The ridge height and its ratio to ridge spacing correlated positively with wear rate on the paved road; whereas there was no correlation of ridge spacing with wear rate. The compounds which gave the lowest wear rate on the paved road, including the HNBR compounds, gave shallow ridges with little or no pattern.

Friction and Abrasion of Rubber

Abstract Experimental evidence is adduced for the view that rubber friction is similar in character to viscous flow and therefore, in contrast to solid friction, not necessarily accompanied by abrasion. This theory implies that the forces of rubber friction are proportional to the true area of contact. The true area of contact is determined by elastic deformation of the asperities on the rubber surface, with the result that Amontons' law is not obeyed by rubber. The laws of rubber friction are deduced from simple models and satisfactorily confirmed by experiment. Abrasion of rubber is due to mechanical failure under the tractive stresses produced frictionally by the asperities of the track. In this process, certain periodic structures are often created on abraded rubber which have been called “Abrasion Patterns”. Abrasion patterns are found to increase the rate of abrasion; a distinction is therefore made between “Intrinsic Abrasion”, occurring in the absence of patterns, and “Pattern Abrasion”. Both types of abrasion are treated theoretically, and qualitative agreement with the experimental results is obtained. The phenomenon of pattern abrasion has the important consequence that the relative abrasion rating of any two compounds can depend pronouncedly on the conditions of the test.

Friction and abrasion of rubber

Experimental evidence is adduced for the view that rubber friction is similar in character to viscous flow and therefore, in contrast to solid friction, not necessarily accompanied by abrasion. This theory implies that the forces of rubber friction are proportional to the true area of contact. The true area of contact is determined by elastic deformation of the asperities on the rubber surface, with the result that Amontons' law is not obeyed by rubber. The laws of rubber friction are deduced from simple models and satisfactorily confirmed by experiment. Abrasion of rubber is due to mechanical failure under the tractive stresses produced frictionally by the asperities of the track. In this process, certain periodic structures are often created on abraded rubber which have been called “Abrasion Patterns”. Abrasion patterns are found to increase the rate of abrasion; a distinction is therefore made between “Intrinsic Abrasion”, occurring in the absence of patterns, and “Pattern Abrasion”. Both types of abrasion are treated theoretically, and qualitative agreement with the experimental results is obtained. The phenomenon of pattern abrasion has the important consequence that the relative abrasion rating of any two compounds can depend pronouncedly on the conditions of the test.