Specific Wear Amount Research Articles

Effect of Counterbody on Friction and Wear Properties of Copper-MgP-Graphite Composites Prepared by Powder Metallurgy

The purpose of this study was to investigate the influence of different counterbodies against Cu/magnesium phosphate treated graphite (Cu-MgPG) composite materials to find the best material combination in terms of friction coefficient and specific wear amount. A Cu matrix composite reinforced with 10 vol% magnesium phosphate treated graphite and pure Cu powder were prepared by powder metallurgy techniques under the same consolidation processing condition. The friction and wear properties of the composites were investigated at 10 N using a pin-on-disc tribometer on Al2O3, SiC and SUJ2 bearing steel counterbodies. The Cu-MgPG/Al2O3 pair showed the lowest friction coefficient, but the specific wear rate tended to increase slightly when compared with Cu/Al2O3 pair. On the other hands, the Cu-MgPG/SUJ2 pair showed about the same specific wear rate as the Cu/SUJ2 pair, but the friction coefficient was significantly reduced. These phenomena are thought to be due to the fact that the added graphite acts as a solid lubricant during sliding and also suppresses the oxidation behavior of the sliding material.

Tribological and electrical properties of C/C composites with bacterial cellulose

Bacterial cellulose (BC) synthesized by Acetobacter xylinum is one of the nano fiber materials. In this paper, the aggregation and dispersion behavior of C/C composite made with the BC and copper powders as a third constituent were considered. It is found that BC microfibril network can set copper powders into fine dispersion in the mBC-C/C composite. The tribological and electrical properties of Cu/mBC-C/C composite containing copper powder were also evaluated. From the experimental results, the mean value of the specific wear amount was at 10-9 order, the dynamic friction coefficient was about 0.2 and the electrical resistivity was at 10-4 order. Furthermore, the wear properties got worse due to the large amount of copper powder and the improvement in electrical conductivity was not enough. It is considered that it is necessary to find the optimum content of copper powder for the improvement of electrical conductivity in order to use for the conduction/friction material, for instance, brush for the DC motor.

Combined plasma carburizing and nitriding of sprayed AISI 316L steel coating for improved wear resistance

Both low-temperature plasma nitriding and carburizing at treatment temperatures below 450°C are known to increase the surface hardness of a sprayed AISI 316L stainless steel coating to above 1000HV, while maintaining corrosion resistance, via production of a supersaturated solid solution of expanded austenite, known as the S-phase. In this work, we investigate combined plasma processes for nitriding and carburizing of sprayed AISI 316L coatings. The sequential process, with carburizing first, immediately followed by nitriding, did not produce a significantly thicker S-phase than that produced using plasma nitriding alone. In contrast, the simultaneous process, in which carburizing and nitriding were performed at the same time, was found to form a thick S-phase at 450°C. Vickers hardness and specific wear amount were improved considerably by both combined plasma processes. In addition, the thickness of the diffusion layers formed on the sprayed 316L coatings was inferior to that of the corresponding diffusion layers formed on AISI 316L steel plates; this was because the sprayed 316L coatings included oxide layers.

S115022 すべり軸受材料の潤滑摩耗形態図の構築([S11502]トライボロジーの基礎と応用(2))

It is one of the main subjects in tribology to systematize the wear theory. It is necessary to know the various wear mode caused under the given condition by clarifying the various wear mechanisms. Various wear mode diagrams have been proposed. However, the wear mode diagram under the lubricated condition is not enough. In the present work, the construction of the lubricated wear mode diagram is tried to predict and to diagnose the wear properties of sliding bearing material used in the lubricated condition. The sliding wear tests of WJ2 were carried out using a block-on-ring apparatus with wide range of experimental conditions. A counter material was SF540 carbon steel. In order to classify wear modes, we investigated the relations among friction coefficient, worn surface, wear debris, specific wear amount of WJ2 and the minimum oil film thickness which were calculated from the EHL theory. The worn surface and the wear debris were observed using an optical microscope and a scanning electron microscope (SEM). As a result, the wear mode of WJ2 was newly classified into three types of large-scale adhesive wear, small-scale adhesive wear and fatigue wear using the experimental results. The availability of the wear mode diagram constructed in this way can be proved by a lot of experimental results tested over wide range of experimental conditions.

