• 한국분말재료학회지
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• 제13권6호
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• pp.450-454
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• 2006

Wear of steel plate was measured during unlubricated sliding against TiC composites. These composites consist of round TiC grains and steel matrix. TiC grain itself exhibits low surface roughness and round shape, which does not bring its counterpart into severe damage from friction. In our work a classical experimental design was applied to find out a dominant factor in counterpart wear. The analysis of the data showed that only the applied load has a significant effect on the counterpart wear. Wear rate of counterpart increased non-linearly with applied load. Amount of wear was discrepant from expectation of being in proportion to the load by analogy with friction force. Our experimental result from treating matrix variously revealed bimodal wear behavior between the composites and counterpart where a mode seems to result from the special lubricant characteristic of TiC grains, and the other is caused by metal-to-metal contact. The two wear mechanisms were discussed.

• Tribology and Lubricants
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• 제21권1호
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• pp.16-20
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• 2005

Friction and wear characteristics between two steel surfaces under fretting condition are investigated experimentally. The fretting damage caused by low-amplitude oscillatory sliding can be classified into three regimes of gross-slip, mixed-slip and partial-slip due to stick-slip phenomenon. One of the most important characteristics of fretting wear is the transition from gross-slip to mixed-slip. This study was focused on getting the degree of stick-slip out of the friction transition under fretting condition. Fretting wear is divided into three conditions of gross-slip/mixed-slip/partial-slip. The criteria for the division are friction and displacement amplitude, wear scar morphology and dissipated energy. In this test, friction force and displacement were measured for detecting the transition from mixed-slip to gross-slip and qualitatively predicting the degree of the wear.

• 소성∙가공
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• 제33권2호
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• pp.112-117
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• 2024

In this study, the friction and wear characteristics of Inconel 600 in the superplastic forming process of Ti6Al4V were evaluated through pin-on-disc tests. To achieve an efficient and systematic experimental design, the Taguchi method was employed. The wear track of the Inconel 600 pin showed scratches in the sliding contact direction, confirming that the wear mechanism is abrasive wear. Through sensitivity analysis such as ANOVA and Main effects, it was confirmed that both normal force and sliding distance have a significant impact on the wear. Changes in sliding velocity and distance did not affect the friction coefficient, which remained relatively constant at approximately 0.380. The wear prediction model for Inconel 600 in the superplastic forming of Ti6Al4V was constructed, which can be utilized as a guideline for the prediction and management of tool wear.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.25-29
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• 1998

Sliding wear test and surface characterization techniques such as micro-Raman spectroscopy were employed to determine the effect of whisker content and orientation on the friction and wear behavior of SiC whisker reinforced alumina. Composites containing unidirectionally oriented whiskers were fabricated by novel technique Addition of SiC whiskers up to 20 vol.% lowered the friction and improved wear resistance. The results of this study indicated that highly disordered graphite and size of the layer behind the whiskers were responsible for variation of wear rate and friction coefficient.

• Tribology and Lubricants
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• 제31권4호
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• pp.183-188
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• 2015

This paper presents the experimental effects of lubricant with nanodiamond particles in sliding friction. In order to improve the performance of lubricants many additives are used, such as MoS₂, cadmium chloride, indium, sulfides, and phosphides. These additives are harmful to human health and to the environment, so alternatives are necessary. One such alternative is nanodiamond powder, which has a large surface area. In order to investigate the effect of nanodiamonds in lubricants under sliding friction, they are dispersed in the lubricant at a variety of concentrations (0 wt%, 0.1 wt%, 0.3 wt%, 0.5 wt%, and 1 wt%) using the matrix synthesis method. Friction and wear tests are performed according to the ASTM G99 method using a pin-on-disc tester at room temperature. The specimens used in this experiment are AISI 52100 ball bearings and AISI 1020 steel discs. During the test, lubricant mixed with nanodiamond is supplied constantly to keep the two bodies separated by a lubricant film. To maintain boundary lubrication, the speed is set to 0.18 m/s and a load of 294 N is applied to the disc through the pin. Results are recorded by using workbench software over the test duration of 10 minutes. Experimental results show that when the concentration of nanodiamond increases, the coefficient of friction decreases. However, above a nanodiamond concentration of 0.5 wt%, both the coefficient of friction and wear volume increase. From this experiment, the optimum concentration of nanodiamond showing a minimum coefficient of friction of 0.09 and minimum wear volume of 0.82 nm² was 0.5 wt%.