자동차 윤활기유의 비마모량에 관한 실험적 연구

본 논문은 자동차의 엔진오일에 사용되는 여러 윤활기유에 대하여 비마모 특성을 실험적 연구에 의해 분석하였다. 비마모량 점도와 온도 등과 같은 여러 가지 속도 조건 하에서의 마찰력과 측정된 수직하증으로부터 계산되었다. 엔진오일에 사용되는 기유는 여러 가지 작동 상태에 따라 마찰 특성의 관계가 확인되었다. This paper have been analyzed specific wear characteristics of various base oils used in the automobile engine by experimental study. Specific wear amount has been calculated by the measured normal force and friction force under various speed operating conditions, such as, viscosities and temperatures. It have been verified that the specific wear characteristics relation of the base oil used in a engine oil is related to the various operating conditions.

Study on the prediction technique of the wear amount of polyoxymethylene

AbstractThe influence of the sliding velocity and atmospheric temperature on the specific wear amount of polyoxymethylene was evaluated with the ring‐on‐ring apparatus. The specific wear amount showed the variation of S‐character type with maximum value, according to the change in the sliding velocity and the atmospheric temperature. When those results are plotted according to the sliding surface temperature, they have been found to be arranged as the same dependence. The specific wear amount of polyoxymethylene was assumed to be proportional to the product of actual contact area and reciprocal of the fracture energy. Then, the temperature dependency of the product of the fracture energy, calculated from stress–strain curve, and the actual contact area, calculated from Hertz's equation with elastic modulus, was able to explain the sliding surface temperature dependency of the specific wear amount well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4212–4218, 2006

In vitro wear behaviour of different ceramic couplings

The overall objective of this study is to introduce a wear map of ceramics which shows the regions of dominant wear modes observed in a wide range of materials and operating conditions. Furthermore, from the wear map, common necessary conditions for the application of various ceramics as wear-resistant tribo-materials in a wide range of operating conditions are discussed. For this purpose, friction and wear tests are carried out using three kinds of ceramics sliding against themselves under various contact pressures, sliding velocities and temperatures. Sliding wear phenomena of ceramics observed in all tests can be classified into two types: “mild wear” and “severe wear”, based on the ration of worn surface roughness Rx to the mean grain size Dg. The specific wear amount is always less than 10−16 mm3 (Nm) −1 when the worn surface roughness becomes relatively small (RyDg < 0.2) in the mild wear region. On the other hand, the relatively rough worn surface (RyDg > 0.5) in the severe wear region gives a wear rate larger than 10−6 mm3 (Nm)−1. The mild wear region is believed to be necessary for the application of ceramics as wear-resistant tribo-materials. The critical condition for mild and severe wear is analyzed with an intergranular fracture model from the view points of both mechanical and thermal aspects. A wear map of ceramics, which can define the regimes of mild and severe wear, is introduced using two dimensionless parameters, namely the mechanical severity of contact (Sc,m) and the thermal severity of contact (Sç,γ), which are used as vertical and horizontal axes, respectively. The availability of the wear map constructed by this method is proven by experimental results observed over a wide range of test materials and operating conditions.

Wear behaviors of ceramics TIN, TIC and TICN with Arc ion plating

In order to determine the wear properties of AIP (Arc Ion Plating) deposition, wear process was evaluated by using a Falex test machine. Also, in order to determine the effects of coating material on the wear process, TiC, TiN, and TiCN coatings of thickness about 5 ㎛-6 ㎛ coated by Arc ion plating deposition method were tested. The wear property was determined under a dry sliding condition as a function of the applied load, sliding distance, sliding velocity and temperature. The results show that when wear of the coating-layer occurred, specific wear amount increased with the wear rate. At initial state, the wear rate rapidly increased, but it gradually reduced as the velocity increased. Also, when raising the temperature, the wear rate increased in the order of TiCN, TiN and TiC due to the frictional heat.

Nano-Scale Fatigue Wear of Carbon Nitride Coatings: Part I—Wear Properties

This paper, the first of two companion papers, reports empirical data on wear properties in carbon nitride coatings by a spherical diamond counter-face in repeated sliding contacts through in situ examination and post-sliding observation, with an emphasis on the effects of friction cycles and normal load. In the repeated sliding, a specific wear amount of about 10−9mm3/Nm was observed on the wear track of the carbon nitride coating when no wear particles were detected. On the other hand, a specific wear amount of about 10−6mm3/Nm was observed on the wear track of the carbon nitride coating, where wear particles were generated after a certain number of friction cycles. Wear rate change corresponds to a wear mode change. From in situ examination, the critical number of friction cycles, Nc, for wear particle generation is proven to be related to a wear mode change.

Micro-wear properties of carbon nitride coatings

Micro-wear tests of amorphous carbon nitride (CNx) coating against a diamond pin were carried out by using a atomic force microscopy. Micro-wear properties of CNx were shown as functions of coating condition, contact load, pin radius and contact pressure. The coating condition provides about 10 times difference of specific wear amount of CNx coating. The depth of wear of CNx coating increased drastically by increasing the contact load to above a critical value. CNx was influenced pin radius. The depth of wear scar of CNx coating changed depending on the pin radius under the same contact load. Combined with the effects of contact load and pin radius, the effect of contact pressure on specific wear amount was made clear. The specific wear amount of CNx coating increased with maximum contact pressure. On the other hand, specific wear amount of DLC was shown to be independent of maximum contact pressure. At the maximum contact pressure lower than about 10 GPa, the specific wear amount of CNx coating was smaller than that of DLC. Contact pressure dependence of wear of CNx coating was introduced by nano-scale delamination of the coating.

Friction and wear properties of graphite/glassy carbon composites

This paper describes the results of an experimental study of the friction and wear properties of graphite/glassy carbon (G/GC) composites. The frictional tests were performed in ambient air with a pin-on-disk friction apparatus. When the composition of graphite and glassy carbon was changed, the G/GC composite with 34 vol.% graphite content showed the lowest friction coefficient ( μ≒0.13) and that with 24 vol.% graphite content showed the lowest specific wear amount ( W s≒2×10 −7 mm 3/Nm) at this test conditions. Compared with graphite and glassy carbon, G/GC composites showed lower friction coefficients and lower specific wear amounts. Consequently, G/GC composites are expected to be useful as self-lubricating materials.

Effect of surface topography on transferred film formation in plastic and metal sliding system

Wear tests were performed with a pad-on-disk type apparatus using aramid fiber reinforced phenolic composite pads and gray cast iron and Ni–Cr–Mo steel disks. The effect of surface topography of metal disk on the film formation by transfer from plastic pads was investigated. The following results were obtained: (1) The roughness valleys across the sliding direction and the small pits on the disk surface accelerate the film formation of pad material on the disk. The transfer film reduces friction and wear of the pad. (2) The amount of Fe on the pads transferred from the cast iron disks is smaller than that from the Ni–Cr–Mo steel disks. (3) Under a low contact pressure (0.03 MPa) condition, the specific wear amount of pads sliding on the Ni–Cr–Mo steel disk is much smaller than that sliding on the cast iron disk. Surface roughness of pads sliding on Ni–Cr–Mo steel disk is smaller than that sliding on the cast iron disk.

黒鉛‐Ｎｉ系複合材の摩擦摩耗特性

Graphite-Ni composites were fabricated by hot pressing from graphite powder electrolessplated with Ni and chopped carbon fiber as the raw materials. The relationship of chopped carbon fiber volume fraction (Vf) and Ni matrix volume fraction (VNi) on mechanical characteristics, friction and wear were reviewed. The results were as followed:(1) Bending strength and Young's modulus increase with Vf at constant porosity. In case that porosity increases, these decrease with porosity.(2) Friction coefficients of these composites increase with an increase of Vf with VNi more than 40 percents.(3) Specific wear amount of these composites decrease by a chopped carbon fiber addition, and the decrease quantity is influenced by Vf, VNi.