• 한국공작기계학회논문집
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• 제15권6호
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• pp.32-37
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• 2006

Micron size Co-alloy(T800) powder was coated on Inconel 718 by HVOF thermal spraying for the studies of the improvement of durability of high speed spindle by using Taguchi program for the parameters of spray distance, flow rates of hydrogen and oxygen and powder feed rate. The optimal coating process was determined by the studies of coating properties such as micro-structure, porosity, surface roughness and micro hardness. Friction and wear behaviors of coatings were investigated by sliding wear test at room temperature and $1000^{\circ}F(538^{\circ}C)$. At both room temperature and $538^{\circ}C$ the sliding wear debris and friction coefficients of the coating were drastically reduced compared with the surface of non-coated parent material. This shows that Co-alloy powder coating is highly recommendable for the durability improvement surface coating of high speed air-bearing spindle. At high temperature wear traces and friction coefficients of both coating and non-coating were drastically reduced compared with those of room temperature since the brittle oxides were formed easily on the surface, and the brittle oxide phases were attrited by the reciprocating sliding wear according to the complicated mixed wear mechanisms These oxide particles, partially melts and the melts play role as lubricant and reduce the wear and friction coefficient. This also shows that Co-alloy powder coating is highly recommendable far the durability improvement surface coating on the surface vulnerable to frictional heat such as high speed spindles.

• The Korean Journal of Ceramics
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• 제3권3호
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• pp.169-172
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• 1997

Sintered diamond/(WC-Co) composites were prepared by spark plasma sintering technique. Tribological properties were measured at temperatures from RT to $500^{\circ}C$ in sliding tests with alumina ball. They show coefficient of friction of 0.1 and below at RT and wear of the diamond composites is hardly detected. Effects of diamond grit size, diamond content and test temperature on the coefficient of friction and the wear are discussed. The wear scars were analyzed.

• Tribology and Lubricants
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• 제34권6호
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• pp.318-324
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• 2018

This study aims to visualize the friction and wear behaviors of metal coatings in real time. The main mechanism of wear is identified by observing all the processes in which wear occurs. The friction coefficients of the moments are monitored to confirm the relationship between the friction and wear characteristics of the coating. Thin Ag coatings, which are several hundred nanometers in thickness, are prepared by depositing Ag atoms on silicon substrates through a sputtering method. A pin-on-disk-type tribo-tester is installed inside a scanning electron microscope (SEM) to evaluate the friction and wear characteristics of the Ag coating. A fine diamond pin is brought into contact with the Ag coating surface, and a load of 20 mN is applied. The contact pressure is calculated to be approximately 15 GPa. The moments of wear caused by the sliding motion are visualized, and the changes in the friction characteristics according to each step of wear generation are monitored. The Ag coating can be confirmed to exhibit a wear phenomenon by gradually peeling off the surface of the coating on observing the friction and wear characteristics of the coating in real time inside the SEM. This can be explained by a typical plowing-type wear mechanism.

• International Journal of Ocean System Engineering
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• 제3권3호
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• pp.147-151
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• 2013

This study was to correctly estimate the friction and wear behavior of carbon fiber and PEEK sheet composites, and the validity of using them as alternatives to the metal-based materials used for artificial hip joints. Moreover, this work evaluated the friction coefficient according to the fiber ply orientation, along with the fractured surfaces of the carbon/PEEK composites. The unidirectional composites had higher friction coefficients than those multidirectional composites. This was caused by the debonding between the carbon fiber and the PEEK sheet, which was proportional to the contact area between the sliding surface and the carbon fiber. The friction test results showed that there was no significant differences in relation to the fiber ply orientation. However, in a case where the speed was 2.5 m/s, the friction coefficient was relatively large for configuration I. The friction surface of the specimen was analyzed using an electron microscope. In all cases, the debonding of the fiber and PEEK could be confirmed.

• Tribology and Lubricants
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• 제36권3호
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• pp.133-138
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• 2020

In this paper, we present an experimental investigation of the friction coefficient and wear area change of carbon/epoxy and E-glass/epoxy composites depending on the fiber direction (0°/90°). We compared the results of the case where the sliding direction is parallel to the fiber direction (0°) with that of the case where it is perpendicular to the fiber direction (90°). The ball-on-plate wear test equipment was used to cause wear in both directions. Two types of specimens were prepared with thicknesses of 3 mm-one made of carbon fiber reinforced plastic composite (CFRP) and the other of glass fiber reinforced plastic composite (GFRP). A normal force of 20 N was applied to the specimen and the sliding speed was 10 mm/s and the sliding distance was set to 20 m to perform the wear test. The CFRP demonstrates superior tribological characteristics compared to the GFRP. This outcome is attributed to graphitization of carbon, which serves as solid lubricating particles. In addition, both CFRP and GFRP are worn more in the 90° direction than in the 0° direction. This is due to the greater occurrence of fiber breakage and separation in the 90° direction than in the 0° direction. This study is expected to be utilized as basic data for understanding the friction and wear characteristics of CFRP and GFRP composites along the fiber direction and to apply the appropriate material.