Wear map of ceramics

The overall objective of this study is to introduce a wear map of ceramics which shows the regions of dominant wear modes observed in a wide range of materials and operating conditions. Furthermore, from the wear map, common necessary conditions for the application of various ceramics as wear-resistant tribo-materials in a wide range of operating conditions are discussed. For this purpose, friction and wear tests are carried out using three kinds of ceramics sliding against themselves under various contact pressures, sliding velocities and temperatures. Sliding wear phenomena of ceramics observed in all tests can be classified into two types: “mild wear” and “severe wear”, based on the ration of worn surface roughness R x to the mean grain size D g . The specific wear amount is always less than 10 −16 mm 3 (Nm) −1 when the worn surface roughness becomes relatively small ( R y D g < 0.2 ) in the mild wear region. On the other hand, the relatively rough worn surface ( R y D g > 0.5 ) in the severe wear region gives a wear rate larger than 10 −6 mm 3 (Nm) −1. The mild wear region is believed to be necessary for the application of ceramics as wear-resistant tribo-materials. The critical condition for mild and severe wear is analyzed with an intergranular fracture model from the view points of both mechanical and thermal aspects. A wear map of ceramics, which can define the regimes of mild and severe wear, is introduced using two dimensionless parameters, namely the mechanical severity of contact ( S c, m ) and the thermal severity of contact ( S c ̧ ,γ ), which are used as vertical and horizontal axes, respectively. The availability of the wear map constructed by this method is proven by experimental results observed over a wide range of test materials and operating conditions.

Sliding Velocity Dependence of Friction and Wear Properties of Oil-Retaining Porous Silicon Carbide

The friction and wear properties of oil-retaining porous silicon carbide for sliding contact in air were investigated by using a pin-on-disk friction machine. The friction tests were carried out under the conditions of various sliding velocities (0.13 to 0.57m/s) and various combinations of oil-retaining porous silicon carbide and dense silicon carbide (pin/disk). In the dense SiC/oil-retaining porous SiC system, the lowest and most stable friction coefficient and the least wear were obtained independent of sliding velocity. This is due to the lubrication effect of the oil supplied from the oil-retaining porous SiC disk at the friction interface. The friction and wear mechanisms of these ceramics were classified into four modes depending on the relation between friction coefficient and specific wear amount and SEM observation of frictional surfaces.

Wear Map of Ceramics. 2nd Report. Construction of Mild-Severe Wear Mode Map.

The overall objective of this study is to introduce a wear map of ceramics which shows the regions of dominant wear modes obtained in a wide range of materials and operating conditions. In the 1st report, it was clarified that the sliding wear mode of ceramics observed under various contact pressures, sliding velocities and temperatures can be classified into two types called "mild wear" and "severe wear" based on the ratio of worn surface roughness, Ry, to mean grain size, Dg, and specific wear amount, Ws. In this paper, the critical condition of the mild and severe wear is analyzed using an intergranular fracture model from both the view points of mechanical and thermal aspects, and a wear map of ceramics, which can define the regimes of mild and severe wear, is introduced; it uses two dimensionless parameters named as the mechanical severity of contact Sc, m and the thermal severity of contact Sc, t, as the vertical and horizontal axes, respectively. The availability of the wear map constructed in this way can be proved by the experimental results observed over a wide range of materials and operating conditions.

Wear Mechanisms and Wear Map of Alumina Sliding against Bearing Steel.

Dry sliding wear mechanisms of alumina sliding against bearing steel were studied using a ball-on-disk wear apparatus. The tribology characteristics of the sliding pairs could be divided into four regimes and consolidated in a simple wear transition diagram with normal load and sliding velocity as the two axies. The controlling mechanism and specific wear amount in each regime are unique and related to the value of μWν (frictional work). As μWν increases above a critical value, a transition in wear and wear mechanism occurs.

The Effect of Temperature on Tribological Properties of Alumina Ceramics in Unlubricated Sliding Contact. Relationship between Wear Properties and Tribo-Film Formation.

The tribological properties of alumina ceramics in unlubricated sliding contact were investigated using a pin on disk test machine under controlled temperature and normal load. The tribological behaviour can be classifled into two groups as follows : (1) At low and high temperature, T<300°C and 800°C<T, wear surface becomes smooth by formation of tribo-film. Friction coefficient or specific wear amounts is less than 0.7 or 10-6mm3/Nm, respectively. (2) At middle temperatures, 300°C<T<800°C, wear surface becomes relatively rough due to brittle fracture. Friction coefficient and specific wear amount show high values. These behaviours are summarized as wear diagram with temperature and normal loadaxes. Furthermore, it is analysed experimentally that formation and preservation of smooth tribo-film on wear surface reduce the wear volume.